Smoking patterns among adolescents with asthma attending upper secondary schools: a community-based study.

OBJECTIVE Smoking among people who have asthma may be a serious health problem. We studied the prevalence of smoking and the relations between smoking and asthma, symptoms, medicine, and gender differences among adolescents with asthma. METHODS A national cross-sectional study on health and lifestyles was performed in 1996-1997 using a computerized questionnaire in upper secondary schools in Denmark. We included 1887 pupils with asthma (defined as self-reported asthma diagnosed by a physician) and 20 688 controls. Smoking was categorized as daily, occasional, ex-smokers, and never smoked. We adjusted for age, gender, parents' job and smoking, family type, body mass index, and exercise habits. RESULTS In total, 37.7% smoked currently and 16.5% smoked daily; more girls than boys smoked. More pupils with asthma than without smoked daily (adjusted odds ratio [OR]: 1.15; 95% confidence interval [CI]: 1.04-1.33), they smoked significantly more cigarettes daily (10.3 vs 9.6), and more were heavy smokers (> or =15 cigarettes daily; adjusted OR: 1.47; 95% CI:1.14-1.91). Furthermore, nearly twice as many pupils who had asthma with symptoms but were not using medicine smoked as pupils who had asthma without symptoms and were using medicine (adjusted OR: 1.84; 95% CI: 0.99-3.41). More boys with asthma than without started smoking before 14 years of age (adjusted OR: 1.75; 95% CI: 1.09-2.81). However, more pupils with asthma had tried to quit (adjusted OR: 1.26; 95% CI: 0.99-1.60). Pupils with and without asthma were occasional smokers and ex-smokers at a similar prevalence. CONCLUSIONS More pupils with asthma than without smoked daily, and they also smoked more cigarettes per day. This is a major health concern, as adolescents have a high smoking prevalence in Denmark.