Background and objective: It is unclear whether private insurance benefit designs align with the most widely used ex-US definition of value, the incremental cost-effectiveness ratio (ICER). A large Pacific Northwest private insurance plan explicitly implemented a tiered formulary based on cost-effectiveness estimates of individual drugs in 2010, resulting in cost savings to the plan without negatively affecting patient health service utilization. Given the pressures of rising costs, we investigate whether employer-based private health insurance plans have adopted value-based cost-sharing approaches that are in line with cost-effectiveness estimates.
Methods: At the drug level, we identified five drug tier designations (0-4) that are tied to increasing ICER ranges in a large claims dataset from 2010 to 2013. We used a random effects model to evaluate whether out-of-pocket (OOP) cost levels and trends were associated with drug value designation, controlling for generic status and list price, and whether the associations varied by insurance plan type and insurance market concentration, as measured by the Herfindahl-Hirschman Index (HHI). We also estimated the weighted mean cost effectiveness of the drug claims in the sample by year and generic status using the formulary's cost-effectiveness value ranges.
Results: The 2010 volume weighted mean OOP cost for a 30-day supply of drugs in tiers 0 through 4 were $US6.87, $US22.62, $US62.22, $US57.36, and $US59.85, respectively (2013 US dollars). OOP costs for cost-saving and preventive drugs (tier 0) decreased 5% annually from 2010 to 2013 (p < 0.01); OOP costs for drugs costing under $US10,000/quality-adjusted life-year (QALY) (tier 1) decreased 4.5% annually (p < 0.01) and OOP costs for drugs costing over $US50,000/QALY (tier 3) and $US150,000/QALY (tier 4) decreased by 2.4% and 2.2%, respectively (p < 0.01 and p = 0.046). OOP costs for drugs valued between $US10,000 and $US50,000/QALY did not change significantly (p = 0.31). Average ICER estimates increased for generic drugs and did not change for brand name drugs.
Conclusion: OOP costs for prescription drugs are decreasing across value levels, with OOP costs for higher-value drugs generally decreasing at a faster rate than lower-value drugs. The relationship between cost sharing and value remains tenuous, however, particularly at higher ICER levels, likely reflecting the persistence of traditional formulary structures and increasing use of generic drugs over brand name drugs.