Interpreting Changes in Endurance Shuttle Walking Performance

Rationale: The endurance shuttle walk has recently been shown to be highly responsive to both bronchodilation and pulmonary rehabilitation. The degree to which changes in endurance shuttle walking performance are perceptible to patients is unknown. Objective: To evaluate the relationship between objective and subjective measures of change in endurance shuttle walking performance. Methods: 129 comparison points were obtained from 69 patients with COPD (FEV1: 47&#177;16%) who completed two or more endurance shuttle walking tests as part of a bronchodilation study. Patients were asked to rate their performance of the day in comparison to their previous performance on a 7&S209; point scale ranging from -3 (large deterioration) to +3 (large improvement). These ratings were related to changes in walking distance and endurance time, expressed both as delta and percent change. Results: Patient ratings of change were significantly correlated with delta walking distance (r=0.44, P < 0.001), delta endurance time (r=0.46, P < 0.001), percent change in walking distance (r=0.54, P < 0.001), and percent change in endurance time (r=0.55, P < 0.001). Deteriorations in walking performance were perceived in 34% of cases, while improvements were detected in 81% of cases. Conclusion: Changes in endurance shuttle walking performance, especially improvements, are well perceived by patients with COPD. From this set of data, it should be possible to identify the smallest change in walking performance with a high likelihood of being perceived by the patients (MCID)