Prevalence and severity of asthma and related symptoms in 6- to 7-year-old schoolchildren of Rio de Janeiro using of the ISAAC questionnaire by telephone survey.

Objective: To evaluate the prevalence and severity of asthma and its association with sex in 6- to 7-year-old schoolchildren from the city of Rio de Janeiro (RJ), obtained by a telephone survey.

Methods: A cross-sectional study using the International Study of Asthma and Allergies in Childhood (ISAAC) Written Questionnaire for Asthma adapted and validated by telephone interviews was conducted. The random sample was recruited systematically, without replacement, taking into account the proportion of school classes and students in each regional coordination of the Municipal Secretariat of Education, which supplied the students' telephone numbers. The data were collected by a polling company from May to July 2010. Prevalence ratios (PRs) and 95% confidence intervals (95% CI) were compared using the difference in proportions test suitable for large samples to analyze the association between asthma and sex.

Results: In total, 3216 interviews from parents/caregivers of children were analyzed; 51.4% of the children were males. Mothers were the primary respondents (71.9%). The prevalence rates of "wheezing ever" and "wheezing in the last 12 months" were 52.2% and 20.9%, respectively, and were significantly higher among boys (PR: 1.10, 95% CI: 1.03-1.18 and PR: 1.27, 95% CI: 1.10-1.45). The same pattern was observed for "asthma ever" (PR: 1.44, 95% CI: 1.12-1.85) and for "severe asthma" (PR: 1.42, 95% CI: 1.11-1.82).

Conclusion: The prevalence of asthma was high among RJ's students. Most of the indicators of the disease were more prevalent among boys. Our results were similar to those observed in other Brazilian and international centers using the traditional ISAAC protocol. The use of this method can be an alternative for epidemiological studies of childhood asthma especially in areas where the telephone coverage is high.