WHY DO ONLY SOME OF THE YOUNG-ADULTS WITH BRONCHIAL HYPERREACTIVITY WHEEZE

The significance of nonspecific bronchial hyperreactivity (BHR) is a c ontroversial issue in asthma. The natural history of BHR has not been investigated adequately although its importance as a cross-sectional r isk factor for asthma is widely accepted. This paper investigates the risk factors for wheeze among people with BHR. Subjects were young adu lts who had participated in the second phase of the European Community Respiratory Health Survey in Melbourne, Australia. We compared the pa rticipants with wheeze and BHR (n = 186) to those with asymptomatic BH R (n = 66). Information was collected on sociodemographic factors, fam ily history of asthma, and relevant environmental factors using an int erviewer-administered questionnaire. Atopy to a range of aeroallergens was examined by skin prick tests. Risk factors were examined by adjus ting the odds ratios (OR) by a logistic regression to control for conf ounding effects. Parental asthma (OR = 4.2), keeping pets during child hood (OR = 3.3), allergy to house dust mite (OR = 2.7), allergic rhini tis (OR = 2.6), and having ever smoked (OR = 2.4) were associated with an increased risk of wheeze, independent of the other factors examine d. When allergic rhinitis was not included as an explanatory variable, being atopic to any of the allergens assessed was found to increase t he risk of current wheeze (OR = 4.8). Allergic rhinitis may represent an intermediate stage in the natural history of BHR. Avoidance of pets during childhood, not smoking, and taking steps to minimize dust expo sure are likely to prevent the progression from asymptomatic BHR to as thma.