Six-minute-walk test in idiopathic pulmonary fibrosis: test validation and minimal clinically important difference. Lack of Specificity of the 6-Minute Walk Test as an Outcome Measure for Patients with Systemic Sclerosis [Reference Equations for the 6-Minute Walk Test in Healthy Individuals.] Six-minute walk test versus two-minute walk test in children with Duchenne muscular dystrophy: Is more time more information? Repeat six-minute walk tests in patients with chronic heart failure: are they clinically necessary? Determining the minimal clinically important difference for the six-minute walk test and the 200-meter fast-walk test during cardiac rehabilitation program in coronary artery disease patients after acute coronary syndrome. Two- and 6-minute walk tests assess walking capability equally in neuromuscular diseases Repeatability of the 6-minute walk test in adolescents and adults with cystic fibrosis. The minimal important difference in the 6-minute walk test for patients with pulmonary arterial hypertension. Comparison between an indoor and an outdoor 6-minute walk test among individuals with chronic obstructive pulmonary disease. Preliminary report of the 6-minute walk test as a predictor of radiation-induced pulmonary toxicity. Six-minute walk test closely correlates to "real-life" outdoor walking capacity and quality of life in patients with intermittent claudication. Use of the six-minute walk test poststroke: is there a practice effect? The influence of alternative instruction on 6-min walk test distance. Updating the minimal important difference for six-minute walk distance in patients with chronic obstructive pulmonary disease. Regression equations to predict 6-minute walk distance in middle-aged and elderly adults Which field walking test should be used to assess functional exercise capacity in lung cancer? an observational study
RATIONALE The 6-minute-walk test ( 6MWT ) is a practical and clinical ly meaningful measure of exercise tolerance with favorable performance characteristics in various cardiac and pulmonary diseases . Performance characteristics in patients with idiopathic pulmonary fibrosis ( IPF ) have not been systematic ally evaluated . OBJECTIVES To assess the reliability , validity , and responsiveness of the 6MWT and estimate the minimal clinical ly important difference ( MCID ) in patients with IPF . METHODS The study population included all subjects completing a 6MWT in a clinical trial evaluating interferon gamma-1b ( n = 822 ) .  Six-minute walk distance ( 6MWD )  and other parameters were measured at baseline and at 24-week intervals using a st and ardized protocol . Parametric and distribution-independent correlation coefficients were used to assess the strength of the relationships between 6MWD and measures of pulmonary function , dyspnea , and health-related quality of life . Both distribution-based and anchor-based methods were used to estimate the MCID . MEASUREMENTS AND MAIN RESULTS Comparison of two proximal measures of 6MWD ( mean interval , 24 d ) demonstrated good reliability ( coefficient = 0.83 ; P < 0.001 ) . 6MWD was weakly correlated with measures of physiologic function and health-related quality of life ; however , values were consistently and significantly lower for patients with the poorest functional status , suggesting good construct validity . Importantly , change in 6MWD was highly predictive of mortality ; a 24-week decline of greater than 50 m was associated with a fourfold increase in risk of death at 1 year ( hazard ratio , 4.27 ; 95 % confidence interval , 2.57- 7.10 ; P < 0.001 ) . The estimated MCID was 24 - 45 m. CONCLUSIONS The 6MWT is a reliable , valid , and responsive measure of disease status and a valid endpoint for clinical trials in IPF Objective . The 6-minute walk test ( 6MWT ) is an important prognostic tool in various cardiovascular diseases and has been considered as a surrogate endpoint . However , conflicting results have been reported in systemic sclerosis ( SSc ) . Our objective was to evaluate the relationships of the 6-min walking distance  ( 6MWD ) and organ damage in SSc . Methods . Eighty-seven consecutive patients with SSc were included and prospect ively investigated ; they underwent 6MWT in addition to conventional assessment of possible lung , heart , kidney , skin , and muscle involvement , and disease activity scoring , severity , and quality of life determination . Results . Twenty-six patients ( 30 % ) had an abnormal 6MWT and the mean 6MWD was 461.8 ± 103.0 m. When considering 6MWT as a binary variable — normal or abnormal — C-reactive protein ( CRP ) was the only independent variable associated with abnormal 6MWT . Considered as a continuous variable , the 6MWD was associated with measures of lung involvement and inflammation , with the activity and severity of disease , and also with quality of life ; nevertheless , calcinosis was the only independent factor associated in multivariate analyses with a trend for an association for CRP . Conclusion . The 6MWD relates to broad factors in SSc and these results raise doubts about the specificity of the 6MWD in this systemic disease , and its relevance to monitoring therapy The six-minute walk test ( 6MWT ) has been broadly used in clinical setting s. Several reference equations for prediction of the total distance walked during the test ( 6MWD ) are available in literature . The present review aim ed to critically discuss studies , published in Portuguese and English ( LILACS , SCIELO , MEDLINE , PUBMED ) , which evaluated normal values and created reference equations for predicting 6MWD in healthy subjects , comparing them with the results that were recently obtained in Brazilian individuals . Age , sex , weight , height and body mass index were the main demographic and anthropometric features more often correlated with 6MWD . The equations derived from these characteristics were able to explain between 25 and 66 % of the total variability in the 6MWD . Unfortunately , the foreign equations were not applicable to the Brazilian population . Even when the 6MWT was performed following strict st and ardization , the difference in 6MWT performance between foreign and Brazilian individuals remains , indicating the necessity of providing specific reference equations for each population and /or ethnic group . Accordingly , these equations developed in Brazil are probably the most appropriate for interpreting 6MWT performance in Brazilian patients with chronic diseases affecting the exercise capacity . Future studies are necessary with larger sample sizes ( e.g. multicentric ones ) and r and omized design for the reference values of the 6MWD to be considered reliable BACKGROUND / PURPOSE The six minute walk test is a widely accepted primary outcome parameter in most studies in Duchenne muscular dystrophy ( DMD ) . To compare information obtained by the six minute walk distance ( 6MWD ) test and the two minute walk distance ( 2MWD ) in patients with DMD , a cohort of 13 voluntary DMD boys did a repeated six minute walking test . METHODS Patients had to be ambulatory with a physical disability according to Levels 1 - 3 on the Vignos-Scale for lower extremity . Measurements were taken at one minute intervals . Reliability was measured by intraclass correlation . RESULTS Test-retest reliability for 6MWD and 2MWD in two different age classes was very good for both subgroups . Test-retest-reliability was lower in patients with more advanced disability in both tests . Walking speed remained completely stable from time points 1 - 6 minutes in the whole study patient collective , which indicates that physical exhaustion is not reached after six minutes even in more disabled patients . CONCLUSION Thus the 6MWD in DMD patients does not give additional information as compared to a 2MWD Background : Owing to a reported learning effect in patients with chronic cardiopulmonary disease , performance of at least two six-minute walk tests ( 6MWT ) are recommended as st and ard practice . Patients with chronic heart failure ( CHF ) are typically elderly and frail and it is unknown whether current guidelines are practical in a clinical setting . Aims : The aim of this study was to determine whether repeat performance of 6MWTs in patients with CHF is related to between-test interval or baseline performance . Methods : This was a multisite observational study enrolling participants entering into heart failure rehabilitation programmes . Participants performed two 6MWTs with r and omly allocated inter-test intervals between 15 and 90 minutes . Distance walked