Impact of Medicaid Expansion Under ACA on Inpatient and Emergency Room Utilization and Substance Use Disorder Treatment

Background The Patient Protection and Affordable Care Act (PPACA) was signed into law by President Obama on March 23, 2010. Two of the most contentious clauses under the PPACA were penalizing all persons who lacked insurance after January 1, 2014 and expansion of Medicaid insurance to all adults with incomes at or below 138% of the federal poverty level. The constitutionality of the act came under scrutiny and led to the "National Federation of Independent Businesses vs Sebelius" case wherein the Supreme Court upheld most of the provisions of the PPACA but decided to give states the option of not expanding Medicaid and at same time retain their Federal funding for the program. This Supreme Court decision resulted in Medicaid expansion becoming optional for states. As of January 1, 2014 24 states and the District of Columbia elected to expand Medicaid coverage as per the PPACA requirements. This variation in Medicaid expansion provided natural experiments to investigate the impact of expansion decisions.

Inpatient care accounts for the largest share of national health care expenditures in the United States. There are several provisions in the PPACA which encourage coordination of care between providers through use of patient centered medical homes and base provider reimbursements on patient outcomes as opposed to volume of care delivered. Through such reforms the PPACA aimed at reducing wasteful use of resources such as preventable hospitalizations. Previous research has shown that inpatient use, specifically preventable hospitalizations can be sensitive to coverage gains and can serve as an indicator of access to primary care. Thus, assessing how insurance expansion under the PPACA has impacted overall inpatient utilization and rate of preventable hospitalizations may provide insight on how successful PPACA has been in replacing high cost wasteful services with lower cost primary care services. Wherry et al, using data from National Health Interview Survey, determined a positive association between the PPACA Medicaid expansion and rate of overnight hospitalizations, whereas Sommers et al, using data from a survey fielded in Arkansas, Kentucky and Texas found no significant association between overnight hospitalizations and Medicaid Expansion. They did not detect any differences in probability of overnight hospitalization and method of expansion (Arkansas vs Kentucky). However, their study was limited by a small sample size and based on results of a survey. Additionally, due to lack of administrative data they were unable to assess outcomes which might be more sensitive to increased access to primary care such as preventable hospitalizations. To the best of our knowledge only one study conducted thus far, assessed the impact of Medicaid expansion under PPACA on overall inpatient utilization and rates of preventable hospitalization. However, their study was limited to California, additionally different counties had different levels of expansions, with some expanding coverage up to 133% FPL, some up to 200% FPL and some were below 100% FPL. None of the studies thus far have determined the impact of different methods of Medicaid expansion under the PPACA on rates of all-cause and preventable hospitalizations using administrative data. One of the goals of the PPACA was to curb health care costs by reducing the volume of care delivered at ED. Certain measures incorporated in the PPACA such as increasing the number of insured persons and hence increasing access to care outside the ED and integration of health care delivery may contribute to reducing ED utilization. Two studies assessing the impact of Medicaid expansion on ED use also analyzed rates of ambulatory care sensitive conditions (ACSC), emergent but primary care treatable conditions and non-emergent ED visits. However, one study was limited to only the state of Maryland lacking a comparison state which did not expand Medicaid and the other was limited to only a single for-profit investor owned chain of hospitals in 6 states which expanded Medicaid and 14 which didn't. Furthermore, none of the studies have assessed how different methods of Medicaid expansion under the PPACA impact rates of overall and non-emergent ED use. Racial/ethnic disparities in various facets of health care such as insurance coverage and overall access to health care is well documented in literature. Combined with the coverage provisions, additional reforms made by the PPACA such as, elevating the National Center on Minority Health and Health Disparities at the National Institutes of Health from a Center to a full Institute, might lead to narrowing of these disparities. The studies that have assessed the impact of Medicaid expansion under PPACA on disparities in inpatient use or ED use have relied primarily on self-reported data which is subject to cognitive, non-response, recall and other biases. Furthermore, granular measures of inpatient or ED use such as preventable hospitalizations and preventable ED visits cannot be accurately obtained from self-reported data. None of the studies thus far have determined the impact of Medicaid expansion or different methods expansions under PPACA on disparities in types of inpatient or emergency department utilization.

Persons with substance use disorders (SUD) have significantly higher health-care costs, higher rates of suicide attempts and disabilities compared to the general population thus posing a burden to society overall. Despite this, in 2012, nearly 90% of the persons aged 12 and older who required treatment for SUDs did not receive adequate treatment. The lack of insurance or insurance not covering SUD treatment services leading to the patient's inability to pay for them are some of the most commonly cited barriers to treatment. The coverage expansions under the PPACA have led to nearly 1.6 million Americans suffering from SUDs in Medicaid expansion states gaining health insurance coverage. Further, under the PPACA, SUD treatment is one of the ten essential health benefits that all plans must offer beginning in 2014. The PPACA also requires all plans to adhere to the federal Mental Health Parity and Addiction Equity Act of 2008 (MHPAEA). Under this act all plans which offer mental health and SUD treatment benefits to their beneficiaries must make the benefits no more restrictive than medical benefits. The PPACA mandates all plans to cover screening, brief intervention and referral to treatment (SBIRT) for SUDs. Along with mandating SBIRT the PPACA also encourages Accountable Care Organizations and Patient Centered Medical Homes which might increase coordinated care for patients suffering from SUDs. The efforts for increasing care coordination and incorporating SBIRT for SUD in primary might translate to increase in number of health care referrals for SUD treatment which has historically, predominantly been through law enforcement agencies. Only one study has examined the impact of 2014 coverage expansions on the eligible adult population (18-64 year olds). The authors used the National Survey on Drug Use and Health data and found a significant increase in mental health treatment utilization without any significant changes in treatment of SUDs. However, they did not draw comparisons between states that expanded Medicaid vs states that did not. The study also did not examine changes in sources of payment for the SUD treatment following Medicaid expansion.

Arkansas, Kentucky and Florida responses. Arkansas was the first state to secure an approval for its "Private Option" demonstration project to implement the Medicaid expansion under the PPACA. Arkansas adopted a premium assistance strategy, which involved using federal funds to provide individual commercial health insurance for all the newly Medicaid eligible persons earning up to 138% of the FPL by placing them into one of the federally qualified health plans. On May 9, 2013 Governor Beshear declared that Kentucky would go ahead with Medicaid expansion as proposed under the PPACA. Kentucky decided to carry out the Medicaid expansion by placing the newly eligible persons in this pre-existing managed Medicaid program. Despite the state's vehement opposition to the PPACA, Governor Rick Scott expressed support for a "limited Medicaid expansion" through a federally funded and privately administered managed care plan. However, Florida opted against the Medicaid expansion. This resulted in almost 764,000 individuals not having any affordable coverage options by virtue of not being eligible for Medicaid coverage or Marketplace subsidies.

Comparing inpatient and emergency room utilization between these three states will highlight the impact Medicaid expansion and different approaches to Medicaid expansion might have on health service utilization. Further, using national level data, comparing the change in rate of SUD treatment admissions after Medicaid expansion in states that expanded Medicaid vs states that did not will determine the impact of Medicaid expansion on SUD treatment utilization.