Abstract
This quasi-experimental analysis examines the association between policy changes in Medicaid dental benefits and emergency department (ED) visits for nontraumatic dental conditions in California.
Access to dental care is challenging for individuals in the US with low income. Evidence suggests that when access to dental care is restricted, individuals often seek treatment for nontraumatic dental conditions (NTDCs) in emergency departments (EDs).1,2,3,4 Although state Medicaid programs can provide dental coverage for adults with low income, adult dental benefits are optional and vary widely across states and over time. In California, Medicaid policy changes include the elimination of extensive dental benefits in July 2009, followed by incremental restoration of benefits in 2014 and 2018. This quasi-experimental analysis examines the association between policy changes in Medicaid dental benefits and NTDC ED visits in California via an interrupted time series design.
Methods
We used the nonpublic ED databases from January 1, 2006, to December 31, 2019, provided by the California Department of Health Care Access and Information. The primary outcome was the monthly rate of NTDC ED visits per 100 000 Medicaid adult enrollees. The policy variables included changes in Medicaid adult dental benefits: elimination (July 1, 2009), partial restoration (May 1, 2014), and full restoration (January 1, 2018) (eTable in Supplement 1). Statistical analysis was performed from March 2022 to December 2024. A segmented linear regression model was used to examine the changes in intercept and slope of NTDC ED visit rates after policy interventions (eMethods in Supplement 1). Rates of ED visits for asthma were used as a comparison outcome. All P values were from 2-sided tests and deemed statistically significant at P < .05. The University of California, San Francisco, institutional review board approved the study and waived informed consent as data were deidentified. We followed the STROBE reporting guideline.
Results
The mean rate of NTDC ED visits was 60.4 per 100 000 Medicaid enrollees per month from 2006 to 2019. The Figure shows the rate of NTDC ED visits during each policy period. Eliminating comprehensive dental benefits was associated with a transient immediate increase in the NTDC ED visit rate (immediate change, 7.21 [95% CI, 3.87-10.54] visits per 100 000 enrollees per month; rate of change, −0.32 [95% CI, −0.45 to −0.19]) (Table). Partial restoration of certain dental benefits was associated with a statistically significant decrease in the rate of NTDC ED visits (immediate change, 3.72 [95% CI, 0.40-7.04] visits per 100 000 enrollees per month; rate of change, −0.39 [95% CI, −0.51 to −0.27]). However, full restoration of dental benefits was not associated with a statistically significant decrease in NTDC ED visit rates. There were no associations between dental policy changes and the control outcome, asthma ED visits (Figure).
Figure. Nontraumatic Dental Condition (NTDC) and Asthma Emergency Department (ED) Visits Per 100 000 California Medicaid Adult Enrollees Per Month, 2006-2019.
Table. Segmented Linear Regression Results for NTDC ED Visits Per 100 000 California Medicaid Adult Enrollees Per Month, 2006-2019a.
| Characteristic | Rate of NTDC ED visits per 100 000 Medicaid enrollees/mo | |
|---|---|---|
| Estimate (95% CI) | P value | |
| R2 value, % | 84.6 | |
| Baseline intercept | 43.03 (40.37 to 45.68) | <.001 |
| Baseline slope | 0.36 (0.26 to 0.47) | <.001 |
| First policy changeb | ||
| Change in intercept | 7.21 (3.87 to 10.54) | <.001 |
| Change in slope | −0.32 (−0.45 to −0.19) | <.001 |
| Second policy changec | ||
| Change in intercept | 3.72 (0.40 to 7.04) | .03 |
| Change in slope | −0.39 (−0.51 to −0.27) | <.001 |
| Third policy changed | ||
| Change in intercept | 0.73 (−3.41 to 4.88) | .73 |
| Change in slope | 0.256(−0.01 to 0.52) | .06 |
Abbreviations: ED, emergency department; NTDC, nontraumatic dental condition.
The change in intercept indicates an immediate change in the rate of NTDC ED visits per 100 000 Medicaid enrollees. The change in slope indicates a gradual change over time in the rate of NTDC ED visits per 100 000 Medicaid enrollees.
First policy change: elimination of comprehensive dental benefits, implemented on July 1, 2009.
Second policy change: partial restoration of some dental benefits, implemented on May 1, 2014.
Third policy change: full restoration of dental benefits, implemented on January 1, 2018.
Discussion
Rates of NTDC ED visits increased immediately after benefits were reduced and decreased when benefits were reinstated, similar to the only other study that examined bidirectional policy changes, in Massachusetts.3 NTDC ED visits may be particularly sensitive to coverage of specific dental services. The restoration of basic preventive, diagnostic, restorative, and root canal treatments for front teeth and complete dentures in 2014 was associated with reversal of increasing rates of NTDC ED visits. However, subsequent coverage for crowns, root canal treatment for back teeth, periodontal services, and partial dentures in 2018 were not associated with changes in NTDC ED visit rates. Several factors in addition to coverage changes may have been associated with the observed trends in NTDC ED visits, including limited follow-up after the 2018 policy change, a backlog of demand for care, lack of awareness of benefit changes, and low dental professional participation in Medicaid.5,6 Limitations of the study include lack of a true control group, constraints inherent to administrative data, inability to assess clinician availability, and contemporaneous policy changes (such as Medicaid expansion). However, the interrupted time series design provided a quasi-experimental framework to examine associations related to policy changes. The nature of the dental policy changes allowed us to explore its association with NTDC ED visits in a “removal of treatment” context, offering insights into potential links for further investigation.
eTable. Dental Benefits Covered During the Study Period for Adult Medicaid Enrollees in California
eMethods.
Data Sharing Statement
References
- 1.CareQuest Institute. Medicaid adult dental coverage checker. Accessed September 20, 2024. https://www.carequest.org/Medicaid-Adult-Dental-Coverage-Checker
- 2.Singhal A, Caplan DJ, Jones MP, et al. Eliminating Medicaid adult dental coverage in California led to increased dental emergency visits and associated costs. Health Aff (Millwood). 2015;34(5):749-756. doi: 10.1377/hlthaff.2014.1358 [DOI] [PubMed] [Google Scholar]
- 3.Ranade A, Young G, Garcia R, Griffith J, Singhal A, McGuire J. Changes in dental benefits and use of emergency departments for nontraumatic dental conditions in Massachusetts. Public Health Rep. 2020;135(5):571-577. doi: 10.1177/0033354920946788 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Chalmers N, Grover J, Compton R. After Medicaid expansion in Kentucky, use of hospital emergency departments for dental conditions increased. Health Aff (Millwood). 2016;35(12):2268-2276. doi: 10.1377/hlthaff.2016.0976 [DOI] [PubMed] [Google Scholar]
- 5.Buchmueller T, Miller S, Vujicic M. How do providers respond to changes in public health insurance coverage? evidence from adult Medicaid dental benefits. Am Econ J Econ Policy. 2016;8(4):70-102. doi: 10.1257/pol.20150004 [DOI] [Google Scholar]
- 6.Vujicic M, Nasseh K, Fosse C. Dentist participation in Medicaid: how should it be measured? does it matter? Research Brief. Health Policy Institute; American Dental Association. October 2021. Accessed October 11, 2023. https://www.ada.org/-/media/project/ada-organization/ada/ada-org/files/resources/research/hpi/hpibrief_1021_1.pdf
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eTable. Dental Benefits Covered During the Study Period for Adult Medicaid Enrollees in California
eMethods.
Data Sharing Statement
