Radiographs are considered essential in orthodontics. However, their diagnostic value and indications for use are still uncertain, while exposure to radiation carries health risks. This study aimed to report on the development of a clinical practice guideline on orthodontic radiology.A Guideline Development Taskforce was set up. The GRADE methodology was used for development and the RIGHT Statement for reporting of the guideline. We systematically reviewed articles to address the main clinical question: how different types of radiographs contribute to orthodontic diagnosis, treatment planning and post-treatment outcome evaluation. After a literature search and data extraction, we formulated conclusions and assessed the strength of the evidence according to the GRADE method. Both literature conclusions and the most important considerations, such as patient preferences, organizational matters and expert opinions were taken into account to finally issue recommendations.7 clinical questions focused on orthopantomograms, lateral cephalograms, hand-wrist radiographs, peri-apical radiographs, bitewings, antero-occlusal radiographs, and cone-beam computer tomographic imaging. The literature search lead to 484 unique studies, of which 17 were included in the analysis. The strength of evidence of the conclusions was graded low or very low. We formulated considerations and took them into account when issuing the 13 clinical recommendations to address the clinical questions.There was a considerable lack of scientific evidence on this topic. Nonetheless, this guideline provides clinicians with a tool for decision-making regarding radiographic records while enhancing patient radiation protection. More research of higher quality is recommended for a future update.The online version of this article (10.1007/s11547-020-01219-6) contains supplementary material, which is available to authorized users. Radiographs are considered essential for orthodontic treatment. Among other indications, radiographs and cephalometric analysis are used for assessing the interrelationships among the maxillofacial skeleton, dentition, and soft tissues , 2.However, diagnostic value of orthodontic radiographs and indications for their use are still debatable, and studies that investigated the validity of cephalometric analysis and its influence on orthodontic diagnosis and treatment planning showed inconsistent results. Moreover, the minimum set of records required for orthodontic diagnosis and treatment planning has never been solidly established or defined in the literature –6.At the same time, exposure to radiation is associated with health risks for patients and staff. These risks, more specifically, the somatic stochastic effects, are widely acknowledged and no radiation exposure, even in small doses, is free of risk, particularly in children , 4. ConsDue to the lack of evidence, there is an on-going discussion on the diagnostic value of orthodontic radiographs and indications for their use , 4. In tTherefore, the present study aims to report on the development of a clinical practice guideline (CPG) with recommendations for orthodontic radiology. By providing more clarity on the contribution of different types of radiographs to orthodontic diagnosis and treatment planning, and consequently their indication, the aim is both to help clinicians in their decision-making process, and protect patients from unnecessary and potentially harmful exposure to radiation.The Dutch Association of Orthodontists initiated and financed the development of this guideline. The Knowledge Institute of the Federation of Medical Specialists provided methodological support. In this report, we followed the RIGHT statement for reporting practice guidelines . The guiFirstly, a Guideline Development Taskforce was set up consisting of six members: 5 renown and experienced orthodontists working in the Netherlands, and one orthodontic resident. None of the Taskforce members reported conflicts that would preclude participation in this effort. The Dutch Patient Federation was also involved to promote the patient perspective. A methodological advisor of the Knowledge Institute of Medical Specialists supported the Taskforce to ensure an evidence-based guideline development. This guideline was developed using the GRADE methodology, in accordance with the requirements stated in the report “Medical Specialist Guidelines 2.0” published by the Quality Council of the Federation of Medical Specialists , 12. Thifull-text article available in Dutch or Englishpublished between 1985 and October 2015study population eligible for orthodontic treatmentstudy design: primary comparative research  or systematic reviewsdescription of the stated clinical questiondescription of the diagnostic modalityStudies on patients with cleft lip and palate or craniofacial anomalies were excluded.A broad literature search was developed. Two electronic databases, Medline (OVID) and Embase, were searched, based on 40 specific search terms (for the detailed search strategy see: Supplementary file S1). The search strategy was developed by a specialized librarian of the Knowledge Institute of the Federation of Medical Specialists. Two Taskforce members (A.K. and B.O.) then selected the articles, independently of each other, based on predefined criteria. The inclusion criteria were:The first selection was based on the title and abstract. The remaining articles were screened based on the full text and content. Differences between the two observers were discussed and resolved by consensus. Additionally, the references of the included articles were reviewed manually. The selected articles were then used to address the clinical questions.Data extraction was conducted by one Taskforce member (A.K.) and confirmed by the methodologist (A.L.). The data extracted included the study reference, study characteristics, patient characteristics, intervention, comparison/control, issues regarding follow-up, outcome measure, and effect size.To estimate the risk of bias, a member of the Taskforce (A.K.), supported by the methodologist (A.L.), systematically assessed the individual studies. These assessments were conducted with validated instruments recommended by the Cochrane Collaboration, including the Cochrane Risk of Bias Tool for randomized controlled trials (2009) , and ACRFor each clinical question and outcome measure, we made one or more conclusions, which summarized the scientific evidence. The strength of the evidence was determined on an outcome-by-outcome basis, according to the GRADE methodology, carried out in consensus by a member of the Taskforce (A.K.) and the methodologist (A.L.) , 16. BasThe full Taskforce then prepared a list of considerations, including patient values and preferences, costs, resource availability, organizational matters, and expert opinions, and formulated recommendations in consensus. Following the GRADE methodology, the literature conclusions, their GRADE rating and these considerations should be taken into account when issuing recommendations, even more so when the scientific evidence is weak or lacking .Both the GRADE rating and the weight assigned to the considerations determined the strength of the recommendation, after weighing all relevant arguments. According to the GRADE methodology, a low level of evidence for the literature conclusions does not exclude a strong recommendation, and conversely, a weak recommendation might be given, even when the strength of scientific evidence is high .The drafted guideline was submitted for comments to all concerned national dental and health insurance associations, the Dutch Patients’ Federation, the Dutch Health and Youth Care Inspectorate (IGJ), the Academic Centre for Dentistry Amsterdam (ACTA), and the University Medical Centre Groningen (UMCG). Their comments were collected, discussed and answered by the Taskforce. Based on these comments, the drafted guideline was adapted and finalized by the Taskforce.Based on the central question the Taskforce established 7 clinical questions (CQs), one per type of radiograph, on the contribution to orthodontic diagnosis, treatment planning and post-treatment outcome evaluation of CQ#1 an orthopantomogram (OPT), CQ#2 a lateral cephalogram (LC), CQ#3 a hand-wrist (HW) radiograph, CQ#4 a peri-apical (PA), CQ#5 a bitewing (BW), CQ#6 an antero-occlusal (AO) and CQ#7 a cone-beam computed tomography (CBCT).The literature search was performed in October 2015. It generated 484 unique hits, and two more articles were added after manual review of article references , for localizing impacted canines, and for assessing root resorption caused by impacted canines?CQ#7.2. What is the diagnostic value of CBCT compared to PA for assessing orthodontically-induced EARR and iatrogenic damage to teeth during inter-radicular miniscrew placement?Based on the literature analysis, two sub-questions for CBCT were formulated:Six studies were included , 26–30: 7.1.1.Detection of EARR, based on CBCT vs OPTLess teeth with EARR were diagnosed with OPT than with CBCT. GRADE: VERY LOW [7.1.2.Severity of EARR, based on CBCT vs OPTIt is unclear whether OPT and CBCT provided significantly different diagnoses of EARR severity. GRADE: VERY LOW [7.1.3.Localization of impacted canines, based on CBCT vs OPTSome evidence showed that impacted canines were more likely to be diagnosed as buccally located and less likely to be diagnosed as palatally located, based on CBCT compared to OPT. GRADE: VERY LOW [7.1.4Detection of root resorption caused by impacted canines, based on CBCT vs OPTThe number of teeth