Prevalence and Severity of Asthma Symptoms in Children of the Tehran-ISAAC Study

Abstract

The aim of this study was to determine the prevalence of asthma and related symptoms among 6–7- and 13–14-year-old school children in Tehran as a part of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III. We used a design of descriptive study. The ISAAC written questionnaire was given to a total of 6127 students of 72 schools in urban area of Tehran. Simple random sampling was performed with a uniform distribution throughout 12 clusters of twenty-two divisions of the municipality. All 1st and 7–8th graders were enrolled into the study. Results showed that 15% of the 6–7-yearolds and 17% of the 13–14-year-olds had positive history of wheezing, among which 8.6% and 10.6%, respectively, had had recent attacks. Physician confirmed asthma was reported in 2.1% of the 6–7-year-olds and 2.6% of the 13–14-year-olds. Severity of asthma assessed by frequency of speech limitation due to wheezing was positive in 1.5% of 6–7-year-olds and 3% of 13–14-year-olds. Exercise-induced wheezing was detected in 2.3% of the 6–7-yearolds compared to 15.3% of the 13–14-year-olds. Nocturnal cough was more prevalent among 13–14-year-olds (18.4%) compared to only 7.2% in the 6–7-year-olds. Overall, no significant change in prevalence of asthma symptoms has occurred since 1997 (the last phase of ISAAC) among children of Tehran. The results of our study suggest higher rates of confirmed asthma among 6–7-year-old girls' compared to boys. However, more extensive and precisely designed studies are needed to further confirm these findings.