Frequency of exacerbations such as dyspnea, cough, and sputum production in chronic obstructive pulmonary disease (COPD) patients may be related to the severity of the disease, according to recent study.
Researchers examined literature to identify randomized controlled trials and cohort studies that directly examined the exacerbation frequency in COPD patients receiving usual care or placebo. Thirty-seven relevant studies were identified, with 43 reports of total exacerbation frequency, including 19 event-based and 24 symptom-based, and 14 reports of frequency of severe exacerbations.
Researchers then determined annual frequencies for total exacerbations defined by an increased use of healthcare, total exacerbations defined by an increase of symptoms, and severe exacerbations defined by hospitalization.
Annual event-based exacerbation frequencies were estimated at 0.82 for mild COPD, 1.17 for moderate, 1.61 for severe, and 2.10 for very severe COPD. Annual symptom-based frequencies were 1.15, 1.44, 1.76, and 2.09, respectively. For severe exacerbations, annual frequencies were 0.11, 0.16, 0.22, and 0.28, respectively.
Researchers note that study duration or type of study did not significantly affect the outcomes.