The impact of drug coverage on COX-2 inhibitor use in Medicare.

Passage of the Medicare drug benefit legislation has renewed attention to the relationship between drug coverage and medication use. This study assesses the impact of drug coverage on COX-2 inhibitor use among elderly people with osteoarthritis, taking into account risk for adverse gastrointestinal events. COX-2 use among aged beneficiaries with the most generous coverage was twice that of those with no third-party coverage. COX-2 use also increased with increasing gastrointestinal risk. However, this risk differential in COX-2 use disappears among those with the most generous coverage. Potential overuse of costly medications should be addressed as the Medicare drug benefit is being phased in.