The aim of this study was to determine the values of different perfusion parameters- such as oxygen saturation, the relative amount of hemoglobin, and blood flow- in healthy subjects compared to patients with gingivitis as a non-invasive measurement method.A total of 114 subjects were enrolled in this study and separated into subjects with gingivitis (50) and without gingivitis (64) based on clinical examination. Gingival perfusion was measured at 22 points in the maxilla and mandible using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS) with the “oxygen to see” device. All patients underwent measurement of gingival perfusion, followed by the clinical evaluation . Perfusion parameters were compared between the groups, associations between the non-invasive and clinical measurements were analyzed, and theoretical optimal cut-off values for predicting gingivitis were calculated with receiver operating characteristics.The mean oxygen saturation, mean relative amount of hemoglobin, and mean blood flow all significantly differed between the groups with and without gingivitis . The cut-off value for predicting gingivitis was > 40 AU .As a non-invasive method, LDF-TS can help determine gingival hyperemia. Flow values above 40 AU indicate a higher risk of hyperemia, which can be associated with inflammation. The LDF-TS method can be used for the objective evaluation of perfusion parameters during routine examinations and can signal the progression of hyperperfusion before any change in clinical parameters is observed.All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the institutional Clinical Research Ethics Committee  and retrospectively registered by the German Clinical Trials Register .The online version contains supplementary material available at 10.1186/s12903-023-03507-9. Gingivitis, a reversible inflammation of the gum, but the potential precursor of periodontal disease, is a common diagnosis in dental examination , 2. Diag2 (%) and the relative amount of hemoglobin rHb in arbitrary units (AU). This data can provide useful information regarding local perfusion and metabolism.Aside from these conventional examination methods, some prior studies have used laser Doppler flowmetry (LDF) as a precise method to determine the amount of gingival hyperemia –15. ThisThe combination of LDF-TS, which is used in the “oxygen to see” (O2C) device , is a common tool in maxillofacial and plastic surgery to monitor microvascular transplants –19. AlthThe present study was the first to use a manufactured gingival probe head connected to the O2C device. This clinical trial aimed to compare various perfusion parameters– such as gingival hemoglobin saturation and blood flow– between healthy subjects and patients with gingivitis using a new, non-invasive measurement method in addition to the conventional clinical examination to improve the diagnosis of gingival inflammation and to use it as a diagnostic tool to detect perfusion alterations before clinical parameters change.This study was approved by the local clinical research ethics committee (Decision Number 286 − 20) and registered at the German Clinical Trials Register (File Number DRKS00024048).All procedures performed in this study were in accordance with the ethical standards of the 1964 Helsinki Declaration. Informed consent was obtained from all individual participants included in the study.All participants were recruited in our clinic between December 2020 and February 2022. To be included in this study, patients had to be at least 18 years of age and in good general health (ASA I–II). All patients were Caucasian to ensure that the pigmentation of the gingiva would be comparable, although it was shown in prior LDF studies that skin pigmentation does not affect perfusion measurements significantly , 22.Based on previous studies –25, gingThe existing literature on clinical trials of gingival perfusion methods was reviewed to calculate a sensible sample size range.In particular, the required sample size was derived based on a study by Rodriguez-Martinez , which iFurthermore, a study by Barry et al. , who useSince LDF-TS is a relatively new method to evaluate gingival perfusion, the basal flow differences were defined as the primary outcome to calculate the sample size.The statistical program G* Power Version 3.1.9.6  was used with an alpha value of 0.05, an effect size of 0.6, and a statistical power of 80%. Based on these parameters, a sample size of 20 patients was determined to reject the null hypothesis concerning primary basal flow differences with 80% power and a 95% confidence interval. Based on the studies mentioned above and other benchmark studies , 28, a sAll the measurements started with the use of the LDF-TS, and all patients were measured and examined by the same physician.2 (%), the relative amount of hemoglobin rHb (AU), and blood flow , which is used in the “oxygen to see” (O2C) device , is a common method in maxillo-facial and plastic surgery.In this study, each patient was lying in a comfortable position, and the light above the dental chair was switched off to ensure an optimal setting for the O2C device measurement without any interference. All measurements used the LSX-41 gingival probe  with a 5 × 2 mm dimension and a predefined measurement depth of 1 mm. The probe head in our study is specifically manufactured for gingival measurements, with two small batches that can be placed on adjacent teeth for constant stability, with the sensor and laser between them , bleeding records (PBI by Saxer and Mühlemann), plaque index, and gingival biotype.The plaque index based on the classification system developed by Löe and Silness  was deteGeneralized gingivitis was defined by a mean PBI higher than 2 based on the findings of Norderyd et al.  and TromPatients with mean PBI values of 0–2  were included in the healthy group. Patients with mean PBI values higher than 2  were assigned to the gingivitis group.Probing depths were measured at the same 22 papillae which were previously examined by LDF-TS. Each patient´s gingival biotype was identified based on the transparency of the periodontal probe through the gingival margin in the buccal sulcus. If the probe shined through the gingiva, the biotype was considered thin; if the probe was not visible, the biotype was registered as thick , 31.After the perfusion and clinical measurements, the resulting datasets were combined, and correlations between the perfusion parameters and clinical findings were evaluated.Our primary aim was to analyze if significant differences in perfusion parameters between patients with and without gingivitis were observable, if there was a significant difference between points with and without BOP, and between patients who smoked compared to non-smokers. Beyond this, we checked for a difference between perfusion parameters between the sexes and the maxilla and mandible.For categorical data , differences between groups were analyzed using chi-square tests. Metric data  were evaluated using Mann–Whitney tests, as they lacked a Gaussian distribution according to the Shapiro- Wilk test.Testing for differences in mean blood flow between groups, we controlled for sex, age, biotype, and smoking habits using multivariate regression analysis. Receiver operating characteristics (ROCs) were calculated, and the Youden Index was used to determine the theoretically optimal cut-off value of mean blood flow for predicting gingivitis . P-valueOur study contains a total of 114 patients , including 64 without gingivitis  and 50 with gingivitis . The mean age of the patients without gingivitis was 31.61 years (SD ± 13.31), while the mean age of those with gingivitis was 33.82 years (SD ± 15.35). There were no statistical differences in the sex (p = 0.155) or age distributions (p = 0.839) between groups.The study sample included 33 patients with regular smoking habits, of whom 12 were assigned to the non-gingivitis group, and 21 were assigned to the gingivitis group. However, all patients confirmed that they had not smoked for at least two hours before the examination. Smoking was observed significantly more often in the gingivitis group (P = 0.007) but had no significant impact on the perfusion parameters measured  and there was also no significant difference in the plaque indices of smokers and non-smokers in our study (p = 0.111).Of all the patients, 74 had a thick gingival biotype (38 without and 36 with gingivitis), and 40 exhibited a thin biotype (26 without and 14 with gingivitis). The gingiva-type distributions did not differ between groups (p = 0.161) (Table ≥ 2 mm (p < 0.001).Patients who were assigned to the gingivitis group exhibited significantly higher values in plaque index values than patients in the non-gingivitis group (p < 0.001) and also showed significantly more often mean probing depths The mean oxygen saturation SO2 (%), the mean relative amount of hemoglobin rHb (AU), and mean blood flow (AU) all differed significantly between the groups with and without gingivitis  Fig. .When controlling for sex (p = 0.114), age (p = 0.939), gingival biotype (p = 0.876), and smoking habits (p = 0.119) through regression analysis, the difference in mean blood flow values between the gingivitis and non-gingivitis patients remained significant (p < 0.001) Table .The optimal cut-off value of mean blood flow for predicting gingivitis was determined to be at > 40 AU .When comparing the single points measured concerning BOP, all three parameters are significantly higher at the points featuring BOP  but no significant differences in mean oxygen saturation SO2 (p = 0.058) or the mean relative amount of hemoglobin rHb (p = 0.125) Fig. .When comparing the perfusion values between smokers and non-smokers, mean oxygen saturation p = 0.207), mean relative amount of hemoglobin (p = 0.724), and mean blood flow (p = 0.171) did not differ significantly  and mean blood flow (AU) were not significantly different between men and women in either group . However, the mean relative amount of hemoglobin rHb (AU) was significantly different between the sexes in favor of men , the mean relative amount of hemoglobin rHb (p > 0.001), and mean blood flow (p < 0.001), with the mandible featuring higher values than the maxilla  and took place at the interdental papilla, they were primarily able to detect marginal gingival hyperemia, rather than underlying periodontitis which takes place at the lower periodontium. Still, higher mean flow values for mean probing depths ≥ 2 mm were found. Since there is a smooth transition between chronic gingivitis and a beginning attachment loss in periodontitis, this underlines the importance of early detection of perfusion changes at the papilla.Smoking can also decrease gum perfusion and mask underlying inflammation , 55. In 2, mean rHb-, nor mean blood flow values or plaque index differed significantly when comparing smokers to non-smokers.Although there were significantly more smokers in the gingivitis group, neither mean SOFurthermore, a regression analysis was performed to control for smoking habits, and the mean blood flow values remained significantly different between the non-gingivitis and gingivitis groups. This finding indicates that LDF-TS seems to be a diagnostic tool suitable for detecting gingival inflammation independent of smoking habits.Gingivitis is common in patients of all ages and sexes . The detIn summary, microvascular processes– such as hypoxia, early vessel degeneration, and inflammatorily increased blood flow– can be detected reliably with the gingival probe of the O2C device and differ significantly between patients with clinically manifest gingivitis and healthy patients.As this study was the first to use a specialized gingival probe with a small head and low measuring depth, future studies with this probe could be conducted to evaluate changes in papillary blood flow between different periodontal and peri-implant conditions, as well as how these conditions change and progress over time.As a non-invasive method, LDF-TS can help detect gingival hyperemia and enrich the clinical examination of the gum and its appearance. Furthermore, this diagnostic tool can be used to quantify the amount of perfusion, as it is one of the main characteristics of interdental inflammation. In particular, flow values above 40 AU are predictive of hyperemic processes in the papillae. The O2C device can be used to objectively evaluate perfusion parameters during routine examinations, after periodontal treatments, or to show the progression of hyperperfusion before any apparent changes in clinical parameters are observed. It can be useful to detect the early diagnosis of gingivitis, however this finding should be validated in future studies.Below is the link to the electronic supplementary material.Supplementary Material 1


