Effects of a Medicaid dental coverage "cliff" on dental care access among low-income Medicare beneficiaries

Abstract

Objective: To evaluate how an abrupt drop-off, or "cliff," in Medicaid dental coverage affects access to dental care among low-income Medicare beneficiaries. Medicaid is an important source of dental insurance for low-income Medicare beneficiaries, but beneficiaries whose incomes slightly exceed eligibility thresholds for Medicaid have fewer affordable options for dental coverage, resulting in a dental coverage cliff above these thresholds.

Data source: Medicare Current Beneficiary Surveys (MCBS) from 2016 to 2019.

Study design: We used a regression discontinuity design to evaluate effects of this dental coverage cliff. This study design exploited an abrupt difference in Medicaid coverage above income eligibility thresholds in the Medicaid program for elderly and disabled populations.

Data collection: The study included low-income community-dwelling Medicare beneficiaries surveyed in the MCBS whose incomes, measured in percentage points of the federal poverty level, were within ±75 percentage points of state-specific Medicaid income eligibility thresholds (n = 7508 respondent-years, which when weighted represented 26,776,719 beneficiary-years).

Principal findings: Medicare beneficiaries whose income exceeded Medicaid eligibility thresholds were 5.0 percentage points more likely to report difficulty accessing dental care due to cost concerns or a lack of insurance than beneficiaries below the thresholds (95% CI: 0.2, 9.8; p = 0.04)-a one-third increase over the proportion reporting difficulty below the thresholds (15.0%).

Conclusions: A Medicaid dental coverage cliff exacerbates barriers to dental care access among low-income Medicare beneficiaries. Expanding dental coverage for Medicare beneficiaries, particularly those who are ineligible for Medicaid, could alleviate barriers to dental care access that result from the lack of comprehensive dental coverage in Medicare.

Keywords: Medicaid and Medicare; coverage cliff; dental coverage.

FIGURE 1

Enrollment in Medicaid and difficulty obtaining dental care due to cost or insurance coverage as a function of income. Graphs show the proportions of Medicare beneficiaries enrolled in Medicaid (left panel) and who reported difficulty getting dental care due to cost or insurance coverage (right panel) as a function of income relative to state‐specific Medicaid eligibility thresholds (pooled across states). Income is measured in percentage points of the federal poverty level (FPL) and centered at state‐specific Medicaid income eligibility thresholds (shown at 0 on horizontal axis). Estimated and reported for 20 equally sized income bins. We omitted individuals within ±5 percentage points of Medicaid eligibility thresholds, shown as dotted vertical lines in the figure, to mitigate attenuation bias from differences in how income may be reported to state Medicaid programs versus in the MCBS (e.g., differences in lookback periods). Fitted regression lines and 95% confidence intervals overlaid on the scatterplots show the relationship between income and outcomes above versus below Medicaid income eligibility thresholds. The vertical distance between the fitted lines at the Medicaid eligibility threshold gives the discontinuity in the outcome (without adjustment for covariates). Estimates are adjusted for survey weights. Based on 7508 observations from the 2016–2019 MCBS. When weighted, this sample represented 26,776,719 beneficiary‐years in the community‐dwelling Medicare population. See Appendix (Supporting information) for plots of other study outcomes [Color figure can be viewed at wileyonlinelibrary.com]