CONTINGENT VALUATION AND UTILITY MODELS FOR ECONOMIC EVALUATION OF PHARMACEUTICALS: A STUDY OF ANTIHISTAMINES.

摘要

The focus of this study was upon validity assessment of an ex ante contingent valuation measure, for antihistamine products used for the relief of allergic rhinitis. Attitudinal measures of utility were used as comparative criteria. Five mathematical models of the utility measure were studied: (1) Unweighted Self-Explicated; (2) Weighted Self-Explicated; (3) Additive Huber-Hybrid; (4) Addilog Huber-Hybrid; and (5) Multiplicative Huber-Hybrid. Responses were obtained to a mail questionnaire from 143 allergic rhinitis sufferers with a history of antihistamine use. For each subject, scores for the five utility models were compared with contingent valuation measures for 16 orthogonal and three holdout antihistamine product profiles. The major results of the study are as follows: (1) For the set of orthogonal product profiles, mean values of intra-individual correlation coefficients were found to be .589, .609, .790, .784, and .759 for the Unweighted Self-Explicated, Weighted Self-Explicated, Additive Huber-Hybrid, Addilog Huber-Hybrid, and Multiplicative Huber-Hybrid models, respectively. (2) Pairwise comparison between these model correlations showed that Huber-Hybrid models had higher mean correlations than the self-explicated utility models. (3) The results of the cross-validation of the five utility models, using market-basket holdout product profiles ("Chlorpheniramine 8 mg.," "Seldane 60 mg.," and "Benadryl 25 mg."), showed that the correlations, between actual and contingent valuations predicted by the models, ranged from .795 to .940. (4) None, of the four demographic measures (sex, age, income or education) tested, was found to be significantly linearly related to the contingent valuation assigned to the avoidance of allergic rhinitis for six months. However, with the exception of asthma, four of the five disease-related variables (allergy severity, cyclicality of symptoms, cost-of-illness, and highest bid for an antihistamine product profile), were found to be significantly related to contingent valuation for six months avoidance of allergic rhinitis.