diagnosed with root resorption caused by impacted canines was underestimated with OPT, compared to CBCT. GRADE: VERY LOW [7.1.5Severity of root resorption caused by impacted canines, based on CBCT vs OPTThe severity of lateral incisor root resorption caused by impacted canines was underestimated with OPT, compared to CBCT. It was unclear whether this difference was statistically significant. GRADE: VERY LOW [VERY LOW .7.1.2.SeVERY LOW .7.1.3.LoVERY LOW , 29, 30.VERY LOW , 29.7.1.VERY LOW .7.2.1Detection of EARR, based on CBCT vs PAMore teeth with root resorption were diagnosed with PA than with CBCT. GRADE: LOW [7.2.2Accuracy of inter-radicular miniscrew placement, based on CBCT vs PACBCT proved to be more accurate than PA for inter-radicular miniscrew placement, but the differences were small and marginally clinically relevant. GRADE: LOW [ADE: LOW .7.2.2AccADE: LOW .Based on the conclusions from the literature study and the Taskforce-determined considerations, the clinical recommendations were drafted. The ensuing guideline was submitted for comments to the concerned professional associations. After reviewing the 138 comments, and adjusting the guideline where necessary, the Taskforce filed the guideline for authorization. In March 2018, the Dutch Association of Orthodontists authorized the final guideline .Together with the literature conclusions, the considerations in the following discussion led to the final recommendations.The Taskforce considered the OPT very useful in orthodontic practice, because it provides a complete overview of the dentition, roots, and the neighboring anatomical structures , 19. HowThe use of an LC is controversial in the literature. The other diagnostic records appeared to be sufficient for treatment planning. However, in some cases, an LC and cephalometric analysis were merited . The LC The HW is limited to assessing skeletal maturity only. Scientific data have indicated that skeletal maturity assessments performed on an LC are as good as assessments performed with the HW method .The Taskforce consensus was that the PA provided a more detailed view of teeth compared to the OPT. However, in most cases, the view offered by an OPT provided sufficient information .No studies were identified that investigated the contribution of a BW. In the absence of evidence, we therefore issued a recommendation based on the consideration that the indication for the BW was dental rather than orthodontic diagnosis.The Taskforce consensus was that the AO offered a detailed view of the premaxilla. In most cases, the view offered by OPT provided sufficient information; nevertheless, the AO can supplement the OPT when a more detailed view is needed for the premaxilla region.A 3D view from CBCT will always provide more information than a 2D view. However, this additional information should contribute substantially to a better orthodontic diagnosis and treatment plan to justify the much higher exposure to radiation .When assessing the location of impacted canines, the CBCT is easier to interpret, but often unnecessary. This is also the point of view of the American Association of Orthodontists .For root resorption, the cause must be differentiated. Significant EARRs can be clearly diagnosed with an OPT or PA , 28. HowBased on the literature conclusions and the considerations, following recommendations were issued and formulated according to the RIGHT methodology .trong recommendation, very low-quality evidence.Consider taking an OPT for orthodontic diagnosis and treatment planning when evaluating root resorption, tooth anomalies, and treatment progress. SStrong recommendation, absence of evidence.Do not take an OPT just before or after removing an orthodontic appliance at the end of active treatment. Strong recommendation, very low-quality evidence.Take an LC when information about skeletal dimensions and relationships is needed, and other diagnostic records do not provide sufficient data. Strong recommendation, very low-quality evidence.Take an LC when information about the position or inclination of the upper or lower incisors is needed, and other diagnostic records do not provide sufficient data. Weak recommendation, very low-quality evidence.Consider taking an LC before, during, and after treatment, when it is necessary to assess the orthodontic and/or orthopedic effect of the treatment. Strong recommendation, very low-quality evidence.Do not take an HW when skeletal maturity needs to be determined. An LC should be taken instead. Strong recommendation, very low-quality evidence.Take a PA only when the available radiographs do not provide sufficient information about a localized problem that has been diagnosed. Strong recommendation, absence of evidence.Do not take a BW for orthodontic diagnosis and treatment planning. Refer the patient to the dentist, when dental caries is suspected. Medium strong recommendation, very low-quality evidence.Consider taking an additional AO only when other available radiographs do not provide sufficient detailed information about the premaxilla. Medium strong recommendation, very low-quality evidence.Consider taking a CBCT to detect and evaluate the severity of root resorptions caused by impacted canines, when other available radiographs do not provide sufficient information, and when in doubt about the prognosis of potentially resorbed teeth. Medium strong recommendation, very low-quality evidence.Consider taking a CBCT to diagnose the localization of impacted canines only when other available radiographs do not provide sufficient information. Strong recommendation, very low-quality evidence.Do not take a CBCT to detect or evaluate the severity of EARR because the CBCT has no added value in comparison with an OPT. Strong recommendation, low-quality evidence.Do not take a CBCT for inter-radicular miniscrew placements, because the CBCT has no added value in comparison with a PA radiograph. Several challenges were encountered during the guideline development process. The existing uncertainties regarding the use of radiographs for orthodontic purposes have led to the assessment of a wide scope of radiographs and a wide amount of data and information. It proved impossible to reduce variety without losing important information. Nevertheless, we found a limited number of studies dealing with the contribution of radiographs to orthodontic diagnosis, treatment planning and post-treatment outcome evaluation. We opted to only include articles in English and Dutch, thus, setting a limitation. We acknowledge that the inclusion of more literature would be beneficial for the guideline, yet, at the time of writing, this was the only available literature that we could retrieve, fitting the predefined criteria for its development.Furthermore, comparisons between the studies that qualified for inclusion were complicated by methodological differences. The outcome measures were derived from the selected literature. Hence, not all possible indications for the selected radiographs were mentioned. This is especially true for CBCT, even though we were able to include significantly more studies than for the other radiographs, with the exception of the lateral cephalogram. To assess the strength of evidence, we used the GRADE method . The vasClinical circumstances and considerations, however, may vary in different settings and clinicians are encouraged to reflect critically. When there are well-founded arguments, it is possible to diverge from the guideline, as the aim is to offer clinicians a guide, hereby not intending to impose limitations.We therefore hope that this guideline will encourage more high-quality research in this field and that by the time of the update of the guideline, scheduled 5 years after publication, more literature will be available.Moreover, as the focus of this guideline was on the contribution of radiographs, and thus their justification, we did not aim to conduct an extensive study on radiation levels. We acknowledge, though, that limiting radiation is very useful when possible, for instance by limiting the field of view . When twGuideline development has been a time-intensive process, involving many actors and stakeholders, with a duration of approximately 3 years, including the final search in October 2015 and publication. We have therefore redone the literature search on 25th of March 2020 for an estimation of newly available literature (see: Supplementary file S6). This search has revealed an interesting evolution. There was a particular increase in studies assessing CBCT, which is not entirely unexpected, being one of the more recent but also more controversial radiographic modalities. It has shown varying insights and conclusions. Pico et al.  stated iMoreover, except for “National guidelines for dental diagnostic imaging in the developmental age” by Firetto et al. , which iThe lack of evidence-based literature on orthodontic radiology led to a CPG where considerations played a significant role. Nevertheless, it is a step forward in providing clinicians with a tool for decision-making regarding acquisition and usage of radiographs, reducing variation and enhancing radiation protection of patients while not depriving the orthodontist of necessary diagnostic information. More research in this field is strongly recommended for a future update.Supplementary material 1 (DOCX 19 kb)Supplementary material 2 (DOCX 18 kb)Supplementary material 3 (DOCX 68 kb)Supplementary material 4 (DOCX 49 kb)Supplementary material 5 (DOCX 26 kb)Supplementary material 6 (DOCX 24 kb)Below is the link to the electronic supplementary material.


