Impact of prolonged exacerbation recovery in chronic obstructive pulmonary disease

Abstract

INTRODUCTION: COPD exacerbations are important and heterogeneous events, but the consequences of prolonged exacerbation recovery are unknown. METHODS: A cohort of 384 COPD patients (FEV1 % predicted 45.8 (SD 16.6) and a median exacerbation rate of 2.13 per year (IQR 1.0-3.2)) were followed for 1039 days (IQR 660-1814) between October 1995 and January 2013. Patients recorded daily worsening of respiratory symptoms and peak expiratory flow (PEF), and when stable underwent 3-monthly spirometry, and completed the St. George's Respiratory Questionnaire (SGRQ) annually. Exacerbations were diagnosed as two consecutive days with one major symptom plus another respiratory symptom. Exacerbation duration was defined as the time from onset to the day preceding two consecutive symptom-free and recovery in PEF as return to pre-exacerbation levels. RESULTS: 351 patients had 1 or more exacerbations. Patients with a longer symptom duration (mean 14.5 days) had a worse SGRQ 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 non-recovered exacerbations showed a 10.8 ml/year (p<0.001) faster decline in FEV1. CONCLUSION: 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.