Synthesizing 30-years of adult medicaid dental policy research: A scoping review to identify gaps and opportunities

Incentivizing dental services in healthy behaviour Medicaid waivers

OBJECTIVE

In the United States, adult dental benefits are optional in the state-managed, public insurance program, Medicaid. States also have the option to adapt their Medicaid program via waivers which pair healthy behaviour incentives (HBI) with cost-sharing. These waivers have proven ineffective, but the empirical evidence has ignored differences between states. This study aims to evaluate the impact of four state's HBI Medicaid waiver on dental visits among low-income adult population subject to incentives and cost-sharing requirements by the HBI waiver.

METHODS

Analysing biannual data from the Behavioural Risk Factor Surveillance System's Oral Health module (2008-2018) with a Difference-in-Differences design, this study estimated the effect of a Healthy Behaviour Incentive waiver on the probability of visiting the dentist in the past year. The three states that implemented an HBI Waiver (Indiana, Michigan and Wisconsin) were analysed separately. Secondary outcomes included being uninsured and having all teeth extracted. Matrix Completion methods accounted for dynamic treatment and tested for non-common trends. Inference was based on randomization inference tests.

RESULTS

Only in Michigan was an HBI waiver consistently associated with a significant increase in the probability of a dental visit (Est. = 5.6%-points, p = .01). There was little convincing evidence that HBI waivers were associated with being uninsured or having all teeth extracted.

CONCLUSIONS

Between 2010 and 2019, many states have implemented an HBI waiver, each with a different approach to incentivizing dental visits. These implementation differences may explain the heterogeneous effects by state. More work is needed to evaluate how Medicaid waivers impact health outcomes in low-income populations.

Eliminating Medicaid dental benefits and early-stage oral cancer diagnoses

BACKGROUND

Despite the importance of regular dental visits for detecting oral cancer, millions of low-income adults lack access to dental services. In July 2009, California eliminated adult Medicaid dental benefits. We tested if this impacted oral cancer detection for Medicaid enrollees.

METHODS

We analyzed Surveillance, Epidemiology, and End Results-Medicaid data, which contains verified Medicaid enrollment status, to estimate a difference-in-differences model. Our design compares the change in early-stage (Stages 0-II) diagnoses before and after dropping dental benefits in California with the change in early-stage diagnoses among eight states that did not change Medicaid dental benefits. Patients were grouped by oropharyngeal cancer (OPC) and non-OPC (oral cavity cancer), type, and the length of Medicaid enrollment. We also assessed if the effect of dropping dental benefits varied by the number of dentists per capita.

RESULTS

Dropping Medicaid dental benefits was associated with a 6.5%-point decline in early-stage diagnoses of non-OPC (95% CI = -14.5, -3.2, p = 0.008). This represented a 20% relative reduction from baseline rates. The effect was highest among beneficiaries with 3 months of continuous Medicaid enrollment prior to diagnosis who resided in counties with more dentists per capita. Specifically, dropping dental coverage was associated with a 1.25%-point decline in the probability of early-stage non-OPC diagnoses for every additional dentist per 5000 population (p = 0.006).

CONCLUSIONS

Eliminating Medicaid dental benefits negatively impacted early detection of cancers of the oral cavity. Continued volatility of Medicaid dental coverage and provider shortages may be further delaying oral cancer diagnoses. Alternative approaches are needed to prevent advanced stage OPC.

Late-Stage Oral Cancer Detection After California and Illinois Restored Medicaid Dental Benefits

Objective

Previous research found an association between California's Medicaid dental coverage and oral cancer detection. However, this relationship has yet to be explored in other states or by subgroup populations.

Study Design

In addition to controlling for sociodemographic and tumor characteristics, this study implemented a traditional difference-in-differences design to compare distant-stage diagnosis trends in states restoring Medicaid dental benefits (California [CA] and Illinois [IL]) with trends in states with constant Medicaid dental benefits.

Setting

This retrospective, observational study analyzed oral cavity and pharynx cancer case data from The Surveillance, Epidemiology, and End Results program (2004-2017).

