Productive vs non-productive chronic cough associated with worse lung health and higher morbidity and mortality in the general population

Background: Whether productive or non-productive chronic cough is worse in the general population is unknown. We tested the hypothesis that productive vs non-productive chronic cough is associated with worse lung health and higher morbidity and mortality in the general population.

Methods: We included 44,436 random adults from the Copenhagen General Population Study, and defined productive chronic cough as a cough lasting more than 8 weeks with mucus production during the day as long as 3 consecutive months a year. We investigated differences in lung function, accompanying respiratory symptoms, morbidity, and mortality.

Results: Among 44,436 individuals, 1416 (3%) had productive chronic cough and 1380 (3%) non-productive chronic cough. Individuals with productive vs non-productive chronic cough had lower lung function (FEV1 88% vs 95% predicted, FVC 97% vs 101% predicted, and FEV1/FVC 0.72 vs 0.75), and more often accompanying respiratory symptoms (dyspnoea 5% vs 3% and wheezing 53% vs 29%), gastro-oesophageal reflux disease (36% vs 28%), and diabetes (11% vs 7%), and higher levels of inflammatory biomarkers in blood at baseline examination. Individuals with productive chronic cough vs controls had adjusted hazard ratios (HRs) of 7.2 (95% confidence interval: 4.3-12) for COPD exacerbation, 2.9 (2.2-3.8) for pneumonia, and 2.1 (1.6-2.6) for all-cause mortality. Corresponding HRs for non-productive chronic cough were 3.0 (1.4-6.2), 1.8 (1.2-2.5), and 1.5 (1.1-2.1), respectively.

Conclusion: Individuals with productive versus non-productive chronic cough have worse lung health and higher risk of morbidity and mortality.