Chronic patients persistently seek for health information on the internet for medication information seeking, nutrition, disease management, information regarding disease preventive actions and so on. Consumers ability to search, find, appraise and use health information from the internet is known as eHealth literacy skill. eHealth literacy is a congregate set of six basic skills . The aim of this study was to assess eHealth literacy level and associated factors among internet user chronic patients in North-west Ethiopia.p < 0.05.Institutional based cross-sectional study design was conducted. Stratified sampling technique was used to select 423 study participants among chronic patients. The eHealth literacy scale (eHEALS) was used for data collection. The eHEALS is a validated eight-item Likert scaled questionnaire used to asses self-reported capability of eHealth consumers to find, appraise, and use health related information from the internet to solve health problems. Statistical Package for Social science version 20 was used for data entry and further analysis. Multivariable logistic regression was used to examine the association between the eHealth literacy skill and associated factors. Significance was obtained at 95% CI and In total, 423 study subjects were approached and included in the study from February to May, 2019. The response rate to the survey was 95.3%. The majority of respondents 268 (66.3%) were males and mean age was 35.58 ± 14.8 years. The multivariable logistic regression model indicated that participants with higher education (at least having the diploma) are more likely to possess high eHealth literacy skill with Adjusted Odds Ratio (AOR): 3.48, 95% CI . similarly, being government employee AOR: 1.71, 95% CI , being urban resident AOR: 1.37, 95% CI , perceived good health status AOR: 3.97, 95% CI , having higher income AOR: 4.44, 95% CI , Daily internet use AOR: 2.96, 95% CI , having good knowledge about the availability and importance of online resources AOR: 3.12, 95% CI , having positive attitude toward online resources AOR: 2.94, 95% CI  and higher level of computer literacy AOR: 3.81, 95% CI  were the predictors positively associated with higher eHealth literacy level.Besides the mounting indication of efficacy, the present data confirm that internet use and eHealth literacy level of chronic patients in this setting is relatively low which clearly implicate that there is a need to fill the skill gap in eHealth literacy among chronic patients which might help them in finding and evaluating relevant online sources for their health-related decisions. Noncommunicable diseases (NCDs) are “also known as chronic diseases, which tend to be of extended period resulted from a combination of genetic, physiological, environmental and behavioral factors” . AccordiThe development in internet access and the improvements in performance due to the new technologies makes the internet to be the focus of many new healthcare improvements , 10. SysAlthough it is not mandatory to have a mastery in all the six literacy skills, the gap in any of these could be a constraint to benefit from eHealth merits. As a result, one has to have at least a moderate level of skills in all the literacies to make an effective use of the outrageous eHealth resources. To explore the eHealth literacy level and its associated factors in a population with chronic disease is more urgent and important now than ever. The lesson from COVID-19 thought the world that eHealth is not optional and luxurious approach to healthcare rather it is necessary, safer and effective way of providing healthcare service for both patients with underlying conditions and others during such times. The escalating number of internet users, information needs and smartphone penetration in African countries are the most important driving reasons ringing the relevance of assessing eHealth literacy & factors thereof among patients to harness eHealth merits. Given the gap in literatures regarding chronic patients’ eHealth literacy skill in Africa, conducting this study will contribute to the scientific knowledge in addressing the research question in this region. Hence, the aim of this study was to assess eHealth literacy level and associated factors among internet user chronic patients in University of Gondar comprehensive specialized hospital, North West Ethiopia.An institutional based cross-sectional study was conducted to assess eHealth literacy skill and associated factor among internet user chronic patients in University of Gondar comprehensive specialized hospital (UOGCSH). Gondar is placed 725-km driving distance North-west from the capital Addis Ababa. The UOGCS hospital is the largest specialized teaching hospital in the Amhara region serving more than five million peoples annually. It provides a specialized care and follow up service for different chronic cases in different days of a week. According to the hospital’s statistics, cardiovascular diseases like hypertension, chronic respiratory diseases like asthma, epilepsy and type2 diabetes are the most common chronic disease morbidities in the hospital at the time when this study was conducted (2019).random sampling method with proportional allocation technique. Stratified sampling is a method of sampling applied for a population with sub-sets of known size where the sub-sets make up different proportions of the whole [The sample size for this study was calculated using single population proportion formula  with 95%he whole . Thus, ihe whole .Data was collected by using interviewer administered questionnaire from February to May 2019. The questionnaire requires 10–15 min to complete and had three parts. The first section contained questions about participant’s socio demographic characteristics (10 items), the second part contained items related with internet use (6 items), knowledge about the availability and importance of online resources (5 items), attitude of participant to use online health resources (4), computer literacy (5 items) and the third section contained items related to eHealth literacy skill (8 items). Except for the first part (sociodemographic related items), all items were measured in 5-point Likert scale ranging from strongly agree (5) to strongly disagree (1). A validated tool was used to determine eHealth literacy skill which was developed by Norman and Skinner , 24. TheThe items were translated to Amharic to avoid language barriers and the reliability of the translated items were assessed for its internal consistency by calculating Cronbach alpha coefficient among 30 chronic patients in other hospital  . Data coA one-day training was delivered to data collectors by the investigator in regard with data handling and participants approach. Continuous and active supervision was done during the data collection and after data collection was completed, it was checked for completeness and accuracy. Finally, the data was entered using statistical package for social science (SPSS) software version 20 for further analysis.p-value < 0.05 and the Hosmer and Lemeshow test shows a good model fit with p-value = 0.608, which signifies the goodness of the model [p-value < 0.2 [P-value< 0.05) associated with eHealth literacy skill. The strength of association was explained in terms of odds ratio (OR) and a 95% confidence interval (CI).Descriptive analysis was performed to summarize participant’s socio-demographic characteristics. The extent of internet use, knowledge and attitude were described using frequency and percentages. Before running the logistic regression model, assumptions were checked for outliers, multicollinearity and independent error terms. Multicollinearity was tested by running a false linier regression iterating the independent variables as a dependent variable and the result showed all the variance inflation factor (VIF) value less than three and tolerance greater than 0.7 which demonstrated the absence of multicollinearity . The dathe model . A bivarue < 0.2  was inclIn total, 423 study subjects were approached and included in the study from March 02 to May 17, 2019. The response rate was 95.3%. The majority of respondents 268 (66.3%) were males and the mean age participants was 35.58 ± 14.8 years. A large number of respondents were diploma holders and above 208 (51.5%). Most of the study participants were urban residents352 (87.1%). About 150 (37.1%) of the respondents were governmental employees. See . similarly, being government employee AOR: 1.71, 95% CI 1.11, 2.68), being urban resident AOR: 1.37, 95% CI , perceived good health status AOR: 3.97, 95% CI , having higher monthly income > 5500ETB AOR: 4.44, 95% CI , being daily internet user AOR: 2.96, 95% CI , having good knowledge about the availability and importance of online resources AOR: 3.12, 95% CI , having positive attitude toward using online resources AOR: 2.94, 95% CI  and higher level of computer literacy AOR: 3.81, 95% CI  were the predictors positively associated with higher eHealth literacy level. See Table .68, beinThe purpose of this study was to determine the level of eHealth literacy skill and associated factors among internet user chronic patients in University of Gondar Comprehensive Specialized Hospital. The result showed that eHealth literacy skill was relatively low with 188 (46.5%) of the participants reporting high eHealth literacy skill. The result also shows 353 (87.3%) use of daily and several days a week internet use of participants with more than three fourth of them using it for browsing social medias like Facebook. Younger, educated and peoples from urban residence were more frequent users of internet. Educational status, occupation type, residence, self-reported health status, monthly salary, frequency of internet use, knowledge about the availability and importance of online resources, attitude toward using online resources and computer literacy level were statistically significant factors associated with eHealth literacy skill among internet user chronic patients in this study. This study also found that, the majority of respondents 268 (66.3%) were males and there was no significant chi square difference among the groups which is different from a study which revealed that males are superior internet users . This cop-value< 0.05). After adjustment for the covariates, except for two variables (residence and frequency of internet use) all the other predictor variables were significantly associated with eHealth literacy skill with p-value< 0.05. See Table p-value< 0.05). This finding is similar with other studies in different populations which underlined the need for capacity building and continuous educational support for chronic patients with lower educational status [P-value< 0.05. Higher income is highly associated with higher eHealth literacy skill in different studies [p-value< 0.05 compared to those who perceive their health status as bad. This finding is similar with other studies done elsewhere which argues the more likely possession of eHealth literacy skill by patients who perceive their health status as good [p-value< 0.05 where chronic patients those who use internet on a daily basis are almost 3 (AOR: 2.96) times more likely to have high eHealth literacy skill when compared to those who use internet 1 day and less than 1 day a week with 95%CI: . This finding is similar with different studies confirming that frequent internet users possess higher eHealth literacy skill [when compared to studies conducted in other countries, the mean eHealth literacy score of chronic patients in this study was relatively lower and this could be due to the less internet penetration and economic berries in low-income countries like Ethiopia –45. The l status , 46, 47.l status , 49 but l status –52. Inco studies , 54. In  as good , 55, 56.cy skill , 57, 58.cy skill –61. Knowcy skill –65.This study found that educational status, perceived health status, income and frequency of internet use have significant impact on consumers eHealth literacy skill confirming with several studies. It also suggested other factors like knowledge about availability and importance of online sources, attitude and computer literacy are important variables associated with eHealth literacy level in this population. Internet use and eHealth literacy level of chronic patients in this setting is relatively low. This clearly implicate the need to fill the skill gap in eHealth literacy among chronic patients which may help them in building their capacity to find and evaluate relevant online sources for their health-related decisions.As this is the first study to investigate eHealth literacy and associated factors among chronic patients in resource limited settings, there were limitations identified for further investigators. This limitation of this study is that more than half of the study participants were from urban resident setting and all participants were selected after confirming their previous internet exposure. Those with previous internet exposure were interviewed further and those who doesn’t know about the internet were excluded. This could have caused a selection bias where urban residing and internet user participants are more likely to possess high eHealth literacy. The other limitation of this study was the small sample size & it was conducted in a single institution in Northern Ethiopia. Therefore, the results may not be generalizable to all chronic patients and future researchers should consider more broader samples from different clusters of populations in the country to ensure generalizability.Considering the importance of chronic patients’ ability to find and evaluate health information for their health management decisions, it is highly important for the Ethiopian Federal ministry of health and other responsible bodies to consider methodical approach to improve the eHealth literacy skill of internet user chronic patients through short trainings and education. Hospitals should also consider facilitating health care providers advisory of online sources for their patients. It is also important for future researchers to consider exploring other relevant factors associated with eHealth literacy skill of chronic patients.Additional file 1.


