Rationale: Exacerbations are important and heterogeneous events in the natural history of chronic obstructive pulmonary disease (COPD).
Objectives: To examine the consequences of prolonged exacerbation recovery in patients with COPD.
Methods: A cohort of 384 patients with COPD (FEV1 % predicted 45.8 [SD, 16.6] and a median exacerbation rate of 2.13 per year [interquartile range, 1.0-3.2]) were followed for 1,039 days (interquartile range, 660-1,814) between October 1995 and January 2013. Patients recorded daily worsening of respiratory symptoms and peak expiratory flow (PEF), and when stable underwent spirometry every 3 months, and completed the St. George's Respiratory Questionnaire annually. Exacerbations were diagnosed as 2 consecutive days with one major symptom plus another respiratory symptom. Exacerbation duration was defined as the time from onset to the day preceding 2 consecutive symptom-free days and recovery in PEF as return to preexacerbation levels.
Measurements and main results: A total of 351 patients had one or more exacerbations. Patients with a longer symptom duration (mean, 14.5 d) had a worse St. George's Respiratory Questionnaire total score (0.2 units per 1 day; P = 0.040). A longer symptomatic duration was associated with a shorter interval between exacerbation recovery and onset of the next exacerbation (hazard ratio, 1.004; P = 0.013). For 257 (7.3%) exacerbations, PEF did not recover within 99 days. These exacerbations were associated with symptoms of a viral infection (cold and sore throat). Patients with these nonrecovered exacerbations showed a 10.8 ml/yr (P < 0.001) faster decline in FEV1.
Conclusions: Prolonged exacerbation symptomatic duration is associated with poorer health status and a greater risk of a new event. Exacerbations where lung function does not recover are associated with symptoms of viral infections and accelerated decline in FEV1.
Keywords: COPD; exacerbations; nonrecovery; recovery; risk interval.