Reliability, Validity, and Responsiveness of the Incremental Shuttle Walk Test in Patients With Interstitial Lung...

To determine the reliability, validity, and responsiveness of the incremental shuttle walk test (ISWT) in patients with interstitial lung disease (ILD).

This was a cross-sectional longitudinal study. Patients (n = 27, 10 males; mean age ± SD, 61 ± 9.8 y) with ILD of any etiology, who participated in an outpatient pulmonary rehabilitation (PR) program, were recruited. Reliability was determined by comparing the distance covered in meters between the ISWT-1 and the ISWT-2. Validity was assessed by correlating the distance covered in the ISWT-1, with the maximum oxygen consumption ((Equation is included in full-text article.)O2max) obtained through cardiopulmonary exercise testing and distance covered during the 6-min walk test (6MWT). Responsiveness was assessed by comparing the distance covered in the ISWT-3, undertaken after the completion of PR, to the ISWT-1.

The distance covered was equivalent between the ISWT-1 (216.7 ± 64.9 m) and the ISWT-2 (220.7 ± 67.3 m), with an excellent intraclass correlation coefficient (ICC2,1 = 0.91; 95% CI, 0.81-0.95). The standard error of measurement and minimal detectable change at the 95% CI (MDC95) values for the ISWT were 19.5 m and 53.9m, respectively. There were significant correlations between the distance covered on the ISWT and (Equation is included in full-text article.)O2max (r = 0.79, P < .0001) and the distance covered on the 6MWT (r = 0.76, P < .0001). Following PR, the change in the ISWT distance showed large effect size (ES = 0.85) and standardized response mean (SRM = 1.58).

The ISWT is a reliable, valid, and responsive measure of estimated functional capacity in patients with ILD.