Asthma is an important chronic disease all over the world. The aim of this study was to determine the prevalence of asthma in a population of male late adolescents and its association with some contributing risk factors in northwest of Iran. This cross-sectional study was carried out in selected high schools of Tabriz, Iran, in 2016. The asthma prevalence and patient background information were examined using a questionnaire that prepared by the ISAAC. One hundred forty-two out of 1134 subjects (12.4%) identified to have asthma, 23.3% had history of current wheeze, and 16.3% had wheezing in the previous year. Family history of asthma was present in 17.1% of the participants; prevalence of active smoking in the study subjects was 3.1%; 25.1% of all subjects had exposure to secondhand tobacco smoke and keeping pets at home was present in 9.1%. Excess weight (overweight and obesity) was positively associated with prevalence of asthma (p < 0.001). No statistically significant associations were observed between asthma and father's education level (p = 0.570), mother's education level (p = 0.584), type of birth subjects (p = 0.571), and time spent outdoors during a full day (p = 0.863). Our results suggest that family history of asthma and atopy, exposure to secondhand tobacco smoke, active smoking, amount of automobile traffic around subjects' home, and keeping pets at homes are important risk factors for asthma, while time spent outdoors, educations of parents, and delivery type (normal vaginal delivery vs. C-section) subjects are not. Therefore, decreased of exposure to some environmental risk factors could be effective to reduce rate of the prevalence of asthma and wheeze.
Keywords: Asthma; ISAAC; Late adolescents; Prevalence.