in the second test was compared with the first test using a paired t test . Results : Eighty-eight participants ( 45 females , age 65 ± 14 years ) with stable CHF were enrolled . Mean distance walked increased from 301 metres in test 1 to 313 metres in test 2 ( p < 0.001 ) . No significant change was recorded between test 1 and test 2 for those whose baseline distance was < 300 metres . The interval between tests had no significant effect on the distance walked . Conclusion : The change in 6MWT distance was significantly associated with better baseline performance but not with the interval between tests OBJECTIVE To estimate the minimal clinical ly important difference ( MCID ) for the 6-minute walk test ( 6MWT ) and the 200-m fast-walk test ( FWT ) in patients with coronary artery disease ( CAD ) during a cardiac rehabilitation program . DESIGN Prospect i ve study using distribution- and anchor-based methods . SETTING Out patients from a cardiac rehabilitation unit . PARTICIPANTS Stable patients with CAD ( N=81 ; 77 men ; mean±SD age , 58.1±8.7y ) enrolled 31±12.1 days after an acute coronary syndrome ( ACS ) . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES  6MWT and 200-m FWT results before and after an 8-week cardiac rehabilitation program and at the 6th and 12th sessions . Patients and physiotherapists who supervised the training were asked to provide a global rating of perceived change in walking ability while blinded to changes in walk test performances . RESULTS Mean change in 6MWT distance ( 6MWD ) in patients who reported no change was -6.5 m versus 23.3 m in those who believed their performance had improved ( P<.001 ) . This result was consistent with the MCID determined by using the distribution method ( 23 m ) . Considering a 25-m cutoff , positive and negative predictive values were 0.9 and .63 , respectively . Conversely , there was no difference in 200-m FWT performance between these 2 groups ( 0.1 vs -1.4s , respectively ) . There was poor agreement with the physiotherapist 's perceived change . CONCLUSIONS The MCID for 6MWD in patients with CAD after ACS was 25 m . This result will help physicians interpret 6MWD change and help research ers estimate sample sizes in further studies using 6MWD as an endpoint Objective : This method ologic study investigates if the 2-minute walk test ( 2MWT ) can be a valid alternative to the 6-minute walk test ( 6MWT ) to describe walking capability in patients with neuromuscular diseases . Methods : Patients ( n = 115 ) with different neuromuscular diseases were invited to participate on 2 test days , each consisting of 1 2MWT and 1 6MWT separated by a minimum 30-minute period of rest . The order of the walk tests was r and omly assigned via sealed envelopes . A group of 38 healthy controls completed 1 6MWT . Results : The mean walking distance for the 2MWT was 142.8 meters and for the 6MWT 405.3 meters . The distance walked in the 2MWT  was highly correlated to the distance walked in the 6MWT ( r = 0.99 , p < 0.001 ) . There was a significant decrease in walking speed from the first to last minute in the 6MWT , both among patients and healthy controls , which was not evident in the 2MWT . Results were consistent across diagnoses and levels of disease severity . Conclusion : The 2MWT is a potential alternative to the 6MWT to describe walking capability among patients with neuromuscular diseases during clinical trials OBJECTIVE To determine the repeatability of the 6-minute walk test ( 6MWT ) in adolescents and adults with cystic fibrosis ( CF ) . METHODS This was a prospect i ve cross-sectional study . We included consecutive patients ages > or=15 years attending an adult CF program . The patients underwent the 6MWT , pulmonary function tests , and clinical evaluation . The second 6MWT was performed following a rest period of 60 min . RESULTS Thirty-one patients were included . The mean+/-SD age was 23.5+/-6.7 y , and the mean FEV1 was 61+/-28 % of predicted . The mean+/-SD walked distance in the first 6MWT was 583.6+/-68.6 m and in the second 6MWT was 590.0+/-72.2 m. The mean difference between the first and second 6MWT was -6.5 m , with limits of agreement between -74.9 m and 61.9 m , and the coefficient of variation was 4.3 % . The mean oxygen desaturation in the first 6MWT