In addition to the Medicaid expansion, the Patient Protection and Affordable Care Act (ACA, P.L. 111-148, as amended) established premium subsidies for the purchase of private coverage on the exchanges for those with incomes between 100 percent and 400 percent of the federal poverty level (FPL). Together with other changes to the insurance market, these new coverage options were intended to increase the number of individuals with health insurance coverage (CBO 2010). It also was anticipated that gains in health coverage would lead to improved access to and use of services.
Enrollment data provide only one data point; to understand the broader impact on coverage, survey data need to be examined. This is the case because the expected increase in the number of covered individuals also reflect the cumulative effect of the Medicaid expansion, other increases in Medicaid enrollment, exchange enrollment, and any new enrollment in employer-sponsored coverage. For more information, see Medicaid enrollment changes following the ACA.
Federal surveys, with their large sample sizes, provide a more complete assessment of the ACA’s impact on coverage rates, although a number of smaller, private surveys also have provided estimates on the law’s effect. Survey data released to date have shown a decline in the number of uninsured adults and a corresponding increase in Medicaid coverage. States that have expanded Medicaid have lower uninsured rates than non-expansion states. For example, according to the American Community Survey, the uninsured rate was lower in states that expanded (7 percent) than in those states that did not (13.1 percent).
While many available studies use survey data, others have used administrative data from hospitals, credit bureaus, or other sources. These studies have examined various aspects of coverage and access, including
- gains in coverage among adults and children;
- the effects of gaining coverage (either through Medicaid or in general) on unmet need, on having a usual source of care, and on utilization of particular types of health care services among low-income adults;
- effects of expansion on racial and ethnic disparities in coverage and access;
- the effects of using an alternative approach to expansion;
- effects of expansion on other measures of well-being, such as personal finances, psychological stress, and problems paying medical bills;
- spillover effects of increased insurance coverage on other public programs, recipients of other types of health insurance, as well as on crime.
The literature on the effects of Medicaid expansion on the goals of the ACA largely indicates that expansion was associated with increased coverage, access, quality of care, and Medicaid spending (Guth et al.). A few studies have found negative consequences, such as increased wait times for appointments (Mazurenko et al.). Selected studies below are listed by date, with newer studies appearing first. This list is not exhaustive of all published studies on the effects of the ACA on coverage and access.
Coverage changes
This study used data from the Medical Expenditure Panel Survey (MEPS) – Household Component for the period 2011 to 2016 to compare rates of coverage disruption in expansion versus non-expansion states, and in subgroups of states that used Section 1115 waivers to implement alternative expansion strategies. It found that among low-income adults ages 19 to 64 in Medicaid expansion states, disruption in coverage decreased 4.3 percentage points following expansion (compared to non-expansion states). Coverage disruptions declined in both expansion states and in states that used Section 1115 waivers for expansion. Men, people of color, and people without chronic illnesses experienced the largest improvements in continuity of coverage.
This study used data from the Health and Retirement Study for 2010 to 2016 to compare outcomes before and after Medicaid expansion among adults age 50 to 64 with income below 100 percent of the federal poverty level. It found that Medicaid expansion was associated with a 15 percentage point increase in Medicaid coverage. The increase in Medicaid coverage was largely offset by declines in other types of health insurance. The study also found that Medicaid expansion resulted in improvements in several measures of physical health, including reductions in metabolic syndrome, gross motor skill difficulties, and compromised activities of daily living. However, the study did not find significant evidence of changes in mental health.
This study used American Community Survey (ACS) data from 2010 to 2013 and 2015 to 2016 to examine how low-income Asian American, Native Hawaiian, and Pacific Islander adults gained health insurance coverage following the ACA. It found that in expansion states, Medicaid coverage gains were 9.67 percentage points greater than in non-expansion states, but private insurance gains were 10.19 percentage points lower. The authors suggest that these findings may reflect differences in willingness to enroll in public versus private coverage, and barriers related to language or citizenship.
This study used 2011 to 2016 ACS data to examine the effect of Medicaid expansion on Medicaid coverage in New York, Vermont, Massachusetts, and Delaware, which had generous Medicaid coverage prior to expansion. It found strong evidence of growth in coverage in New York, but weak or no evidence in the other three states.
This study used 2010 to 2015 MEPS data to study changes in health insurance disparities between full- and part-time workers. It found that uninsured rates decreased significantly for both types of workers. In expansion states, part-time workers primarily gained coverage through Medicaid, whereas in non-expansion states, they gained coverage primarily from exchange plans.
This study used Current Population Survey (CPS) data for 2011 to 2016, and from the ACS for 2010 to 2015. It found that among adults with income between 100 and 138 percent FPL, living in an expansion state (relative to a non-expansion state) was associated with a $344 reduction in average out-of-pocket spending, a 4.1 percentage point decrease in the likelihood of having out-of-pocket spending in excess of 10 percent of income, and a 7.7 percentage point decline in the probability of having any out-of-pocket spending at all.
Using 2018 ACS data, the authors estimate that nearly one-fifth (4.8 million) of the remaining uninsured population is eligible for Medicaid or CHIP. Of these, 2.3 million uninsured individuals fall into the so-called coverage gap, meaning that they earn too much to be eligible for Medicaid, but not enough to qualify for subsidized exchange coverage. These individuals would likely be eligible for Medicaid if their states chose to expand coverage.