Lung protective ventilation (LPV) comprising low tidal volume (VT) and high positive end-expiratory pressure (PEEP) may compromise cerebral perfusion in acute brain injury (ABI). In patients with ABI, we investigated whether LPV is associated with increased intracranial pressure (ICP) and/or deranged cerebral autoregulation (CA), brain compensatory reserve and oxygenation.2O) or high PEEP (12 cmH2O). Between each intervention, baseline ventilation (VT 9 ml/kg/pbw and PEEP 5 cmH2O) were resumed. The safety limit for interruption of the intervention was ICP above 22 mmHg for more than 5 min. Airway and transpulmonary pressures were continuously monitored to assess respiratory mechanics. We recorded ICP by using external ventricular drainage or a parenchymal probe. CA and brain compensatory reserve were derived from ICP waveform analysis.In a prospective, crossover study, 30 intubated ABI patients with normal ICP and no lung injury were randomly assigned to receive low VT [6 ml/kg/predicted (pbw)]/at either low (5 cmHp < 0.001), low brain compensatory reserve (p < 0.01) and mechanical power (p < 0.05).We included 27 patients , of whom 6 reached the safety limit, which required interruption of at least one intervention. For those without intervention interruption, the ICP change from baseline to “low VT/low PEEP” and “low VT/high PEEP” were 2.2 mmHg and 2.3 mmHg, respectively, and considered clinically non-relevant. None of the interventions affected CA or oxygenation significantly. Interrupted events were associated with high baseline ICP (2O in both interventions. Partial arterial pressure of carbon dioxide was kept in the range 34–36 mmHg by adjusting the respiratory rate, hence, changes in carbon dioxide were not associated with the increase in ICP.The transpulmonary driving pressure was 5 ± 2 cmHThe present study found that most patients did not experience any adverse effects of LPV, neither on ICP nor CA. However, in almost a quarter of patients, the ICP rose above the safety limit for interrupting the interventions. Baseline ICP, brain compensatory reserve, and mechanical power can predict a potentially deleterious effect of LPV and can be used to personalize ventilator settings.Trial registrationNCT03278769. Registered September 12, 2017.The online version contains supplementary material available at 10.1186/s13054-023-04383-z. The optimal ventilator settings are still debated in patients with severe acute brain injury (ABI) admitted to the intensive care unit (ICU) –4. Lung In patients with ABI, lower tidal volumes may improve outcomes –12. A re2) [It is generally accepted that in patients with ABI, monitoring and treatment of the ICP as the only single cerebral parameter is of limited value . By comb2) .As a first step, recognizing the need to enrich the evidence behind the recommendations for ventilator management in ABI patients without lung injury, we hypothesized that LPV would not induce significant changes in neuromonitoring-derived variables in this setting, provided that the baseline ICP was less than 22 mmHg. Therefore, the aim was to conduct the brain vent study to investigate the effects of LPV on brain pathophysiology, determined by simultaneous monitoring of TPP, brain oxygenation and indices derived from ICP waveform analysis.Brain vent is as a single centre, randomised, crossover interventional clinical trial, which was approved by the Regional Committee for Medical Research Ethics Northern Norway (2017/1941/REK North). The study was conducted between May 2019 and August 2021 in the ICU of a tertiary trauma and neurosurgery centre, affiliated with the University Hospital of North Norway, Tromsø, Norway. The trial is reported according to the Consort guidelines [2), minute ventilation was kept as close to the baseline as possible by adjusting the respiratory rate (RR) when VT was changed. Blood gases were sampled after a stabilization period of approximately 30 min after each change in ventilator settings. For safety reasons, the interventions were interrupted if ICP increased above the predefined limit of 22 mmHg for more than 5 min. A healthcare worker blinded to the intervention arm monitored the safety endpoint for the interruption.An overview of the study procedures and interventions is presented in Fig. 2/FiO2 < 300 mmHg and presence of infiltrates on the chest X-ray), a history of severe lung disease, body mass index (BMI) > 35 kg/m2, or known cardiac failure. We treated hypovolemia with fluid resuscitation prior to inclusion. All patients were managed according to the local protocols  were screened for inclusion at the ICU admission. Exclusion criteria were ICP > 22 mmHg, preceding decompressive craniectomy, presence of open external ventricular drainage (EVD), acute hypoxaemic respiratory failure (defined as PaOAirway pressure and flow (pneumotachograph) were measured proximal to the endotracheal tube. Oesophageal pressure was measured by using an oesophageal balloon catheter . Airway and oesophageal pressures and airflow signals were recorded with FluxView software on a computer connected to a respiratory monitor . TPP was calculated as the difference between airway and oesophageal pressures, as described by others , 23. Res2), RR, PEEP, minute ventilation and near-infrared spectroscopy (NIRS)-derived percentage of regional cerebral oxygen saturation (rSO2) from both hemispheres  [Intensive care monitoring software   was usedic, USA) . A scree2, pH, arterial partial pressure of oxygen (PaO2). The data were collected and managed using RedCap electronic data capture tools [Additionally, the following demographic and clinical data were retrieved from the medical records of the patients: age, sex, BMI, predicted body weight (PBW), Glasgow Coma Scale (GCS), type of brain injury, severity of traumatic brain injury (TBI) by Marshall classification , severitre tools .Number and percentage (%) of patients in whom the ICP response to interventions was below the safety limit of 22 mmHg and therefore could complete the whole protocol.‘Noninferiority’ of mean ICP, to be understood as an intervention ICP mean value not exceeding the preceding baseline values by more than 3 mmHg. Hence, an increase in ICP ≥ 3 mmHg was considered clinically significant.No worsening in PRx between the intervention value and the preceding baseline value.The primary outcome was the effect of LPV on ICP and PRx. We identified three endpoints:2.The secondary outcome was the effect of LPV on RAP and brain oxygenation, rSOThe full set of variables considered in the analysis in addition to outcome variables are presented in the Additional file ICM + software was used for data preprocessing of the high-resolution recordings prior to statistical analysis. The secondary indices, PRx and RAP were calculated as 5 min window moving Pearson correlation coefficients between 30 consecutive 10-s averages between ABP and ICP, and between intracranial pulse pressure amplitude and ICP, respectively, and updated every minute . Fisher Each variable was considered as one average value (for data collected with ICM +) or one single value (for data collected with FluxMed) per each study period and patient.The sample size calculation was based on the primary outcome and the crossover study design. Assuming a difference of zero, a standard deviation of 4 mmHg  and a not-test (two-tailed) or Wilcoxon signed-rank test). We assessed the effect of the increase in PEEP by comparing mean values between the two interventions. Noninferiority of mean ICP was tested with paired t-test (one-tailed) on mean values (baseline vs intervention).Continuous variables were tested for normality and are presented as the mean and standard deviation or median and interquartile range, and categorical variables are presented as counts and percentage. Carry-over and group effects were ruled out. The analysis was performed to investigate the treatment effect, assessed as a comparison between the intervention and preceding baseline  were interrupted, we set out to explore reasons for such outcomes with between-group comparisons. The groups were defined as follows: in the “interrupted group”, the patients had at least one interrupted intervention due to safety reasons; the “completed group” completed the interventions successfully. For between-group comparisons, we used the Mann–Whitney U test and presented the results as boxplots or violin plots. Lastly, we investigated the relationships between the changes induced by the interventions and neurological, haemodynamic, and respiratory variables, using scatterplots and Pearson correlations.p value < 0.05 was considered statistically significant. Bonferroni corrections for multiple comparisons were performed for the exploratory analysis (between-group comparisons and relationships with changes in ICP). The statistical analysis was performed with R software version 4.0 [A sion 4.0 .Fifty-eight patients were assessed for eligibility, of whom 27 were included in the analysis  difference between the two interventions, which was statistically significant, albeit not considered clinically relevant. RAP tended to increase during the interventions as compared with the preceding baselines but was not different between interventions. Only the increase during the intervention “low VT/low PEEP” was statistically significant (p < 0.05).We found no significant differences in the mean rSOne Table . Left-siAdditional file Below we report the most relevant findings. Additional exploratory analyses on variables associated with the increase in ICP are presented in the Additional file Effect of LPV on respiratory mechanics and gas exchange. PaCO2 was 35 ± 3 mmHg at baseline and 36 ± 3 mmHg in both interventions. Although there was a statistically significant increase in PaCO2 between baseline and intervention, the increase was small (< 2 mmHg). TPPee was higher in the “low VT/high PEEP” intervention. Of note, TPPee was negative with PEEP 5 cmH2O. MP was significantly different both between preceding baselines and interventions and between interventions. The highest MP was in the “low VT/high PEEP” intervention, 13 [tion, 13 –14 J/minVariables associated with increased ICP that warranted the interruption. Figure 2 and MP were all significantly different between the completed and the interrupted groups. TPP and compliance of the respiratory system (Crs) or lung were not different between completed and interrupted interventions.2 was determined to 33.6 ± 1.4 mmHg and 34.9 ± 2.7 mmHg in completed and interrupted interventions, respectively (p = 0.81). The alveolar dead space during the intervention was not significantly different between completed (12 ± 8%) and interrupted (18 ± 9%) interventions (p = 0.19).Baseline PaCOee and MP. To our knowledge, this is the first clinical study attempting to elucidate the effects of lung protective ventilation on brain physiology in ABI patients without lung injury, as assessed by simultaneous monitoring of respiratory mechanics and neurophysiological variables.In the present clinical, prospective study, the main finding was that most of the patients with ABI had no adverse effects of LPV, neither on ICP nor on PRx, independent of PEEP levels applied in this study. However, nearly one-quarter of the patients exhibited a transient rise in ICP during the intervention, requiring it to be interrupted. The high PEEP strategy was as expected associated with higher TPP2O rise in PEEP above 5 cmH2O [Studies dealing with the influence on ICP of various types of MV and associated PEEP levels remain inconclusive , 31, 32. 