The six-minute walk test (6MWT) is a self-paced, submaximal exercise test used to assess functional exercise capacity in patients with chronic diseases (Chang 2006, Solway et al 2001). It has been used widely in adults, and is being utilised increasingly in paediatric populations; it has been used as an estimate of physical fitness in, for example, children with severe cardiopulmonary disease, cystic fibrosis, and juvenile idiopathic arthritis (Hassan et al 2010).
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 SPORTDiscus 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.
The six-minute walking test (6MWT) may be a practical test for the evaluation functional exercise capacity in children with end-stage renal disease (ESRD). The aim of this study was to investigate the 6MWT performance in children with ESRD compared to reference values obtained in healthy children and, secondly, to study the relationship between 6MWT performance with anthropometric variables, clinical parameters, aerobic capacity and muscle strength. Twenty patients (13 boys and seven girls; mean age 14.1 ± 3.4 years) on dialysis participated in this study. Anthropometrics were taken in a standardized manner. The 6MWT was performed in a 20-m-long track in a straight hallway. Aerobic fitness was measured using a cycle ergometer test to determine peak oxygen uptake (V⋅O2peak)(V⋅O2peak), peak rate (Wpeak) and ventilatory threshold (VT). Muscle strength was measured using hand-held myometry. Children with ESRD showed a reduced 6MWT performance (83% of predicted, p < 0.0001), irrespective of the reference values used. The strongest predictors of 6MWT performance were haematocrit and height. Regression models explained 59% (haematocrit and height) to 60% (haematocrit) of the variance in 6MWT performance. 6MWT performance was not associated with V⋅O2peakV⋅O2peak, strength, or other anthropometric variables, but it was significantly associated with haematocrit and height. Children with ESRD scored lower on the 6MWT than healthy children. Based on these results, the 6MWT may be a useful instrument for monitoring clinical status in children with ESRD, however it cannot substitute for other fitness tests, such as a progressive exercise test to measure V⋅O2peakV⋅O2peak or muscle strength tests.
