DOSES AND MODELS IN RISK ASSESSMENT ANALYSIS FOR BRONCHIAL HYPERRESPONSIVENESS

The aims of this study are: (1) to evaluate whether the estimates of t he association of risk factors with bronchial hyperresponsiveness (BHR ) depends on the accumulated dose administered in challenge tests; and (2) to verify whether a model developed for survival studies (Weibull regression) is suited to analyze methacholine dose-response curves. F or these purposes, 863 challenge tests, from EC Respiratory Health Sur vey in Italy, up to a cumulative dose of 6 mg methacholine, were analy zed by Weibull regression and by traditional methods (logistic model a nd linear model), both before and after truncation of the curves at 2 mg. With all methods the main risk factors for BHR were respiratory sy mptoms and atopy while age and airway caliber exerted a protective act ion. Our results confirmed that in epidemiological surveys 2 mg methac holine is enough to fully appreciate the effect of risk factors on BHR and showed chat the Weibull model explains the observed variability b etter than linear and logistic regressions. (C) 1998 Elsevier Science Inc.