Longitudinal associations between exclusive, dual and polytobacco use and respiratory illness among youth.

Background: The health consequences of polytobacco use are still well not understand. We evaluated prospective associations between exclusive, dual, and polytobacco use and diagnosed bronchitis, pneumonia, or chronic cough among US youth. Methods: Data came from Waves 1-5 of the Population Assessment of Tobacco and Health Study. We categorized time-varying past 30-day tobacco use into seven categories: (1) non-current use; exclusive use of 2) cigarettes, 3) electronic nicotine delivery systems (ENDS), or 4) other combustible products (OC; pipes, hookah, and cigars); dual use of 5) ENDS + cigarettes or ENDS + OC 6) cigarettes + OC; or 7) polyuse of all three products. The outcome was incident diagnosis of bronchitis, pneumonia, or chronic cough. We conducted weighted multilevel Poisson models (person n = 17,517, 43,290 observations) to examine the longitudinal exposure-outcome relationship, adjusting for covariates: sex, age, race and ethnicity, parental education, body mass index, secondhand smoke exposure, and household use of combustible products. Results: Compared to nonuse, exclusive cigarette use (Incidence Rate Ratio (IRR) = 1.83, 95% CI 1.25-2.68), exclusive ENDS use (IRR = 1.53, 95% CI 1.08-2.15), combustible product + ENDS dual use (IRR = 1.90, 95% CI 1.18-3.04), cigarettes + OC dual use (IRR = 1.96, 95% CI 1.11-3.48), and polytobacco use (IRR = 3.06 95% CI 1.67-5.63) were associated with a higher incidence of bronchitis, pneumonia, or chronic cough. Conclusion: We found that exclusive, dual, and poly tobacco use was associated with higher incidence of bronchitis, pneumonia, or chronic cough; Moreover, the incidence rate ratio for polytobacco use was higher than the incidence rate ratio for exclusive use compared to non-current use.