Typhoons are among the greatest natural hazards along East Asian coasts. Typhoon-related precipitation can produce flooding that is often only predictable a few hours in advance. Here, we present a machine-learning method comparing projected typhoon tracks with past trajectories, then using the information to predict flood hydrographs for a watershed on Taiwan. The hydrographs provide early warning of possible flooding prior to typhoon landfall, and then real-time updates of expected flooding along the typhoon’s path. The method associates different types of typhoon tracks with landscape topography and runoff data to estimate the water inflow into a reservoir, allowing prediction of flood hydrographs up to two days in advance with continual updates. Modelling involves identifying typhoon track vectors, clustering vectors using a self-organizing map, extracting flow characteristic curves, and predicting flood hydrographs. This machine learning approach can significantly improve existing flood warning systems and provide early warnings to reservoir management. Tropical cyclones can cause severe flooding when making landfall, but these water flows can often only be forecasted a few hours before. Here, the authors present a new approach using self-organizing maps and flow characteristic curves to predict tropical cyclone related runoff up to two days in advance. For example, the passage of Typhoon Morakot had major flooding produced by 2777 mm of rainfall3.Taiwan’s location makes it vulnerable to the western North Pacific Ocean tropical cyclone that regularly produces damaging typhoons. Although small in size, Taiwan is 400 km long and 150 km wide, mountains reach elevations of 4000 m. With a northeast to southwest orientation the mountains dominate the eastern part of the island. Rivers in Taiwan are characterized as steep gradient and short length producing high flows within a few hours of typhoon passage. Existing reservoirs, in general, are small and are rapidly filled during typhoon-related rainfall resulting in significant flood hazards5. In Taiwan, global temperature change is expected to increase the frequency of damaging typhoons8. When typhoons cross landscapes with mountainous terrains, such as Taiwan, intense localized rainfall and flooding is common due to orographic effects. Flood damage potential is related to typhoon intensity class, the track each typhoon takes across the island, and orographic influences of topography, which influence local rainfall amount and intensity. To minimize typhoon-related flood damage there is a clear need for improved flood forecasting with early warnings that provide sufficient time to implement flood hazard mitigation using reservoir storage and local flood defense.The increase in the number of unprecedented weather events, including typhoons, is a part of weather patterns related to global temperature change10. Predictive model advancements are needed to provide the lead time needed to adjust reservoir capacity for flood control and implement flood defense procedures while meeting long-term water supply requirements. Improved sensor networks in Taiwan now provide easily accessible remote sensing data, expanding modelling potentials12. A recent study of rainfall-runoff modeling based on remote rainfall information found that reliable real-time flood forecasts could be obtained up to six hours before a typhoon event3. This six-hour forecast falls well short of the time needed for reservoir storage development, which is measured in days. Therefore, it is important to improve traditional modeling and rainfall-runoff analyses to develop typhoon track and flood hydrograph predictions several days before typhoon landfall.Accurate advanced forecasting of flooding is a formidable challenge in Taiwan. Variable typhoon tracks, trajectory, speed, and rainfall intensity related to mountainous terrain produce spatial and temporal variability in rainfall amounts and related runoff21. The AI techniques analyzed geographic, hydrological, and meteorological data sets to enable automatic information extraction from advanced sensor arrays through machine learning28. There is ample evidence that the use of AI-based approaches has improved site-specific rainfall-runoff prediction for individual typhoons, bridging the gap between track prediction and flood forecasting by combining the analysis of massive historical datasets and real-time remote sensing data.Prediction of flood hydrographs is based on the spatio-temporal variability of storm characteristics and the uncertainty of hydro-geo-meteorological outcomes along a track produced by track/terrain interactions. Artificial intelligence (AI) techniques have recently emerged as an approach to analyzing highly dimensional complex data sets to classify phenomena and support predictionsThe AI-based methodology developed in this study predicts flood hydrographs based on the forecasts of a typhoon track both before and after typhoon landfall and then constantly refines flood forecasts during typhoon passage. Our study made the first attempt to digitize analog typhoon tracks so that the whole typhoon track, together with corresponding hydrologic and geographic characteristics, could be integrated to support hydrograph prediction. We based predictions on clusters of vectorized historic typhoon tracks using a self-organizing map (SOM) with event-specific flow characteristic curves (FCCs), which are based on reservoir measurements related to typhoon landfall, overland transit expectations and rainfall amount. Our study showed that it was possible to make predictions with a lead time of two days prior to typhoon landfall. We could provide an early warning coupled with continuous prediction updates of flooding along the typhoon track. Better predictions improve reservoir operation, flood defense and integrated water resources management.3/year to meet the domestic, agricultural, and industrial needs of the Taipei metropolitan area, thus requiring careful management. The reservoir has a capacity of 197 million m3 with a watershed area of 763 km2. The annual precipitation for the Shihmen Reservoir watershed is about 2500 mm, primarily from typhoon-related rainfall. Reservoir operational rules require reduction in the water level before typhoon arrival to increase storage capacity. Storage is an element of flood defense that is balanced against maintaining a high water level to meet water supply needs. Therefore, reliable and accurate flood hydrograph prediction during typhoon periods is crucial for reservoir management to provide flood defense while meeting water supply requirements.In this study, the Shihmen Reservoir watershed was the focus for flood forecasting. This watershed experiences an average of three typhoons annually. The Shihmen Reservoir is a pivotal multi-objective reservoir that provides flood protection and a water supply of more than 800 million m34, but these methods must be improved to provide digital representations of typhoon tracks to support the location-specific analysis for predicting rainfall intensity related to terrain. Improvements needed include analog to digital conversion of typhoon movement into digital track vectors, characterization of track variability, and accounting for track interactions with terrain.Typhoon track predictions are possible by analyzing historic tracks. Similar tracks can be grouped, and groups can be classified based on the path over Taiwan using K-means and fuzzy clustering as prediction toolsWe assembled hydro-meteorological data from 97 typhoons occurring between 1965 and 2019 that tracked through the Shihmen Reservoir watershed producing flood hydrographs exceeding 600 cms. The maximum flow from the reservoir during this period was 8594 cms. The data set supporting the AI-based flood hydrograph prediction model developed in this research used total rainfall, typhoon track, the date and time warnings issued by the Central Weather Bureau (CWB), and hourly reservoir inflow data from the Water Resources Agency (WRA). The 97 typhoon events were divided into two groups, where 87 events were used to train the model and 10 events were used to test model reliability.Prediction of typhoon-induced flood hydrographs involved the sequential implementation of four key modules, which were typhoon track vectorization, track vector clustering in a SOM, FCC extraction, and flood hydrograph prediction.We first converted each typhoon track from an analog to a digital data set (vector). Recognizing potential track variability, a diffusion process was applied to better characterizing each track. Figure The second module used a SOM algorithm to cluster the 87 tracks occurring between 1965 and 2015 selected for model training into a topological display. The 87 tracks are illustrated in the Supplementary Fig. Typhoon tracks in clusters #1–#7 came mainly from southeast, made landfall on the east coast, and moved across the 4000 m high mountains. In typhoons with this east to west movement, the orographic processes caused rain to fall in other watersheds while producing lower inflows to the Shihmen Reservoir. As for typhoon tracks in clusters #11 and #15, these tracks were east or north of the watershed, again resulting in lower reservoir inflows. According to the 16 clusters, the cluster that a new typhoon track best matched could be quickly and objectively identified.FCC is a cumulative curve that shows the percent of time specified discharges were equaled or exceeded during a typhoon event. It has a long history in the field of water resource engineering and for scientific comparisons of streamflow characteristics across watersheds. The normalized flow characteristic curve plots the fraction of total discharge in the vertical axis against the fraction of duration in the horizontal axis. The third module produced FCCs, where the primary indicator used was the slope for the rising and recession limbs of the hydrograph. Different watersheds have site-specific flow characteristics and duration time for the FCC. For the Shihmen Reservoir watershed, typhoon effect on inflow would last for an average of 28 h with an average time interval between the arrival and departure of a typhoon reaching 56 h (based on 87 typhoon events). To provide reservoir capacity for flood control the change from 245 m (full reservoir storage) to 240 m (the upper limit) would take about 11 h at a rate of 1000 cms or about 37 h at a rate of 300 cms. Therefore, the prediction of flood hydrograph with a lead time of two days prior to typhoon landfall would be satisfactory for flood control as well as water management.Hydrographs were predicted from rainfall forecasts and typhoon duration (TD). In this study, the FCC of a typhoon event was normalized by a cumulative flow curve where both the total flow rate and TD were converted to the same 0 to 1 scale. It is understood that terrain complexity and flow travel distance produced