Chronic cough associated with COPD exacerbation, pneumonia and death in the general population

Abstract

BackgroundChronic cough affects up to 10% of the general population and was previously perceived as a comorbidity of underlying conditions, but is nowadays classified as a disease in its own entity that could confer increased risk of morbidity and mortality. We tested the hypothesis that chronic cough is associated with increased risk of COPD exacerbation, pneumonia and all-cause mortality in the general population.MethodsWe identified 2801 individuals with chronic cough, defined as cough lasting >8 weeks, among 44 756 randomly selected individuals from the Copenhagen General Population Study, and recorded COPD exacerbations, pneumonia and all-cause mortality during follow-up.ResultsDuring up to 5.9 years of follow-up (median 3.4 years), 173 individuals experienced COPD exacerbation, 767 experienced pneumonia and 894 individuals died. Individuals with chronic coughversusthose without had cumulative incidences at age 80 years of 12%versus3% for COPD exacerbation, 30%versus15% for pneumonia, and 25%versus13% for death from all causes. After adjustment for age, sex and smoking, individuals with chronic coughversusthose without had adjusted hazard ratios of 4.6 (95% CI 2.9–7.2) for COPD exacerbation, 2.2 (1.7–2.7) for pneumonia and 1.7 (1.4–2.0) for all-cause mortality. Among current smokers aged >60 years with airflow limitation, those withversuswithout chronic cough had an absolute 5-year risk of 10%versus4% for COPD exacerbation, 16%versus8% for pneumonia and 19%versus12% for all-cause mortality.ConclusionChronic cough is associated with higher risks of COPD exacerbation, pneumonia and death, independent of airflow limitation and smoking.