Test-retest reliability, concurrent validity and correlates of the two-minute walk test in outpatients with psychosis

The aim of this study was to investigate the test-retest reliability of the 2-minute walk test (2MWT) and the concurrent validity with the 6-minute walk test (6MWT) in outpatients with psychosis. We also explored whether there was a practice effect, determined minimal detectable changes (MDC) and assessed which factors are associated with the 2MWT performance. Fifty outpatients [22 women; 33.5 (14.3) years] performed the 2MWT twice and the 6MWT once and completed the Simple Physical Activity Questionnaire (SIMPAQ) and Brief Symptoms Inventory -18. The median (interquartile) 2MWT score on the first and second test were 128.0 (44.0) meters and 128.0 (31.5) meters, without significant difference between the two trials. The intraclass coefficient was 0.94 (95% confidence interval=0.91-0.97). The significant Spearman Rho correlation between the second 2MWT and the 6MWT was 0.69. The MDC was 22 meters for men and 21 meters for women. There was no evidence for a practice effect. Variability in SIMPAQ sedentary, exercise, incidental physical activity and leg pain following the test explained 54.6% of the variance in 2MWT score. The current study demonstrates that the 2MWT is a reliable, valid and clinically feasible tool for assessing and evaluating the functional exercise capacity in outpatients with psychosis.