Affordable Care Act Spillover Gains to Private Dental Coverage for Dependents Widely Shared but Limited Evidence of Increased Utilization

1. Introduction

The dependent coverage mandate was an early and largely successful provision of the Affordable Care Act, increasing health insurance coverage for many young adults and resulting in meaningful spillover gains in dental coverage^1,2. In this paper, we evaluate whether those gains in dental coverage were widely shared by race/ethnicity and income. Though the mandate, which began in late 2010, only required that private health insurance plans cover dependents up to age 26, many employers also extended access to other benefits for dependents including dental coverage³. Shane and Wehby⁴ found that this increased coverage led to greater use of dental treatments among 25 year-olds affected by the mandate compared to unaffected 27 year-olds. However, that work did not distinguish young adults based on race/ethnicity or income and did not evaluate over the entire range of young adults affected by the mandate. We want to understand whether the spillover gains in private dental coverage were widely shared and whether any subsequent changes in utilization among young adults were shared across racial/ethnic groups and income.

Despite the growing understanding of the importance of oral health, dental care utilization among non-elderly adults declined during the last 10–15 years⁵. Private dental coverage among adults also declined primarily due to the recession⁵. Furthermore, many state Medicaid programs that cover lower income adults offer limited or no dental benefits. Inadequate dental coverage for adults worsens income-based disparities in oral health and restricts access to dental care particularly for racial and ethnic minorities with less access to dental care.

Between one-quarter and one-third of low-income adults report cost as a reason for not obtaining dental care⁶. Recent work by Vujicic et al.⁷ further finds that across ages, income levels, and insurance types, more people report cost as a barrier for dental care compared to other health care. Dental benefits are widely thought to be important for improving access to dental care, with recent evidence showing increased dental visits following the recent Medicaid income expansions and generous dental coverage⁸. In terms of private dental benefits, however, the empirical evidence regarding the value of coverage remains ambiguous. Private dental coverage has been associated with a greater likelihood of having an annual dental visit⁹. As noted above, the recent dependent coverage mandate has been associated with increased use of dental treatments among 25 year-olds⁴. Other work, however, calls into question the overall value of private dental insurance for many. Yarbrough and co-authors¹⁰ examined a large sample of adults with private dental benefits and found that the benefit structure may not meaningfully reduce the cost burden for many adults compared to simply paying for services at market rates out-of-pocket.

There are large racial/ethnic and income disparities in unmet dental health needs in the US that would suggest potential heterogeneity in effects of private dental coverage across these factors. Among nonelderly adults, the rate of untreated caries among Hispanics (36%) and non-Hispanic Blacks (42%) is much higher than the rate for non-Hispanic Whites (22%)¹¹. Similarly, untreated caries rates among low-income adults (below 200% FPL) are more than twice as high compared to higher income adults (~40% versus 17%)¹². These disparities relate closely to disparities in dental coverage and visits. For example, nearly a quarter of low-income adults have never had a dental visit or have not returned for a dental visit for more than 5 years compared to less than 10% of higher income adults whose coverage rate is more than double that of low income adults¹³. Furthermore, income disparities in dental visits have been consistent over the past decade¹⁴. The similarity in socioeconomic gaps of oral health, dental coverage, and visits suggest that improving coverage and dental services use is a potential pathway to reducing oral health disparities, although the causal evidence on such links remains scant, especially for direct oral health outcomes and private dental coverage. There is evidence, however, that Medicaid dental coverage for adults is related to more dental visits and reduced prevalence of untreated dental caries¹⁵. As noted above, there is also evidence of increased dental visits in states that recently expanded Medicaid and provided generous dental coverage⁸, although there is no evidence yet (to our knowledge) on effects from these recent expansions on clinical measures of oral health.