5 cmH2O . This is2 or CPP, then PRx-based CPP targets would be difficult to implement in clinical practice. In our study, LPV did not affect PRx. Consequently, PRx-based CPP management protocols can most likely be applied regardless of the ventilator settings, provided that PaCO2 levels are kept stable.To date, no prospective phase III clinical trials showing a better outcome with multimodal neuromonitoring have been published . Neverth2 can be considered as an indirect, surrogate measure of cerebral blood flow. The fact that rSO2 did not decrease with the application of LPV supports the hypothesis that LPV can be safe in ABI patients. In patients with the combination of ABI and ARDS, Nemer et al. have reported an increase in brain tissue oxygenation during a short trial of high PEEP [The modest increase in RAP observed during the intervention periods, suggesting a slightly decrease in cerebral compliance, was consistent with a small and clinically unimportant increment of ICP. rSOigh PEEP .2 control to minimize the confounding effects of a rise in EtCO2 on ICP and PRx. Patients also had stable haemodynamics and hypovolemia was treated prior to the start of the study. This allowed us to look for other mechanisms of intracranial hypertension that made interruption of interventions necessary. Notably, the latter patients experienced a higher ICP level at baseline, and the subsequent rise in ICP might well have emerged in a state of low brain compliance, as determined with the RAP index at the preceding baseline. Our result is supported by an early report that examined the potential role of brain compliance in the ICP response to PEEP, employing cerebral pressure–volume measurements[In the present study, we specifically targeted tight EtCOsurements. Contrarsurements. However2–EtCO2 gap at the baseline in patients in whom we interrupted the intervention. The present study was not designed to elucidate the interaction between ICP and CO2. Therefore, we cannot draw any conclusions from this observation. Monitoring the PaCO2–EtCO2 gap is easily feasible, and we hope future studies will consider this observation.We observed a tendency towards a wider PaCOMP is described as energy delivered to the respiratory system over time. In neurocritical care patients, increased MP may be related to higher ICU mortality . The preee was negative with PEEP 5 cmH2O. We cannot exclude the possibility that the patients might be at risk of developing atelectasis by applying PEEP of 5 cmH2O or below [In this investigation on non-ARDS patients, we found no relationship between increased TPP and interrupted events. Of note, TPPor below . Conside2O to 15 cmH2O [2O [rs. Notably, PaCO2 was higher than in our study, and the patient´s head level was positioned flat for computer tomography. These variations can partly explain the different results. Moreover, Mascia et al. reported a significant correlation between ICP, PaCO2 and Crs in response to changes in PEEP in patients with moderate to severe lung injury [Our study did not demonstrate significant associations between respiratory compliance and the responses of ICP to LPV. Previous studies of lung compliance and ICP have given contradictory results , 43, 44.mH2O [2O . The autThe present study has some limitations. A major one is that it is a single-centre study with a small sample size. Notably, the interrupted group is too small, to draw any firm conclusions from. The power analysis was based on local retrospective ICP data in parallel with clinical judgement, in combination with a previous observational study . We consIt is possible, albeit not proven, that another study design with slowly increasing PEEP would have given other changes in ICP. We did not test the response to high tidal volume and high PEEP, because of the risk of overdistention. However, the study design allowed us to explore the effect of low tidal volume and high PEEP separately, which had not been done before. A limitation is also the fact that we did neither have recordings of brain tissue oxygen tension, nor cardiac output measurement, since this type of devices are used sparingly in our ICU in this patient group.2 and MP were significant predictors of an ICP increase, suggesting that they can be used to individualize ventilator settings in this context. Our findings provide a basis for further clinical investigations of the interaction between ventilator settings and ABI complicated with ARDS, using TPP and multimodal neuromonitoring tools.LPV seems to be safe and feasible for most but not all patients with ABI. In patients with suspected low brain compliance, LPV should be performed under careful monitoring, with an emphasis on respiratory mechanics and ICP waveform-derived variables when available. Baseline ICP, RAP, etCOAdditional file 1. Detailed methods, supplemental tables and figures.


In patients with ≥10 p/y smoking history, nonobese group had a significantly higher TEC compared to obese group . Within the nonobese group, nonatopic patients had a significantly higher TEC compared to atopic patients . Both biologic agents had similar effects on improving asthma control test and in reducing asthma attacks; however, mepolizumab was more effective in suppressing TEC. The improvement in FEV1 in obese group following biologic 2 agents was very similar but in nonobese group, mepolizumab was found to be superior . In our real-life study, nonobese severe asthmatics with ≥10 p/y smoking history and those that were nonatopic had higher TEC. Compared to omalizumab, mepolizumab was superior at reducing TEC in all asthmatics and in improving FEV1 in nonobese group.In obese severe asthmatics, the degree of type 2 inflammation may vary according to their atopic status and past smoking history. In this study, we aimed to analyze the clinical and physiopathological features of obese and nonobese severe asthmatics treated with omalizumab or mepolizumab treatment. In addition we aimed to compare the clinical, spirometric outcomes and total peripheral eosinophilic count (TEC) changes after treatment with these 2 biologic agents in obese and nonobese groups. In this retrospective, cross sectional study, 121 severe asthmatic treated with biologic agents  for at least 16 weeks were included. Obese (n: 44) and nonobese severe asthmatics (n: 77) were analyzed according to whether they provided a ≥ 10 pack/years (p/y) or <10 p/y smoking history and were found to be atopic. Obese and nonobese groups were compared in terms of the change in the asthma control test, asthma attacks, TEC, and forced expiratory volume in the first second (FEV Obesity is a risk factor for many life-threatening conditions such as atherosclerosis, hypertension and type 2 diabetes mellitus. Obesity has also been proven to be a major risk factor for asthma. Asthma with obese patients is usually severe and difficult to control. Although severe asthma accounts for only 10% of all asthma cases, the severe asthma patient group accounts for 60% of the total medical cost of asthma treatment.,4 Considering that up to 60% of patients with severe asthma are obese, it is obvious that this is a major health problem and socio-economic burden. The obese asthma phenotype varies both clinically and physiologically depending upon whether asthma develops before or after the onset of obesity. Asthma with subsequent obesity is characterized by early-onset disease , elevated markers of allergic inflammation , more severe physiological changes (airway obstruction and hypersensitivity) whereas asthma developing after obesity is characterized by a later onset disease (≥12 years of age), female dominance, less allergic inflammation, less airflow obstruction, and less hypersensitivity.The worldwide prevalence of overweight and obesity has nearly tripled over the past 4 decades, and represents one of the most serious unmet public health challenges of the 21st century.,7,8 Total peripheral eosinophil count (TEC) may vary depending on whether the patients have atopy or ≥10 pack/year (p/y) smoking history (≥10 p/y).Although the underlying pathobiological mechanism of obese asthmatic patients is associated with non-type 2 inflammation and many groups have reported decreased sputum eosinophils with increasing body mass index (BMI), increased eosinophil count was detected in the airway wall.–11 In the Severe Asthma Research Program study 58% of asthmatics included in the late-onset, nonatopic eosinophilic phenotype were obese. However, in the unbiased biomarkers for the prediction of respiratory disease outcomes study, the cluster 2 group, which included ≥10 p/y smoking history 41% of whom were obese, had the highest TEC [301 cells/μL (119–560)]. Cluster 4, a more atopic group, 56% [200 cells/μL (99.7–385)] of whom were obese, had only moderately TEC and frequent exacerbations. Thus, in obese severe asthmatics, the degree of type 2 inflammation may vary according to their atopic status and past smoking history.In fact, in many cluster analysis studies, atopic asthma has been associated with reduced TEC.,13 Published studies suggest that omalizumab gives a less positive response in obese compared to nonobese asthmatics. Data on the responses of obese patients to mepolizumab treatment have not been published yet except post hoc analyzes. In this study, we compared the efficacy of omalizumab and mepolizumab in obese and nonobese asthmatics. All patients received a biological agent for a minimum of 16 weeks. Both between and within the obese and nonobese groups, we looked at the effect of the 2 biological agents regarding the change in clinical improvement, spirometric measurements and TEC.Current biological agents used to treat severe asthma mainly target type 2 inflammation.In this retrospective study we analyzed the response of severe asthmatics to 1 of 2 biological agents, omalizumab or mepolizumab, based upon their clinical and pathophysiological features, including the presence or absence of obesity. Three centers  were included in this study. The study protocol was approved by the local ethics