This study used 2011 to 2015 Behavioral Risk Factor Surveillance System (BRFSS) data to examine health disparities in Kentucky, and found that following the Medicaid expansion, high-poverty communities experienced a decrease in the share of residents who were uninsured that was 8 percentage points greater than in lower poverty areas. They also experienced a decrease in unmet need to costs that was 7.5 percentage points greater than lower poverty areas.
In this article, the authors used 2008 to 2015 National Health Interview Survey (NHIS) data to look at Medicaid expansion coverage effects. Although the uninsured rate fell in both expansion and non-expansion states between 2010 and 2015, declines were significantly greater (7.5 percentage points) in expansion states. Additionally, Medicaid expansion was associated with significantly better quality of coverage as reported by low-income adults.
Using 2013 to 2015 NHIS data, this study found a link between parents gaining Medicaid eligibility and increased enrollment among children. Among children whose parents gained coverage under the Medicaid expansion, public coverage increased by 5.7 percentage points compared to 2.7 percentage points among children whose parents remained ineligible for Medicaid following the expansion (including those who remained ineligible due to their state not expanding Medicaid or for a different reason). An additional 200,000 low-income children would have gained coverage if all states had adopted the expansion.
Access to care and service use
This study examined changes in the reasons for emergency department (ED) use associated with Medicaid expansion. It used NHIS data for 2012 to 2017 for adults who were U.S. citizens with incomes below 138 percent FPL. It found that Medicaid expansion was not associated with statistically significant changes in overall ED use; however, it was associated with a significant decrease in ED use due to barriers to outpatient care.
The authors reviewed evidence on whether the ACA was effective in addressing cost barriers to coverage and care, and barriers to comprehensive risk protection provided by insurance. They found that the law substantially improved protection against the financial risk of illness. Coverage expansions reduced uninsured rates and lowered out-of-pocket spending.
This study examined the effects of Medicaid expansion on emergency department (ED) utilization and admissions, using data from 151 EDs in 14 expansion states for the period 2014 to 2016. It found that the volume of uninsured visits decreased by 44 percent and the volume of Medicaid ED visits increased by 49 percent, relative to non-expansion states. The effects on payer mix leveled off in 2015, suggesting that among individuals newly eligible for Medicaid, sicker individuals may have been more likely to enroll earlier. During the three-year period, there was no evidence that expansion after overall ED volume or admission rates.
This study used data from the 2016 and 2017 National Survey of Children’s Health to examine whether expanding Medicaid to adults had an effect on preventive health care utilization of children from low-income families. The study examined the effects on children in one expansion state, Louisiana, and two non-expansion states, Texas and Mississippi. It found that children in poverty residing in Louisiana were more likely to have an annual preventive care visit following Medicaid expansion, compared with children in Texas and Mississippi.
Using hospital-level data from the Centers for Medicare & Medicaid Services from 2007 to 2017 linked with U.S. Census data for all 50 states and the District of Columbia, this study examined the relationship between state Medicaid expansion and emergency access to acute care hospitals. It found that relative to expansion states, states that did not expand Medicaid experienced an increase in the population without access to hospitals overall, and an increase in the population without access to safety-net hospitals.
This study used data from the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases to examine inpatient discharges for 36 states during the period 2009 to 2015. It found larger reductions in discharge rates for ambulatory care-sensitive conditions (i.e., conditions for which hospital admission could be prevented by primary care interventions) among expansion states than in non-expansion states. Medicaid expansion was associated with a 3.47 percent reduction in annual discharge rates for such conditions, equivalent to 0.54 fewer discharges per 1,000 adult residents. Moreover, Medicaid expansion was associated with lower hospital costs associated with ambulatory care-sensitive conditions (-$4.23 per adult resident per year).
This study used patient-level discharge data to examine the effects of Medicaid expansion on hospital service use. It found that Medicaid expansion increased Medicaid visits and decreased uninsured visits, resulting in net-positive visits overall; this suggests that those who newly gained Medicaid coverage consumed more hospital services than they would have if they remained uninsured. The effects of expansion varied by state, with some states experiencing large increases in hospital utilization and others experiencing little change. Increases were larger for Medicaid expansion states that had more residents gaining coverage.
This study used 2011 to 2015 data from the Uniform Data System, and found that after two years, Medicaid expansion was associated with an 11 percentage point decrease in the share of community health center patients who were uninsured and a 13 percentage point increase in the share of patients covered by Medicaid. For community health centers in rural areas, Medicaid expansion was associated with significant improvements in quality indicators (e.g. percentage of patients with asthma receiving appropriate treatment, adults receiving a body mass index screening, blood pressure control for patients with hypertension). For rural community health centers, Medicaid expansion was associated with a significant increase in the number of visits for 18 of the 21 visit types, versus just 4 of the 21 visit types in urban centers.
This study used data obtained from California’s Office of Statewide Health Planning and Development to look at characteristics of frequent ED users in California, following Medicaid expansion. It found that the odds of being a frequent ED user (i.e., of having more four annual ED visits) were significantly lower for Medicaid-insured patients. The largest predictors of frequent ED use included having a diagnosis of a mental health condition or a substance use disorder.
Using data from the 2016 NHIS, the U.S. Government Accountability Office (GAO) found that low-income adults in expansion states were significantly less likely to report having unmet medical needs or financial barriers to medical and other types of health care than those in expansion states. Additionally, they were more likely to report having a usual source of health care when sick or in need of medical advice.
Using 2008 to 2014 MEPS data, this study found that in 2014, newly eligible adults in expansion states were 9.1 percentage points more likely to have an office-based primary care visit and 6.9 percentage points more likely to have a specialist visit, relative to their counterparts in non-expansion states.