was 2.5+/-4.5 % , and in the second test it was 1.8+/-4.0 % . The mean difference between the first and second test was 0.6 % , and the coefficient of variation was 104 % . CONCLUSIONS Although the 6MWT distance was reproducible , the wide limits of agreement exceeded the minimum important difference for this test . These findings indicate that , in the routine evaluation of CF patients , at least two 6MWTs are required on any testing occasion to obtain a reliable estimate of the 6MWT distance RATIONALE Although commonly used as the primary outcome measure of clinical trials in pulmonary arterial hypertension ( PAH ) , the minimal important difference ( MID ) of the 6-minute walk test ( 6MWT ) has not been well defined for this population of patients . OBJECTIVES To estimate the MID in the 6MWT in patients with PAH . METHODS Study subjects from the clinical trial of tadalafil in PAH , a 16-week , parallel-group , r and omized clinical trial of patients who were treatment naive or on background therapy with an endothelin receptor antagonist , were eligible . 6MWT was performed using a st and ardized protocol . Distributional and anchor-based methods were used to estimate the MID ; the latter method used the Physical Component Summary Score ( PCS ) of the Medical Outcomes Study 36-item short form ( SF-36 ) . MEASUREMENTS AND MAIN RESULTS Four hundred five subjects were analyzed .  Domains of the SF-36 were weakly to modestly associated with 6MWT . Change in the PCS of the SF-36 was most strongly associated with change in 6MWT ( r = 0.40 , P < 0.001 ) and thus was selected as the anchor for subsequent anchor-based analyses . Distributional analyses yielded estimates of the MID ranging from 25.1 to 38.5 m , whereas anchor-based analyses yielded an estimate of 38.6 m. CONCLUSIONS Using both distributional and anchor-based methods , the estimated consensus MID in the 6MWT for PAH is approximately 33 m. These results have important implication s for ( 1 ) assessing treatment responses from clinical trials and metaanalyses of specific PAH therapy , and ( 2 ) sample size calculations for future study design OBJECTIVES To investigate the feasibility of an outdoor 6-minute walk test ( 6MWT ) as a measure of functional status among individuals with chronic obstructive pulmonary disease ( COPD ) , and to examine the relationship between performance on an indoor and an outdoor 6MWT . DESIGN An experimental , repeated- measures crossover design . Subjects were studied on 2 separate days in the same week . Two 6MWTs-one indoors and the other outdoors-were performed on each study day , with a rest in between . The test order was r and omly selected on the first day and reversed on the second day . Outdoor tests were performed on days of moderate weather conditions ( mean temperature + /- st and ard deviation , 21 degrees + /-3 degrees C ; mean wind speed , 15+/-7 km/h ; no precipitation ) and on a flat surface ( sidewalk ) . SETTING  Outpatient rehabilitation program in Ontario . PARTICIPANTS Eighteen subjects with COPD ( 10 men , 8 women ; age , 70+/-8y ) , 5 using supplemental oxygen at rest ( forced expiratory volume in 1s , 1.0+/-0.3L ; 42%+/-8 % of predicted ) . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES Distance walked in 6 minutes ( in meters ) , duration of rest ( in seconds ) , and change in rate of perceived dyspnea . RESULTS There was no significant effect of setting ( indoors vs outdoors ) on distance walked ( 394+/-86 m vs 398+/-84 m , P=0.4 ) , duration of rest ( 13+/-28s vs 9+/-20s , P=0.4 ) , or change in rate of perceived dyspnea ( 2.3+/-1.7 vs 2.3+/-2.0 , P=0.8 ) . Testing day had no significant effect on walk test performance ( all P>0.1 ) . CONCLUSIONS The results indicate that the 6MWT performed outdoors within reasonable climatic parameters may be reflective of 6MWT performance indoors PURPOSE To assess the 6-minute walk test ( 6MWT ) as a predictor of  radiation therapy-induced lung injury ( RTLI ) .  