- We take advantage of Oregon’s Medicaid lottery to gauge the causal effects of Medicaid coverage on mental health care, how effectively it addresses unmet needs, and how those effects differ for those with and without a history of depression.
- Medicaid coverage reduced the prevalence of undiagnosed depression by almost 50% and untreated depression by more than 60%. It increased use of medications and reduced the share of respondents reporting unmet mental health care needs by almost 40%.
- There are likely to be substantial mental health consequences of policy decisions about Medicaid coverage for vulnerable populations.
Expanding Medicaid to previously uninsured adults has been shown to increase detection and reduce the prevalence of depression, but the ways that Medicaid affects mental health care, how effectively it addresses unmet needs, and how those effects differ for those with and without a history of depression remain unclear.
We take advantage of Oregon’s Medicaid lottery to gauge the causal effects of Medicaid coverage using a randomized‐controlled design, drawing on both primary and administrative data sources.
Medicaid coverage reduced the prevalence of undiagnosed depression by almost 50% and untreated depression by more than 60%. It increased use of medications frequently prescribed to treat depression and related mental health conditions and reduced the share of respondents reporting unmet mental health care needs by almost 40%. The share of respondents screening positive for depression dropped by 9.2 percentage points overall, and by 13.1 for those with preexisting depression diagnoses, with greatest relief in symptoms seen primarily in feeling down or hopeless, feeling tired, and trouble sleeping—consistent with the increase observed not just in medications targeting depression but also in those targeting sleep.
Medicaid coverage had significant effects on the diagnosis, treatment, and outcomes of a population with substantial unmet mental health needs. Coverage increased access to care, reduced the prevalence of untreated and undiagnosed depression, and substantially improved the symptoms of depression. There are likely to be substantial mental health consequences of policy decisions about Medicaid coverage for vulnerable populations.
Almost one‐third of low‐income Americans report having been diagnosed with depression—twice the rate of the nation overall.1 Depression has been correlated with worse health and lower quality of life, along with increased health care use.2-6 Effective treatments for depression exist, but the uninsured are less likely to have their depression treated than those with Medicaid.7 Medicaid coverage may thus result in substantial improvements in depression and quality of life, but because of the many differences between Medicaid enrollees and the uninsured, the causal connections between insurance coverage, treatment, and outcomes are difficult to discern. At a time when policymakers are reevaluating the scope of Medicaid coverage, better information about the effects of Medicaid on mental health care and outcomes is crucial.
In 2008, Oregon allocated by random lottery a limited number of slots in its Medicaid program for low‐income adults. This lottery provides a unique opportunity to study the effects of Medicaid coverage without the influence of confounding factors that otherwise plague comparisons of insured to uninsured populations. In previous analyses using the lottery, we found that Medicaid coverage increased health care use (including primary, hospital, prescription, and emergency department care); improved financial security (although had no significant effect on employment or earnings); and improved self‐reported health and mental health but had no detectable effects on several measures of physical health.8-11 In particular, we found that Medicaid coverage decreased the probability of screening positive for depression by 9.15 percentage points (95% CI: −16.70 to −1.60; p = .018), a relative reduction of 30%, and found a borderline‐significant increase in use of broadly related medications.8
Understanding the multiple pathways through which Medicaid may have affected management of depression, the nature of health needs for populations with and without depression, and the aspects of the disease that were most affected by coverage can help patients, practitioners, and policymakers better understand the implications of coverage for this widespread condition. In this paper, we explore the ways in which Medicaid coverage affected the diagnosis, treatment, and symptoms of depression and the degree to which Medicaid successfully met mental health needs. Oregon’s Medicaid program covered inpatient care, outpatient care (including some psychotherapy), and psychiatric prescription drugs with no copayments. We examine the effect of insurance on the prevalence of undiagnosed and untreated depression, how the effects of insurance differed between patients with and without known diagnoses of depression, the use of different treatments and specific mental health medications, and a range of depressive symptoms.– Katherine Baicker, Heidi L. Allen, Bill J. Wright, Sarah L. Taubman, Amy N. Finkelstein