The minimal important deterioration of the incremental shuttle walk test in chronic obstructive pulmonary disease: a prospective cohort study

Abstract

Introduction: The incremental shuttle walk test (ISWT) is a standardized field walking test used to assess cardiorespiratory fitness, particularly in individuals with chronic cardiorespiratory conditions like chronic obstructive pulmonary disease (COPD), bronchiectasis, and idiopathic pulmonary fibrosis.1–3 It has been widely adopted as a validated measure of exercise tolerance in pulmonary rehabilitation.

The minimum important difference (MID)—sometimes called the Minimal Clinically Important Difference—is the smallest change in an outcome that patients or their clinicians perceive as beneficial (or harmful). The MID is useful for evaluating the effectiveness (or not) of clinical interventions, and for epidemiological research, but can also be used to evaluate decline over time, especially in progressive conditions.

To date, the minimum important improvement for the ISWT in COPD cohorts undergoing pulmonary rehabilitation has been established as between 35.0 m and 36.1 m using distribution- and anchor-based methods.1 However, the minimum important decline of the ISWT has not been established, and it is plausible that patients with COPD may perceive decline in a different way to improvement.

The aims of this study were to describe the change in ISWT over 1 year in people with COPD and to estimate the minimum important decline of the ISWT using distribution- and anchor-based methods.