METHODS AND MATERIAL S The 6MWT is a simple , economical , and reproducible test that measures both how far a person can walk in 6 min and any associated changes in vital signs . As part of a prospect i ve trial to study RTLI , a pre-RT 6MWT was performed in 41 patients . The predictive capacities of pre-RT 6MWT , forced expiratory volume in 1 s ( FEV1 ) , and single-breath diffusing capacity for carbon monoxide ( DLCO ) for the development of RTLI were assessed with receiver operating curve ( ROC ) techniques . To evaluate the 6MWT , alone or with mean lung dose ( MLD ) of radiation , as a predictor of RTLI , the rates of RTLI in patient subgroups defined by 6MWT results were compared by using Fisher 's exact test . RESULTS Thirty-one patients with > or =3 months ' follow-up were evaluable . The median baseline 6MWT result was 1400 ft . Of 31 patients , 7 developed Grade > or = 2 RTLI . Of 15 patients with an MLD > 18 Gy ( the median ) , 5 developed RTLI , compared with 2 of 16 with MLD < or = 18 Gy ( p = 0.22 ) . Among those with an MLD < or = 18 Gy , the RTLI rates were 0 of 8 and 2 of 8 for 6MWT results > or = 1400 ft or < 1400 ft , respectively , p = 0.46 . The ROC area under the curve for individual metrics was as follows : FEV1 0.66 , MLD 0.70 , DLCO 0.61 , and 6MWT 0.47 . Combining FEV1 with 6MWT increased the ROC to 0.71 , suggesting that the ratio might be a better predictor than the individual values . Patients with a high 6MWT/FEV1 ratio had a lower rate of RTLI than those with a relatively low ratio . CONCLUSIONS The 6MWT might provide prognostic information beyond pulmonary function tests and dosimetric parameters in predicting RTLI . Additional work is needed to better assess the utility of these functional metrics OBJECTIVE We used outdoor walking distance measured during 40 minutes as " real-life " outdoor walking capacity in 49 patients with intermittent claudication ( IC ) . The outdoor walking distance was measured by a global positioning system application for a smartphone . The relationships of self-reported maximum walking distance ( SR-MWD ) , the MWD on a grade d treadmill test , and the 6-minute maximum walk distance ( 6MWD ) vs outdoors walking capacity were investigated . Also studied were the associations of SR-MWD , MWD , and 6MWD with health-related quality of life assessed with the disease-specific instrument the  Vascular Quality of Life Question naire ( VascuQoL ) . METHODS In this prospect i ve observational cohort study , 49 IC patients underwent an  outdoor walking capacity test for 40 minutes , and MWD and 6MWD were measured . SR-MWD was recorded , and all subjects completed the VascuQoL question naire . Associations between the different walk estimates and outdoor walking capacity and health-related quality of life were investigated by correlation analysis ( Spearman ρ ) . RESULTS Outdoor walking distance during 40 minutes was a median 2495 m ( range , 1110 - 3300 m ) . SR-MWD correlated moderately and MWD correlated strongly to outdoor walking capacity ( r = 0.56 and r = 0.65 ; P < .001 , respectively ) . The 6MWD test showed the largest correlation to the outdoor walking capacity ( r = 0.78 ; P < .001 ) . The 6MWD was the only test that showed correlations with the VascuQoL sum score ( r = 0.53 ; P < .01 ) and all of the domain scores , whereas SR-MWD and MWD showed weak correlations to the VascuQoL. CONCLUSIONS The distance walked during the 6-minute walk test is closely correlated to outdoor walking capacity and health-related quality of life in IC patients . Our data support the use of 6MWD for routine clinical evaluation of walking capacity in IC patients OBJECTIVES To determine whether a practice effect occurs across 2 trials of the six-minute walk test ( 6MWT ) among community-dwelling people within 1 year poststroke and to identify characteristics distinguishing people who show a practice effect from those who do not . DESIGN Secondary analysis of scores on 2 trials of the 6MWT administered approximately 30 minutes apart at baseline in a r and omized controlled trial . SETTING General community . PARTICIPANTS People ( N=91 ) living in the community with a residual walking deficit within the first year of a first or recurrent stroke . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURE Distance walked on the 6MWT .  