Comparison of Anticancer Medication Use and Spending Under US Oncology Parity Laws With and Without Out-of-Pocket Spending Caps

IMPORTANCE: By 2020, nearly all states had adopted oncology parity laws in the US, ensuring that patients in fully insured private health plans pay no more for orally administered anticancer medications (OAMs) than infused therapies. Between 2013 and mid-2017, 11 states implemented parity with out-of-pocket spending caps, which may further reduce patient out-of-pocket spending. OBJECTIVE: To compare OAM uptake and out-of-pocket and health plan spending on OAMs in states with parity with and without spending caps, as well as to assess out-of-pocket spending for caps that apply predeductible vs postdeductible. DESIGN, SETTING, AND PARTICIPANTS: This cohort study analyzed OAM users enrolled in commercial health plans offered by Aetna, Humana, and United Healthcare in the US from 2011 to 2017, aggregated by the Health Care Cost Institute, using difference-in-difference-in-differences (DDD) analysis. Data analysis was conducted between June and August 2020. EXPOSURES: Time (before vs after parity), whether the state parity law included an out-of-pocket spending cap, and whether the plan was fully insured (subject to parity) or self-funded (not subject to parity). Among states with caps, out-of-pocket spending was also compared by whether the cap was applied predeductible and postdeductible vs only postdeductible. MAIN OUTCOMES AND MEASURES: Monthly OAM prescription fills per 100 000 enrollees, per-OAM prescription-fill out-of-pocket spending, and annual per-user health plan spending on OAMs. RESULTS: In this study of 23 states (11 with caps and 12 without) and 207 579 OAM prescription fills, caps were associated with a modest increase in OAM use (DDD, 7.40 [95% CI, 3.41-11.39] per 100 000 enrollees). There was no difference in mean out-of-pocket spending comparing fully insured and self-funded enrollees in states with vs without caps (DDD, −$17 [95% CI, −$57 to $24), but caps were associated with lower spending among OAM users in the 95th percentile of out-of-pocket spending by $831 (95% CI, −$871 to −$791) per OAM prescription fill. Caps applied predeductible were associated with greater out-of-pocket savings relative to caps applied only postdeductible. This included per-OAM prescription-fill savings at the 75th, 90th, and 95th percentiles. Postparity, mean annual spending on OAMs among users was $113 589 in states without caps and $102 252 in states with caps, with no differences between groups (DDD, $9799 [95% CI, −$4230 to $23 829). CONCLUSIONS AND RELEVANCE: In this cohort study, among states adopting oncology parity laws between 2013 and 2017, mean out-of-pocket spending per OAM prescription fill and mean health plan spending among OAM users was similar in states with and without caps. However, enrollees in states with parity plus out-of-pocket caps had greater reductions in out-of-pocket spending among the highest spenders. Caps may offer improved financial protection for the highest spenders without increasing mean health plan spending on OAMs.