by each typhoon track brings different effects on the watershed. We argue that similar typhoon tracks would produce similar effects reducing analytical complexity. FCCs in the same cluster could be estimated by use of the total flow volume that was converted directly from total rainfall. The advantage of this approach is that the calculation of flow hydrographs no longer requires actual rainfall–runoff data, which is only available post-event. Further, using this approach a flood hydrograph could be converted from a FCC cluster and an expected typhoon track supporting the development of advanced flood warnings.We investigated the characteristics of the flood hydrographs in each cluster, which was initiated with an extraction of the FCC for each typhoon event. We then analyzed the features  and similarity of all the FCCs in each cluster. Figure This approach allowed us to explore how typhoon stage/duration would influence the group behavior of FCCs in each cluster Figs. –6. We noA storm may approach the watershed from various directions with different rainfall histograms (patterns), causing the timing of flow rising to peak (TP) to be variable. As shown in Fig. 35, and with these analyses impact prediction can be further improved with flood forecasting using our AI approach.Given the predicted track of an approaching typhoon, a flood hydrograph prediction process began by identifying from the SOM topological map a cluster (denoted as the best matched cluster) that incorporated a typhoon track the most similar to the predicted track. The FCC prediction could use either of the following two selection strategies. The first strategy selected the FCC of the best matched typhoon track while the second strategy selected the average (ensemble) of all FCCs in this best matched cluster. Using either approach, the prediction of the flood hydrograph of an approaching typhoon could be made and flood warnings could be generated. To summarize model training, we recognize that past methods for predicting typhoon impacts can benefit from improved methods of typhoon track prediction38. Figures We next evaluated the reliability of the constructed SOM embedded with FCCs using the remaining 10 typhoon events occurring in 2013 and 2019 as tests of our approach. The test results for 10 typhoon events are shown in the Supplementary Table 39. These constraints restrict operational hydrology applications in watershed management.Because of variation in typhoon intensity and track is influenced by landscapes in Taiwan, flash flooding is common within few hours of typhoon passage, and reservoirs quickly fill during typhoon events. Using hydrographs for reservoir capacity management is a crucial non-structural approach to flood defense in water resources management. Modeling the rainfall–runoff processes is one of the most popular yet complex practices of hydro-informatics approaches  while the high degree of spatio-temporal heterogeneity of typhoon-induced rainfall and the notoriously nonlinear nature of rainfall–runoff relationship make reliable and accurate flood forecasts very challenging, if not impossible. Moreover, traditional approaches now only make short-term (hourly-based in our case) forecasts due to the lack of reliable rainfall predictions. As noted in the literature, forecast accuracy deteriorates as the lead time increases41.To translate short-term (hourly-based) flood forecasting into long-term (daily-based) flood warning using typhoon tracks, we adopted the AI-based approach to predict flood hydrograph based on the forecasted typhoon tracks and corresponding total rainfall obtained from our CWB. To assess the reliability and accuracy of this AI-based approach, we compared the prediction results with those of a commonly used conceptual rainfall-runoff model, i.e., the storage function model (SFM)R2 values, especially apparent for events with high peaks. To demonstrate the goodness-of-fit of both methods, we examined performance for two special typhoon events, i.e., the most recent typhoon in 2019, Typhoon Lekima , it would be classified into neighboring clusters and produce relatively good predictions. Thus, the proposed method could tolerate small errors in typhoon track prediction, which provides a robust error-tolerant approach. We present a recent case, Typhoon Lekima in 2019, which had a poorly predicted track, with an error of 80 km away from the north of Taiwan. The original predicted track should be mapped into cluster #15, while the actual track is found in cluster #16. The projected results of the actual track and the original predicted track are given in Supplementary Figs. 42, and an averaged error <100 km has been achieved for the test typhoon events43. We expect that typhoon track forecasts for areas with topographic influence will be improved by the new prediction technology coupled with our CWB typhoon warnings before typhoon landfall. In this setting, input data of our model can be improved and more accurate flood hydrograph predictions can be made by our approach, which will provide new critical information for flood defense and water management.We notice that the quality of tropical cyclone (TC) track forecasts, especially for the track of the TC’s center, has been significantly improved over the last three decades, where errors have been reduced by two-thirds in just 25 yearsWe recognize that it is not possible to define the timing of rainfall cessation as well as the timing of typhoon departure from a watershed in advance. However, this information could be extracted simply from historical records and/or be estimated based on simple calculation, such as dividing the distance by the speed, with acceptable estimation accuracy. To improve the accuracy and reliability of flood hydrograph prediction, the next step will include the total rainfall amount and TC velocity. Although, in the present study, predictions are conducted two days ahead, extension of the prediction time interval is straightforward once improved data becomes available.While typhoon tracks may change when crossing Taiwan, the proposed methodology allows for continual updates of flood hydrograph predictions based on recent track forecasts and total rainfall before and/or during typhoon passing over Taiwan. This approach generates real-time flood hydrograph predictions needed for reservoir flood control operation as well as water resources management. For example, flood peaks and timing demand for different reservoir operations. For example, a high flood peak and rapid filling of the reservoir may threaten dam safety. An unnecessary reduction in reservoir freeboard may threaten water supply requirements.Uncertainty is intrinsic in the current state of hydro-metrological science. To capture uncertainty a more holistic and transdisciplinary science that represents important linkages between hydrology, metrology, and topography is needed in water resources management. Further, improved approaches and tools to communicate uncertainty and provide advanced warning for flood defense are more urgent than ever. Our study digitizes analog typhoon tracks for the first time. Now the vectorized track can be associated with hydrologic data and geographic characteristics to support flood hydrograph forecasting and flood defense. The framework we developed can serve as an intelligent diagnostic tool for hydro-meteorologists and can be used to characterize an approaching typhoon for making flood hydrograph predictions with real-time updates. This not only provides an adaptive early warning for flood defense as well as critical information for reservoir operation but also better communicates concerning uncertainty in support of decision and policy making to best serve our society. The methodology is simple to use and flexible with applications to tackling problems, ranging from climatic change prediction extreme event series to financial markets.The proposed AI-based methodology has three stages: typhoon track vectorization and clustering; FCC extraction; and flood hydrograph prediction, shown as follows.A total of 97 typhoons were used to build the flood hydrograph prediction model, among them 87 typhoons were used for model training and the remaining 10 typhoons were used for model testing. In the first stage, typhoon tracks required an analog to digital conversion followed by clustering of track vectors. Individual typhoon tracks were projected onto a 5 × 5 geographic grid established between 116˚ and 126˚E longitude and 20˚ and 30˚N latitude. This grid included Taiwan and surrounding areas. To provide a watershed focus this study used the Shihmen Reservoir watershed where smaller grids were developed, i.e., the grid size was further reduced to four smaller ones including huge (2˚*2˚), large (1˚*1˚), medium (0.5˚*0.5˚), and small (0.25˚*0.25˚) grids. Then a grid was marked if a typhoon passed through this grid. The size of a grid was determined mainly by the density of marked points present (the number of times a grid was marked in response to 87 typhoon events). The higher the density was, the smaller the size was. The largest grid size represented the lowest density while the smallest grid size represented the highest density, which allowed location specificity to connect typhoon tracks with watershed impacts produced by flooding. Accordingly, a total of 277 grids of different sizes constituted the gridded zone by resizing the 25 grids into finer grids, as shown in Fig. We next designed two rules to effectively vectorize typhoon tracks one by one over the gridded zone. For each typhoon, track passage over a grid element was identified. If a cluster had multiple tracks over the same grid element a positive weight value was assigned based on grid element size ; otherwise, grid elements were assigned a zero value (a zero-weight grid). Then, a weight diffusion process was carried out to address the issue of neighboring zero-weight grids that would be the most likely to reflect track variability. For large and medium weighted grid cells the adjacent zero-weight grids were re-assigned values of 0.8 and 1.5, respectively. We also diffused the weight values over two successive layers adjacent to small weighted grids by assigning their zero-weight neighbors with 2.5 (within a radius of 1) and 1 . As a result, each typhoon track could be converted into a digital vector of 277 variables (grids) with weight values  of the SOM. Because the number of input variables is limited (87-diffused vectors) and the dimension of the data is large (277 grids), only three SOMs with small map sizes  were trained to configure topological maps for selecting a suitable SOM topology for clustering purpose. The results of map size evaluation found that the 3 × 3 network could not distinctly present the classification while the 5 × 5 network resulted in a dispersion of few tracks in each cluster. In contrast, the SOM with 4 × 4 neurons provided the best mix of