Effects of federal parity legislation on access to mental health and substance use disorder treatment: Results from the NSDUH, 2004-2013

Background: Historically, insurance coverage for mental health and substance use disorder (MH/SUD) care has been more restrictive than coverage for other forms of general health care. For decades, insurers justified the difference by claiming that equal coverage for MH/SUD care would lead to excessive use and high costs. The resulting, reduced level of coverage has contributed to a substantial treatment gap in which most people in need of MH/SUD care do not receive it. For those who have received care, financial protection has tended to be weaker. Since the mid-1990s, there have been numerous legislative attempts to regulate insurance coverage and mandate parity. One of the most comprehensive efforts was the Paul Wellstone and Pete Domenici Mental Health Parity and Addiction Equity Act of 2008 (MHPAEA). This federal law has strengthened many key protections for consumers of MH/SUD care, but a number of important problems remain unaddressed. In this study, our aim was to investigate how treatment rates have changed for individuals with private insurance in association with implementation of MHPAEA.

Methods: We conducted secondary analysis of existing survey data (National Survey on Drug Use and Health, 2004-2013). Difference-in-differences models were specified with multiple comparison groups (private insurance vs. Medicare, Medicaid, military, and uninsured) and multiple observation periods pre- and post-intervention (2004-2009 vs. 2010, 2011, 2012, and 2013). Treatment rates were compared between insurance groups pre- and post-MHPAEA, adjusting for demographics, socioeconomic status, measures of health, and need for treatment. Sample weights and design variables were used to account for the complex survey design and to provide nationally representative results.

Results:  Before MHPAEA (2004-2009), about 4.0% of individuals with private insurance and an SUD received specialty SUD treatment. This was lower than the rate among all other comparison groups. The rate increased marginally post-parity for individuals with private insurance, but the difference was not significantly different than changes observed in the comparison groups. For individuals who reported at least some psychological distress in the past year, about 15.7% of those with private insurance reported receiving MH treatment (inpatient, outpatient, and/or medication). This was higher than the rate among people with Medicare and those who were uninsured, but lower than in the other comparison groups. The rate increased post-parity for individuals with private insurance, but the differences were not significantly different than those observed in the comparison groups.

Conclusions: No evidence was found of MH/SUD treatment rates increasing in association with MHPAEA for individuals with private insurance. These findings fall in line with previous studies of various federal and state parity laws, which have found little to no impact on treatment rates but significant improvements in financial protection for those who do receive care. While MHPAEA was an important health policy milestone, it is not expected to be a panacea for addressing gaps in access to MH/SUD treatment. Other substantial barriers to treatment, such as stigma, treatment unavailability, and lack of awareness about insurance coverage, remain in place.