Smoking and the incidence of respiratory affliction in young adults

Background: Although suspected, detailed evidence from population-based cohort studies on the relation of smoking to incidence of respiratory disease in young adults is limited. Methods: We report data from the Study of Occupational Allergy Risks (SOLAR) conducted in Dresden and Munich (Germany). The study population (n=1869) was first studied in 1995/96at age 9–11 years with a parental questionnaire and a clinical examination. At the follow-up in 2002/03 and 2007/08 the young adults completed questionnaires on respiratory health, living and exposure conditions. At the second follow-up they again underwent a clinical examination. We calculated relative risks (RR) with 95% confidence intervals (95% CI) and adjusted for confounders using a modified poisson regression approach. Results: In total, 45.3% smoked for at least one year. The median duration of smoking was 6.5 years. Of the smokers, about 30% consumed more than 10 cigarettes per day in the month preceeding each follow-up. Parental smoking increased the likelihood of adolescent smoking while higher parental education and parental allergic disease independently decreased it. Wheeze or atopy at baseline did not contribute to this decrease. Smoking increased the incidence of both, cough and wheeze without a cold almost 2.5-fold. Smoking before the age of 16 conferred greater risk than later onset of smoking, in particular for wheeze without a cold [RR 2.79, 95% CI (1.70; 4.58) vs. 1.74 (0.98; 3.08)]. For both, intensity and duration of smoking we detected dose response relationships: the more the worse. Conclusion: Smoking in adolescence has significant influence on respiratory health of young adults and has to remain in the focus of public health efforts.