Methods

The outcome was a binary variable indicating whether a patient was diagnosed at a distant stage. Subgroup analyses were conducted by state, race/ethnic group, sex, age, and county-level household income.

Results

The sample included 109,997 adults diagnosed with cancer of the oral cavity and pharynx. Restoring Medicaid dental benefits was associated with a statistically significant 2.7%-point decline in the probability of a distant-stage oral cancer diagnosis. This estimate represented a 14% relative change from baseline rates. Results were consistent for CA and IL and by county-level median income. Estimates were significantly larger for adults under age 65, males, and adults identifying as Hispanic; non-Hispanic Black; American Indian; or Asian American or Pacific Islander.

Conclusion

Restoring Medicaid dental coverage improved early detection in both CA and IL, with the greatest reductions in distant-stage diagnoses occurring in younger adults, males, and minoritized racial/ethnic groups. Future research should investigate whether earlier detection reduces oral cancer mortality disparities.

Examining the effect of Medicaid expansion on early detection of head and neck cancer of the oral cavity and pharynx by HPV-type and generosity of dental benefits

BACKGROUND

Over a decade of evidence supports the claim that increased access to insurance through Medicaid expansions improves early detection of cancer. Yet, evidence linking Medicaid expansions to early detection of head and neck cancers (HNC) of the oral cavity and pharynx, specifically, may be limited by the lack of attention to Human Papillomavirus (HPV) etiology, generosity of dental coverage, and valid inference analyzing state cancer registry data.

AIMS

This study reexamined the effect of Medicaid expansion on early detection of HPV+/- HNC in states offering extensive dental benefits.

MATERIALS AND METHODS

Specialized data from the Surveillance, Epidemiology, and End Results (SEER) program was analyzed to account for, previously unmeasurable, differential detection patterns of HNCs associated with HPV. Then, to identify the effect of increasing Medicaid eligibility on staging patterns in states offering extensive benefits amidst potentially non-common trends between states, a "Triple Differences" design identifies the differential effect of Medicaid Expansion (with dental coverage) on HPV-negative HNCs relative to the change in HPV-positive HNCs. For valid inference analyzing a small number of state clusters (12) in cancer registry data, each regression model applies a Wild Cluster Bootstrap.

RESULTS

Expanding Medicaid eligibility was found to be associated with a decrease in the proportion of distant-stage diagnoses of HPV(-) HNCs, but only among states which increased Medicaid dental generosity at the time of Medicaid expansion.

CONCLUSIONS

These results suggest that adding extensive Medicaid dental benefits was the primary mechanism impacting HNC detection. This study highlights the potential positive spillover effects of policies which increase access to public dental coverage for low-income adults, while also showing the limitation of access to dental services for improving early detection of HPV+ HNCs.

Estimating the Within-Person Change in Dental Service Access Measures during the COVID-19 Pandemic in the United States

Background

American adults delay dental care more than any other healthcare service. Unfortunately, the COVID-19 pandemic may have stalled efforts to address dental service delays. Early evidence has suggested substantial declines in dental service visits in the early phase of the pandemic; however, our study is among the first to measure within-person changes from 2019 to 2020 and conduct subgroup analyses to examine if changing dental patterns were mediated by exposure to the pandemic, risk of adverse COVID-19 outcomes, or dental insurance.

Methods

We analyzed a National Health Interview Survey panel of individuals initially surveyed in 2019, with subsequent follow-up in 2020. The outcomes included dental service access measures and the interval of a most recent dental visit. By constructing a probability-weighted linear regression model with fixed-effects, we estimated the average within-person change from 2019 to 2020. Robust standard errors were clustered within each respondent.

Results

From 2019 to 2020, adults reported a 4.6%-point reduction in the probability of visiting the dentist (p < 0.001). Significantly higher declines were found in Northeast and West regions compared to Midwest and South regions. We find no evidence that declining dental services in 2020 were associated with more chronic diseases, older age, or lack of dental insurance coverage. Adults did not report more financial or nonfinancial access barriers to dental care in 2020 compared to 2019.

Conclusions

The long-term effects of the COVID-19 pandemic on delayed dental care warrant continued monitoring as policymakers aim to mitigate the pandemic's negative consequences on oral health equity.