Background: In this study we sought to estimate the association between oral oncology parity law adoption and anticancer medication use for patients with chronic myeloid leukemia (CML) or multiple myeloma.
Methods: This was an observational study of administrative claims from 2008-2017. Among individuals initiating tyrosine kinase inhibitors (TKI) for CML or immunomodulatory drugs for multiple myeloma, we compared out-of-pocket spending, adherence, and discontinuation before and after parity among individuals in fully-insured plans (subject to parity) versus self-funded plans (exempt from parity) using propensity-score weighted difference-in-differences regression models.
Results: Among patients initiating TKIs (N = 2,082) or immunomodulatory drugs (N = 3,326) there were no statistically significant differences in adherence or discontinuation associated with parity. The proportion of patients with initial out-of-pocket payments of $0 increased in fully-insured plans after parity from 5.7% to 46.1% for TKIs and from 10.9% to 48.8% for immunomodulatory drugs. Relative to changes in self-funded plans, those in fully-insured plans were 4.27 (95%CI:2.20-8.27) times as likely to pay nothing for TKIs and 1.96 (95%CI:1.40-2.73) times as likely to pay nothing for immunomodulatory drugs after parity. Similarly, the proportion paying >$100 decreased from 30.3% to 24.7% for TKIs and 30.6% to 27.5% for immunomodulatory drugs in fully-insured plans after parity. Relative to changes in self-funded plans, those in fully-insured plans were 0.74 (95%CI:0.54-1.01) times as likely to pay >$100 for TKIs and 0.85 (95%CI:0.68-1.06) times as likely to pay >$100 for immunomodulatory drugs after parity.
Conclusions: Among patients initiating TKIs or immunomodulatory drugs, parity was not associated with better adherence or less discontinuation of therapy, but yielded decreased patient out-of-pocket payments for some patients.
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