Background: The International Study of Asthma and Allergies in Childhood (ISAAC) has developed an international version of the asthma video questionnaire (AVQ3.0) to measure asthma prevalence. This questionnaire has not been validated in adolescents from a mixed ethnic background.
Objective: The aims of this study were to compare the video questionnaire with a written questionnaire in the detection of airway hyperresponsiveness to hypertonic saline in a population of adolescents from a mixed ethnic background, and to establish the repeatability and psychometric properties of the asthma video questionnaire.
Methods: The study was conducted in four secondary schools in Sydney, an area with a high proportion of people from a non-English speaking background. Four hundred and seventy-five students from schools 1 and 2 completed the video questionnaire and a subgroup of these students (n = 170) completed the written questionnaire and a hypertonic saline inhalation challenge. Reproducibility of the questionnaire was evaluated by administering the questionnaire to a subsample of students 2 weeks later. The psychometric properties of the video questionnaire were examined in 852 students at two other schools (schools 3 and 4).
Results: One hundred and sixty-nine students aged 13.5 (sd 1.3) years completed both written and video questionnaires, and the hypertonic saline challenge. The students had widely different cultural backgrounds including Asian, South Pacific, Middle Eastern, European and African countries. There was good agreement between the questionnaires for wheeze (kappa 0.42). Questions on the video questionnaire concerning wheezing had good sensitivity (90%) and specificity (68%) for airway hyperresponsiveness to hypertonic saline. The video questionnaire was reproducible (kappa 0.82), had good internal consistency (Cronbach's alpha 0.81) and each question pertained to a single construct explaining 58% of the variance in total score.
Conclusion: This study has validated the international version of the ISAAC video questionnaire against airway hyperresponsiveness to hypertonic saline in adolescents from a mixed ethnic background, and identified that the questionnaire has good psychometric properties. The ISAAC video has proved to be a valuable tool for the assessment of asthma prevalence in populations of ethnic diversity.