We investigate heterogeneity in the effects of the dependent coverage mandate on private dental coverage and dental care utilization by race/ethnicity and income using a quasi-experimental difference-in-differences design comparing changes among 19–25 year-olds who would be eligible for parental coverage under the mandate to ineligible 27–30 year-olds. No prior work has examined whether dental coverage gains following the dependent mandate were similar by race/ethnicity or income. Previous work evaluating the dependent coverage mandate on health insurance gains by race found similar increases in coverage across non-Hispanic Whites, Hispanics, and non-Hispanic Blacks¹⁶. Given differences in parental employer-sponsored benefits by race/ethnicity and income¹⁷, however, dental coverage gains may have varied among young adults following the mandate. Similarly, no prior work has examined the mandate effects on dental services use by race/ethnicity or income. Despite the widespread increases in health insurance following the mandate, average utilization of key health services such as office-based doctor visits, emergency room visits, and prescriptions has not changed regardless of race/ethnicity¹⁶. Groups experiencing greater unmet needs such as non-Hispanic Blacks and Hispanics compared to non-Hispanic Whites or low-income young adults compared to higher income young adults may experience greater benefits from a similar gain in dental coverage. In contrast, if for example, non-Hispanic Whites are more likely to have parents with more generous employer-sponsored benefits, then the spillover gains from the mandate may worsen existing disparities. Availability of dentists in one’s community may also affect whether coverage changes utilization similarly across racial/ethnic or income groups, with recent evidence suggesting that the Medicaid expansions increased dental visits when combined with generous coverage primarily in areas with high dentist supply⁸.

2. Methods

The dependent coverage mandate provision within the Affordable Care Act took effect in September 2010. Private health insurance plans were required to take eligible dependents up to age 26, a significant expansion compared to previous age limits in most states. Though dental insurance was not included in the ACA mandate, many companies increased the dependent age limit to 26 for dental coverage in addition to health coverage^1–3. Whether this spillover had similar effects for young adults across race/ethnicity or income is not clear. Between the dependent coverage implementation in 2010 and the ACA insurance expansions that began in 2014, no other national policies affected private dental coverage. We employ a difference in difference design to explore possible heterogeneity in the effects of the dental coverage spillover and subsequent dental services use by race/ethnicity. We compare pre-post ACA changes in dental coverage and dental services use among 19–25 year-olds to changes among 27–30 year-olds who were not eligible under the dependent coverage mandate. The focus on this broad group of young adults eligible for the dependent coverage mandate mirrors early work on this topic¹⁶ in terms of evaluating changes in utilization, particularly when stratifying by racial/ethnic groups to allow the largest sample size for such comparisons. The difference-in-differences design minimizes the possibility that changes unrelated to the ACA might influence the outcomes of interest.

Data

We use the publically available data from the Medical Expenditure Panel Survey (MEPS). The MEPS, a nationally representative survey, contains detailed information on dental insurance and dental services use as well as demographic and socioeconomic factors. To evaluate annual changes in private dental coverage and dental care use due to the dependent coverage mandate, we include MEPS participants from 2006 through 2009, defined as the pre-mandate period and from 2011 through 2015 as the post-mandate period. As of September 2010, renewable private health insurance plans were required to accept young adults up to age 26, making 2011 the first full year for the dependent coverage mandate to take effect. Since our analysis relies on annual changes in coverage and the policy was in effect only for the last few months of 2010, we do not include data from 2010. This avoids any confusion on whether to classify 2010 as a pre-mandate mandate year or a post-mandate mandate year. ACA changes post-2013 such as the Medicaid expansions did not differentially affect either group in policy terms¹⁸; therefore, we include those years for additional evidence on changes in dental outcomes.

