The Six-Minute Walk Test in Chronic Pediatric Conditions: A Systematic Review of Measurement Properties

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 systematically review all published clinimetric studies on the 6MWT in chronic pediatric conditions. Data Sources. The databases MEDLINE, EMBASE, CINAHL, PEDro, and SPORT-Discus were searched up to February 2012. Study Selection. Studies designed to evaluate measurement properties of the 6MWT in a chronic pediatric condition were included in the systematic review. Data Extraction. The methodological quality of the included studies and the measurement properties of the 6MWT were examined. Data Synthesis. A best evidence synthesis was performed on 15 studies, including 9 different chronic pediatric conditions. Limited evidence to strong evidence was found for reliability in various chronic conditions. Strong evidence was found for positive criterion validity of the 6MWT with peak oxygen uptake in some populations, but negative criterion validity was found in other populations. Construct validity remained unclear in most patient groups because of methodological flaws. 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. Limitations. Unavailability of a specific checklist to evaluate the methodological quality of clinimetric studies on performance measures was a limitation of the study. Conclusions. Evidence for measurement properties of the 6MWT varies largely among chronic pediatric conditions. Further research is needed in all patient groups to explore the ability of the 6MWT to measure significant and clinically important changes. Until then, changes measured with the 6MWT should be interpreted with caution. Future studies or consensus regarding modified test procedures in the pediatric population is recommended.