BACKGROUND: Previous studies of 3-tier formularies are rare, although the evidence suggests that their cost-sharing structure reduces overall drug spending. However, it is unclear how incentive-based formularies affect the selection of medications with safety advantages, or restrict the access that high-risk populations have to recommended therapies in the higher tiers. This study was designed to determine whether 3-tier formularies influence the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in a population of patients with arthritis. METHODS: This retrospective study used the 2000 MarketScan Research Database, which contains person-level claims data for employer-sponsored health plans. The sample for this study consisted of 20 868 individuals treated for osteoarthritis or rheumatoid arthritis and using NSAIDs while enrolled in tiered drug plans (n = 32). The likelihood of any use of cyclo-oxygenase (COX-2)-selective inhibitors was determined as a function of tiered drug plan coverage, adjusting for other person-level and plan-level covariates. RESULTS: Use of COX-2-selective inhibitors decreased (63.0% vs 53.6% vs 41.6%, respectively) and use of generic NSAIDs increased (37.7% vs 40.7% vs 55.7%, respectively) as formularies incorporated 1, 2, and 3 tiers. Enrollees in 3-tier plans with arthritis and serious gastrointestinal comorbidities (odds ratio, 0.51; 95% confidence interval, 0.40-0.66) were significantly less likely to use COX-2-selective inhibitors compared with patients in 1-tier plans. CONCLUSIONS: Three-tier formularies appear to reduce the use of COX-2-selective inhibitors among all patients with arthritis, even those at risk of experiencing gastrointestinal complications from using nonselective NSAIDs. These findings are among the first to suggest that tiered-copayment drug plans may be influencing the selection of medications beyond generic and branded products.

This study examined the association between incentive-based formularies and antihypertensive drug selection and spending. We compared the use of drugs from five drug classes by the number of tiers and copayment differentials. We found that raising copayments within a single-tier formulary system had a relatively modest impact on use of antihypertensives, compared with raising them in multi-tier systems. Likelihood of using ACE inhibitors and angiotensin II receptor blockers was lower among two-tier plans with generic/brand differentials of dollars 10 relative to flat-copayment plans. Incentive formularies were associated with lower total antihypertensive spending by plans, but enrollees paid more out of pocket.