The Mental Health Parity and Addiction Equity Act (MHPAEA) evaluation study: Did parity differentially affect substance use disorder and mental health benefits offered by behavioral healthcare carve-out and carve-in plans?

Abstract

To assess whether implementation of the Mental Health Parity and Addiction Equity Act (MHPAEA) was associated with: 1. Reduced differences in financial requirements (i.e., copayments and coinsurance) for substance use disorder (SUD) versus specialty mental health (MH) care and 2. Reductions in the level of cost-sharing for SUD-specific services. MH and SUD copayments and coinsurance, 2008-2013, were obtained from benefits databases for carve-in and carve-out plans from Optum^®. Linear regression was used to estimate the association of MHPAEA with differences between MH and SUD care financial requirements among carve-in and carve-out plans. A two-part regression model investigated whether MHPAEA was associated with changes in the use or level of financial requirements for SUD-specific services among carve-out plans. MHPAEA was not associated with significant changes in the difference between SUD and MH copayments or coinsurance levels among either carve-in or carve-out plans. MHPAEA was associated with decreases in the levels of inpatient (in-network: -$51.17; out-of-network: -$34.39) and outpatient (in-network: -$10.26) detox copayments, but increases in the levels of in-network outpatient detox coinsurance (6 percentage points) among all carve-out plans. Even if SUD benefits had been historically less generous than MH benefits, SUD financial requirements were already at parity with MH financial requirements by the time MHPAEA was passed, among Optum^® plans. MHPAEA's SUD parity mandate reduced cost-sharing for detox services via copayments, but, for outpatient detox, the law simultaneously increased cost-sharing via coinsurance.