classification presentation and track numbers in clusters producing a typology supporting our analysis  of the typhoon. Therefore, the rise in flow in the same cluster could be inconsistent at the early stage, which would make FCCs rather different in the same cluster. The second scheme emphasized the rising limb characteristics related to the departure of the typhoon from the gridded zone. As a typhoon was approaching the watershed and an obvious increase in flow was detected, the watershed was indeed influenced by the typhoon, where flow at this stage consistently increased to reach the peak and then dropped. The influence of typhoons on flow at this stage was complicated particularly where mountains were coupled with other complex geomorphological features. A particular issue is the change in intensity class from a typhoon category to a tropical depression, which was related to the localized influence of rainfall. The third scheme was centered on the rising limb characteristics related to the cessation of rainfall. After a typhoon passed through the watershed, rainfall might cease or keep falling subject to external circulation. We noticed that the FCCs in each neuron would become more consistent in shape if the duration between the rise of flow and the cessation of rainfall was adopted. This provided good evidence that flow patterns in the same cluster (neuron) were closely related to the corresponding typhoon tracks and similar typhoon tracks would produce similar FCCs.We recognized that it was not possible to define the timing of rainfall cessation in advance. We further noticed that the timing for flow increase related to the timing of typhoon departure from a watershed could be extracted simply from historical records and/or be estimated based on simple calculation, such as dividing the distance by the speed, with acceptable estimation accuracy.The TD calculation method we developed effectively addressed concentration time in a flood hydrograph, particularly considering the inclusion of rising limb characteristics.In this study, flood hydrograph prediction offered by our proposed methodology depends mainly on four components including the forecasted typhoon track, forecasted total rainfall, typhoon track classification, and FCC extraction. For an approaching typhoon, the representative FCC of a cluster can be determined by visually identifying a matched cluster that had a typhoon track the most similar to the forecasted typhoon track announced by the CWB. Consequently, the flood hydrograph of the approaching typhoon can be derived based on the representative FCC of the best matched cluster together with the forecasted total rainfall.Supplementary InfoPeer Review File


Guidelines on public health and health system interventions often involve considerations beyond effectiveness and safety to account for the impact that these interventions have on the wider systems in which they are implemented. This paper describes how a complexity perspective may be adopted in guideline development to facilitate a more nuanced consideration of a range of factors pertinent to decisions regarding public health and health system interventions. These factors include acceptability and feasibility, and societal, economic, and equity and equality implications of interventions.A 5-step process describes how to incorporate a complexity perspective in guideline development with examples to illustrate each step. The steps include: (i) guideline scoping, (ii) formulating questions, (iii) retrieving and synthesising evidence, (iv) assessing the evidence, and (v) developing recommendations. Guideline scoping using stakeholder consultations, complexity features, evidence mapping, logic modelling, and explicit decision criteria is emphasised as a key step that informs all subsequent steps.Through explicit consideration of a range of factors and enhanced understanding of the specific circumstances in which interventions work, a complexity perspective can yield guidelines with better informed recommendations and facilitate local adaptation and implementation. Further work will need to look into the methods of collecting and assessing different types of evidence beyond effectiveness and develop procedural guidance for prioritising across a range of decision criteria. Guidelines are a key instrument in clinical practice, public health, and health system decision-making and offer recommendations on how to choose among different interventions and policies to improve health. Development of clinical practice guidelines follows a systematic and transparent process primarily focusing on and prioritising questions about the health effects of interventions . Howevercomplex intervention has often been used to describe public health and health system interventions, which: (i) have many interacting components; (ii) involve complex behaviours during their delivery and receipt; (iii) target different groups and levels; (iv) influence many health and non-health outcomes; or (v) require flexible implementation across different contexts [Complex systems, on the other hand, refer to the dynamic networks of social interactions in which interventions take place [complexity perspective to refer to the broad changes that interventions bring into the dynamic systems in which they are delivered regardless of their design features. To operationalise this perspective, we highlight key aspects of complexity derived from complex systems theory and illustrate them in the context of public health and health system interventions  guiWhether to take a complexity perspective is a decision that should be made by considering the topic and aims of a guideline and the needs of guideline users. Taking a complexity perspective entails examination of a broader range of questions in guidelines, which may require additional time and resources. In this early phase, this can be facilitated by stakeholder consultations, examination of the relevant aspects of complexity, logic modelling, evidence mapping, and a review of Evidence to Decision (EtD) criteria. Guideline panels should choose the most suitable procedure or several among these. As illustrated in Fig. While stakeholder consultation is commonly used in guideline development and increasingly in systematic reviews –27, it iThe means of involving stakeholders and their level of engagement in guideline development will depend on the topic, the stakeholders concerned, and feasibility considerations . For exaThe aspects of complexity outlined in Table Logic models provide another useful approach to facilitate decisions on taking a complexity perspective , 29, 30.Process-oriented logic models, on the other hand, display the linear or non-linear pathways that lead from the intervention to multiple outcomes considering the temporal sequence of events . Such loEvidence maps are also increasingly used in guideline scoping to obtain an overview of the existing evidence and thereby inform decisions on which aspects of complexity to consider in the guideline. Evidence maps involve systematic searches of a broad field to provide an overview and identify gaps in the evidence and/or future research needs . They ofEtD frameworks can also be used to help define guideline priorities, including important aspects of complexity, determine where systematic reviews are indicated, and add transparency in guideline development. They specify a set of criteria that inform the formulation of guideline recommendations, their direction and strength. For example, the EtD frameworks developed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group highlight the priority of the problem, balance of benefits and harms, values and preferences, quality of evidence, resource implications, equity and human rights, acceptability and feasibility . HoweverTo better address the sexual and reproductive health and human rights (SRHR) of women living with HIV, a World Health Organization (WHO) guideline was developed . To scopTaking a complexity perspective will affect both the types of questions asked and how these questions are formulated. Typically, guidelines prioritise and/or are limited to questions of effectiveness. Often these are formulated as broad questions asking whether an intervention works compared with an alternative intervention, following the PICO  framework . HoweverQuestions that extend beyond intervention effectiveness can be formulated using frameworks other than PICO. For example, PerSPEcTiF  can be used to formulate guideline questions related to stakeholder experiences with the intervention in a specific context  , 57. As  , 57. Aspositive pregnancy experience as the primary outcome. The scoping process and stakeholder consultation also led to identification of guideline priority questions and outcomes related to the effectiveness of interventions for a positive pregnancy experience. Examples of the specific questions include the following: for pregnant women (P), do diet and/or exercise interventions (I) compared with standard ANC (C) improve maternal and perinatal outcomes (O) ? Should pregnant women carry their own ANC case notes to improve quality of care ?To address aspects of complexity, the guideline panel developing recommendations on antenatal care (ANC) for a positive pregnancy experience first conducted a scoping exercise to identify and map existing guidelines related to ANC , 59. ThiStandard approaches to evidence retrieval and synthesis can be used to explore the details of the guideline PICO questions and contextual variations of the effect . For exaEvidence on questions beyond intervention effectiveness can be synthesised using quantitative, qualitative, and mixed methods synthesis. Quantitative approaches include model-driven meta-analysis, which can be used to explore intervention mechanisms driving the overall effect . Model-bSynthesis of both qualitative and quantitative evidence  might be required to answer some guideline questions. For example, quantitative evidence can inform whether the effects of a levy on soft drinks differ for people from different socio-economic backgrounds . QualitaTo inform development of a guideline on protecting, promoting, and supporting breastfeeding practices in healthy mothers with healthy full-term babies , a systeThe next step in guideline development is to assess the quality of each type of contributing evidence, including evidence on effectiveness, as well as evidence addressing broader guideline questions pertinent to complexity. Different approaches can be used based on the question and type of evidence synthesis  capacity, a broad approach to formulating questions, evidence synthesis, and evidence assessment was adopted . The guiTo develop recommendations, guideline panels should consider relevant criteria, such as those published in EtD frameworks , 52 alonTo illustrate how the criteria of the WHO-INTEGRATE framework may be used to develop specific recommendations .