RESULTS Mean 6MWT scores + /- SD for trials 1 and 2 were 196+/-119 m and 197+/-126 m , respectively ( n=83 ) . The mean difference in 6MWT performance across trials was 0+/-35 m ( 95 % confidence interval [ CI ] , -7 to 8 m ) . The Pearson correlation coefficient between 6MWT distances was .96 ( P<.001 ) , and the intraclass correlation coefficient was .98 ( 95 % CI , .97-.99 ) . The Bl and -Altman plot showed no clear pattern . Participants whose improvement was equal to or greater than the minimal detectable change of 29 m between trials ( 14 % ) did not significantly differ from those in the rest of the study sample ; however , they tended to be younger ( P=.05 ) and more likely to have a mild or moderate gait deficit ( P=.06 ) . CONCLUSIONS Findings do not support a practice effect across 2 trials of the 6MWT in individuals within 1 year poststroke . Thus , a practice walk does not appear necessary . Further research is recommended to evaluate the influence of young age , acute stroke , and mild-to-moderate gait deficit on practice effects BACKGROUND The goal of the 6-min walk test ( 6MWT ) is to enable patients to walk " as far as possible " as a measure of their functional ability . The impact of the specific walk instructions on patient 6MWT performance is unknown . METHODS Patients with pulmonary arterial hypertension ( PAH ) , idiopathic pulmonary fibrosis ( IPF ) , and other forms of interstitial lung disease ( ILD ) were recruited to perform four identical 6MWTs with one differing instructional phrase . The st and ard instruction to walk " as far as possible " was substituted in r and om order with " as fast as possible , " " at your normal pace , " or " at a leisurely pace . " RESULTS Twenty-four patients ( 10 with PAH , eight with IPF , six with other ILD ) were enrolled and completed all four 6MWTs . Patients attained the greatest distance with the fast instruction , exceeding the st and ard instruction distance by a mean of 52.7 m ( P < .001 ) . The mean difference between the fast and st and ard walks was 41.5 m in the PAH group , 66.5 m in the IPF group , and 53 m in the other ILD group . CONCLUSIONS Patients do not walk as far as they are able with the st and ard American Thoracic Society instruction for 6MWT . Changing the wording from " far " to " fast " may facilitate a better effort and greater distance during the test . It is possible that this modified 6MWT instruction may result in improved accuracy and reproducibility , thereby enhancing its clinical and research trial usefulness OBJECTIVE To establish the minimal important difference ( MID ) for the six-minute walk distance ( 6MWD ) in persons with chronic obstructive pulmonary disease ( COPD ) . DESIGN Analysis of data from an observational study using distribution- and anchor-based methods to determine the MID in 6MWD . SETTING Outpatient pulmonary rehabilitation program at 2 teaching hospitals . PARTICIPANTS Seventy-five patients with COPD ( 44 men ) in a stable clinical state with mean age 70 years ( SD 9 y ) , forced expiratory volume in one second 52 % ( SD 21 % ) predicted and baseline walking distance 359 meters ( SD 104 m ) . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES Participants completed the  six-minute walk test  before and after a 7-week pulmonary rehabilitation program . Participants and clinicians completed a global rating of change score while blinded to the change in 6MWD . RESULTS The mean change in 6MWD in participants who reported themselves to be unchanged was 17.7 meters , compared with 60.2 meters in those who reported small change and 78.4 meters in those who reported substantial change ( P=.004 ) . Anchor-based methods identified an MID of 25 meters ( 95 % confidence interval 20 - 61 m ) . There was excellent agreement with distribution-based methods ( 25.5 - 26.5 m , kappa=.95 ) . A change in 6MWD of 14 % compared with baseline also represented a clinical ly important effect ; this threshold was less sensitive than for absolute change ( sensitivity .70 vs .85 ) . CONCLUSIONS The MID for 6MWD in COPD is 25 meters . Absolute change in 6MWD is a more sensitive indicator than percentage change from baseline . These data support the use of 6MWD as a patient-important outcome in research and clinical practice Six-minute walk distance ( 6MWD ) is commonly used as a measure of functional exercise capacity in clinical practice and research . Regression equations to predict 6MWD in healthy individuals are available , but the equations predict distances that vary considerably for an individual . The aims of this study were to 1 ) measure 6MWDs in healthy Caucasian Australians aged 45 - 85 years ; 2 ) determine whether evidence exists for Australian-specific prediction equations for Caucasian individuals by comparing measured 6MWDs with predicted 6MWDs derived by using published regression equations ; and 3 ) develop regression equations for males and females . One hundred nine subjects ( 48 males ) completed the 6-minute walk test ( 6MWT ) . Measurements of height , leg length , weight , habitual physical activity , and peak heart rate ( HR ) achieved during the 6MWT were obtained . 