committee of University of Health Sciences, Süreyyapaşa Chest Diseases and Thoracic Surgery Training and Research Hospital . Patients with comorbid diseases such as malignancy, rheumatological disease, bronchiectasis, vasculitis, sarcoidosis, bronchopulmonary aspergillosis or interstitial lung disease, HIV and pregnancy were excluded from the study. The data was collected from electronic or paper hospital medical records and consisted of all medical care received between 2012 and 2021. To be included in the study, patients had to have asthma that could not be controlled on high-dose inhaled corticosteroids therapy and a second asthma control agent; have had 2 or more asthma exacerbations over the previous year requiring systemic steroids for a minimum of 3 days; or have had an asthma exacerbation requiring hospitalization over the previous 1 year. All patients were required to have been compliant with all prescribed inhaler medications, to have demonstrated correct inhaler technique, and to have had optimization of concomitant diseases. If all of these conditions were met, the patient was considered to have severe asthma. All patients diagnosed with severe asthma were required to complete a 3-month trial of montelukast or a long-acting muscarinic antagonist. Those who failed to achieve good asthma control were started on omalizumab or mepolizumab.Patients’ asthma diagnosis was confirmed according to the criteria specified in the global initiative for asthma guidelines.2 are classified as obese, while patients with a BMI < 30 kg/m2 were classified nonobese.Among these patients; patients over 18 years of age with a total immunoglobulin (Ig) E level of 30–1500 IU/mL, who had perennial allergen sensitivity as determined by specific IgE  or by skin prick test, were started on Omalizumab  therapy for at least 16 weeks. Omalizumab treatment dose and dose intervals were determined based on the patient’s weight and baseline total IgE level. Patients with peripheral blood eosinophil level ≥ 150 cells/μL while on systemic steroid therapy or ≥300 cells/μL during the previous year were started on mepolizumab 100 mg  therapy for at least 16 weeks. Mepolizumab was preferred in patients who were candidate for both biologics, with the presence of nasal polyps and peripheral eosinophil predominance. According to the definition of the World Health Organization (WHO), patients with a BMI ≥ 30 kg/m1), forced expiratory flow between 25% and 75% of forced vital capacity (FEF25–75) values (mL) and percentages, TEC, total IgE levels and duration of treatment with biological agents were recorded. Although a total of 180 patients were examined, 121 patients were included in the study because 59 patients were excluded due to missing data. 32 patients with missing spirometrics parameters and 27 patients with missing other parameters  were excluded from the study.Demographic characteristics of patients, age of asthma onset, duration of disease, smoking history, presence of atopy, BMI, asthma control test (ACT) scores, number of asthma attacks, forced expiratory volume in the first second , FEF25/75 (%), and changes in TEC were evaluated after omalizumab and mepolizumab treatments.The efficacy of the biological agents was assessed using the ACT, numbers of asthma attacks, FEV1 after treatment with both biological agents.Obese and nonobese patients were compared in terms of change in ACT, number of asthma attacks, TEC, and FEV1. This constituted 3 responder groups: ACT responders, asthma attack responders, and FEV1 responders. They are defined as follows:The obese and nonobese patient groups were each subdivided into 2 groups based upon their baseline TEC (≥300 cells/μL or <300 cells/μL). The treatment response of these 4 groups to the 2 biologics was determined based upon the change from baseline in ACT, number of asthma attacks and FEVACT responder: A patient with an increase of ≥3 points in ACT or an ACT score of ≥20 points or higher.Asthma attack responder: A patient who had a decrease of more than 50% in the number of attacks.1 responder: A patient who had an increase of more than 100 mL or an increase of 10%.FEVt-test. Mann–Whitney U-test were used to compare numerical variables that did not show normal distribution. The different clinical and biological markers before and after treatment were evaluated by the paired sample t-test if normal distributed, and by the Wilcoxon signed-rank test if not normally distributed. Statistical significance was accepted when the 2-sided P-value was <.05.Statistical analyzes were performed using SPSS software . Parametric variables were presented as means and standard deviations, nonparametric variables as medians and minimum–maximum (min–max). Number of cases and percentages were used for categorical variables. Chi-square test was used in the analysis of categorical variables. Whether the continuous variables were normally distributed or not was determined by Kolmogorov–Smirnov and histogram analysis. Normally distributed numerical variables were analyzed using an independent sample When 121 adult patients with severe asthma from a total of 3 centers, including 55 from Istanbul, 44 from Kocaeli and 22 from Diyarbakir, were evaluated retrospectively, 44 patients (36.4%) were obese. Most of the patients were women (82.6%), and the mean age of all patients was 48.45 ± 12.50 years.1, and FEF25–75 were similar. But atopy rate and TEC tended to be higher in nonobese severe asthmatics. Most of the patients in both groups used omalizumab as a biologic agent , and there was no difference between the groups in terms of treatment duration , other demographic characteristics such as sex, age of onset of asthma, disease duration, smoking history, clinical features such as presence of atopy, asthma control level, and frequency of attacks, as well as biophysiological features such as TEC, FEV1 (mL), FEF25–75 (%) levels and number of attacks were similar according to their smoking history  1200 cells/μL (100–2100) vs 310 cells/μL (0–2730)), p: 0.021] . Regardless of which biologic was taken, there was a significant improvement in ACT, a reduced number of asthma attacks, an improvement in FEV1 but only in the nonobese group , in obese group: 270.00 mL .The improvement in ACT score and reduced number of asthma attacks did not differ regardless of the biological agent taken in either the obese or nonobese severe asthmatics. However, mepolizumab produced a greater reduction in the TEC in both the obese and nonobese groups compared to omalizumab. Mepolizumab also produced a greater increase in FEV1 responders, as defined in the method section, within both the obese and nonobese groups did not differ significantly regardless of whether they had a baseline TEC that was ≥300 cells/μL or < 300 cells/μL  overlap. And so, in obese severe asthmatics atopy status have not effect TEC.The patients were analyzed by considering the presence of atopy and history of heavy smoking, which may contribute to the phenotypic heterogeneity of both obese and nonobese severe asthmatics. In our study, patients with ≥ 10 p/y smoking history had a higher TEC if they were in the nonobese group vs the obese group. Furthermore, only in the nonobese groups the TEC was higher in the nonatopic compared to the atopic asthmatics. While many clustering studies have shown that the presence of atopy and obesity are associated with lower TEC, In this study cluster 2 group, which included ≥10 p/y smoking history, 41% of whom were obese, had the highest TEC. But in our study, we analyzed the patients according to the presence of obesity, which is the confounder factor. We found that in nonobese asthmatics, a history of ≥10 p/y smoking was associated with a higher TEC; but this did not reach statistical significance , in obese group: 270.00 mL . However, when asthmatics were evaluated in regards of biological preference , FEV1 response to omalizumab was similar in both obese and nonobese groups, but the response to mepolizumab was much greater in the nonobese asthmatics , rather than the overlap population that was a candidate for both biological agents. In our study, the efficacy of omalizumab and mepolizumab treatments were compared in obese and nonobese patients for the first time, and the clinical efficacy was found to be similar between the two biological treatments in both groups. However, though not statistically significant, the improvement in ACT was in favor of omalizumab treatment and the decrease in attacks was in favor of mepolizumab in both groups.When comparing omalizumab with mepolizumab in terms of clinic parameters in severe asthmatics not well controlled with high dose inhaled corticosteroids, a 2018 network meta-analysis found them to have similar efficacy in terms of improvement in asthma control while the increase in quality of life was evaluated in favor of omalizumab.–32 In our study, when the patients in the obese and nonobese groups were compared at baseline, asthma control, number of attacks, and FEV1 values were similar at baseline, the percentages of responder patients according to all these parameters, is similar too when the high and low eosinophilic groups are considered separately.TEC is a biomarker used to determine the efficacy of treatment with both biological agents; there are conflicting studies on whether biologic agents are more effective in highly eosinophilic patients (≥300cells/μL). One of the most important reasons for the confusion in these studies is the evaluation of different parameters ranging from the global evaluation of treatment effectiveness scale to the spirometric change in evaluating the efficacy of the treatment, and another issue is the confounders, such as worsening of the parameters  evaluated at baseline in the compared arm.Our study has several limitations. It is retrospective, thus at risk of bias. The mepolizumab group had fewer patients who were treated for a shorter period of time than the omalizumab group. However, our multicenter study drew attention to confounders such as atopy, smoking history, which may affect TEC. According to our current knowledge, this is the first study to indirectly compare the outcomes of omalizumab and mepolizumab treatment in obese and nonobese severe asthmatics.1 only in the nonobese group. Randomized controlled head-to-head comparative studies with larger numbers of patients are needed to provide more precise information.Obese and nonobese asthma phenotypes have heterogeneity within themselves. ≥10 p/y smoking history is associated with higher TEC if they were in nonobese group vs. the obese group. Whereas only in nonobese group the presence of atopy is associated with lower TEC versus absence of atopy. However, atopy and ≥10 p/y smoking history do not significantly affect the TEC in obese severe asthmatics. Omalizumab and mepolizumab produced similar improvement in ACT score and in reducing the number of asthma attacks in both the obese and nonobese groups. However, mepolizumab produced a greater reduction in the TEC in both of these groups compared to omalizumab. Compared to omalizumab, mepolizumab resulted in a greater increase in FEVConceptualization: Şeyma Özden, Cihan Örçen, Tuğçe Yakut.Data curation: Fatma Merve Tepetam, Tuğçe Yakut.Formal analysis: Fatma Merve Tepetam.Methodology: Fatma Merve Tepetam, Cihan Örçen.Project administration: Cihan Örçen, Tuğçe Yakut.Writing – original draft: Şeyma Özden, Fatma Merve Tepetam, Cihan Örçen.Writing – review & editing: Şeyma Özden.


