Is outdoor use of the six-minute walk test with a global positioning system in stroke patients' own neighbourhoods reproducible and valid?

Objective: To examine the reproducibility, responsiveness and concurrent validity of the six-minute walk test (6MWT) when tested outdoors in patients' own neighbourhoods using a global positioning system (GPS) or a measuring wheel.

Methods: A total of 27 chronic stroke patients, discharged to their own homes, were tested twice, within 5 consecutive days. The 6MWT was conducted using a GPS and an measuring wheel simultaneously to determine walking distance. Reproducibility was determined as test-retest reliability and agreement, using the intraclass correlation coefficient, standard error of measurement and Bland & Altman plots. Responsiveness was expressed as the smallest real difference and visualized in Bland & Altman plots. Pearson's correlation coefficient (r) was used to study concurrent validity between the GPS and measuring wheel.

Results: Intraclass correlation coefficiens were 0.96 for the GPS and 0.98 for the measuring wheel, and standard error of measurement scores were 11.9 m for the measuring wheel and 18.1 m for the GPS, resulting in smallest real differences of 33.0 m and 50.2 m, respectively. Concurrent validity was strong (r = 0.99).

Conclusion: These results indicate that the outdoor 6MWT using a GPS or measuring wheel is reproducible, responsive and concurrently valid. This suggests that therapists working in the community can use the outdoor 6MWT as a reliable, responsive and valid test.