Mental Health Parity and Addiction Equity Act and the Use of Outpatient Behavioral Health Services in the United States, 2005-2016.
Level 4 - case-series / case-control
Interrupted time-series study using historical baseline without a concurrent control group (graded by design analogy for health policy)
PubMed 31242013 · doi:10.2105/AJPH.2019.305023
What was done
The authors evaluated the impact of the 2008 Paul Wellstone and Pete Domenici Mental Health Parity and Addiction Equity Act (MHPAEA) on behavioral health care among Americans covered by private, large-group employer-sponsored insurance. They analyzed claims data from the IBM MarketScan Commercial Database spanning January 2005 through September 2015 using population-level interrupted time-series regression models. Key outcomes were utilization and spending for outpatient mental health and substance use disorder services, including separate assessments of opioid use disorder versus nonopioid substance use disorder services and a spending decomposition analysis.
What was found
MHPAEA implementation had significant positive associations with outpatient service utilization for both mental health and substance use disorders over a 5-year post-implementation period. Spending decomposition showed that higher utilization was the primary driver of increased overall spending. The associations were observed for both opioid use disorder and nonopioid substance use disorder services. Specific quantitative metrics (e.g., effect sizes, spending amounts, percentages, and confidence intervals) were not reported in the abstract.
Why it matters
This study provides evidence that federal parity legislation was followed by sustained, long-term increases in access to outpatient mental health and addiction care for commercially insured individuals, with spending growth driven by increased care volume rather than higher unit costs.
Limits
The abstract reports no numerical estimates, effect sizes, or p-values. The dataset is limited to individuals in large-group employer-sponsored commercial plans, so findings cannot be generalized to small-group markets, individual plans, public insurance programs (Medicare/Medicaid), or uninsured populations. As an interrupted time-series design without an unexposed control group, the study may be susceptible to confounding from concurrent secular trends in behavioral health awareness and clinical practice.
Cited by
- supports Federal mental health and addiction parity legislation passed in the United States in 2008 requiring commercial insurance plans to cover mental health and addiction benefits at comparable levels to medical and surgical benefits.