Active smoking increases risk for asthma symptoms in adolescents

Smoking significantly increases the risk for asthma symptoms and reduced lung function in adolescents, Korean study results show.
“Active smoking is known to increase asthma symptoms and bronchial hyper-responsiveness (BHR) while decreasing pulmonary function in adults, but few studies have addressed these issues in adolescents,” explain S Hong (University of Ulsan College of Medicine, Seoul) and colleagues.
The team therefore studied 1492 adolescents, aged between 15 and 16 years, from three urban areas of South Korea. All the participants completed a questionnaire on active smoking, passive smoking, and respiratory symptoms. They also supplied urine samples for analysis of cotinine levels.
Participants were defined as current smokers if they had smoked more than one cigarette a day over the previous 30 days or had urine cotinine levels of at least 100 ng/ml.
A subgroup of 724 adolescents also underwent spirometry, skin prick tests, and methacholine challenge.
Overall, 8.2% of boys and 2.4% of girls who participated in the study were identified as current smokers.
The researchers found that 15.2% of adolescent smokers reported wheezing and 20.4% reported experiencing exercise-induced wheezing in the previous 12 months compared with 8.5% and 10.7%, respectively, of non-smoking adolescents.
After accounting for factors such as passive smoking and a family history of asthma, the researchers calculated that current smoking was associated with a 4.5-fold increased risk for wheeze and an 8.7-fold increased risk for exercise-induced wheeze in the previous 12 months, compared with never smoking.
Furthermore, smokers had poorer lung function than non-smokers, but there was no significant difference in the prevalence of BHR between the two groups.
The researchers also note in the journal Pediatric Pulmonology that the effect of smoking on wheeze and exercise-induced wheeze was more pronounced in non-atopic than atopic individuals.
Hong and team conclude: “We herein show that active smoking appears to increase self-reported wheezing, especially in non-atopic adolescents, and lower pulmonary function, but does not appear to affect BHR.
“Therefore, smoking may be an independent risk factor for the development of asthma symptoms [in adolescents].”
Sources: Medwire News, 17 September 2009
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