Recognition of phenotypic variability in pediatric asthma allows for a more personalized therapeutic approach. Knowledge of the underlying pathophysiological and molecular mechanisms (endotypes) of corresponding biomarkers and new treatments enables this strategy to progress. Biologic therapies for children with severe asthma are becoming more relevant in this sense. The T2 phenotype is the most prevalent in childhood and adolescence, and non-T2 phenotypes are usually rare. This document aims to review the mechanism of action, efficacy, and potential predictive and monitoring biomarkers of biological drugs, focusing on the pediatric population. The drugs currently available are omalizumab, mepolizumab, benralizumab, dupilumab, and 1ezepelumab, with some differences in administrative approval prescription criteria between the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Previously, we described the characteristics of severe asthma in children and its diagnostic and therapeutic management. According to published studies, the prevalence of severe asthma (SA) ranges from 2% to 10% among asthmatic children ,4. DespiBased on the previously exposed, preventing asthma exacerbations as well as an adequate SA treatment is a priority objective in these children. Due to its heterogeneity, there is no universally accepted definition for SA in children. Both, the Global Initiative for Asthma (GINA)  and the The diagnosis of UCSA  requires a multidisciplinary evaluation in order to exclude other clinical disorders with similar symptoms. In this process, it is also crucial to distinguish between UCSA and difficult-to-trat SA . Apart of objective diagnostic techniques, such as bronchodilator or bronchoprovocation tests , a flowcAsthmatic children classified as UCSA should be referred to a specialized consult. Their clinical study should include: (1) pre- and post-bronchodilator spirometry , (2) inflammation marker determination  quantification, induced sputum analysis, or bronchoalveolar lavage if fibrobronchoscopy is performed); and (3) atopy study . Other techniques, such as fibrobronchoscopy or imaging studies , are reserved for selected cases, mainly for the assessment of comorbidities and other diseases .Among the most frequently comorbidities, obesity, allergic rhinitis, dysfunctional breathing, or psychological problems are included. They can significantly contribute to worsening asthma control if their management is not included as a global treatment.Apart of comorbidities, other factors known as potentially modifiable factors also contribute towards poor asthma control. In this regard, treatment adherence, drug inhalation technique, or aeroallergens and/or environmental pollutant exposure should be taken into account .After potentially modifiable factor identification and control (when possible), if asthma symptoms are still poorly controlled, escalation of the treatment level should be considered. The aim of treatment escalation should lead to the prevention of exacerbations as well as to improve pulmonary function, minimizing the side effects of drugs, particularly glucocorticoids. In this way, including monoclonal antibodies (mAb)  provides an opportunity to reduce corticosteroid dosage. Before considering mAb indication, reevaluation of the aforementioned (modifiable) factors, comorbidities, and other psychosocial factors should be reconsidered. Many patients with apparently diagnosed UCSA can significantly improve their response to treatment when these items are controlled. In order to choose the optimal pharmacological strategy, an evaluation of clinical and inflammatory phenotypes is crucial ,22. The most universally accepted recommendations regarding the use of mAbs in pediatric asthma can be find at step 5 (GINA)  or step Asthma phenotype is an observable characteristic that can be associated with an underlying mechanism called an endotype. Establishing a phenotype in patients with SA is critical, as it may lead to a different clinical treatment, carrying future implications .The primary phenotype classifications were based on different factors, which included clinical presentation, age, or time course. Current asthma phenotype classification is based on the inflammatory pattern, or the predominant type of bronchial cellularity. For its assessment, biostatistical cluster analysis of different variables  has been used . AccordiTwo major inflammatory phenotypes have been defined : T2 phenOn one hand, the allergic-T2 phenotype usually involves polysensitization to different allergens, in association with other atopic comorbidities. Immunologically, it is defined by a T2 inflammatory response  . On the The Asthma Phenotypes in the Inner City (APIC) longitudinal study has identified up to five phenotypic clusters, two of them severe . It defiBased on the previously exposed explanation is the challenge of phenotyping children with SA. However, the interpretation of lower respiratory tract samples should be carefully done, especially if they are under treatment .Beyond phenotypes, an attempt for a better understanding of asthma through patients’ classification into endotypes has also be performed. Endotypes can be defined as different subtypes of asthma based on a single pathophysiological mechanism. They are characterized by different biomarkers and different responses to treatment. It has to be considered that the same endotype could include different phenotypes. However, the development of new analysis techniques has increased the interest in a new concept: molecular phenotyping of asthma. In this regard, a recent trial of mepolizumab in children and adolescents was published . AccordiThe inclusion of biomarker analysis has taken a crucial role in the phenotypic classification of patients with SA. It allows for concrete pathogenesis pathway identification as well as the prediction of treatment response, its monitoring, or early of disease progression. However, phenotype-/endotype-specific biomarkers are currently unavailable, with the most commonly used being the ones related to the T2 phenotype. They include the quantification of peripheral blood and sputum eosinophil concentration, FeNO measurement, and determination of serum IgE and periostin.One of the most important biomarkers is total eosinophil count in peripheral blood. It is easy to obtain and widely used, predicting not only the risk of exacerbations in children and adults  but alsoAirway eosinophil quantification is probably more directly related to the inflammatory phenotype of asthma; however, sampling, either by bronchoalveolar lavage or sputum, is difficult in terms of its inclusion in a routinary study of children.Within the exhaled biomarkers, FeNO, as an indicator of IL-13-mediated inflammation, is another non-invasive marker that allows for the identification of a T2 phenotype (FeNO ≥ 25 ppb) . NeverthOther exhaled biomarkers such as volatile organic acids (VOCs) , oxidatiTotal IgE and specific IgE levels are also important as T2 inflammation biomarkers. High levels, as an indicator of allergic sensitization, are associated with asthma development and an increasing in asthma morbidity in early childhood . Indeed,With regard to periostin, it is a cell matrix protein induced by IL-13 and IL-4 that is secreted by bronchial epithelial cells and that can be detected in the blood. Its synthesis has been associated with airway remodeling, subepithelial fibrosis, eosinophilic recruitment, and the regulation of mucus production by goblet cells. For this reason, periostin quantification could help in the identification of patients with severe uncontrolled asthma and those susceptible to anti-IL-13 therapy. However, periostin’s usefulness in childhood asthma is still unclear. Some studies have shown significantly higher values in children with asthma than in healthy controls. In the same way, a positive correlation between higher serum periostin levels and induced bronchial hyperresponsiveness (BHR) has been described. On the contrary, the relationship between blood eosinophils and IgE is still unclear. In a real-life study , it was Evidence regarding the stability of these biomarkers in children and adolescents is limited. Longitudinal studies performed in adults suggest the need for repeated evaluations as T2 inflammation marker levels seem to vary from one determination to another .Regarding the non-T2 phenotype, although neutrophils are the predominant cells in the airway, their quantification has not been defined as a marker. In fact, the quantification method makes it unattractive for routine practice, being necessary to establish cut-off points to standardize decision making. Their quantification in children’s peripherical blood is easy to perform, but it correlates poorly with counts of airway neutrophils .Currently, some biomarkers are still under development and validation. Among them, YKL-40, a chitinase-like protein that has been detected in peripheral blood and in the lungs, seems to be related to asthma severity indices and risk of exacerbation. Nevertheless, in the pediatric population, it has shown a slight relationship with high FeNO levels (r = 0.48), serum neutrophilia (r = 0.63), and airway remodeling (r = 45) .In the same way, urinary bromotyrosine, a biomarker resulting from eosinophil degranulation, is still under experimentation. It can be determined by a non-invasive method and has been directly related to the T2 inflammatory pathway. This marker has been associated with asthma exacerbations in children, or with monitoring glucocorticoid clinical response, especially when combined with increased FeNO and elevated sputum eosinophils .Since 2014, when GINA, followed by the rest of the clinical guidelines, proposed the new recommendations for asthma clinical management, mAbs have become a key treatment for maintenance therapy in UCSA, displacing classical treatments such as corticoids. Development of mAbs for new therapeutic targets  in recenOmalizumab is an anti-IgE humanized mA that binds to the Fcε3 segment (high-affinity receptor) of free IgE, preventing its binding to the FcεRI receptor at the surface of mast cells, eosinophils, and basophils. This leads to a rapid removal of the circulating IgE–mAbs complex by the endothelial reticulum system, decreasing both circulating IgE levels and receptor expression at the cell surface. It will finally result in a reduction of cytokine release at the allergic inflammatory cascade.Omalizumab was the first biologic drug approved for treatment of asthma in children over 12 years old by the U.S. Food and Drug Administration (FDA) in 2003, as well as by the European Medicines Agency (EMA) in 2005. For children over 6 years of age, it was approved in 2016. To explain certain effects of this drug, it is worth recalling virus- and pneumoallergen-induced inflammation in patients older than 3 years. For instance, allergic sensitization with increased IgE levels against house dust mites may increase the likelihood that a respiratory tract infection, particularly when rhinovirus is involved, could lead to asthma exacerbation . A link 1 <90%, or comorbidities , chronic rhinosinusitis, nasal polyps, and psychological disorders) can be considered as clinical predictors of poor response to treatment [Omalizumab has been indicated for SA patients aged ≥6 years with an allergic high-T2 phenotype who meet the following criteria: perennial pneumoallergen sensitization, increased total serum IgE (>30 and <1500 IU/mL), and chronic idiopathic urticaria. However, not all patients respond to this treatment. The following are considered as good predictors of treatment response: presenting multiple sensitizations, elevated total Ig E levels, elevated FeNO (≥20 ppb) , and bloreatment . This mAb should be administered subcutaneously every 2–4 weeks, using a weight and pretreatment IgE-serum-level-based normogram for dosage calculation. Final doses will range from 75 to 600 mg (0.016 mg/kg/IgE (I.U./mL) per 4 weeks). The maximum dose is 600 mg and 375 mg every 2 weeks in Europe and the USA, respectively. Plasma half-life time is about 26 days . There aRegarding off-label use of omalizumab when IgE levels are higher than 1500 IU/mL, the dose calculation can be done considering a 0.016 mg/kg/IgE (I.U./mL) minimum doses every 4 weeks with a maximum dose of 600 mg every 2 weeks . In the Numerous studies have evaluated real-life results of omalizumab in pediatric patients, including different