There is dearth of data that can establish an association between chronic productive cough (CPC), environmental tobacco smoke (ETS) exposure, and asthma in children. Hence, the present study evaluated the prevalence of CPC and estimated the interrelationship between CPC, ETS exposure, and asthma in young teenagers.

 The authors conducted a cross sectional survey of 2397 middle school students, 11–15 years old, with the help of a written and video respiratory-symptom questionnaires.  CPC was defined as daily cough productive of phlegm for at least 3 months out of the year. Current asthma was defined as yes to "Have you had wheezing or whistling in your chest in the past 12 months?" and yes in the past year to any of the four video wheezing/asthma video scenarios; and ETS exposure as exposed to tobacco smoke at least several hours each day. Multilogistic regression was used to appraise association between CPC, asthma, and ETS exposure and the potentially confounding variables race, gender, and allergic rhinitis were included in the model.

The outcome of the study revealed that prevalence of CPC was 7.2%. Almost 47% of children with CPC met criteria for current asthma, among which only 10% patients without CPC had current asthma. The strongest association of current asthma was reported with CPC, odds ratio (OR) 6.4 [95% CI 4.5–9.0], and ETS was independently related to both CPC, OR 2.7 [1.8–4.1] and asthma, OR 2.7 [1.5–4.7].

Thus, the study concluded that in a population of young teenagers, a strong association existed between CPC and report of current asthma symptoms and with ETS exposure, suggestive of the fact that asthma and ETS exposure might be implicated in the development of CPC in children.

Source: Carter ER, Debley JS, Redding GR. Chronic productive cough in school children: prevalence and associations with asthma and environmental tobacco smoke exposure. Cough. 2006 Dec 27;2:11.