The authors examined data from the 2014 NHIS and 2014 BRFSS and found that following the first open enrollment period of October 2013 to March 2014, previously uninsured individuals gaining coverage through Medicaid expansions were between 47.1 and 85.6 percent more likely to report having a usual source of care.
Using BRFSS data for 2011 to 2016, this study found that the Medicaid expansion had mixed effects on disparities in several health care outcomes among people of different socioeconomic status (as measured by income). For example, it appeared to reduce the socioeconomic disparity among people reporting financial ability to access health care, having a personal doctor, and receiving routine care. However, there was no effect on the socioeconomic gap in rates of preventive health care or dental care visits.
This study used NHIS data for 2008 to 2015, and found that adults with incomes between 100 and 138 percent of the federal poverty level experienced similar increases in having a usual source of care and primary care whether covered by Medicaid in expansion states or by the exchanges in non-expansion states. Although adults in expansion states experienced larger reductions in out-of-pocket spending, they also had greater difficulty accessing physicians relative to their counterparts in non-expansion states.
Using data from the September 2015 round of the Health Reform Monitoring Survey (HRMS), the authors found that individuals with Medicaid coverage were just as likely to report having a usual source of care or a recent routine checkup, but more likely to report difficulty getting a doctor’s appointment than other insured enrollees. Compared with enrollees in exchange plans, Medicaid enrollees were less likely to report unmet health needs due to affordability or problems paying medical bills.
This study used 2013 to 2014 MEPS data to look at access to care among previously uninsured individuals. It found that 18 percent of individuals who were uninsured in 2013 gained coverage through Medicaid, while only 11 percent remained uninsured in 2014. In general, individuals who gained insurance coverage in 2014 experienced improved access to care, but those who remained uninsured did not.
This study used NHIS data for 2010 to 2014. It found that in the second half of 2014, among adults with incomes below 138 percent FPL, Medicaid expansions were associated with higher utilization of certain services (including those provided by general practitioners and overnight hospital stays). They were also associated with increased diagnoses for certain health conditions including diabetes and high cholesterol.
This study used 2013 to 2015 HRMS data and found that nationally, adults with income below 138 percent FPL were more likely to report a usual source of care as well as a routine checkup within the last year than prior to implementation of the ACA, as well as a decline in unmet need due to cost and problems paying medical bills. However, more than 20 percent reported an access problem within the past 12 months.
The 2014 Kaiser Survey of low-income Americans and the ACA found that adults who gained coverage following the ACA were more likely to have a usual source of care, regardless of coverage type. They also were more likely to have used medical care compared to those who remained uninsured. However, newly insured adults were more likely to report difficulties finding a physician that would take them as a new patient.
Access to behavioral health and substance use disorder treatment
This study used data collected in 2018 in 22 cities for the National HIV Behavioral Surveillance (NHBS) to assess differences in healthcare access and utilization among persons who inject drugs by state Medicaid expansion status. It found that compared to those in non-expansion states, persons who inject drugs in Medicaid expansion states were more likely to have insurance and a usual source of healthcare, and have used medication-assisted treatment. They were less likely to have an unmet need for care.
Using the Treatment Episode Data Set, this study compared annual rates of specialty substance use disorder treatment (SUD) admissions in expansion versus non-expansion states for the period 2010–2017. It found that admissions to treatment increased in the four years after expansion; and in the fourth year after expansion, the number of individuals admitted to treatment was 36 percent higher in expansion states than in non-expansion states. The largest changes were in the number of people entering intensive outpatient treatments and in those seeking medication treatment for opioid use disorder (OUD). Moreover, the share of admissions paid for by Medicaid increased 24 percentage points in expansion states compared to non-expansion states.
This study tested the association between Medicaid expansion and Medicaid-paid prescriptions of opioid pain relievers and opioid addiction therapies using 2010–2016 Medicaid State Drug Utilization Data. It found that overall prescription use per Medicaid enrollee increased after 2014 in expansion states relative to non-expansion states; however, this growth was smaller than growth in prescriptions for medications used to treat depression, hypertension, diabetes, and high cholesterol. Growth in prescriptions for medications used to treat OUD outpaced other drugs, particularly in states with higher pre-2014 overdose death rates.
For this study, the authors examined the impact of the 2015 Pennsylvania Medicaid expansion on postpartum insurance coverage and preventive care utilization among pregnant women with OUD. They conducted a retrospective cohort study of 1,562 women using 2013–2015 administrative data provided by Pennsylvania. Post expansion, more women remained enrolled in Medicaid at 300 days postpartum, but Medicaid coverage was not associated with differences in postpartum visit attendance or contraceptive use.
This study used Medicaid claims data for 2014 to 2016 to identify trends in opioid use disorder (OUD) treatment among West Virginia Medicaid expansion enrollees. It found that about 5.5 percent of enrollees were diagnosed with OUD per year, with the monthly prevalence of diagnoses increasing three-fold over the three-year period. The ratio of people filling buprenorphine prescriptions to the number diagnosed with OUD increased from one-third in 2014 to three-quarters by late 2018. Additionally, most people receiving buprenorphine also received counseling and drug testing. However, uptake of treatment was uneven across race and ethnicity, rural status, and comorbidities.
