ABSTRACT: BACKGROUND:The federal Mental Health Parity and Addiction Equity Act (MHPAEA) sought to eliminate historical disparities between behavioral health and medical health insurance benefits among the commercially insured. This study determines whether MHPAEA was associated with increased BH expenditures and utilization among a population with substance use disorder (SUD) diagnoses. METHODS:Claims and eligibility data from 5,987,776 enrollees, 2008-2013, were obtained from a national, commercial, managed behavioral health organization. An interrupted time series study design with segmented regression analysis estimated time trends of per-member-per-month (PMPM) spending and use before (2008-2009), during (2010), and after (2011-2013) MHPAEA compliance. The study sample contained individuals with drug or alcohol use disorder diagnosis during study period (N=2,716,473 member-month observations). Outcomes included: total, plan, patient out-of-pocket spending; outpatient utilization (assessment/diagnostic evaluation visits; medication management; individual, group and family psychotherapy, and structured outpatient care); intermediate care utilization (day treatment; recovery home and residential); and inpatient utilization. RESULTS:Starting at the beginning of the post-parity period, MHPAEA was associated with increased levels of PMPM total and plan spending ($25.80 [p=0.01]; $28.33 [p=0.00], respectively), as well as the number of PMPM assessment/evaluation, individual psychotherapy, and group psychotherapy visits, and inpatient days (0.01 visits [p=0.01]; 0.02 visits [p=0.01]; 0.01 visits [p=0.03]; 0.01days [p=0.01], respectively). Following these initial level changes, MHPAEA was also associated with monthly increases in PMPM total, plan, and patent out-of-pocket spending ($2.56/month [p=0.00]; $2.25/month [p=0.00]; $0.27 [p=0.03], respectively), as well as structured outpatient visits and inpatient days (0.0012 visits/month [p=0.01]; 0.0012days/month [p=0.00]). CONCLUSION:MHPAEA was associated with modest increases in total, plan, and patient out-of-pocket spending and outpatient and inpatient utilization. These increases, while modest in magnitude, are larger in magnitude than increases detected among a sample of all enrollees (i.e. not only those with SUD diagnoses).