Pseudomonas aeruginosa. ɸEL, an evolutionarily distant homolog of bacterial GroEL, is active in ATP hydrolysis and prevents the aggregation of denatured protein in a nucleotide-dependent manner. However, ɸEL failed to refold the encapsulation-dependent model substrate rhodanese and did not interact with E. coli GroES, the lid-shaped co-chaperone of GroEL. ɸEL forms tetradecameric double-ring complexes, which dissociate into single rings in the presence of ATP. Crystal structures of ɸEL (at 3.54 and 4.03 Å) in presence of ATP•BeFx revealed two distinct single-ring conformational states, both with open access to the ring cavity. One state showed uniform ATP-bound subunit conformations (symmetric state), whereas the second combined distinct ATP- and ADP-bound subunit conformations (asymmetric state). Cryo-electron microscopy of apo-ɸEL revealed a double-ring structure composed of rings in the asymmetric state (3.45 Å resolution). We propose that the phage chaperonin undergoes nucleotide-dependent conformational switching between double- and single rings and functions in aggregation prevention without substrate protein encapsulation. Thus, ɸEL may represent an evolutionarily more ancient chaperonin prior to acquisition of the encapsulation mechanism.Chaperonins are ubiquitous molecular chaperones found in all domains of life. They form ring-shaped complexes that assist in the folding of substrate proteins in an ATP-dependent reaction cycle. Key to the folding cycle is the transient encapsulation of substrate proteins by the chaperonin. Here we present a structural and functional characterization of the chaperonin gp146 (ɸEL) from the phage EL of  Escherichia coli . In. In39]. ntration . Note thntration , suggestsa GroES . To furt1/2 ~35 min at 25°C) [We next analyzed the effect of SP on the ATPase of ɸEL. We used as model SP the double mutant of maltose binding protein (DM-MBP), which folds slowly (tat 25°C)  in the aat 25°C) . BindingE. coli GroES) and SP.In summary, GroEL and ɸEL differ substantially with regard to their interaction with co-chaperone . This protein has a high propensity to aggregate upon dilution from denaturant into buffer, but folds efficiently upon transient encapsulation in the GroEL-GroES cage , 45–48. E. coli GroES , consistent with cycling between double- and single-ring complexes . Rho fraIn conclusion, ɸEL can bind non-native Rho in the presence of nucleotide thereby preventing aggregation. However, ATP-dependent cycling of Rho fails to promote productive folding, independent of the presence of GroES. Apparently, during cycling Rho is transiently released in an unfolded state, explaining its aggregation during gel filtration when rebinding to ɸEL is precluded.X (ADP•BeFX is a mimic of bound ATP prior to hydrolysis). However, only crystals of ɸEL with ATP•BeFX diffracted below 7 Å resolution. Two crystal forms were identified that diffracted to 4.03 and 3.54 Å resolution , an intermediate domain (residues 131–188 and 388–424), and an apical domain (residues 189–387) . These dsubunits . The apiThe ɸEL heptamer in crystal form I (4.03 Å resolution) consisted of subunits in closely similar conformations  . In confX bound in the equatorial domain. For simplicity, we modelled the bound nucleotide as ATP. ATP was cradled by the αA-β2 loop (residues 30–33), the N-terminal ends of helix αD (residues 86–90) and helix αN1 (residues 428–430), helix αO (residues 474 and 478) and residues 504–506 and 519–521 (E. coli GroEL) was at ~6.5 Å distance to the γ-phosphate of ATP, consistent with a conformation poised for ATP hydrolysis , and two new states could be assigned (conformations II and III) Figs . Subunitx was not detectable. The nucleotide electron density for the subunits with inward-oriented intermediate domain  was consistent with nucleoside triphosphate, modelled as ATP and Mg2+ , the tip of the αA-β2 loop, which cradles the nucleotide in the ATP-bound subunits, was remodeled and flipped away from ADP  and between subunits , which are important in allosteric regulation of GroEL [P. aeruginosa revealed that the protein is ATPase active and functions in aggregation prevention of denatured proteins. ɸEL forms tetradecameric double ring complexes, which dissociate into a population of single rings in the presence of ATP and at physiological salt concentration. In contrast, the recently observed dissociation of GroEL into single rings occurs only transiently during the reaction cycle [Our structural and functional analysis of the chaperonin ɸEL from the bacteriophage EL of on cycle . The nucon cycle . Our funon cycle , 5.Based on our structural and functional analysis, we propose the following hypothetical model for the chaperonin cycle of ɸEL in SP binding and release, coupled to transitions between single- and double-ring complexes. Unlike group I and II chaperonins, the ability of ɸEL to prevent protein aggregation, as tested with Rho as a model SP, was strictly nucleotide-dependent. In the apo-state, ɸEL is a double ring with six of the seven subunits per ring assuming alternating states (conformations II and III) and one subunit in conformation I . The putOnly some bacteriophage genomes encode their own chaperonin, presumably to assist in the folding of an essential phage protein(s) that cannot utilize  the host chaperonin system for folding , 54. AltS1 FigE. coli and P. aeruginosa. The mobile loop contact residues of E. coli GroES with GroEL in the crystal structure of the GroEL:GroES complex (pdb code 1pcq) are indicated by asterisks (cyan). TT, beta turn.(A) A Coomassie Blue stained gel is shown. Purified GroEL and GroES were also analyzed. The positions of molecular weight markers are indicated. (B) Absence of effect of GroES on the ɸEL ATPase. ATPase measurements were performed with increasing molar excess of GroES heptamer over ɸEL tetradecamer, as indicated. (C) Alignment of amino acid sequences of GroES from (EPS)Click here for additional data file.S2 Fig(A) ɸEL was incubated with denatured Rho in the presence of ATP for 30 min as in (EPS)Click here for additional data file.S3 Fig(A) Superposition of subunit conformers found in crystal form I. Perpendicular views of backbone traces are shown. The subunit colors are the same as in (EPS)Click here for additional data file.S4 FigC2-symmetry averaged (bottom) 3D classes. The fraction of particles and the estimated resolution of the 3D classes are indicated. The refined classes are boxed. (D) Gold-standard FSC corrected curve with unmasked map. The resolution was ~3.45 Å at the FSC cutoff of 0.143. (E) Local resolution map for the apo-ɸEL structure. Local resolutions between 7 and 3 Å are represented as a rainbow color gradient from red to blue.(A) Motion-corrected and dose-weighted raw micrograph of apo-ɸEL. For better contrast, the image was low pass filtered. The scale bar indicates 200 Å. (B) 2D class averages of apo-ɸEL particles. (C) Symmetry-free (top) and (EPS)Click here for additional data file.S5 Fig(A) Comparison of the subunits in the apo-ɸEL complex with crystal form I. Superposed backbone traces of only the apical and intermediate domains in a single ring are shown for clarity. The subunit colors of apo-ɸEL are the same as in (EPS)Click here for additional data file.S6 Fig Motion-corrected and dose-weighted raw micrographs of ɸEL•ADP (panel A) and ɸEL•ATPγS (D). The scale bar indicates 500 Å.  2D class averages of ɸEL•ADP (B) and ɸEL•ATPγS (E) particles.  Gold-standard FSC corrected curve with unmasked maps of ɸEL•ADP (C) and ɸEL•ATPγS (F). The respective resolutions were ~5.9 Å and ~5.8 Å at the FSC cutoff of 0.143.(EPS)Click here for additional data file.S7 FigE. coli are indicated above and below the sequences, respectively. Similar residues are shown in red and identical residues in white on a red background. Blue frames indicate homologous regions. The Uniprot accession codes for the sequences are: Q2Z0T5, chaperonin from Pseudomonas phage EL; P0A6F5, GroEL from E. coli.Secondary structure elements for ɸEL and GroEL from (EPS)Click here for additional data file.S8 FigApical domains of GroEL (A) and ɸEL (B) in ribbon representation (left) and surface representation (right) showing the distribution of hydrophobic and charged residues. In the GroEL apical domain, helices αI and αH are separated by a wide, deep cleft, revealing the hydrophobic underlying segment. In the ɸEL apical domain, the respective helices contact each other, resulting in a shallow furrow. The underlying hydrophobic segment is occluded. Positively and negatively charged functional groups are indicated in blue and red, respectively, hydrophobic side chains in yellow and the rest of the surface in white.(EPS)Click here for additional data file.