This study used national, cross-sectional data for Medicaid-reimbursed prescription opioids, Medicaid enrollment information, and annual opioid overdose-related mortality rates for the period 2008 to 2016. It found that Medicaid expansion states experienced larger increases in prescription opioid availability compared with non-expansion states. Mortality rates were higher in expansion states than non-expansion states, and were not significantly mediated by higher Medicaid-reimbursed prescription opioid availability.
For this study, authors surveyed Medicaid programs in all states and the District of Columbia regarding their addiction treatment benefits and utilization controls in 2014 and 2017, after the ACA’s parity requirements took effect. They found that an increasing number of states covered benefits for residential treatment and medications used to treat opioid use disorder under their state plan. The number of states imposing annual service limits on outpatient addiction treatment decreased by over half, and fewer states required preauthorization for many other services. This trend was present among both alternative benefit plans and standard ones.
This study used a random-digit-dial survey of adults age 19 to 64 with incomes below 138 percent FPL in two expansion states (Arkansas and Kentucky) and one non-expansion state (Texas) conducted over 2013 to 2016. It found that Medicaid expansion was associated with a 23 percentage point reduction in the proportion of adults with depression who were uninsured. It was also associated with significant reductions in delaying care or medications due to cost.
This study used data for 2008 to 2015 from the National Survey on Drug Use and Health to examine changes in coverage and SUD treatment among low-income adults following Medicaid expansion. It found that the percentage of expansion state residents with SUD who were uninsured decreased by 14 percentage points between 2014 and 2015, compared to a 6.6 percentage point decline among their counterparts in non-expansion states. However, there was no corresponding increase in SUD treatment in either expansion or non-expansion states.
This study used all-payer prescription fill data from five states to examine whether Medicaid expansion affected prescription fills for buprenorphine with naloxone and opioid pain relievers. It found that Medicaid expansion was associated with a significant increase in prescription fills for buprenorphine with naloxone, suggesting improved access to OUD treatment. Medicaid expansion did not significantly increase fills per 100,000 county residents of prescription opioid pain relievers overall, but was associated with an increase in fills for opioid pain relievers paid for by Medicaid.
GAO looked at 2014 Medicaid Statistical Information System data for four expansion states: Iowa, New York, Washington, and West Virginia. It found that between 20 and 34 percent of expansion enrollees received behavioral health treatment in 2014, including psychotherapy and prescription drugs. Among individuals in these states diagnosed with opioid abuse or dependence, between 62 and 81 percent used some outpatient treatment services, and between 11 and 41 percent used medication-assisted treatment.
This study used administrative data from the Treatment Episodes Data Set for 2010 to 2015, and Medicaid State Drug Utilization Data for 2011 to 2015. It found that following Medicaid expansion, there was no evidence of increased admission to specialty treatment for SUD in expansion states relative to non-expansion states. However, Medicaid-covered prescriptions for outpatient medications used for SUD treatment increased by 33 percent in expansion states relative to non-expansion states.
Using National Survey on Drug Use and Health data for 2004 to 2014, the authors found that the uninsured rate among adults who reported past-year criminal justice contact and met screening criteria for substance use disorder declined from 38 to 28 percent. However, overall treatment rates among this population were unchanged in 2014.
Access to other specific types of care and services
This study used survey data from the 2012 to 2017 Pregnancy Risk Assessment Monitoring System to estimate the effect of Medicaid expansion on continuity of coverage for low-income women at three points: preconception, delivery, and postpartum. It found that Medicaid expansion resulted in a 10.1 percentage point decrease in churning (i.e., moving between different insurance coverage or between insurance and insurance for beneficiaries in expansion states. There was a 5.8 percentage point decease in the portion of women who were continuously insured. However, there was a 4.2 percentage point increase in churning between Medicaid and private insurance.
This study examined the effect of Medicaid expansion on the maternal mortality ratio. It found that Medicaid expansion was significantly associated with 7.01 fewer maternal deaths per 100,000 live births, relative to non-expansion states. These effects were concentrated among non-Hispanic black mothers, suggesting that Medicaid expansion is helping decrease racial disparities in maternal mortality.
Using Medicaid claims data for 2013 to 2015, this study compared postpartum Medicaid coverage and outpatient utilization among new mothers in Colorado (which expanded Medicaid) and Utah (which had not yet expanded Medicaid as of 2015). After expansion, new mothers in Utah experienced higher rates of Medicaid coverage loss and accessed fewer Medicaid-financed outpatient visits during the six-months postpartum, relative to their counterparts in Colorado. The effects of Medicaid expansion were largest among women who experienced significant maternal morbidity at delivery.
This study used National Health Interview Survey (NHIS) data for 2010 to 2018 to examine the effect of Medicaid expansion on dental coverage and use of oral health services among low-income adults. It found that Medicaid expansion increased rates of dental coverage by 18.9 percentage points in states that provide Medicaid dental benefits. Although the expansion was associated with a significant increase in the share of white adults who had a dental visit in the past year, there was no significant change in this metric for adults overall.
This study compared changes in diagnosis and management of colon cancer following Medicaid expansion using data from the National Cancer Data Base for 2010 to 2012 and 2015 to 2016. It found that patients in expansion states experienced increases in Medicaid coverage. They also experienced significant increases in stage I diagnoses and treatment at integrated network programs. Significantly more early-stage patients were treated within 30 days and more stage IV patients received palliative care. Among surgical patients, Medicaid expansion was also correlated with fewer urgent cases and more minimally invasive surgery. However, there were no significant differences in postoperative outcomes.