populations ,52,53,54These studies also described a progressive drop in peripheral blood eosinophil level. However, there is no global consensus on the improvement on lung capacity . Despite current evidence, the optimal duration of treatment and long-term side effects are unknown. It is proposed that response to treatment can be assessed at 4 months, being extendable to 6 months for late responders. Therapy could be prolonged for 6 years  or interDifferent meta-analyses ,60 have Despite omalizumab having not shown evidence on disease evolution modification, the Preventing Asthma in High-Risk Kids (PARK) study (NCT02570984) is currently underway . Its aimMepolizumab is a recombinant humanized IgG1 mAb against IL-5, blocking its interaction with its receptor. This prevents the specific signaling cascade from being triggered. IL-5 is a potent mediator of the inflammatory cascade in the allergic response, one that binds to the α-chain of the IL-5 receptor (IL-5R). This binding modulates eosinophil maturation in the bone marrow, as well as its recruitment, alongside activation at sites of allergic inflammation. It also regulates the functions of basophils and mast cells, enhancing the release of their mediators . In thisMepolizumab is an adjunctive treatment that is indicated in patients with eosinophilic UCSA who had peripheral blood eosinophil count >150 cells/µL or >300 cells/µL in the last year, as well as who, despite having been treated with the GINA step 4–5 proposed treatment , did notThe recommended dose is 100 mg every 4 weeks in children ≥12 years and 40 mg every 4 weeks in children between 6 and 11 years. It is administered subcutaneously, being easy to handle at home.The MENSA study, which included adolescents, observed that the patients were more atopic, with a shorter disease course and a higher number of hospitalizations for exacerbations than the general population . The eosWhen both age groups, adults and adolescents, were analyzed, the magnitude of reduction in exacerbations was greater in those patients with higher peripheral blood eosinophil counts (≥150 cell/μL) than in those with lower counts. It seems that this is the best biomarker for predicting response to treatment . On the The MUPPITS-2 study performed in the USA included a much larger sample: 290 African American and Hispanic schoolchildren, aged 6 to 17 years, from socioeconomically disadvantaged urban neighborhoods. A randomized, double-blind, placebo-controlled, parallel-group trial was carried out . The autAn observational, open-label, multicenter, observational cohort study is currently under way in Spain and the United Kingdom. This study includes children aged from 6 to 17 years with a clinical diagnosis of eosinophilic SA treated with mepolizumab, with the aim of analyzing the effectiveness and safety .Regarding the duration of treatment, its long-term use could maintain a stable effect. However, the optimal duration is still unclear .To study pharmacokinetics and pharmacodynamics, 36 patients aged from 6 to 12 years who met the criteria for eosinophilic SA were recruited. A 40 mg dose was administered to children weighing less than 40 kg and a 100 mg dose if the weight was greater than 40 kg . The druBenralizumab is a humanized mAb IgG1κ afucosylated mAb that binds to the α-subunit of the IL-5 receptor, specifically expressed on the surface of eosinophils and basophils. Therefore, benralizumab is able to inhibit their activation, inducing a rapid and almost complete eosinophil depletion by a mechanism of cytotoxicity mediated by N.K. cells.Its prescription is indicated for additional maintenance therapy in patients with eosinophilic SA that requires a high dose of inhaled glucocorticoids plus LABA. It has been included for individuals aged ≥12 years by the US-FDA. On the contrary, its use has not been authorized for the pediatric population by the EMA.The recommended dose is 30 mg, injectable subcutaneously, every 4 weeks for the first 3 doses and every 8 weeks after that. There are preloaded syringes or pens available. Home administration is possible.1 in clinical disease control scales and the reduction of oral corticosteroid cycles  were also described. These results were independent of serum IgE concentrations and atopy status [Two randomized, placebo-controlled, phase III clinical trials, SIROCCO   or 8 (n = 61) weeks for an extra period of 2 years, finding similar efficacy and safety profiles [A phase III extension study of patients included in the SIROCCO and CALIMA studies, the BORA study, demonstrated that efficacy and safety were maintained during a second year of treatment . This stprofiles . Both grAmong patients included in the SIROCCO and CALIMA studies, the predictors of clinical effectiveness were higher eosinophil levels (≥300 eosinophils/μL) and previous exacerbations . In addiSeveral studies have recently been completed in the pediatric population. An open-label phase III study to evaluate the pharmacokinetics, pharmacodynamics, and safety of benralizumab (PATH-HOME study) was performed on 30 children aged from 6 to 11 years . In paraDupilumab is a fully human mAb that inhibits inflammatory signaling by specifically blocking the α-subunit of the IL-4R receptor shared by both IL-4 and IL-13.The US-FDA approved its use for treating SA in 12-year-old patients in October 2018, and the EMA did so in March 2019. It was subsequently approved by both the FDA and EMA for children aged 6 to 11 years.On the one hand, IL-4 plays a crucial role in differentiating virgin CD4+ T cells into Th2 cells. It also drives IgE isotype switching in B cells. On the other hand, IL-13 induces the expression of the inducible nitric oxide synthase (iNOS) enzyme in epithelial cells, leading to an increase in the exhaled fraction of nitric oxide (FeNO); it causes mucosal hypersecretion and stimulates airway smooth muscle cell contraction, leading to bronchoconstriction. IL-4 and IL-13 play an important role in the recruitment of eosinophils from the blood circulation to the airway mucosa by two main mechanisms: by enhancing the expression of adhesion molecules on endothelial cells, and by inducing the production of chemokines and eotaxin by epithelial cells. Likewise, eosinophils will be recruited by eosinophil extracellular traps, Charcot–Leyden crystals, and oxidants generated by eosinophil peroxidase. Airway eosinophils mediate the formation of mucus plugs and contribute to chronic airflow obstruction . DupilumDupilumab is indicated for patients older than 6 years with SA and T2 inflammation who have elevated peripheral blood eosinophils (>150 cells/µL < 1500) and/or elevated FeNO (>20 ppb). Atopic dermatitis, eosinophilia > 300 cells/µL, and/or FeNO > 50 ppb is associated with a better response. It is also approved in patients with severe-to-moderate atopic dermatitis from 6 months of age, chronic rhinosinusitis with severe nasal polyposis not controlled with medical and/or surgical treatment, severe moderate nodular prurigo, and eosinophilic esophagitis in patients >12 years.Doses vary according to the pathology to be treated , being aIts bioavailability is 61–64% after subcutaneous administration, and the mean time to peak serum concentration is 3–7 days . Subcuta1, were observed. These results suggested a potential effect on airway remodeling. Dupilumab has demonstrated its efficacy and safety profile in several studies including adults and adolescents ,89,90. AThe response was better if eosinophilia was ≥300 cells/µL and FeNO ≥ 50 ppb . The safn = 107). This study concluded that there was an improvement in lung function, asthma control, and quality of life. The response was greater as the higher initial increase in T2 biomarkers was described. Concerning the reduction of exacerbations, a discrepancy was observed between patients treated with a 200 mg dose (46% reduction) and those treated with a 300 mg dose, in whom there was an increase when compared with the placebo. The authors justified this finding by an imbalance in the matching, by the number of severe exacerbations presented in the last year, and between the two groups, which could have affected the adjusted rate of exacerbations. The post hoc analysis of the phase III LIBERTY ASTHMA QUEST study  evaluate1 was described. The response was rapid and was maintained for at least 52 weeks. The side effects were similar to those reported in adults and adolescents, with cases of eosinophilia  reported without an association with clinical symptoms. The long-term safety profile for 104 weeks reported in the EXCURSION study [Similarly, the VOYAGE study , conductON study  was in cON study . The incON study .Tezepelumab is a humanized IgG2λ mAb that binds to thymic stromal lymphopoietin (TSLP), preventing it from interacting with its heterodimeric receptor. TSLP is a cellular-epithelium-derived alarmin-group cytokine that is released in response to an allergen, viruses, and/or pollution exposure. Its function is to induce T2 and non-T2 cytokine production, with increased bronchial hyperresponsiveness, mucus hypersecretion, and airway remodeling.It is indicated as an additional maintenance therapy in patients with UCSA, regardless of their phenotype, despite being treated with high doses of inhaled glucocorticoids in combination with other maintenance therapy medication. It has been authorized by the FDA and EMA for patients aged ≥12 years. There is also the possibility of home use. The recommended dose is 210 mg, injectable subcutaneously by syringe or prefilled pen every 4 weeks.1, degree of asthma control, and quality of life. It also decreased the number of eosinophils, FeNO levels, and serum IgE. This study included 82 adolescents with a reduction in the rate of severe exacerbations of 0.70 . The authors found no differences according to perennial allergen sensitization status. A phase III, multicenter, randomized, double-blind, placebo-controlled study (the NAVIGATOR study) included 1061 patients aged from 12 to 80 years with UCSA. As inclusion criteria, the pre-treatment with medium-high doses of ICS (≥500 μg fluticasone propionate) plus other controller medication was defined. No OCS diagnosis or pre-study biomarker levels were defined as initial variables. Patients were randomized to receive placebo or 210 mg of tezepelumab subcutaneously every 4 weeks for 52 weeks . The stuRecently, a systematic review analyzed the efficacy of different biologics treatments in UCSA, which were stratified by eosinophil levels. Only tezepelumab showed a reduction in the annualized rate of exacerbations in patients with eosinophil levels <150/µL . A multiA phase I study that evaluated pharmacokinetics in 18 children with asthma aged from 5 to 11 years has recently been completed  . In addiThe choice of the most appropriate biological drug for a given patient in daily clinical practice remains a significant challenge in the pediatric population. The selection is based on a specific assessment of uncontrolled asthma-contributing factors. It includes, among others, the determination of some biomarkers, such as peripheral blood eosinophil count, exhaled fraction of nitric oxide (FeNO), allergic sensitization, or IgE levels . There iAs was previously mentioned, the T2 inflammatory phenotype is most commonly described in children with SA. This phenotype is characterized by a combination of pneumoallergen sensitization, elevated peripheral blood eosinophil levels, and/or elevated FeNO levels. Although these biomarkers are not closely correlated, more than 70% of patients with SA have one or more markers of T2 inflammation, and almost 40% of patients have two markers ,107. As In essence, it is a matter of seeing what the patient´s phenotype (T2 or non-T2) and endotype  are, bearing in mind that the current dichotomy between allergic and eosinophilic asthma classifications, although practical, is probably too simplistic. In fact, pathophysiology of eosinophil-mediated disease is quite similar in both classifications and also has some limitations in the pediatric setting . The conTaking into consideration all of the above, we present an algorithm  that allThe decision-making process is complicated due to the absence of head-to-head comparative trials of biological treatment to determine whether the “best” option exists for a given patient. In this sense, a shared decision-making model could also be useful when choosing a drug for a particular patient . Each paHowever, currently