The association of consumer cost-sharing and direct-to-consumer advertising with prescription drug use^{{star, open}}

Background: Previous research on the impact of various cost-sharing strategies on prescription drug use has not considered the impact of direct-to-consumer (DTC) advertising. Objective: To explore the association of cost-containment strategies with prescription drug use and to determine if the association is moderated by DTC prescription drug advertising. Methods: The study population included 288 280 employees and dependents aged 18 to 65 years with employer-sponsored health insurance contributing to the MEDSTAT MarketScan administrative data set. Person-level enrollment and claims data were obtained for beneficiaries enrolled continuously during July 1997 through December 1998. Direct-to-consumer advertising data were obtained from Competitive Media Reporting and linked to the MEDSTAT enrollment files. Localized DTC advertising expenditures for one class of medication were evaluated and matched with prescription claims for eligible MEDSTAT contributors. The association of various types and levels of cost-sharing incentives with incident product use was evaluated, controlling for the level of DTC advertising, health status, and other demographic covariates. Results: The relationship of cost-sharing amounts with drug use was modified by the level of DTC advertising in a geographic market. This relationship was dependent on the type of cost-sharing, distinguishing between co-payments for provider visits and co-payments for prescription drugs. Compared with low-advertising markets, individuals residing in markets with high levels of advertising and paying provider co-payments of $10.00 or more were more likely to use the advertised product. In the same markets, higher prescription drug co-payments were associated with a decreased likelihood of using the advertised product. A similar relationship was not observed for the nonadvertised competitor. Conclusions: Among insured individuals, response to cost-sharing strategies is moderated by DTC prescription drug advertising. The relative ability of cost-sharing strategies to influence drug use should be interpreted with caution in the presence of DTC advertising.