This study used data from the National Cancer Data Base to determine whether Medicaid expansion is associated with improved mortality among patients with cancer, including data from patients newly diagnosed from January 1, 2012, to December 31, 2015. It found that after Medicaid expansion, mortality significantly decreased in expansion states but not in nonexpansion states, primarily among patients with nonmetastatic cancer. However, after adjusting for cancer stage, mortality improvement following Medicaid expansion was no longer evident.
This study examined access to cancer-specific surgical care in the U.S. It used data from the Surveillance, Epidemiology, and End Results (SEER) database for approximately 1 million patients with the 8 most prevalent cancers between 2007 and 2015. It found that following Medicaid expansion, patients were diagnosed at an earlier stage, and lack of insurance decreased. Additionally, patients of lower socioeconomic status had improved access to surgical care.
Myerson, R., S. Crawford, and L.R. Wherry. 2020. Medicaid expansion increased preconception health counseling, folic acid intake, and postpartum contraception. Health Affairs 39, no. 11: 1883-1890.
Using data from the BRFSS, this study evaluated whether increased coverage following Medicaid expansion affected ten preconception health indicators. It found that expansion was associated with greater preconception health counseling, prepregnancy folic acid intake, and postpartum use of effective birth control methods among low-income women. It did not find evidence of changes on other preconception health indicators.
This study examined the association between Medicaid expansion and changes in insurance status, stage at diagnosis, and timely treatment among patients with breast, colon, and non-small cell lung cancer. It included adults age 40 to 64 with a new diagnosis from January 1, 2011 to December 31, 2016 in the National Cancer Database. It found that Medicaid expansion was associated with a decreased rate of uninsured patients and an increased rate of early-stage cancer diagnosis, but was not associated with changes in the rate of timely treatment.
Using Health and Retirement Study data for 891 individuals from 2008 to 2016, this study examined whether Medicaid expansion is associated with long-term care use among newly eligible adults, and older adults whose eligibility did not change. The study found that the expansion was associated with a significant increase in the probability of any long-term care use among low-income, middle-aged adults.
Using 2012 to 2016 MEPS data, this study found that Medicaid expansion had not significantly improved utilization of mammograms or Pap tests among low-income women.
Clapp, M., A. Kaimal, B. Sommers, and J. Daw. 2019. Association of Medicaid expansion with coverage and access to care for pregnant women. Obstetrics & Gynecology. Published online October 8.
This study used national birth certificate data from 2009 to 2017 to assess changes in access to care for pregnant women following Medicaid expansion. Although Medicaid expansion was associated with increased Medicaid coverage for childbirth in expansion states, there was no association with changes in early access to prenatal care, preterm birth, or small for gestational age birth weights. Findings were similar across the two subgroups: women for whom this was the first delivery, and women with no more than a high school diploma.
This study used a national all-payer pharmacy transactions database to examine the effect of health insurance on prescription drug utilization among low-income non-elderly adults. It found that within 15 months of Medicaid expansion, aggregate Medicaid-paid prescriptions increased by 19 percent. There was no evidence of reductions in uninsured or privately insured prescriptions. The largest increases occurred for medications used to treat diabetes and heart disease. Increases were larger for generic drugs than brand-name drugs and smaller in expansion states with higher Medicaid copayments, indicating price sensitivity among low-income populations.
This study examined changes in bariatric surgery rates by insurance and income between 2012 and 2015 using the HCUP State Inpatient Database. It found that the adjusted incidence rate of bariatric surgery among Medicaid or uninsured and low-income patients increased significantly in expansion states. Rates increased for both African American and white patients, but not significantly, indicating that racial disparities persisted. There was no change for privately insured and high-income patients.
This study examined changes in use of and out-of-pocket costs for antidiabetic drugs among adults affected by Wisconsin’s Medicaid coverage expansion in April 2014. Using Wisconsin Medicaid enrollment records, medical claims, and pharmacy claims for the period April 2013 to March 2015, the study found that childless adults experienced a significant increase in the use of these drugs compared to parents and caretakers. They also experienced a significant 70 percent reduction in average out-of-pocket spending for these drugs.
This study examined the effects of Medicaid expansion on access to cancer-specific surgical care using the SEER database. It found that following expansion, cancer patients were diagnosed at an earlier stage, the portion of patients who were uninsured decreased, and patients of low socioeconomic status experienced improved access to surgical care.
This study found that the share of uninsured adult trauma patients in expansion states decreased by 13.7 percentage points relative to non-expansion states. It also found a 7.4 percentage point increase in discharge to rehabilitation among adult trauma patients.
This study used BRFSS data from 2012 to 2016 to examine whether Medicaid expansion improved colorectal screening for low-income or minority patients. It found that screening rates increased significantly for low-income and African American patients in states that adopted the Medicaid expansion early. There was no significant increase in states that adopted Medicaid expansion in 2014, or for Hispanic patients in either expansion state type.
Using 2011 to 2016 data from the United Network of Organ Sharing database, the authors looked at listings for kidney transplantation among adults with dialysis dependence. They found that expansion states had a 59 percent relative increase in Medicaid-covered preemptive listings following expansion. Non-expansion states had only an 8.8 percent relative increase. Additionally, the share of listings covered by Medicaid increased significantly (3 percentage points) in expansion states, and the increase was significant across race and ethnicity categories.
Hospital administrative data for 2010 to 2015 showed that Medicaid expansion was associated with improved receipt of timely care among hospital patients with five common surgical conditions; specifically, a 1.8 percentage point increase in the probability of early uncomplicated presentation with common diagnosis and a 2.7 percentage point increase in the probability of receiving optimal care management.
