Prevalence and risk factors for childhood asthma in Zonguldak, Turkey

Prevalence of asthma and other allergic diseases varies between different regions throughout the world. The aim of this study was to determine the prevalence of asthma and allergies and some risk factors for asthma in schoolchildren, aged between 6 and 16 years old, in Zonguldak, Turkey. We prepared 1500 questionnaires according to the International Study of Asthma and Allergies in Childhood criteria and distributed them in schools, to be completed at home by parents. Appropriately completed 1349 questionnaires, including complementary questions for risk factors, were taken into consideration. Data for air-pollutant levels of sulfurdioxide (SO₂) and total suspended particles were obtained also. The prevalence of current wheezing symptoms was 9.6% in children aged between 13 and 16 years old and 11.2% in the total sample. In terms of physician-diagnosed asthma, allergic rhinitis, and eczema, the prevalences were 4.9, 37.7, and 13.2%, respectively. A family history of allergy, diagnosis, or symptoms of allergic rhinitis and bronchitis (age range, 6-9 years) and male gender were found to be significant predictors for asthma symptoms with adjusted odds ratios of 2.089, 0.336, 4.707, 1.652, and 0.599, respectively. Strongly positive correlation between number of symptomatic asthmatic patients and air pollution levels for SO₂ (r = 0.864; p = 0.001) and total suspended particles (r = 0.891; p = 0.001) were observed also. The prevalence of asthma is high in Zonguldak, Turkey, and there is a strong correlation between air pollution and asthma symptoms. Allergy in the first-degree relatives, diagnosis of bronchitis and allergic rhinitis, age, and male gender are more important than the other factors in predicting asthma.