Objective: To evaluate criteria for the diagnosis of asthma in an epidemiological survey. Methods: Adolescents (13-14 years of age) and legal guardians of schoolchildren (6-7 years of age) in the city of Santo André, Brazil, completed the International Study of Asthma and Allergies in Childhood (ISAAC) standard written questionnaire. Affirmative responses regarding wheezing within the last 12 months, asthma ever, bronchitis ever (question added at the end of the questionnaire), as well as the overall ISAAC score above the predefined cutoff points, were considered indicative of asthma. Results: The legal guardians of 2,180 schoolchildren and 3,231 adolescents completed the questionnaires properly. Depending on the criterion adopted, the prevalence of asthma ranged from 4.9% to 26.8% for the schoolchildren and from 8.9% to 27.9% for the adolescents. The criteria with the lowest and highest prevalences were, respectively, physician-diagnosed asthma and physician-diagnosed bronchitis. When compared with other criteria, physician-diagnosed bronchitis showed concordance levels between 71.9% and 79.4%, positive predictive values between 0.16 and 0.63 and poor concordance (kappa: 0.21-0.46). Strong concordance levels were found only between wheezing within the last 12 months and the overall ISAAC score (kappa: 0.82 and 0.98). Conclusions: The prevalence of asthma varied significantly, depending on the criterion adopted, and there was poor concordance among the criteria. Wheezing within the last 12 months and the overall ISAAC score are the best criteria for the diagnosis of asthma, whereas the question regarding bronchitis ever did not improve the questionnaire. Modifications in this instrument can make it difficult to draw comparisons and should therefore be carefully evaluated.Keywords: Asthma; Bronchitis; Diagnosis; Epidemiology; Child; Adolescent.
ResumoObjetivo: Avaliar critérios para o diagnóstico de asma em um estudo epidemiológico. Métodos: Adolescentes (13-14 anos) e responsáveis por escolares (6-7 anos) do município de Santo André, São Paulo, responderam o questionário escrito padrão do International Study of Asthma and Allergies in Childhood (ISAAC). Respostas afirmativas quanto a ter sibilos nos últimos 12 meses, ter asma ou ter bronquite (pergunta adicionada ao final do questionário), assim como o escore global do ISAAC acima dos pontos de corte pré-definidos, foram consideradas como indicativo de asma. Resultados: Os questionários foram adequadamente preenchidos por 2.180 responsáveis por escolares e 3.231 adolescentes. Dependendo do critério empregado, a prevalência de asma variou de 4,9% a 26,8% para os escolares, e de 8,9% a 27,9% para os adolescentes. Os critérios com as menores e maiores prevalências foram, respectivamente, diagnóstico médico de asma e diagnóstico médico de bronquite. A análise comparativa entre o diagnóstico médico de bronquite e os demais critérios mostrou níveis de concordância entre 71,9% e 79,4%, valores preditivos positivos entre 0,16 e 0,63 e concordância fraca (kappa: ...