The authors used data on prescription fills in the 50 states and the District of Columbia for 2008–2018 to examine the effects of Medicaid expansion on access to diabetes medications. They found that expansion was associated with 30 additional Medicaid-covered diabetes prescriptions filled per 1,000 compared to non-expansion states. Additionally, Medicaid-covered prescription fills for insulin and metformin each grew by 40 percent following expansion.
The authors examined data from the National Cancer Database for the periods 2004–2009 and 2011–2014, finding that women age 21 to 26 with gynecologic cancer were more likely to be insured and diagnosed at an early stage of disease following the ACA. However, privately insured women were more likely to be diagnosed at an early stage and receive fertility-sparing treatment than publicly insured or uninsured women both before and after the ACA.
Effects on racial and ethnic disparities in coverage and access
Using data from the ACS and BRFSS for the period 2008–2017, this study found that after the ACA, health insurance coverage increased significantly for all racial and ethnic groups. However, it increased more for non-Hispanic black and Hispanic populations than it did for non-Hispanic white populations, decreasing disparities in health insurance coverage. Disparities decreased more in expansion states than non-expansion states. Disparities in common measures of access to care (e.g., percentage of individuals who reported foregoing care due to cost) similarly decreased.
This issue brief describes findings from a review of literature investigating the effects of Medicaid expansion on racial disparities in coverage, access to care and use of care, health outcomes and quality of care, and payer mix and other economic outcomes. Key takeaways include (1) most studies found that Medicaid expansion reduced, but did not eliminate, racial disparities in coverage; (2) most studies found evidence that expansion was associated with improvements in access to and use of care for some, but not all groups; (3) some studies found that Medicaid expansion helped reduce disparities in health outcomes for Black and Hispanic individuals, particularly for measures of maternal and infant health; and (4) studies on effects of expansion on disparities in economic measures had mixed results.
This study used data from the 2011 to 2017 waves of the ACS to examine the effects of Medicaid expansion, subsidized exchange plans, and insurance market reforms on disparities in insurance coverage after four years. It found that the fully implemented ACA reduced disparities in coverage by 44 percent across income groups, 26.7 percent across racial groups, 45 percent across marital status, and 44 percent across age groups. These changes were attributable to both Medicaid expansion other aspects of the law.
This study examined unadjusted trends in health insurance coverage among American Indians and Alaska Natives across 10 regions, using 2010 to 2017 ACS data. It found inconsistent results among regions, with the Albuquerque, California, Nashville, and Portland, Oregon regions experiencing the highest increases in any coverage and public coverage, and coverage disparities between American Indians and Alaska Natives and non-Hispanic whites decreasing. However, there was no significant increase in health insurance coverage among American Indians and Alaska Natives in the Oklahoma, Bemidji, or Alaska regions.
This analysis used state-level breast cancer mortality data obtained from the Centers for Disease Control and Prevention (CDC) to examine effects of Medicaid expansion on breast cancer mortality disparities. It found that the black/white mortality ratio increased in Medicaid expansion states for all age groups, with significant effects in younger age groups.
This study used data from the CDC Compressed Mortality File to look at the difference in age-adjusted diabetes mortality rates among African Americans before and after Medicaid expansion. It found a slight reduction in diabetes mortality following Medicaid expansion: from 41.14 per 100,000 for 2008 to 2010 to 38.94 for 2014 to 2016. Across states, the change in mortality rates ranged from a decrease of 15.43 per 100,000 to an increase of 9.53 per 100,000. Rates declined in 16 of the 24 expansion states included in the study, and in 8 states that did not expand coverage.
This study used 2010 to 2015 ACS data to study the effects of Medicaid expansion on insurance coverage among U.S. natives, naturalized citizens, and non-citizen immigrants. It found that the uninsured rates decreased significantly across all three groups. For non-citizen immigrants, the uninsured rate declined from 69.6 percent to 53.5 percent between 2010 and 2015. However, the share of uninsured non-citizen immigrants remained high, at 44.9 percent in expansion states, compared to an uninsured rate of 16.3 percent among U.S. natives.
Effect of alternative approaches to expansion
To analyze the effects of Arkansas’ Medicaid work requirements, the authors of this study conducted a telephone survey of low-income adults in the state in late 2019. The researchers found the work requirements did not increase employment over eighteen months of follow-up. Among people ages 30 to 49 who lost Medicaid in 2018, 50 percent reported serious problems paying off medical debt, 56 percent delayed care because of cost, and 64 percent delayed taking medications because of cost. These rates were significantly higher than among Arkansans who remained in Medicaid all year. The researchers also found that most of the coverage losses that occurred in 2018 were reversed in 2019 after a court order suspending the policy.
This study examined the effects of Iowa’s healthy behaviors program, which was designed to incentivize Medicaid expansion enrollees to use preventive care by requiring them to complete an annual wellness exam and health risk assessment. The study used Medicaid enrollment and claims data for 2012 to 2017 from the Iowa Department of Human Services, and the department’s records of healthy behavior actions for 2014 to 2017. It found that healthy behavior program participants were 9.6 percentage points less likely to visit the emergency department, and 2.8 percentage points less likely to be hospitalized than nonparticipants. However, they had higher total health care spending, even after adjusting for increased spending associated with Medicaid expansion.
