Time course and recovery of exacerbations in patients with chronic obstructive pulmonary disease

Although exacerbations of chronic obstructive pulmonary disease (COPD) are associated with symptomatic and physiological deterioration, little is know n of the time course and duration of these changes. We have studied symptom s and lung function changes associated with COPD exacerbations to determine factors affecting recovery from exacerbation. A cohort of 101 patients wit h moderate to severe COPD (mean FEV, 41.9% predicted) were studied over a p eriod of 2.5 yr and regularly followed when stable and during 504 exacerbat ions. Patients recorded daily morning peak expiratory flow rate (PEFR) and changes in respiratory symptoms on diary cards. A subgroup of 34 patients a lso recorded daily spirometry. Exacerbations were defined by major symptoms (increased dyspnea, increased sputum purulence, increased sputum volume) a nd minor symptoms. Before onset of exacerbation there was deterioration in the symptoms of dyspnea, sore throat cough, and symptoms of a common cold ( all p < 0.05), but not lung function. Larger falls in PEFR were associated with symptoms of increased dyspnea (p = 0.014), cords (p = 0.047), or incre ased wheeze (p = 0.009) at exacerbation. Median recovery times were 6 (inte rquartile range [tQR] 1 to 14) d for PEFR and 7 (IQR 4 to 14) d for daily t otal symptom score. Recovery of PEFR to baseline values was complete In onl y 75.2% of exacerbations at 35 d, whereas in 7.1% of exacerbations at 91 d PEFR recovery had not occurred. In the 404 exacerbations where recovery of PEFR to baseline values was complete at 91 d, increased dyspnea and colds a t onset of exacerbation were associated with prolonged recovery times (p < 0.001 in both cases). Symptom changes during exacerbation do not closely re flect those of lung function, but their increase may predict exacerbation, with dyspnea or colds characterizing the more severe. Recovery is incomplet e in a significant proportion of COPD exacerbations.