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 .
Enzyme replacement therapy for mucopolysaccharidosis I: a randomized, double-blinded, placebo-controlled, multinational study of recombinant human alpha-L-iduronidase (laronidase).
OBJECTIVE To confirm the efficacy and safety of recombinant human alpha-L-iduronidase ( laronidase ) in patients with mucopolysaccharidosis I ( MPS I ) . STUDY DESIGN This was a r and omized , double-blinded , multinational study of 45 patients with MPS I administered 100 U/kg ( 0.58 mg/kg ) laronidase , or placebo intravenously weekly for 26 weeks . The co primary efficacy end points compared the median change from baseline to week 26 between groups in percentage of predicted normal forced vital capacity ( FVC ) and in 6-minute walk test ( 6MWT ) distance through the use of the Wilcoxon rank sum test . RESULTS The laronidase ( n=22 ) and placebo ( n=23 ) groups had similar baseline characteristics . After 26 weeks , patients receiving laronidase compared with placebo showed mean improvements of 5.6 percentage points in percent of predicted normal FVC ( median , 3.0 ; P=.009 ) and 38.1 meters in 6MWT distance ( median , 38.5 ; P=.066 ; P=.039 , analysis of covariance ) . Laronidase also significantly reduced hepatomegaly and urinary glycosaminoglycans , and , in more severely affected patients , improved sleep apnea/hypopnea and shoulder flexion .  Laronidase was well-tolerated . Nearly all patients receiving enzyme had development of IgG antibodies , without apparent clinical effects . CONCLUSIONS In patients with MPS I , laronidase significantly improves respiratory function and physical capacity , reduces glycosaminoglycan storage , and has a favorable safety profile
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 .