Using landline and cellular phones between November 8 and December 30, 2018, the authors conducted a survey of adults age 19 to 64 with incomes below 138 percent FPL in Arkansas. They found that following implementation of Medicaid work requirements in Arkansas and three comparison states, there was a significant decrease in Arkansas Medicaid coverage, with no significant increase in employer-sponsored insurance. Additionally, there was no significant change in employment, hours worked, or community engagement activities. Descriptive results also indicated confusion and lack of knowledge about the requirements among enrollees.
This study used 2009 to 2016 American Community Survey (ACS) data to look at coverage effects of Indiana’s alternative approach to Medicaid expansion. It found little evidence to indicate that Indiana’s waiver program features (e.g., premiums, disenrollment and lock out for non-payment) caused smaller coverage effects as compared with traditional expansion states. Relative to pre-ACA uninsured rates, Indiana’s coverage gains following the Medicaid expansion were smaller than gains in neighboring expansion states, but larger than gains in non-neighboring expansion states (e.g., Arizona, Delaware, and North Dakota).
The authors collected survey data from low-income adults in three states in 2016: Kentucky, which expanded Medicaid; Arkansas, which expanded Medicaid through a Medicaid-funded exchange plan premium assistance; and Texas, which did not expand. They found that by the end of 2016, the uninsured rate in Kentucky and Arkansas declined by more than 20 percentage points relative to that in Texas. Among previously uninsured individuals, gaining coverage was associated with a 41 percentage point increase in the likelihood of having a usual source of care, a 23 percentage point increase in the likelihood of being in self-reported excellent health, and a $337 decrease in average annual out-of-pocket spending.
Using survey data collected in Kentucky, Arkansas, and Texas from November 2013 through December 2015, this study looked at changes in utilization and health following Medicaid expansion. It found that in 2015, the second year of expansion, Kentucky and Arkansas both saw significant changes in coverage and access. Expansion was associated with a 22.7 percent decrease in the uninsured rate; significant increases in access to primary care, outpatient utilization, preventive care, improved health quality, and improved self-reported health; and, significant decreases in emergency department use. There were few differences between the traditional expansion state (Kentucky) and the state using an alternative approach to expansion (Arkansas).
The authors conducted a telephone survey between November and December 2013 to look at access to care and affordability paying for medical care among low-income adults. They found that in two expansion states, Kentucky and Arkansas, difficulty paying for medical care and skipping medication due to cost declined and the share of adults with chronic conditions who obtained regular care increased. There were few differences between the traditional expansion state (Kentucky) and the state using an alternative approach to expansion (Arkansas).
Effect of expansion on other measures of well-being
The authors combined projections from the state of Michigan’s House Fiscal Agency with estimates from a proprietary macroeconomic model to project the state fiscal effects of Michigan’s Medicaid expansion. They found that for at least the period fiscal year (FY) 2014 to FY 2021, Medicaid expansion will produce fiscal benefits that exceed state costs in every year. These benefits include savings on other non-Medicaid health programs, increases in revenue from provider taxes and broad-based sales and income taxes.
This study examined the effects of Medicaid expansion on financial strain among trauma patients. The authors analyzed trauma patients age 18–64 admitted to the sole Level 1 trauma center in Washington from 2012 to 2017. They found that after Medicaid expansion, the Medicaid coverage rate among these patients grew from 20.4 percent to 41 percent, and the uninsured rate decreased from 19.2 percent to 3.7 percent. The risk of catastrophic health expenditure among these patients fell from 26.4 percent to 14 percent.
Using 2015 to 2018 BRFSS data, this study evaluated the effect of Medicaid expansion on caregiver’s mental health. After adjusting for demographics, socioeconomic status, and health behaviors, the study found that caregivers in Medicaid expansion states had a significantly fewer number of poor mental health days in the previous month than caregivers in non-expansion states.
This study used commercial evictions data from American Information Research Services to compare eviction rates before and after California’s early Medicaid expansion, using a difference-in-differences model. It found that early expansion was associated with 24.5 fewer evictions per month in each of the 51 early expansion counties, and that for every 1,000 new Medicaid enrollees, there were 22 fewer evictions per year. The effects were concentrated among counties with the highest pre-expansion uninsured rates.
Buchmueller, T.C., H.G. Levy, and R.G. Valletta. 2019. Medicaid expansion and the unemployed. December. Cambridge, MA: National Bureau of Economic Research.
This study examined how Medicaid expansion affected health insurance coverage, access to care, and labor market transitions of unemployed workers. It used a combination of survey data sources, for 2007 to 2017, including the ACS, CPS, and BRFSS. It found that expansion substantially increased insurance coverage and improved access to care among unemployed individuals. It found no meaningful statistical evidence of reduced job-finding rates or labor force attachment in expansion states relative to non-expansion states.
To examine the effects of Medicaid expansion on low-income, childless household savings, this study used Current Population Survey Supplement data. It found that Medicaid expansion increased unearned income generated from savings for childless households with income below 100 percent FP, but had no effect on earned or total income.
This study used data from the Consumer Expenditure Survey for 2010 to 2016 to look at trends in insurance coverage and consumption for households in expansion or non-expansion states. It found significant increases in Medicaid coverage and significant reductions in quarterly health spending of approximately $60 per household in expansion states relative to non-expansion states. It found no significant changes in non-health consumption.
The authors linked ACS data with administrative death records to examine the relationship between Medicaid enrollment and mortality for near-elderly adults age 55 to 64 in expansion and non-expansion states. They found that Medicaid expansion was associated with a 0.13 percentage decline in annual mortality and a 9.3 percent reduction over the sample mean.
