Acute exacerbations of COPD in subjects completing pulmonary rehabilitation.

BACKGROUND: Improvements in health status following pulmonary rehabilitation (PR) diminish with time. Acute exacerbations of COPD (AECOPDs) negatively impact adherence after PR and likely accelerate this diminution of benefit. This study was designed to characterize the pre-AECOPD status of patients with moderate or severe COPD who had completed PR, and then to measure the impact of AECOPDs on health-related quality of life (HRQL) and functional exercise capacity.
METHODS: Sixty subjects who completed PR were enrolled in a 6-month observational study and were followed up until an AECOPD occurred. In the event of an AECOPD, primary outcome measures, the 6-min walk test (6MWT) and the chronic respiratory disease questionnaire (CRDQ), were repeated 2 weeks after the onset of symptoms. Between-group and repeated-measures analyses were performed.
RESULTS: The mean (+/- SD) age of the 53 subjects (49% female) completing the study was 68 +/- 9 years. Baseline airflow obstruction was moderate in 35 subjects (66%) and severe in 18 subjects (34%). Thirty-four subjects experienced a moderate or severe AECOPD. The mean distance walked on the baseline 6MWT in those subjects who experienced AECOPDs was 350 +/- 95 m, compared to 416 +/- 95 m walked in those subjects who did not (difference, 66 m; p < 0.02). The presence of an AECOPD was associated with significant reductions in 6MWT distance walked (difference, 59.3 +/- 80 m; p < 0.01) and in the CRDQ domains of fatigue (difference, 1 +/- 1.3; p < 0.01), emotion (difference, 0.6 +/- 0.95; p < 0.01), and mastery (difference, 0.5 +/- 1.4; p < 0.05).
CONCLUSIONS: Patients with lower functional exercise capacity are more likely to experience AECOPDs following PR. AECOPDs are associated with significant and clinically meaningful reductions in functional exercise capacity and HRQL.