Sample

We restrict the sample to people ages 19 to 30 years. We exclude individuals who were 26 years old at the time of the survey since we cannot confirm age at the time of the parent’s insurance renewal and therefore cannot determine whether the mandate would apply. The dependent coverage mandate only affected private plans and our measure of dental coverage is for private coverage given the spillover could only occur through private plans. We exclude persons with any public health insurance to focus on the group affected by the policy to avoid any changes in utilization driven by public coverage. The potential for indirect effects stemming from the Medicaid expansion may be an issue if the expansion affected 19–25 year-olds and 27–30 year-olds differentially. Existing evidence, however, points to very similar effects for these groups¹⁸. Because we stratify by race/ethnicity or income level, we include all age eligible young adults (except age 26) in the treatment group (19–25) and extend the control group to age 30 in order to increase the sample size and power. The main analysis sample consists of 37,101 observations including 23,132 in the “treatment group” of 19–25 year-olds and 13,969 in the “control” group of 27–30 year-olds.

Dental Coverage and Utilization Measures

MEPS collects detailed visit-level information on utilization of many dental services as well as a measure of private dental coverage. In addition to capturing whether a person had any dental visits during the year, we use visit-level information to separately detail whether a person had preventive dental services and/or dental treatments. We construct aggregate binary indicators for both types of care. Included in the preventive services category are cleanings, fluoride treatments, and dental exams (outcome equals ‘1’ if any of these services occurred). Under the dental treatments category, we include cavity fillings, tooth extractions, crowns, and root canals (outcome equals ‘1’ if any of these treatments occurred). We also include a binary measure for dental coverage equal to ‘1’ if that person had private dental insurance during the year.

Estimation

We employ a difference-in-differences regression approach that compares the change in private dental coverage or dental service use outcomes among 19–25 year-olds pre-post mandate to the change for 27–30 year-olds (through 2015). We estimate the following regression:

$$DENTA{L}_{it}\text{ = }\alpha \text{+}{\beta }_{\text{1}}YOUNGADUL{T}_{it}\times POSTAC{A}_t\text{ + }{\beta }_{\text{2}}YOUNGADUL{T}_{it}+{\beta }_{3}POSTAC{A}_t+X_{it}^{\prime }{\beta }_4+{ϵ}_{it}$$ (1)

The dependent variable in equation (1) DENTAL_it is one of the coverage or dental services use outcomes previously described. The group indicator YOUNG ADULT_it is a binary variable that takes the value 1 if individual i is 19–25 and takes the value 0 if individual i is 27–30. The variable POSTACA_it is a binary indicator for observations in 2011–2015, the post-mandate implementation years. The coefficient β₂ captures mean difference in dental outcomes between 19–25 year olds and 27–30 year olds, while β₃ captures secular trends between 2006–2009 (pre-mandate) and 2011–2015 (post-mandate). The main parameter of interest is the coefficient on the interaction term (β₁) which represents the change over time in dental coverage or dental care use for 19–25 year-olds compared to 27–30 year-olds. This coefficient captures the dependent coverage mandate effect on dental coverage or dental services use.

To control for observable differences that may affect sample composition and dental outcomes (X), we include sex, race, and a set of dummy variables for census region. Table 1 provides a descriptive summary of these variables as well as the outcome variables across groups. Dental coverage rates for 19–25 year-olds were notably lower than rates for 27–30 year-olds pre-mandate but other outcomes were similar between groups. All estimations include survey weights that account for the complex nature of the survey design and cluster sampling using survey-analysis commands in STATA¹⁹.

Table 1.

Pre-ACA (2006–2009) Descriptive Characteristics of Affected ACA Group and Older Control Cohort^&

Variable	Definition	n=10,071 Age 19–25 Mean/Proportion	n=5,851 Age 27–30 Mean/Proportion
Demographic/Socioeconomic
Female	1 if Female	45%	49%
Black	1 if Black	12%	11%
Hispanic	1 if Hispanic	18%	19%
White	1 if White	63%	62%
Other	1 if Other Race	8%	8%
Region** Northeast	1 if live in Northeast Region	17%	17%
Midwest	1 if live in Midwest Region	22%	21%
South	1 if live in South Region	38%	38%
West	1 if live in West Region	23%	24%
Coverage/Utilization
Dental Coverage	1 if has Private Dental Coverage#	43%	52%
Any Dental Visits	1 if Any Dental Visits During Year	33%	35%
Any Preventive Services	1 if Any Preventive Dental Services During Year	29%	31%
Any Treatments	1 if Any Dental Treatments During Year	11%	13%

