Prevalence, incidence and characteristics of chronic cough among adults from the Canadian Longitudinal Study on Aging

Abstract

The global prevalence of chronic cough is highly variable, ranging from 2% to 18%. There is a lack of data on the prevalence and incidence of chronic cough in the general population. The objective of this study was to investigate the prevalence and incidence of chronic cough in a sample of Canadian adults, and how these are influenced by age, sex, smoking, respiratory symptoms, medical comorbidities and lung function. Participants with chronic cough were identified from the Canadian Longitudinal Study on Aging (CLSA) based on self-reported daily cough in the past 12 months. This is a prospective, nationally generalisable, stratified random sample of adults aged 45-85 years at baseline recruited between 2011 and 2015, and followed-up 3 years later. The prevalence and incidence per 100 person-years are described, with adjustments for age, sex and smoking. Of the 30 097 participants, 29 972 completed the chronic cough question at baseline and 26 701 did so at follow-up. The prevalence of chronic cough was 15.8% at baseline and 17.6% at follow-up with 10.4-17.1% variation across seven provinces included in the CLSA comprehensive sample. Prevalence increased with age and current smoking, and was higher in males (15.2%), Caucasians (14%) and those born in North America, Europe or Oceania (14%). The incidence of chronic cough adjusted for age, sex and smoking was higher in males and in underweight and obese subjects. Subjects with respiratory symptoms, airway diseases, lower forced expiratory volume in 1 s (% predicted), cardiovascular diseases, psychological disorders, diabetes and chronic pain had a higher incidence of chronic cough. The prevalence and incidence of chronic cough is high in the CLSA sample with geographic, ethnic and gender differences, influenced by a number of medical comorbidities.

FIGURE 1

Prevalence of chronic cough based on age, sex and smoking status at baseline.

FIGURE 2

The associations of symptoms, lung function, airflow obstruction and airways diseases on the prevalence of chronic cough at baseline. Data are presented as mean (95% CI). FEV₁: forced expiratory volume in 1 s; CAO: chronic airflow obstruction; LLN: lower limit of normal; SOB: shortness of breath.

FIGURE 3

Adjusted (age, sex, smoking) incidence rates of chronic cough for respiratory symptoms, airways diseases, lung function and airflow obstruction. Data are presented as mean (95% CI). FEV₁: forced expiratory volume in 1 s; CAO: chronic airflow obstruction; LLN: lower limit of normal; SOB: shortness of breath.

FIGURE 4

Adjusted (age, sex, smoking) incidence rates of chronic cough in the presence of other medical comorbidities. Data are presented as mean (95% CI). AMI: acute myocardial infarction; CHF: congestive heart failure; GI: gastrointestinal.