6MWD ( better of two tests ) was 682 ± 73 m ( mean ± SD ) and 643 ± 70 m in the males and females , respectively ( p<0.01 ) . Published regression equations underestimated 6MWDs in female subjects . Gender-specific regression equations using age and anthropometric data explained 40 % and 43 % of the variance in 6MWD in males and females , respectively . Validation of the regression equations in a prospect i ve subject cohort is required Background There is emerging evidence regarding the efficacy of exercise training to improve exercise capacity for individuals with non-small cell lung cancer ( NSCLC ) .  Cardiopulmonary exercise testing ( CPET ) is the gold st and ard measure of exercise capacity ; however this laboratory test has limitations for use in research and clinical practice . Alternative field walking tests are the six-minute walk test ( 6MWT ) , incremental-shuttle walk test ( ISWT ) and endurance-shuttle walk test ( ESWT ) ; however there is limited information about their clinimetric properties in NSCLC . Aims : In NSCLC to determine the 1 ) criterion validity of the 6MWT , ISWT and ESWT against CPET ; 2 ) construct validity of the 6MWT , ISWT and ESWT against measures of function , strength , respiratory function and health-related quality of life ( HRQoL ) ; and 3 ) clinical applicability of the tests . Methods Twenty participants ( 40 % male , mean ± SD age 66.1 ± 6.5 years ) with stage I-IIIb NSCLC completed the 6MWT , ISWT , ESWT and CPET within six months of treatment . Testing order was r and omised . Additional measures included Eastern Cooperative Oncology Group Performance-Status ( ECOG-PS , function ) , respiratory function , h and -grip dynamometry and HRQoL. Correlations and regression analyses were used to assess relationships . Results The ISWT demonstrated criterion validity with a moderate relationship between ISWT distance and CPET peak oxygen consumption ( r = 0.61 , p = 0.007 ) . Relationships between CPET and six minute walk distance ( 6MWD ) ( r = 0.24 , p = 0.329 ) or ESWT time ( r = 0.02 , p = 0.942 ) were poor . Moderate construct validity existed for the 6MWD and respiratory function ( forced vital capacity % predicted r = 0.53 , p = 0.019 ; forced expiratory volume in the first second % predicted r = 0.55 , p = 0.015 ) . There were no relationships between the walking tests and measures of function , strength or HRQoL. The ESWT had a ceiling effect with 18 % reaching maximum time . No floor effects were seen in the tests . The mean ± SD time required to perform the individual 6MWT , ISWT and ESWT was 12.8 ± 2.5 , 14.7 ± 3.7 and 16.3 ± 5.0 min respectively ; in comparison to CPET which was 51.2 ± 12.7 min . Only one assessor was required to perform all field walking tests and no adverse events occurred . Conclusions The ISWT is a promising measure of functional exercise capacity in lung cancer . Findings need to be confirmed in a larger sample prior to translation into practice
Limited evidence to strong evidence was found for reliability in various chronic conditions .
Little evidence was available for responsiveness and measurement error .
Studies showed large variability in test procedures despite existing guidelines for the performance of the 6MWT .
Evidence for measurement properties of the 6MWT  varies largely among chronic pediatric conditions .
BACKGROUND The Six-Minute Walk Test ( 6MWT ) is increasingly being used as a functional outcome measure for chronic pediatric conditions .
Knowledge about its measurement properties is needed to determine whether it is an appropriate test to use .
PURPOSE The purpose of this study was to systematic ally review all published clinimetric studies on the 6MWT in chronic pediatric conditions .