^&Calculated using MEPS person weights

^**There are 136 individuals with missing values for region, thus percentages do not sum to 100%

^#Individual denoted private dental coverage as part of establishment insurance coverage

Given our focus on examining differences in these outcomes by race/ethnicity and income, we estimate the model separately for non-Hispanic Whites, non-Hispanic Blacks, and Hispanics, in addition to splitting the sample by income: those with household incomes lower than 200% of FPL and those with household incomes equal to or higher than 200% of FPL.

Testing Pre-Trends

Difference-in-difference models assume that outcome trends prior to the policy change are similar for the two groups under study (pre-trends assumption). To evaluate this assumption, we examine whether the pre-mandate trends in dental coverage and service use are similar between the two groups by examining interactions between year fixed effects and the group indicator (19–25 versus 27–30) for the years prior to the ACA mandate controlling for group and year fixed effects and the same demographic covariates in equation (1) above. We focus on the joint significance of the interactions between 2006, 2007, and 2008 indicators (with 2009 as the reference category) and the treatment group as the pre-trend test and note significant tests where observed.

3. Results

Descriptive Findings

We show first a descriptive comparison of pre-mandate and post-mandate rates of private dental coverage and dental services use for 19–25 year olds by race/ethnicity and by income (Table 2). As is clear from these comparisons, private dental coverage rates increased across the three examined racial/ethnic groups and the two income groups. The increases ranged from 7 percentage points for non-Hispanic Blacks (41% to 48%) to 10 percentage points for non-Hispanic Whites (47% to 57%). Because of the relatively close gains across groups, it does not appear from descriptive evidence that the existing disparities in private dental coverage across racial/ethnic lines changed after the mandate. Similarly, coverage increased from 26% to 33% for those with incomes less than 200% of FPL and from 51% to 60% for those at or above 200% of FPL.

Table 2.

Pre/Post Mandate Comparison of Coverage and Dental Services Use Rates among 19–25 Year-Olds^&

	By Race/Ethnicity						By Income
	Non-Hispanic Blacks		Hispanic		Non-Hispanic Whites		Less than 200% FPL		Greater than 200% FPL
Outcome	Pre-mandate	Post-mandate	Pre-mandate	Post-mandate	Pre-mandate	Post-mandate	Pre-mandate	Post-mandate	Pre-mandate	Post-mandate
Dental Coverage	41%	48%	27%	36%	47%	57%	26%	33%	51%	60%
Any Dental Visits	20%	21%	18%	21%	40%	40%	23%	23%	38%	38%
Any Preventive Services	16%	17%	14%	18%	35%	36%	19%	19%	34%	34%
Any Treatments	8%	7%	7%	7%	13%	12%	9%	7%	13%	12%

^&Calculated using MEPS person weights

Pre-mandate: 2006–2009; Post-mandate: 2011–2015

Despite the gains in private dental coverage, the descriptive comparisons overall show minimal change in dental services use. Among Hispanics, there is a small increase in likelihood of any dental visits and preventive services. However, for the other groups across race/ethnicity or income, there appears to be minimal changes pre/post mandate mandate. We note, however, that these descriptive comparisons may be biased by contemporaneous trends happening at the same time as the mandate. Therefore, we turn to our DD analysis to understand further whether the mandate spillover effect had differential effects across race/ethnicity and income.