The authors conducted a mixed-method study made up of qualitative interviews and computer-assisted telephone surveys to understand Michigan’s Medicaid expansion on enrollees’ health, ability to work, and ability to seek employment. Half of respondents reported better physical health following Medicaid expansion and one-third reported better mental and dental health. Among employed enrollees, two-thirds reported that Medicaid helped them do a better job at work, and among unemployed enrollees, half agreed that it made them better able to look for a job.
Zewde, N., and C. Wimer. 2019. Antipoverty impact of Medicaid growing with state expansions over time. Health Affairs 38, no. 1: 132–138.
This study used 2010 to 2016 CPS data to examine the effect of Medicaid expansion on the poverty rate. It found that Medicaid expansion reduced the poverty rate among Medicaid expansion by 0.92 percentage points, a significant reduction. The effect was concentrated among non-elderly adults, the primary beneficiaries of Medicaid expansion.
Using Michigan Medicaid administrative data as well as TransUnion consumer credit history information, this study examined the effect of the ACA on the financial well-being of newly eligible Medicaid beneficiaries. It found that enrollment was associated with reductions in unpaid bills, over limit credit card spending, delinquencies, and public records including evictions and bankruptcies. Individuals with greater medical need experienced the largest improvements.
This study examined survey responses from 2013 to 2017 from low-income households who used free online tax preparation software when filing their taxes. It found that low-income families in financial stress who became eligible for Medicaid saved more of their tax refund. Low-income families that were not financially stressed did not make changes to their saving habits after becoming eligible for Medicaid.
The authors used national data on payday loans from 2009 through early 2014 obtained from the Community Financial Services Association of America. They found that following early Medicaid expansion in California, there were significant reductions in the number of loans and number of unique borrowers per month. There was also a significant reduction in the amount of payday loan debt in early expansion counties in California relative to non-expansion counties nationwide.
Using data collected from credit records, the authors found that Medicaid expansion reduced unpaid medical bills sent to collection by $3.4 billion in the first two years. Individuals’ improved financial health led to better terms for available credit valued at $520 million per year.
The authors used credit bureau data to look at the effects of Medicaid expansion on personal finance, finding that individuals in expansion states experienced improved credit scores and reduced past due balances; and were less likely to experience a medical collection of over $1,000, have one or medical bills go to collection, have derogatory balances at any time, or file for bankruptcy.
This study used 2010 to 2015 NHIS data to examine the effects of Medicaid expansion for low-income parents. It found that between 2010 and 2015, Medicaid expansion resulted in increased coverage and decreased psychological stress and problems paying medical bills. There were no significant effects on health status, affordability of prescription drugs, or mental health care, and only limited effects on increased use of care overall.
Spillover effects on other public programs
This study examined the effects of Medicaid expansion on applications for Supplemental Security Income (SSI) and Social Security Disability Insurance (SSDI) using county-level data on applications provided by the Social Security Administration. It found no significant effects of Medicaid expansion on either applications to or awards from SSI or SSDI.
Using 2010 to 2015 MEPS data, this study looked at the effects of Medicaid expansion on offers of employer-sponsored health insurance, eligibility, take-up, and out-of-pocket premiums. It found that employer provision of health insurance was unaffected by Medicaid expansion.
This study examined rates of employer-sponsored insurance following Medicaid expansion using June 2013 through March 2017 Health Reform Monitoring Survey data. It found that between June 2013 and March 2017, offer rates for employer-sponsored insurance remained stable and take-up rates increased. The share of workers with family incomes below 138 percent FPL who had employer-sponsored insurance remained the same, and uninsured rates declined.
Using MEPS data for 2008 to 2014, this study found no relationship between increases in insurance coverage at the local level and access to care for adults in the area that continuously had health insurance over the period. Specifically, there was no relationship across eight measures of access (e.g., receipt of preventive care) and no relationship in vulnerable subpopulations, including Medicaid beneficiaries and individuals residing in health care professional shortage areas.
This study examined the effect of Medicaid expansions on health care spending and utilization among Medicare beneficiaries using data from the Medicare Current Beneficiary Survey. It found that a 1 percentage point increase in the share of non-elderly adults eligible for Medicaid was associated with a $477 reduction in average beneficiary spending for individuals dually eligible for Medicare and Medicaid.
This study used data from the ACS as well administrative data from the Women, Infants, and Children (WIC) and Supplemental Nutrition Assistance Program (SNAP) to look at the effects of Medicaid expansion on enrollment in other programs. It found that while enrollment in means-tested programs decreased after 2014 regardless of whether a state expanded Medicaid, states that both expanded Medicaid and conducted Medicaid enrollment outreach experienced smaller SNAP and WIC enrollment decreases than other states.
This study used several different data sources, including public use data available from the Center for Consumer Information and Insurance Oversight at the Centers for Medicare & Medicaid Services to look at the effect of Medicaid expansion on premiums for plans on the exchange. It found that exchange plan premiums are 11 percent lower in Medicaid expansion states, after controlling for demographic and health characteristics and measures of health access.
This study used a combination of crime-related data sets for 2010–2015 to look at the relationship between access to health care and criminal behavior following Medicaid expansion. It found that following Medicaid expansion, reported instances of violent and property crime per 100,000 people fell by 5 percent in expansion states and 3 percent in non-expansion states, a statistically significant difference. Crime reductions were even more pronounced in counties that experienced the largest decreases in uninsured rates following expansion.