Are incentive-based formularies inversely associated with drug utilization in managed care?

To review recent studies comprehensively assessing the impact of incentive-based multitier formularies on pharmaceutical costs and utilization.

PubMed (2001-December 2003) was searched using the key terms formularies, cost-sharing, and drug costs.

Studies addressing the impact of implementing multitiered incentive-based formularies as a central component of an outpatient drug benefit were selected.

One study using pharmacy claims from 25 employers with data from 402 786 members modeled the range of anticipated plan/employer savings associated with single- to 3-tier shifts and found that, going from a single- to 3-tier benefit results in decreased plan/employer pharmaceutical costs from $650 to $494 (24% decrease) per member per year and decreased pharmaceutical utilization from 12.3 to 9.4 (23.6% decrease) prescriptions per member per year. Another study demonstrated that adding an additional tier decreased pharmaceutical utilization, with a dramatic increase in member contribution offsetting the plan's expected increase in expenditures. This shift in pharmaceutical expenditures appeared to have no effect on overall medical utilization over a 3-year follow-up. Finally, a study converting members from a single- to 3-tier incentive-based formulary, associated with two- to fourfold copayment increases, resulted in a 10% discontinuation rate for angiotensin-converting enzyme inhibitors, statins, and proton-pump inhibitors among members who were primarily hourly employees. For salaried workers, the addition of a tier to their benefit appeared to have minimal impact on pharmaceutical utilization.

Emerging data suggest a potential inverse relationship between pharmaceutical utilization and incentive-based formularies that increase member contribution to drug costs. Future research should focus on identifying price points and percentage increases at which members are likely to begin discontinuing necessary medications.