RESUMO
The prevalence of asthma remains difficult to determine with precision with no absolute or gold standard for diagnosis. International Study of Asthma and Allergies in Childhood [ISAAC] developed video questionnaire for epidemiological studies with less reliance on understanding written asthma questionnaire. The aim of this research was to determine the agreement between the ISAAC written and video questionnaires [AVQ3.0] on respiratory symptoms and reported asthma. We studied 3000 children aged 13-14 years in Urmia, Iran who completed sequentially the ISAAC written and video questionnaires [AVQ3.0] at school. The agreement between responses to the two questionnaires for reported wheeze ever, current wheeze, wheeze on exercise, and nocturnal wheeze [the latter three questions relating to symptoms in the previous 12 months], and to any combination of the latter three questions was examined by using concordance and kappa coefficients as measures of agreement. The prevalence of wheeze ever, current wheeze, wheeze on exercise, and nocturnal wheeze were significantly lower based on responses to the video questionnaire compared to the written questionnaire. Although concordance between video and written questionnaires was high [75% to 93%] for related questions, agreement measured by the kappa statistic for each question was only poor i.e. 0.22, 0.21, 0.13 for resting wheeze, exercise induced wheeze, and nocturnal wheeze respectively. We conclude that the video questionnaire yields lower reported prevalence rates for asthma symptoms, and that there is poor agreement between responses to the two questionnaires in Iranian children