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

Background Chronic 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. Methods We 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. Results During 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 cough versus those without had cumulative incidences at age 80 years of 12% versus 3% for COPD exacerbation, 30% versus 15% for pneumonia, and 25% versus 13% for death from all causes. After adjustment for age, sex and smoking, individuals with chronic cough versus those 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 with versus without chronic cough had an absolute 5-year risk of 10% versus 4% for COPD exacerbation, 16% versus 8% for pneumonia and 19% versus 12% for all-cause mortality. Conclusion Chronic cough is associated with higher risks of COPD exacerbation, pneumonia and death, independent of airflow limitation and smoking.