available studies suggest the possibility that new technologies combining both multiple data sources and artificial intelligence–machine learning, have the opportunity to offer a significant shift in asthma patient care and actual precision medicine in which therapeutic decisions are tailored to patient needs, clinical characteristics, specific markers of inflammation, comorbidities, and how these factors influence disease activity and progression .Once treatment with a biologic has been initiated, a close follow-up is essential to determine clinical response. In adults, although different proposals have been published, a consensus of experts has classified responses into three categories: super-responders, partial responders, and non-responders . In thisWith all the limitations involved in extrapolating studies from adults, and in the absence of similar reports in children, studies are needed to check whether this approach can be interesting and useful. In addition, we must highlight the relatively small number of children treated with biological drugs compared to adults, as well as the potential impact of the natural course of the disease in regard to the definition of responders/super-responders to treatment. In any case, there would be agreement on including four major domains when assessing response: severe flare-ups, use of oral corticosteroids, symptoms, and pulmonary function, to which should be added the assessment of quality of life and biomarkers. From a practical point of view, it is easy to identify responders  and non-responders. The problem lies in cases of partial response and the need or not to modify the biological drug. Recently, a working group, COMSA, Working Group in the 3TR Consortium, was created that aims to provide information on the definitions of nonresponse and response to biological therapy for SA ,125. SomA period of 4 to 6 months after the beginning of the treatment has been proposed to analyze the impact on exacerbations, lung function, asthma control, symptom burden, quality of life, and oral glucocorticoid use . The occIn its most recent update, the GINA considers that the evaluation should be performed at 3–4 months, including the following elements: asthma control , frequency and severity of flare-ups, pulmonary function, management of comorbidities (if any), medication-related aspects , and patient satisfaction . If the According to different studies, therapy with biological treatments would provide a 12.7–37% remission rate , althougConsidering the different mechanisms underlying the pathogenesis of SA and response to treatment, guidelines based solely on clinical features compromise treatment success . As noteIn recent decades, the development of molecular techniques has led to high-throughput analysis including different biological fields. This is called multilayer analysis, better known as omics-analysis  . IntegraPharmacogenomics involves the study of genetic variation in the genome and its role in response to treatment. Most genetic studies of complex diseases such as asthma have focused on single-nucleotide polymorphisms (SNPs). Because of the patterns of polymorphisms, millions of genetic variants can be inferred from hundreds of thousands of SNPs. Thus, genome-wide association studies (GWAS)  can stud1 after 6 weeks of treatment. The SNP rs62081416 near L3MBTL4-ARHGAP28 was associated with the response to ICS in children of mixed African race. L3MBTL4 and ARHGAP28 have been associated with pulmonary function after bronchodilator administration [p = 3.8 × 10−8). The SNP rs1144986 (C5orf46) showed consistent effects for severe asthma exacerbations in all Hispanic/Latino subgroups but was not validated in non-Hispanics/Latinos. This SNP was associated with DPYSL3 DNA methylation and SCGB3A2169 gene expression levels [Most early pharmacogenomic studies of childhood asthma focused on populations of European descent ,138. Recstration . Likewisstration  identifin levels .Farzan et al. , within On the other hand, our group  was ableShrine et al.  studied An individual’s susceptibility to disease is not exclusively determined by the influence of the different genes and their combination but also by the environment, whose influence will be determined by the characteristics of the environmental factor itself and the time of life in which it interacts. In this genetic–environmental exposure relationship , the time of development of the immune system at which the interaction occurs is fundamental .Epigenetics studies mechanisms that regulate gene expression without modifying the DNA sequence, such as DNA methylation (mDNA), microRNA (miRNA) regulation, and histone modifications. Today, epigenetic changes can be analyzed genome-wide (epigenomics) using high-throughput techniques. The most studied field is mDNA patterns, which consist of methylation of a cytosine base that occurs most frequently in regions where the cytosine is followed by a guanine in the 5′–3′ direction (CpG sites) . 1 after ICS treatment. Two epigenome-wide association studies (EWAS) by Wang et al. ,165 analIn this regard, our group  studied Kho et al.  evaluateTranscriptomics studies all RNA transcripts by high-throughput methods such as RNA sequencing (RNA-seq) or microarrays. Most transcriptomic studies of treatment response in pediatric asthma have focused on ICS. Microarray analysis of peripheral blood mononuclear cells (PBMC) from asthmatic children revealed that patients with poor disease control showed specific transcriptomic patterns associated with ICS signaling and immune response compared to other asthmatic children . In addip-value < 0.001) in lung epithelial cells. Interestingly, this gene codes for a protein involved in an apoptosis pathway and thus could potentiate the anti-inflammatory effect of ICS [McGeachie et al.  performet of ICS .Katayama et al.  performeMetabolomics aims to profile biological samples’ complete metabolite composition (metabolome). High-throughput analytical techniques, such as mass spectrophotometry, nuclear magnetic resonance, or spectroscopic methods, allow metabolites to be characterized in invasive samples such as blood and non-invasive ones such as exhaled air (breathomics) and have been successfully applied for asthma phenotyping ,175, helKelly et al.  evaluateThe composition of microbial communities, or microbiota, is conditioned by intrinsic and extrinsic factors. Microbial exposure is essential for developing the immune system, and differential changes in the microbiota have been associated with allergic diseases . DysbiosThe airway microbiome is altered in asthmatic patients and differs from immune response models, especially in the levels of T2 inflammation . ClinicaWithin the Genomics and Metagenomics of Asthma Severity (GEMAS) project , which iIn recent decades, the role of the gut microbiome and its metabolites in the pathogenesis of asthma has also been studied. In this regard, Van Nimwegen et al. , in a prHowever, although omics studies have provided information on the biological mechanisms involved in treatment response, further studies are required to refine predictive markers with clinical relevance. A better understanding and identification of the molecular mechanisms underlying the different phenotypes within pediatric asthma, especially those with a higher tendency to exacerbate and worse response to conventional treatment, could lead to better classification and management of patients and the identification of new therapeutic targets. The integration of clinical characteristics with multiple omics data is a very promising avenue that will facilitate the management of the disease since it will contribute to providing genetic and non-genetic biomarkers that will allow for the identification and classification of the different phenotypes of asthmatic patients with poor or partial response to the usual treatment with ICS.Ongoing research into new mAbs focuses on new therapeutic targets or cytokines, including alarmins ,43,195. IL-23 promotes Th17 cell proliferation, neutrophil recruitment, and T2 cytokine production. A 24-week, multicenter, randomized, double-blind, placebo-controlled, multicenter, phase IIA study, which included 214 patients with moderate–severe asthma, evaluated the efficacy and safety of 90 mg S.Q. of risankizumab every 4 weeks. This is a mAb acting on IL-23. According to this study, during the analysis, time to asthma worsening was shorter, as well as and the annualized rate of asthma worsening being higher when risankizumab was compared with the placebo . Other aTL1A is a member of the TNF superfamily of ligands. It binds to the DR3 receptor, which is constitutively expressed at low levels on T, B, and N.K. cell surfaces. This binding is important for sustained pathological T2 responses. Its blockade with neutralizing antibodies reduced inflammation and levels of IL-4, IL-5, and IL-13 cytokines in a murine ovalbumin-induced asthma model. A new human antibody (C03V), which binds to an epitope of TL1A, allows for a very potent and selective neutralization of DR3 signaling and is potentially useful for the treatment of diseases involving TL1A dysregulation, including diseases with a fibrotic component, such as asthma . CurrentFB704A  may reduce BHR, as well as airway T1, T2, and T17 inflammatory responses, thus having the potential to improve symptoms of SA (with elevated neutrophils) and severe mixed granulocytic asthma. A phase IIA, randomized, placebo-controlled, double-blind, study is underway to evaluate the safety, tolerability, pharmacokinetics, and clinical activity of multiple intravenous doses of FB704A in adults with SA (NCT05018299) .Another future strategy could be the design of new forms of administration that would improve therapeutic concordance, effectiveness, and side effects by reducing systemic impact. An inhaled anti-TSLP mAb, ecleralimab, is currently under investigation. A phase II study showed that ecleralimab significantly attenuated allergen-induced bronchoconstriction and airway inflammation and was safe in adult patients with mild asthma, which represents a promising route of administration in the future .The appearance of new biological treatments for pediatric patients with UCSA has meant a paradigm shift and an improvement in the personalized management of the disease. Still, more studies are needed to provide answers to different aspects that have not yet been clarified ,41. Thes


Objective: Diminished physical capacity is common and progressive in patients undergoing dialysis, who are also prone to deficiency in carnitine, which plays a pivotal role in maintaining skeletal muscle and cardiac function. The present study aimed to evaluate the association of carnitine profile with exercise parameters in patients with incident dialysis.Design and Methods: This was a single-center cross-sectional study including 87 consecutive patients aged 20–90 years who were initiated on dialysis in Keio University Hospital between December 2019 and December 2022 and fulfilled the eligibility criteria. Exercise parameters were evaluated via cardiopulmonary testing (CPX) using the electronically braked STRENGTH ERGO 8 ergometer, whereas the carnitine profile was assessed by determining serum free carnitine (FC), acylcarnitine (AC) levels and AC/FC ratio.Results: The mean cohort age was 62.1 ± 15.2 years, with male and hemodialysis predominance . AC/FC was 0.46 ± 0.15, and CPX revealed peak oxygen consumption (VO2) of 13.9 ± 3.7 (mL/kg/min) with percent-predicted peak VO2 of 53.6% ± 14.7% and minute ventilation (VE)/carbon dioxide output (VCO2) slope of 35.1 ± 8.0. Fully-adjusted multivariate linear regression analysis showed that AC/FC was significantly associated with decreased peak VO2 , −10.15 to −0.70]) and percent-predicted peak VO2  and with increased VE/VCO2 slope ; FC and AC did not exhibit similar associations with these parameters. Moreover, only AC/FC was associated with a decreased peak work rate (WR), percent-predicted WR, anaerobic threshold, delta VO2/delta WR, and chronotropic index.Conclusion: In patients on incident dialysis, exercise parameters, including those related to both skeletal muscle and cardiac function, were strongly associated with AC/FC, a marker of carnitine deficiency indicating altered fatty acid metabolism. Further studies are warranted to determine whether carnitine supplementation can improve exercise capacity in patients on incident dialysis. CPX is the gold-standard