Research

Publications

2024

Chima D. Ndumele, Hannah Factor, Matthew Lavallee, Anthony Lollo Jr, Jacob Wallace. 2024. Supplemental Nutrition Assistance Program Work Requirements and Safety-Net Program Participation JAMA Internal Medicine.

Importance: Work requirements are a controversial feature of US safety-net programs, with some policymakers seeking to expand their use. Little is known about the demographic, clinical, and socioeconomic characteristics of individuals most likely to be negatively impacted by work requirements.

Objective: To examine the association between work requirements and safety-net program enrollment.

Design, Setting, and Participants: This cohort study included Medicaid and Supplemental Nutrition Assistance Program (SNAP) enrollees in Connecticut. The impact of SNAP work requirements for able-bodied adults without dependents—the target population—was estimated using a triple-differences research design comparing outcomes before and after the policy (first difference) in affected and exempted towns (second difference) between the targeted population and untargeted parents and caregivers (third difference). SNAP and Medicaid enrollment trends were assessed for a 24-month period, and the characteristics of individuals most likely to lose coverage were examined. Data were collected from August 2015 to April 2018, and data were analyzed from August 2022 to September 2024.

Exposures: The reintroduction of SNAP work requirements in 2016.

Main Outcomes and Measures: Proportion of enrollees disenrolled from SNAP and Medicaid.

Results: Of 81,888 Medicaid enrollees in Connecticut, 46,872 (57.2%) were female, and the mean (SD) age was 36.6 (7.0) years. Of these, 38,344 were able-bodied adults without dependents, of which 19,172 were exposed to SNAP work requirements, and 43,544 were parents or caregivers exempted from SNAP work requirements. SNAP coverage declined 5.9 percentage points (95% CI, 5.1-6.7), or 25%, following work requirements. There were no statistically significant changes in Medicaid coverage (0.2 percentage points; 95% CI, −1.4 to 1.0). Work requirements disproportionately affected individuals with more chronic illnesses, targeted beneficiaries who were older, and beneficiaries with lower incomes. Individuals with diabetes were 5 percentage points (95% CI, 0.8-9.3), or 91%, likelier to lose SNAP coverage than those with no chronic conditions; older SNAP beneficiaries (aged 40 to 49 years) with multiple comorbidities were 7.3 percentage points (95% CI, 4.3-11.3), or 553%, likelier to disenroll than younger beneficiaries (aged 25 to 29 years) without chronic conditions; and households with the lowest incomes were 18.6 percentage points (95% CI, 11.8-25.4), or 204%, likelier to lose coverage than the highest income SNAP beneficiaries. Conclusions and Relevance: In this cohort study, SNAP work requirements led to substantial reductions in SNAP coverage, especially for the most clinically and socioeconomically vulnerable. Work requirements had little effect on Medicaid coverage, suggesting they did not lead to sufficient increases in employment to transition beneficiaries off the broader safety net.

Jacob Wallace, Chima D. Ndumele, Anthony Lollo, Danil Agafiev Macambira, Matthew Lavallee, Beniamino Green, Kate A. Duchowny, J. Michael McWilliams. 2024. Attributing Racial Differences in Care to Health Plan Performance or Selection JAMA Internal Medicine.

Importance: There is increased interest in public reporting of, and linking financial incentives to, the performance of organizations on health equity metrics, but variation across organizations could reflect differences in performance or selection bias.

Objective: To assess whether differences across health plans in sex- and age-adjusted racial disparities are associated with performance or selection bias.

Design, Setting, and Participants: This cross-sectional study leveraged a natural experiment, wherein a southern US state randomly assigned much of its Medicaid population to 1 of 5 plans after shifting to managed care in 2012. Enrollee-level administrative claims and enrollment data from 2011 to 2015 were obtained for self-identified Black and White enrollees. The analyses were limited to Black and White Medicaid enrollees because they accounted for the largest percentages of the population and could be compared with greater statistical power than other groups. Data were analyzed from June 2021 to September 2024.

Exposures: Plan enrollment via self-selection (observational population) vs random assignment (randomized population).

Main Outcomes and Measures: Annual counts of primary care visits, low-acuity emergency department visits, prescription drug fills, and total spending. For observational and randomized populations, models of each outcome were fit as a function of plan indicators, indicators for race, interactions between plan indicators and race, and age and sex. Models estimated the magnitude of racial differences within each plan and tested whether this magnitude varied across plans.

Results: Of 118,101 enrollees (mean [SD] age, 9.3 [7.5] years; 53.0% female; 61.4% non-Hispanic Black; and 38.6% non-Hispanic White), 70.2% were included in the randomized population, and 29.8% were included in the observational population. Within-plan differences in primary care visits, low-acuity emergency department visits, prescription drug use, and total spending between Black and White enrollees were large but did not vary substantially and were not statistically significantly different across plans in the randomized population, suggesting minimal effects of plans on racial differences in these measures. In contrast, in the observational population, racial differences varied substantially across plans (standard deviations 2-3 times greater than in the randomized population); this variation was statistically significant after adjustment for multiple testing, except for emergency department visits. Greater between-plan variation in racial differences in the observational population was only partially explained by sampling error. Stratifying by race did not bring observational estimates of plan effects meaningfully closer to randomized estimates.