Clostridioides difficile or Salmonella Typhimurium infection, inflammatory bowel disease, type 1 diabetes, asthma, metabolic syndrome, obesity, Parkinson’s disease, schizophrenia and epilepsy. As we cannot address all of these interesting underlying pathophysiologic mechanisms here, we summarize the current knowledge about the physiologic and pathogenic interplay of local site microbiota and the enterohepatic BA metabolism using a few selected examples of liver and gut diseases.After their synthesis from cholesterol in hepatic tissues, bile acids (BAs) are secreted into the intestinal lumen. Most BAs are subsequently re-absorbed in the terminal ileum and are transported back for recycling to the liver. Some of them, however, reach the colon and change their physicochemical properties upon modification by gut bacteria, and vice versa, BAs also shape the composition and function of the intestinal microbiota. This mutual interplay of both BAs and gut microbiota regulates many physiological processes, including the lipid, carbohydrate and energy metabolism of the host. Emerging evidence also implies an important role of this enterohepatic BA circuit in shaping mucosal colonization resistance as well as local and distant immune responses, tissue physiology and carcinogenesis. Subsequently, disrupted interactions of gut bacteria and BAs are associated with many disorders as diverse as  The microenvironment, the tissue milieu and metabolic processes of the host’s own cells and colonizing microbial commensals have a tremendous impact on the development and function of various hematopoietic and non-hematopoietic cell populations in humans. The gut microbiota and their metabolites, for example, contribute to the regulation of many physiological processes and exhibit a pivotal role in maintaining human health. Thus, microbiota signal not only to neighboring but also to distant organs and tissues in the body and interfere, for example, with the brain (brain–gut axis), the liver (liver–gut axis) and the immune and hormone system of the host , and vicNonetheless, disrupted intestinal microbiota that accompany inflammatory processes in the gut and the subsequent altered availability of microbial- or host-derived products and metabolites are frequently associated with the pathogenesis of various complex disorders ,8,9,10. One interesting aspect of host–microbiota interactions is that host- and microbiota-derived enzymes frequently regulate the same pool of intraluminal metabolites . Some phBile acids (BAs) are hydroxylated, amphipathic steroid acids that are synthesized in the peroxisomes of the liver from cholesterol . In hepaOnce synthesized, these primary BAs are secreted into the bile, where they comprise about 80% of the organic compounds  and are However, small quantities of primary BAs also reach the colon, where certain gut bacteria transform them into secondary BAs, such as deoxycholic acid (DCA), ursodeoxycholic (UDCA) and lithocholic acid (LCA), by deconjugation, oxidation/epimerization, (7-α-) dehydroxylation and esterification ,33,34,35Both, primary and secondary BAs exert biological effects on cells of the host by activating nuclear and plasma membrane receptors, including the nuclear farnesoid X receptor (FXR) or the G protein-coupled receptor (TGR5) ,38,39,40In summary, the main functions of BAs include (a) emulsifying and digesting fat, (b) regulating and excreting cholesterol, (c) exerting antimicrobial effects and (d) eliminating bilirubin from the body ,36. HoweThe intestine hosts complex and dynamic populations of highly diverse microorganisms. These include various bacteria, archaea and eukarya, which form a mutually beneficial relationship with the host ,7. Diet,Similar to the gut, the gallbladder also harbors a complex microbiota. In contrast to the intestine, the microbiota of the biliary tract contains relatively low levels of Bacteroidetes, while numbers of Proteobacteria, Tenericutes, Actinobacteria and Cyanobacteria are increased ,60,61. SThe regulation of the BA pool is one example of the interference of the microbial metabolism with the host . The decFor example, the deconjugation of BAs by microbial bile salt hydrolases (BSH)—abundant enzymes found in all major bacterial phyla —enhances7-α-Dehydroxylation converts the primary BAs cholic (CA) and chenodeoxycholic acids (CDCA) into the secondary BAs deoxycholic (DCA) and lithocholic acids (LCA) . It is qThe effects of the intestinal microbiota presumably extend further beyond BA composition and biotransformation. In fact, germ-free and antibiotic-treated mice exhibit reduced BA excretion in the feces. In contrast, the BA pool is increased along with enhanced BA secretion and re-absorption from the intestine and an overall altered metabolic homeostasis of the host ,67,68,69As mentioned above, their amphipathic character also supplies BAs with antimicrobial activities. Thus, BAs alter the fluidity, permeability and function of cellular membranes and membrane-bound proteins ,70,71. BA disruption of the versatile interactions between BAs and microbiota can lead to many disorders. However, it has remained unclear whether compositional changes in the intestinal microbiota and/or the intraluminal metabolome are the consequence or the cause of the respective individual diseases. Nonetheless, dysbiosis usually accompanies many disorders, such as inflammatory bowel disease (IBD), or forms the basis for infections with gastrointestinal pathogens. Below, we summarize a few examples of these diseases affecting the liver–gut axis.Microbial metabolism affects BA composition. Microbiota and microbiota-derived products also confer colonization resistance against many gastrointestinal pathogens, and vice versa, BAs as well as dietary habits shape the composition of the microbiota ,79,80. TSalmonella enteritidis serovar Typhimurium (S. Typhimurium) [Salmonella spp. adapt to bile [Salmonella serovars include the upregulation of efflux pumps and outer membrane proteins, the modification of lipopolysaccharide (LPS) and membrane structures and the induction of many virulence factors, including the repression of the type 3-secretion system (T3SS), which is essential for bacterial invasion of intestinal epithelial cells [Salmonella spp. to survive in bile is a longstanding observation that is utilized for their selection and isolation in selective media, such as the bile-salt containing MacConkey agar [Dietary fat, for example, boosts intraluminal primary BA concentrations and subsequently gut colonization by imurium) , as Salm to bile , upregul to bile  and thus to bile . Survivaal cells . This abkey agar .Escherichia coli (E. coli) strains utilize several mechanisms to resist bile. These include the activation of stress response genes, promoting the repair of DNA or membrane damage, the induction of efflux pumps or the upregulation of toxin/antitoxin systems to remove bile compounds [E. coli strains, including enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and enterohemorrhagic E. coli (EHEC), also express virulence genes in response to bile exposure [E. coli strains following bile exposure.Both commensal and pathogenic ompounds ,21,22,23exposure . These pShigella flexneri and Shigella dysenteriae, two of the causative agents of Shigellosis [Exposure to bile in the small intestine also increases the virulence of gellosis , prior tClostridioides difficile (C. difficile), a spore-forming Gram-positive bacterium and the causative agent of antibiotic-associated diarrhea (AAD). The application of antibiotics disrupts the commensal microbiota that converts primary BAs into secondary BAs, which usually inhibit the germination of C. difficile spores into vegetative bacteria [C. difficile spores, bacterial replication and the production of colitis-mediating enterotoxins.Bile and the microbiota also influence the life cycle of bacteria ,25,26. SClostridium (C.) scindens [C. difficile-inhibiting metabolites from host-derived bile salts, C. scindens enhances resistance to infection with C. difficile in a secondary BA-dependent fashion [Clostridium is an example of a bile-mediated colonization resistance mechanism by intestinal microbiota. The knowledge of such mechanisms and the ecological context of microbes underlying these effects will facilitate the amplification of microbiota-mediated pathogen resistance in individuals at risk for infection.One of the few intestinal bacterial species that can actually convert primary BAs such as cholic acid into toxic secondary BAs such as deoxycholic acid is scindens . Due to  fashion . Thus, tAccumulating evidence demonstrates that intestinal microbiota also modulate enteric virus infections. For example, the modification of BAs by commensal bacteria primes type III interferon responses and subsequently inhibits an infection of the proximal small intestine with norovirus . PrimaryInflammatory bowel diseases (IBDs), such as ulcerative colitis (UC) and Crohn’s disease (CD), are characterized by immune-mediated inflammation within the gastrointestinal (GI) tract of affected patients . AlthougThe absorption of BAs in the intestine is predominantly impaired in both pre-clinical models of experimental enterocolitis and in human IBD patients . In addiC. difficile infections [Chronic cholestatic liver diseases, such as primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), are characterized by hepatic portal inflammation and slowly progress to obliterative fibrosis and eventually liver cirrhosis . The subfections . WhetherIt is well-known that the intestinal microbiota influences the efficacy of immunotherapy against tumors ,116,117.Cholecystectomy alters the bile flow into the intestine and the enterohepatic circulation of BAs and can cause intestinal microbial dysbiosis ,122,123.Bacteroides fragilis toxin (BFT or fragilysin), a metalloprotease encoded by enterotoxigenic Bacteroides fragilis (ETBF) that leads to tumorigenesis in susceptible mice, and is enriched in the mucosa of CRC patients [Secondary BA-induced dysbiosis due to other medical reasons also promoted intestinal carcinogenesis  and adenpatients  . CDCA triggered the production of the chemokine CXCL16 by liver sinusoidal endothelial cells, which subsequently led to an accumulation of natural killer T (NKT) cells, an innate (-like) lymphocyte population endowed with potent immunomodulatory properties [Removal of operties , in the operties   ,133. SexThere exists compelling evidence that co-metabolism between the host and the microbiota, as exemplified here for the enterohepatic circulation of BAs, is involved in the pathogenesis of many disorders of the gut–liver axis. Thus, the application of antibiotics to selectively deplete distinct microbiota or of BA sequestrants might be an alternative therapeutic option for the treatment of these complex disorders. However, many antibiotics are not specific for distinct bacterial species ,138, sim