Significance of changes in endurance shuttle walking performance

Abstract

BackgroundThe endurance shuttle walking test (ESWT) has shown good responsiveness to interventions in patients with chronic obstructive pulmonary disease (COPD). However, the minimal important difference (MID) for this test remains unknown, therefore limiting its interpretability. Methods Patients with COPD who completed two or more ESWTs following pulmonary rehabilitation (n¼132; forced expiratory volume in 1 s (FEV 1 ) 48622%) or bronchodilation (n¼69; FEV 1 50612%) rated their performance of the day in comparison with their previous performance on a 7-point scale ranging from À3 (large deterioration) to +3 (large improvement). The relationship between subjective perception of changes and objective changes in performance during the shuttle walk was evaluated.Results Following pulmonary rehabilitation, the anchorbased approach did not allow a valid estimation of the MID in the ESWT performance to be obtained. After bronchodilation, patient ratings of change correlated significantly with the difference in walking distance (r¼0.53, p<0.001) and endurance time (r¼0.55, p<0.001). For the pharmacotherapy data, regression analysis indicated that a 65 s (95% CI 45 to 85) change in endurance time and a 95 m (95% CI 60 to 115) change in walking distance were associated with a 1-point change in the rating of change scale. These changes represented 13e15% of the baseline values. Conclusions A change in endurance shuttle walking performance of 45e85 s (or 60e115 m) after bronchodilation is likely to be perceived by patients. This MID value may be specific to the intervention from which it was derived.

Prospective validation of the endurance shuttle walking test in the context of bronchodilation in COPD

“…In addition, these values are in accordance with previously suggested MID values obtained in patients with COPD [13]. The present estimates were Data are presented as intraclass correlation (95% CI).…”

“…MID values were estimated using both distribution-and anchor-based approaches, similarly to our previous investigation [13]. For the distribution-based approach, half the SD of the change in ESWT performance provided the MID estimates [17].…”

“…The use of the ESWT for the evaluation of patients with COPD has become increasingly popular in research and clinical fields [8,9,13]. However, the methodological validation of the ESWT is limited.…”

“…As previously suggested [13,25,26], different methods should be combined for the determination of MID values, considering that there is no consensus in favour of a single best methodology for the determination of MID estimate and that this estimate should be viewed as a range of probable values rather than as a discrete value.…”

“…Another issue is the interpretation of changes in ESWT performance after an intervention. In a prior study from our group, estimates of the minimal important difference (MID) from the patients' perspective were provided for changes in ESWT performance [13]. In this prior study, it was determined that a change in ESWT performance of 45-85 s or 60-115 m after bronchodilation could be perceived by patients (n569).…”