Conclusions and Relevance: This cross-sectional study showed that selection bias may mischaracterize plans’ relative performance on measures of health care disparities. It is critical to address disparities in Medicaid, but adjusting plan payments based on disparity measures may have unintended consequences.


2023

Matthew Lavallee, Sandro Galea, Nadia N. Abuelezam. 2023. Supplemental Nutrition Assistance Program Emergency Allotments and Food Security, Hospitalizations, and Hospital Capacity JAMA Network Open.

Importance: Understanding how social policies shape health is a national priority, especially in the context of the COVID-19 pandemic.

Objective: To understand the association between politically motivated changes to Nebraska’s Supplemental Nutrition Assistance Program (SNAP) policy and public health measures during the COVID-19 pandemic.

Design, Study, and Participants: This cross-sectional study used synthetic control methods to estimate the association of Nebraska’s decision to reject emergency allotments for the SNAP with food security and hospital capacity indicators. A counterfactual for Nebraska was created by weighting data from the rest of the US. State-level changes in Nebraska between March 2020 and March 2021 were included. Data were acquired from the Census Bureau’s Household Pulse Survey on individual food security and mental health indicators and from the US Centers for Disease Control and Prevention on hospital-level capacity indicators. Data analysis occurred between October 2022 and June 2023.

Intervention: The rejection of additional SNAP funds for low-income households in Nebraska from August to November 2020.

Main Outcomes and Measures: Food insecurity and inpatient bed use indicators (ie, inpatient beds filled, inpatient beds filled by patients with COVID-19, and inpatients with COVID-19).

Results: The survey data of 1 591 006 respondents from May 2020 to November 2020 was analyzed, and 24 869 (1.56%) lived in Nebraska. Nebraska’s population was composed of proportionally more White individuals (mean [SD], 88.70% [0.29%] vs 78.28% [0.26%]; P < .001), fewer individuals who made more than $200 000 in 2019 (4.20% [0.45%] vs 5.22% [0.12%]; P < .001), and more households sized 1 to 3 (63.41% [2.29%] vs 61.13% [1.10%); P = .03) compared with other states. Nebraska’s rejection of additional funding for SNAP recipients was associated with increases in food insecurity (raw mean [SD] difference 1.61% [1.30%]; relative difference, 19.63%; P = .02), percentage of inpatient beds filled by patients with COVID-19 (raw mean [SD] difference, 0.19% [1.55%]; relative difference, 3.90%; P = .02), and percentage of inpatient beds filled (raw mean [SD] difference, 2.35% [1.82%]; relative difference, 4.10%; P = .02).

Conclusions and relevance: In this cross-sectional study, the association between social policy, food security, health, and public health resources was examined, and the rejection of emergency allotments in Nebraska was associated with increased food insecurity. Additionally, this intervention was associated with an increased rate of hospitalizations for COVID-19 and non–COVID-19 causes.


2022

Jacob Wallace, Anthony Lollo, Kate A. Duchowny, Matthew Lavallee, Chima D. Ndumele. 2022. Disparities in Health Care Spending and Utilization Among Black and White Medicaid Enrollees JAMA Health Forum.

Importance: Administrative records indicate that more than half of the 80 million Medicaid enrollees identify as belonging to a racial and ethnic minority group. Despite this, disparities within the Medicaid program remain understudied. For example, we know of no studies examining racial differences in Medicaid spending, a potential measure of how equitably state resources are allocated.

Objective: To examine whether and to what extent there are differences in health care spending and utilization between Black and White enrollees in Medicaid.

Design, Setting, and Participants: This cross-sectional study used calendar year 2016 administrative data from 3 state Medicaid programs and included 1 966 689 Black and White Medicaid enrollees. Analyses were performed between January 28, 2021, and October 18, 2021. EXPOSURES Self-reported race.

Main Outcomes and Measures: Rates and racial differences in health care spending and utilization (including Healthcare Effectiveness Data and Information Set [HEDIS] access measures).

Results: Of 1 966 689 Medicaid adults and children (mean [SD] age, 20.3 [17.1] years; 1 119 136 [56.9%] female), 867 183 (44.1%) self-identified as non-Hispanic Black and 1 099 506 (55.9%) selfidentified as non-Hispanic White. Results were adjusted for age, sex, Medicaid eligibility category, zip code, health status, and usual source of care. On average, annual spending on Black adult (19 years or older) Medicaid enrollees was $317 (95% CI, $259-$375) lower than White enrollees, a 6% difference. Among children (18 years or younger), annual spending on Black enrollees was $256 (14%) lower (95% CI, $222-$290). Adult Black enrollees also had 19.3 (95% CI, 16.78-21.84), or 4%, fewer primary care encounters per 100 enrollees per year compared with White enrollees. Among children, the differences in primary care utilization were larger: Black enrollees had 90.1 (95% CI, 88.2-91.8) fewer primary care encounters per 100 enrollees per year compared with White enrollees, a 23% difference. Black enrollees had lower utilization of most other services, including high-value prescription drugs, but higher emergency department use and rates of HEDIS preventive screenings.

Conclusions and relevance: In this cross-sectional study of US Medicaid enrollees in 3 states, Black enrollees generated lower spending and used fewer services, including primary care and recommended care for acute and chronic conditions, but had substantially higher emergency department use. While Black enrollees had higher rates of HEDIS preventive screenings, ensuring equitable access to all services in Medicaid must remain a national priority.


Work In Progress