VALIDATION OF QUESTIONNAIRE AND BRONCHIAL HYPERRESPONSIVENESS AGAINSTRESPIRATORY PHYSICIAN ASSESSMENT IN THE DIAGNOSIS OF ASTHMA

Background. The Tasmanian Asthma Survey (TAS) and the international St udy of Asthma and Allergies in Childhood (ISAAC) have used questionnai res to measure the prevalence of asthma in adults and children, We hav e investigated the validity of these questionnaires by comparing respo nse to questionnaire with a physician assessment of asthma status in t he past 12 months. Methods. Ninety-three adults were given the TAS que stionnaire to complete and 361 children were given the ISAAC questionn aire. Ninety-one adults and 168 children completed bronchial challenge with hypertonic saline. A consultation with a respiratory physician b linded to the results of the questionnaire and bronchial challenge was given to all subjects, Results. In both adults and children, question naires showed high agreement with respiratory physician diagnosis with respect to asthma symptoms in the past 12 months, For the TAS questio nnaire the positive and negative predictive values (95% confidence lim its) for physician diagnosis for adults were 0.89 (0.68-0.98) and 0.94 (0.86-0.98) respectively. The instrument was also sensitive 0.80 (0.5 8-0.93) and highly specific 0.97 (0.90-0.99). For the ISAAC questionna ire the positive and negative predictive values for physician diagnosi s of asthma in children were 0.61 (0.50-0.71) and 0.94 (0.88-0.98) res pectively. Sensitivity and specificity were 0.85 (0.73-0.93) and 0.81 (0.76-0.86) respectively. Compared to the physician diagnosis, the sen sitivity of bronchial hyperresponsiveness (BHR) for asthma was low for adults 0.39 (0.21-0.61) and children 0.54 (0.48-0.67) as were the pos itive predictive values: 0.55 (0.31-0.79) for adults and 0.64 (0.49-0. 77) for children, A definition of asthma requiring both a positive que stionnaire response and BHR was highly specific but not sensitive for adults 0.37 (0.20-0.59) or children 0.47 (0.35-0.60), Conclusion. Both the TAS and ISAAC questionnaires are valid instruments for the determ ination of asthma symptoms in the past 12 months.