Limited agreement between written and video asthma symptom questionnaires

The prevalence of asthma remains difficult to determine with precision with no absolute or "gold" standard for diagnosis. A recently developed video q uestionnaire for epidemiological studies with less reliance on understandin g written questions provides another tool for determining prevalence and se verity of asthma. This report from the International Study of Asthma and Al lergies in Childhood (ISAAC) examines the agreement between the ISAAC video questionnaires on respiratory symptoms and reported asthma. Between Decemb er 1993 and April 1995, 4952 children aged 13-14 years in two Canadian comm unities completed sequentially the ISAAC written and video questionnaires a t school. The agreement between responses to the two questionnaires for rep orted wheeze ever, current wheeze, wheeze on exercise, and nocturnal wheeze (the latter three questions relating to symptoms in the last 12 months), a nd to any combination of the latter three questions was examined in the ful l sample and in those reporting diagnosed asthma, using concordance and kap pa coefficients as measures of agreement. The prevalences of wheeze ever, current wheeze, wheeze on exercise, and noc turnal wheeze were significantly lower based on responses to the video ques tionnaire compared with the written questionnaire in both regions in the fu ll sample and in those labeled as having asthma. Although concordance betwe en video and written questionnaires always exceeded 60% and often exceeded 70% for related questions, agreement measured by the kappa statistic for ea ch question was only fair to moderate (kappa = 0.22-0.51). We conclude that the video questionnaire yields lower reported prevalence r ates for asthma symptoms, and that there is limited agreement between respo nses to the two questionnaires that is not explained by issues of language, culture, or literacy. Pediatr Pulmonol, 2000; 30:307-312, (C) 2000 Wiley-L iss, Inc.