Short Physical Performance Battery: Response to pulmonary rehabilitation and minimal important difference estimates in patients with chronic obstructive pulmonary disease

ABSTRACT Objective To determine the response to a pulmonary rehabilitation (PR) program and minimal important differences (MIDs) for the Short Physical Performance Battery (SPPB) subtests and SPPB summary score in patients with Chronic Obstructive Pulmonary Disease (COPD). Design Retrospective analysis using distribution- and anchor-based methods. Setting PR center in the Netherlands including a comprehensive 8-week inpatient and 14-week outpatient program of 40 sessions. Participants 632 patients with COPD (age: 65±8 years, 50% male, FEV1: 43 (27-47) % predicted) Intervention Not applicable. Main outcome measure Baseline and post PR results of the SPPB, consisting of three balance standing tests, 4-meter gait speed (4MGS) test and 5-repetition sit-to-stand (5STS) test. The chosen anchors were 6-minute walk test and COPD Assessment Test. Patients were stratified according to their SPPB summary scores into a low-performance, moderate-performance or high-performance group. Results 5STS (∆= -1.14 (-4.20- -0.93) seconds) and SPPB summary score (∆= 1 (0-2) points) improved after PR in patients with COPD. In patients with low-performance at baseline, balance tandem and 4MGS significantly increased as well. Based on distribution-based calculations, the MID estimates range between 2.19-6.33 seconds for 5STS and 0.83-0.96 points for SPPB summary score. Conclusions The 5STS and SPPB summary score are both responsive to PR in patients with COPD. The balance tandem test and 4MGS are only responsive to PR in patients with COPD with a low-performance at baseline. Based on distribution-based calculations, a MID estimate of 1 point for the SPPB summary score is recommended in patients with COPD. Future research is needed to confirm MID estimates for SPPB in different centres.