Shuttle walking test as predictor of survival in chronic obstructive pulmonary disease patients enrolled in a rehabilitation program

Abstract

Background: The Incremental Shuttle Walking Test (ISWT) is used to assess exercise capacity in chronic obstructive pulmonary disease (COPD) and is employed as an outcome measure for pulmonary rehabilitation. We studied the value of this test in predicting survival in COPD patients enrolled in a rehabilitation program.

Methods: A total of 416 patients performed an ISWT before entering a 7-week outpatient pulmonary rehabilitation program. Their survival was observed over a mean period of 4.5 years (range = 1.2-7.2 years).

Results: During the observation period, 169 (40.6%) patients died. Univariate analyses showed that the ISWT as well as age, gender, present and previous tobacco smoking, forced expiratory volume in 1 second, body mass index, oxygen saturation at rest, long-term oxygen therapy, Medical Research Council dyspnea score, and treatment with oral corticosteroids were significantly associated with survival. Multivariate analysis, including relevant confounders, revealed that low ISWT was independently associated with poor survival (P = .001). The association was not linear and the risk of dying increased markedly when ISWT was lower than 170 m (RR = 2.84, 95% CI: 2.05-3.93).

Conclusion: This study shows that the ISWT is a strong and independent predictor of survival in patients with COPD enrolled in a rehabilitation program.