Effects on Dental Coverage and Dental Services Use by Race/ Ethnicity

Table 3 presents difference-in-differences regression estimates of the dependent coverage mandate effects in 2011–2015 on private dental coverage and dental services use separately by race/ethnicity. Young adults ages 19–25, regardless of race, have higher rates of private dental coverage post-mandate compared to 27–30 year-olds, confirming descriptive evidence. Non-Hispanic Blacks experienced the largest increase post-mandate over this time period, more than 12 percentage points (+29% relative to mean) higher coverage relative to the older group of non-Hispanic Blacks. Hispanics had an increase of nearly 7 percentage points (+26% relative to mean rate), while non-Hispanic Whites had an increase of about 8 percentage-points (+17% relative to mean). In terms of dental visits, we find differences in how the mandate has affected each group. For non-Hispanic Blacks, the likelihood of having at least one dental visit is 8 percentage points (+40% relative to mean) higher for 19–25 year-olds post-mandate compared to 27–30 year-olds. We further find that this increase for non-Hispanic Black young adults is primarily driven by greater likelihood of preventive services (+5.6 percentage points post-mandate), with a very small and insignificant effect on curative services. For non-Hispanic Whites, we do not find significant changes in dental visits, preventive services, or dental treatments. For Hispanics, the estimates for visits and all services are small and statistically insignificant. However, we observe significant differential pre-mandate trends in these outcomes between 19–25 and 27–30 year-old Hispanics, suggesting that the difference-in-differences estimates are likely confounded by unobservable changes that differentially affect the two groups; therefore the estimates on use of services for Hispanics should be viewed with caution.

Table 3.

Difference in Difference Results Comparing Changes in Dental Outcomes Pre/Post Dependent Coverage Mandate for 19–25 Year-Olds versus 27–30 Year-Olds Split by Race/Ethnicity (2006–2015)

	Private Dental Insurance	Any Dental Visits	Any Preventive Services	Any Curative Services
White
19–25 Year-olds x 2011–2015	0.084***	0.023	0.016	0.020
	(0.030, 0.138)	(−0.028, 0.073)	(−0.035, 0.067)	(−0.009, 0.049)
Black
19–25 Year-olds x 2011–2015	0.123***	0.078**	0.056*	0.002
	(0.053, 0.192)	(0.013, 0.143)	(−0.001, 0.113)	(−0.037, 0.042)
Hispanic
19–25 Year-olds x 2011–2015	0.069**	0.002	0.002	0.002
	(0.010, 0.128)	(−0.045, 0.049)	(−0.042, 0.047)	(−0.028, 0.032)

Notes: Abbreviated regression results -- full results available upon request; all regressions include survey weights; standard errors clustered to account for complex survey design using STATA survey commands, those with public insurance and 26 year-olds excluded from model

Effects on Dental Coverage and Dental Services Use by Income

Results from the difference-in-differences regressions for lower income (<200% FPL) and higher income (200+ FPL) groups are noted in Table 4. We find that both income groups benefitted from the dependent coverage spillover effect although the increase in coverage rates was slightly lower among those under 200% FPL (7.1 versus 9.2 percentage points). For lower income young adults however, there is no evidence of changes in dental services use following this increase in dental coverage; estimates for dental visits and both preventive services and treatments are insignificant. In the higher income young adult group, we find a marginally significant increase in likelihood of dental visits by 3.6 percentage-points. Effects on preventive and curative services are also positive but only the increase in likelihood of dental treatments is marginally significant (2.4 percentage-points).

Table 4.

Difference in Difference Results Comparing Changes in Dental Outcomes Pre/Post Dependent Coverage Mandate for 19–25 Year-Olds versus 27–30 Year-Olds by Income

	Private Dental Insurance	Any Dental Visits	Any Preventive Services	Any Curative Services
Low Income (<200% FPL)
19–25 Year-olds x 2011–2015	0.071***	0.005	0.007	−0.005
	(0.020, 0.122)	(−0.040, 0.050)	(−0.037, 0.051)	(−0.034, 0.023)
High Income (>=200% FPL)
19–25 Year-olds x 2011–2015	0.092***	0.036*	0.027	0.024*
	(0.051, 0.133)	(−0.003, 0.077)	(−0.012, 0.067)	(−0.001, 0.048)

Notes: Abbreviated regression results -- full results available upon request; all regressions include survey weights; standard errors clustered to account for complex survey design using STATA survey commands, those with public insurance and 26 year-olds excluded from model

