Validity and reproducibility of the asthma core International Study of Asthma and Allergies in Childhood (ISAAC) written questionnaire obtained by telephone survey.

OBJECTIVE

To assess the reproducibility and validity of the International Study of Asthma and Allergies in Childhood (ISAAC) asthma written questionnaire (IAWQ) for 6- to 7-year-old children administered to their parents/caregivers through a telephone interview.

METHODS

Our study included 100 children selected from three health units in Rio de Janeiro, Brazil. In total, 50 asthmatic and 50 non-asthmatic children were evaluated; all participants were required to own a household telephone line. Initially, telephone interviews were conducted with the parents/caregivers using the IAWQ. After 2 weeks, parents/caregivers were invited to complete the IAWQ under supervision provided by the researchers. After fifteen days, the telephone interviews were repeated. The reproducibility between the two telephone interviews was assessed using kappa (κ) coefficients; the construct validity was assessed by comparing the answers obtained in the initial telephone interview in both groups according to the clinical diagnosis of asthma performed by a specialist using sensitivity and specificity coefficients.

RESULTS

Overall, data from 75 children (39 asthmatics) were analyzed, as 25 patients were excluded from the study (11 did not answer phone calls and the responding parents/caregivers for 14 patients were not the same in all study phases). Perfect agreement was observed for the indicator "wheezing in the last 12 months" (κ = 1), while substantial agreement was observed for the "wheezing with exercise," "speech limited by wheezing," and "asthma ever" indicators (κ range, 0.7-0.8). The sensitivity and specificity for "wheezing within the last 12 months" were 64.1% (95% confidence interval (CI), 47.2-78.8) and 88.9% (95% CI, 73.9-96.9), respectively. For the "asthma ever" indicator, the sensitivity and specificity were 87.2% (95% CI, 77.6-95.7) and 100% (95% CI, 90.3-1), respectively. Questionnaire specificity was high for all asthma severity indicators.

CONCLUSIONS

The IAWQ for children aged 6-7 years adapted for telephone interviews showed good reproducibility and adequate validity with an ability to distinguish between asthmatic and non-asthmatic participants. Thus, this method could be utilized in epidemiological studies on childhood asthma in locations where telephone lines are available.