Ethnic and Gender Differences in Cough Reflex Sensitivity

Abstract

Background: Although recent studies have suggested that the cough reflex is more sensitive in women than in men, ethnic differences in cough reflex sensitivity have not previously been investigated. Objectives: To evaluate ethnic and gender differences in cough reflex sensitivity. Methods: We performed capsaicin cough challenge testing in 182 healthy volunteers of three distinct ethnic groups: Caucasian (white, non-Hispanic, of European origin), Indian (originating from the Indian subcontinent) and Chinese. The concentration of capsaicin inducing 2 or more (C₂) and 5 or more coughs (C₅) was determined in each subject. Results: Mean (±SEM) values for log C₅ demonstrated that, within each ethnic group, the cough reflex was more sensitive in women: p = 0.00002 for Caucasian subjects; p = 0.003 for Indian volunteers; and p = 0.002 for Chinese subjects. Examination of C₂ data yielded similar results. When subjects were evaluated by gender, multivariate analysis of variance demonstrated no ethnic differences in sensitivity to capsaicin. Conclusion: Our data do not support the presence of significant ethnic differences in cough reflex sensitivity, but do confirm previous data demonstrating lower cough thresholds in women.