method used to independently assess muscle, cardiac, and pulmonary function during exercise . In the r events . This inConsecutive patients aged 20–90 years who were newly initiated on hemodialysis or peritoneal dialysis (PD) in Keio University Hospital between December 2019 and December 2022 were assessed for their eligibility to undergo CPX after several dialysis sessions; CPX was therefore usually performed within 1 month following dialysis induction. Patients with the following conditions were excluded from the study : uncontrThis was a single-center cross-sectional observational study. The study protocol was reviewed and approved by the Ethics Committee of Keio University Hospital  was obtained from all participants, and informed consent for participation in the present study and for publication was obtained using an online opt-out form.In patients undergoing hemodialysis, CPX was performed on a day without hemodialysis between regularly scheduled hemodialysis sessions. In patients undergoing PD, CPX was performed at any time as long as the patient’s abdomen was free of dialysis fluid. Additionally, CPX was performed after several dialysis sessions following the confirmation of absence of ESRD symptoms, such as uremia and congestive HF. On the day of CPX, the patients were instructed to avoid heavy physical activity before testing. Height (m) and body weight (kg) measured immediately before testing were used to calculate body mass index (BMI).As previously described, CPX was performed using the electronically braked STRENGTH ERGO 8 ergometer . This deHeart rate (HR) was continuously monitored and blood pressure was measured every minute during CPX. Peak work rate (WR) and peak HR were recorded during CPX, and chronotropic index (%) was evaluated using the following equation: chronotropic index (%) = (peak HR − rest HR)/(220 − age − rest HR) × 100 .2, and VCO2, were continuously monitored and measured using 10-sec averages. Peak VO2 was defined as mean oxygen consumption during the last 30 s of exercise. The VE/VCO2 slope was based on data from the onset of exercise to the respiratory compensation point and was calculated using linear regression analysis of data acquired throughout the entire exercise period. Anaerobic threshold (AT) was determined using V-slope and time trend of VE/VO2, VE/VCO2, gas exchange ratio , and end-tidal O2 and CO2, as previously described (2 and divided by body weight. Ratio of VO2 increase (delta VO2) to WR increase (delta WR) was determined using linear regression of VO2 plots , as previously described . Brieflyescribed . AT was O2 plots .Demographic data, including age, sex, dialysis modality , presence or absence of diabetic kidney disease (DKD), history of cerebro-cardiovascular disease (CCVD), and use of antihypertensive drugs, were obtained from the medical records. Smoking status was recorded as non-smoker or smoker, which was further categorized as current smoker or ex-smoker.For biochemical analyses, blood samples were collected immediately before hemodialysis during the mid-week session in patients undergoing hemodialysis; blood samples were collected at any time in patients undergoing PD. Serum carnitine profile was determined using an enzyme cycling method, and carnitine deficiency was defined as decreased serum FC level and increased AC/FC . The fol2 and VE/VCO2 slope, and secondary outcomes were peak WR, AT, delta VO2/delta WR, and chronotropic index; all were determined during CPX. Additionally, given that peak VO2 and peak WR are affected by age, sex, and body weight, percent-predicted peak VO2 (%peak VO2) and percent-predicted peak WR (%peak WR) were obtained using age-, sex-, and body weight-predicted values in healthy Japanese subjects for assessment , respectively. Skewed data were log-transformed before analyses. Categorical data were expressed as numbers (%).t-test was used for comparisons between the following prespecified patient subgroups: male versus female, DKD versus non-DKD, hemodialysis versus PD, presence versus absence of history of CCVD, presence versus absence of smoking, presence versus absence of β-blocker use.Statistical analyses included simple linear regression analysis followed by multiple linear regression analysis, with exercise parameters included as dependent variables. Results were reported using β coefficients . For simple linear regression analysis, only FC, AC, and AC/FC ratio were included as independent variables. Unpaired Student’s 2 and AT were already divided by body weight; therefore, BMI was excluded from independent variables when peak VO2, %peak VO2, and AT were selected as dependent variables. Additionally, considering that β-blockers slow HR, β-blocker use was included as an independent variable when chronotropic index was set as a dependent variable.Multivariate regression models were created based on variables that were previously reported as predictors of exercise capacity and were not dependent on an association with exercise capacity identified in simple linear regression analysis in the current study . Consequp-value of < 0.05 was considered to indicate statistical significance.All statistical analyses were performed using EZR , a graphical user interface for R  . A two-sAmong 125 Japanese patients who were initiated on dialysis during the study period, 87 patients who fulfilled the inclusion and exclusion criteria were included in final analyses . The cli2 and peak WR were 13.9 ± 3.7 mL/kg/min and 61.8 ± 22.8 W, respectively. Both parameters were significantly lower than the estimated values in healthy Japanese individuals, and %peak VO2 and %peak WR were 53.6% ± 14.7% and 54.3% ± 15.7%, respectively. Chronotropic index was also lower than its estimated value in healthy individuals, with a chronotropic index of 48.1 ± 22.0. The VE/VCO2 slope was 35.1 ± 8.0, which was higher than the cutoff value of 29.9, implying a negligible risk of major cardiac events (CPX was performed a median of 7 (5–21) days after dialysis induction. The mean peak VOc events .2 and peak WR were significantly higher in male patients than in female patients   .Comparison of the exercise parameters between specific patient subgroups revealed that %peak VOctively) . DKD wasctively) . Additio2 , %peak VO2 , and VE/VCO2 slope , whereas FC level did not correlate with any of these variables . The AC level did not show any significant correlation with either of these variables .The results of simple linear regression analyses are shown in 2, %peak VO2, and VE/VCO2 slope in all models whereas FC level was not a significant predictor of any of these parameters  and %peak VO2  and was significantly and positively correlated with VE/VCO2 slope . FC and AC levels did not show any significant correlation with these primary outcomes.In multiple linear regression analyses, AC/FC remained a significant predictor of peak VOrameters . Specifi2/delta WR , and chronotropic index . However, FC level was not significantly correlated with any of these variables . The AC level was not significantly correlated with either of these variables .The results of simple linear regression analyses for secondary outcomes are shown in 2/delta WR, and chronotropic index, with statistical significance or borderline statistical significance . AC/FC also tended to negatively correlate with peak WR  and chronotropic index . AC/FC was significantly and negatively correlated with AT only in Model 1A . FC and AC levels did not show any significant correlation with these secondary outcomes.In multiple linear regression analyses, AC/FC remained negatively correlated with peak WR, %peak WR, delta VOificance . Specifi2, %peak VO2, and %peak WR. Additionally, an increase in AC/FC was independently associated with impaired cardiac function, including lower VE/VCO2 slope and higher delta VO2/delta WR.The current study, which aimed to determine the association between carnitine deficiency and exercise parameters assessed using CPX, revealed that not a decrease in FC level but an increase in AC/FC was an independent significant predictor of reduced exercise capacity determined using peak VO2. Using CPX among patients on incident dialysis. This is also the first study to demonstrate that exercise capacity was severely decreased in these patients, although the participants underwent CPX after several dialysis sessions to improve overt ESRD symptoms. Specifically, the mean peak VO2 was 13.9 mL/kg/min in the present study. Patients with HF and a peak VO2 of ≤14 mL/kg/min are considered to have poor prognosis . Similarly, in the present study population, %peak WR was severely decreased to 54.3% ± 15.7%.To our knowledge, this is the first study assessing exercise capacity parameters, including peak VOrognosis . The meaectively . Additiorognosis . Indeed,2 slope is a useful parameter to assess the ventilatory response to exercise and is as effective as peak VO2 in the prediction of cardiovascular events and survival in patients with HF. Previous studies have suggested that a VE/VCO2 slope of approximately >30–35 is associated with increased mortality, cardiac-related hospitalizations, and serious cardiovascular events , suggesting that poor ventilation/perfusion matches poor prognosis. The delta VO2/delta WR ratio shows the severity of HF and daily living activities in patients with HF. A study including Japanese patients with chronic HF revealed that mortality progressively increased in patients with delta VO2/delta WR values of ≥9, 7–9, and <7 mL/min/W  in the present study population was moderately low. Additionally, a decreased chronotropic index may reflect an underlying dysregulation of the autonomic nervous system function. In this regard, it has been reported that a decrease in the chronotropic index to <60% is associated with an increased risk of all-cause mortality, cardiovascular mortality, and hospitalization for HF  and cardiac function . A previous study reported that patients with HF showed higher circulating AC levels than control subjects regardless of EF. Moreover, a high AC profile may be significantly associated with high N-terminal pro-BNP levels and serve as an indicator of defective mitochondrial β-oxidation (via enhancing mitochondrial β-oxidation (Carnitine deficiency defined by low FC level or high AC/FC is prevalent in patients on maintenance dialysis, and its prevalence increases in parallel to an increase in dialysis vintage . The prexidation . In addixidation . Severalxidation . The resxidation . HoweverThis observational study has several limitations. First, this was a single-center study with a relatively small sample size, leading to lower power to detect significant determinants. However, the proportion of enrolled patients was very high, as only five patients declined to participate, which minimized the adverse effect of small sample size on external validity. Nonetheless, caution is warranted in extrapolating these results to non-Japanese patients. Second, due to the cross-sectional design, the current study could not determine causality and was limited to demonstrating relationships between variables. Third, the impact of several dialysis sessions on clinical and exercise parameters could not be ruled out, although dialysis modality did not affect any exercise parameters and performing CPX in patients with apparent ESRD-related symptoms including congestive HF and uremia would be unethical. Fourth, the study design did not allow the examination of longitudinal effects of impaired exercise parameters and increased AC/FC on clinical outcomes such as HF-related hospitalization, cardiovascular events, and, more importantly, patient survival. Carefully designed prospective cohort studies and interventional trials are needed to confirm these results. Finally, serum AC and FC might not reflect muscle carnitine levels. Nonetheless, this approach allowed us to explore the correlation between the AC/FC ratio and carnitine since a muscle biopsy to determine its concentration is unethical due to the invasiveness of the procedure.2, %peak VO2, and %peak VO2, and of impaired cardiac parameters, including increased VE/VCO2 slope and decreased delta VO2/delta WR, in Japanese patients on incident dialysis.In conclusion, in this prospective observational cohort study, we demonstrated that increased AC/FC was an independent and significant predictor of deterioration of various exercise parameters determined using the gold-standard CPX, including peak VO