Rhinitis is an independent risk factor for developing cough apart from colds among adults

Background: In cross-sectional clinical studies, rhinitis has been shown to be strongly associated with co-existing chronic cough. However, to date, this association has been poorly delineated from a prospective and epidemiological standpoint. Methods: We used data from the 'Pisa Prospective Study', a population-based longitudinal cohort study composed of a baseline and a follow-up survey taken approximately 5 years apart from each other. Information on cough, rhinitis, and other risk factors was collected by standardized questionnaire. Cough apart from colds was denned as either 'chronic' (most days for at least 3 months for at least two consecutive years) or 'occasional' (if the three above temporal conditions were not met). 'Any' cough was denned as the presence of either occasional or chronic cough. Results: Complete information was available for 1670 subjects who were ≥15 years old and had no positive history of cough apart from colds at the baseline survey. Among them, 299 (18%) had rhinitis at baseline. By the follow-up survey, 16% of the subjects with rhinitis had developed any cough apart from colds, as compared with only 10% of the subjects without rhinitis (OR 1.7, 95% CI 1.2-2.5, P < 0.005). After adjustment for age, gender, asthma status, smoking, and occupational exposure, rhinitis remained significantly associated with an increased risk both for any cough (OR 1.8, 95% CI 1.2-2.6) and for occasional and chronic cough separately (OR 2.2, 95% CI 1.1-4.5, and OR 1.7, 95% CI 1.1-2.6, respectively). Conclusions: Rhinitis is a significant and independent risk factor for developing cough among adults. Further research is needed to assess potential implications in terms of prevention.