Eliminating Medicaid dental benefits and early-stage oral cancer diagnoses

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.

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.

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).

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.