Prevalence of asthma and related symptoms in primary school children of Isfahan, Iran, in 1998.

As developing countries adopt an industrialized style of living, an increase in asthma prevalence can be expected. A cross sectional study was undertaken to evaluate the prevalence rates of asthma and related symptoms and clinical findings in Isfahan, Iran. A randomly selected population of Isfahan primary school children, consisting of 3,982 children aged 6 to 11 was enrolled in the study. Parents completed a Persian questionnaire modified from ISAAC and ECRHS questionnaires. The returned 3,828 (96.1%) questionnaires were reviewed and 686 children suffering from asthma or any of the related symptoms were invited for further evaluations. In this stage 655 children (95.5%) underwent a medical interview and physical examinations, of which 415, underwent post exercise spirometry and body-plethysmography. The prevalence rates for previously diagnosed asthma, dyspnea and wheezing ever, dyspnea and wheezing in the last 12 months and frequently recurring dyspneal attacks were 0.71%, 7.6%, 3.9% and 1.6%, respectively. Wheezing was heard upon auscultation of the chests of 70 children (10.7%). Forced expiratory volume in 1st second (FEV1) < 80% of prediction was recorded in 3.1% of the children, other findings included reduced peak expiratory flow rate (PEF), mean expiratory flow 25 to 75 percent (FEF 25-75), forced expiratory flow at 75% of FVC (FEF 75), and increased residual volume (RV) and air-ways resistance in 4.3%, 10.6%, 21.2%, 30.1% and 63.2% of the pupils, respectively. We conclude that asthma screening programs employing clinical methods should be encouraged, but measurement of airway resistance is not a suitable tool for epidemiologic studies.