Impact of Productive and Dry Chronic Cough on Mortality in the Canadian Longitudinal Study on Aging (CLSA)

Background: Chronic cough is a common troublesome condition and accounts for a high burden on quality of life. Previous data investigating the mortality associated with chronic cough has been derived in patients with chronic bronchitis. No data exists on chronic dry cough. Therefore, we investigated if chronic dry and productive cough is independently associated with increased mortality.

Methods: The Canadian Longitudinal Study on Ageing (CLSA) is a prospective, nationally generalizable, stratified random sample of adults aged 45-85 years at baseline recruited between 2011-2015 and followed up three years later. Chronic cough was identified based on a self-reported daily cough in the last 12 months. Deaths were confirmed by the Ministry of Health and/or completion of descendent questionnaire by a family member. Models were investigated for dry and productive chronic cough and was adjusted for age, sex, smoking, body mass index (BMI), and respiratory diseases.

Results: Of the 30,016 participants, 4,783 (15.9%) reported chronic cough at baseline; 2,724 (57%) had a dry cough, and 2,059 (43%) had productive chronic cough. There was a total of 561 deaths between baseline and follow-up-1 (3 years later). There was a 49% higher risk of death in participants with chronic productive cough {adjusted odds ratio (aOR) 1.49 [95% confidence intervals (CI): 1.08-2.07]}, but not dry chronic cough [aOR 0.85 (0.60-1.20)]. The effects of chronic productive cough on mortality were persistent in those with no airflow obstruction [chronic productive cough aOR 1.90 (1.09-3.31)].

Conclusions: Chronic productive cough is associated with a higher risk of death, while chronic dry cough has no impact on mortality risk of death in middle-aged and older adults. This highlights the importance of careful evaluation of patients with chronic cough.