4. Discussion

We evaluate the heterogeneity of a known spillover benefit of the Affordable Care Act for young adults by race/ethnicity and income. From previous work, we know private dental insurance overall increased by nearly as much as medical insurance for the group of young adults affected by the dependent coverage mandate, implemented in 2010. We also know that the increase in coverage led to an increase in the likelihood of dental treatments for older dependents. We contribute to the building evidence on this mandate spillover by investigating effects across racial/ethnic groups as well as by income given their known associations with disparities in coverage and dental services use. We estimate effects for the broadest young adult mandate eligibility group (19–25 year-olds). For this group, we find evidence suggesting that the spillover increase in dental coverage was widely shared across race/ethnicity for dental coverage although it was nearly twice as high among non-Hispanic Blacks compared to Hispanics. However, across race/ethnicity subgroups, we only find evidence of a significant increase in dental visits among non-Hispanic Blacks driven by an increase in use of preventive services (cleanings, oral exams, or fluoride treatments). This finding suggests a slight decline in gaps of preventive services use between non-Hispanic Blacks and Whites ages 19–25 following the mandate.

There is no evidence of significant changes in treatments for non-Hispanic Blacks or any of the other groups. However, the lack of significant effects on dental visits or services is partly due to reduced power after stratifying into subgroups. Indeed, we cannot reject relatively moderate or even large effects in certain cases such as a 6 percentage point increase in likelihood of preventive services and 4.5 percentage point increase in likelihood of treatments for non-Hispanic Whites. For Hispanics, we cannot reject increases of about 4 percentage points in likelihood of either preventive or curative services but again there are significant differential pre-trends between 19–25 and 27–30 year old Hispanics in the difference-in-differences model. Descriptive evidence points to possible increases in dental services use among 19–25 year-old Hispanics after the mandate but we are not able to confirm that with our modeling. The lower power is likely one reason why the results for treatments in these subgroups differ from the prior finding of an increase in the likelihood of treatment services among older dependents when stratifying by race/ethnicity⁴. Potential differences across ages within the 19–25 group may be another reason.

When evaluating differences by income, we find that private dental coverage rates increased post-mandate for young adults with household incomes below 200% of FPL and for those with incomes at or above 200% of FPL. There is some evidence of an increase in visits and treatments only in the higher income group. Power is a potential concern with this comparison as well: moderate changes in visits or services cannot be ruled out.

Overall, we find evidence of a large increase in private dental coverage rates among young adults across race/ethnicity and income groups. We find declining gaps in private dental coverage and preventive service use between non-Hispanic Blacks and Whites in the mandate age group. In addition to lower power, differences in access to dentists among the newly covered and limited generosity of private dental plans may be partly responsible for the mild response to large increases in coverage. Recent work shows that Medicaid expansions under the ACA led to increased dental visits only when Medicaid provides extensive dental coverage and only in states with high supply of dentists⁸. We are unable to examine heterogeneity by dentist supply (as we only use publicly available data) and have no data on the generosity of dental coverage. Studying whether there are differences in the effects of the mandate spillover by availability of dentists and generosity of coverage is an area for future work.

Biography

Dan M. Shane:

I affirm that this work adheres to the ICMJE criteria for authorship. I have participated sufficiently in the conception, design, and analysis of this work, as well as the writing of the manuscript, to take public responsibility for it. I reviewed the final version of the submitted manuscript and approve it for publication. Neither this manuscript nor one with substantially similar content under our authorship has been published or is being considered for publication elsewhere.

George L. Wehby

I affirm that this work adheres to the ICMJE criteria for authorship. I have participated sufficiently in the conception, design, and analysis of this work, as well as the writing of the manuscript, to take public responsibility for it. I reviewed the final version of the submitted manuscript and approve it for publication. Neither this manuscript nor one with substantially similar content under our authorship has been published or is being considered for publication elsewhere.