The Responsiveness of Exercise Tests in COPD

Background

COPD is characterized by reduced exercise tolerance, and improving physical performance is an important therapeutic goal. A variety of exercise tests commonly are used to assess exercise tolerance, including laboratory and field-based tests. The responsiveness of these tests to common COPD interventions is yet to be compared, but the results may inform test selection in clinical and research settings.

Research question

What exercise test possesses the greatest sensitivity to change from before to after intervention in patients with COPD?

Study design and methods

One hundred fifty-four patients with symptomatic COPD were recruited and randomized (2:1:1) to 6 weeks of long-acting muscarinic antagonist (LAMA), pulmonary rehabilitation (PR), or usual care. Before and after intervention, participants performed a ramp-incremental cycle exercise test (ICET) and constant work rate cycle test (CWRCT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT), 6-min walk test (6MWT), and 4-m gait speed test.

Results

One hundred three participants (mean ± SD age, 67 ± 8 years; 75 male participants [73%]; FEV₁, 50.6 ± 16.8% predicted) completed the study. Significant improvements in the ICET, CWRCT, ISWT, ESWT, and 6MWT results were observed after PR (P < .05), with the greatest improvements seen in the constant work rate protocols (percentages change: CWRCT, 42%; ESWT, 41%).

Interpretation

The ESWT and CWRCT seemed to be the most responsive exercise test protocols to LAMA and PR therapy. The magnitude of change was much greater after a program of rehabilitation compared with bronchodilator therapy.

Trial registry

ISRCTN; No. 64759523.