Impact of disability diagnosis on dental care use for adults in the United States

Abstract

Background.

Approximately 25% of adults in the United States have a disability that limits function and independence. Oral health care represents the most unmet health care need. This population has been found to have decreased oral health outcomes compared with the general population.

Methods.

The authors used the 2018 adult National Health Interview Survey to assess the association between disability status and dental care use (dental visit within or > 2 years). Disability status was categorized as adults with an intellectual, acquired, or developmental disability (IADD) that limits function, other disability that limits function, or no disability, on the basis of diagnoses of birth defect, developmental diagnosis, intellectual disability, stroke, senility, depression, anxiety, or emotional problem, all causing problems with function.

Results.

Adults with an IADD with functional and independence-limiting disabilities experienced higher crude odds of going 2 years or more without a dental visit than adults without disabilities (odds ratio [OR], 2.29; 95% CI, 1.96 to 2.67). This association was part of a significant interaction and was stronger among those with IADDs who could afford oral health care (OR, 1.73; 95% CI, 1.47 to 2.14) than among those who could not afford oral health care (OR, 1.21; 95% CI, 0.88 to 1.67; P value of interaction <.01).

Conclusions.

Adults with IADDs have decreased access to oral health care compared with adults with other disabilities or without disabilities. The inability to afford oral health care lessens the impact of disability status.

Practical Implications.

Dentists can use this study to understand the implications of IADD diagnoses on dental care use and make efforts to facilitate care for these patients.

Approximately 1 in 4 US adults has a disability.¹ For people with disabilities, oral health care has been found to be among the most common unmet health care needs.^2–4 Any diagnosis of disability may be associated with inferior oral health outcomes compared with the general population. Disability is defined as a condition that limits the activities that a person is able to perform and limits their participation and interaction in the world around them.¹ Intellectual, acquired, or developmental disabilities (IADDs) are defined as “disabilities characterized by significant limitations in both intellectual functioning and adaptive behavior.”⁵ A disability is “developmental” when it originates before the age of 22 years, and “acquired” when it originates at age 22 years or later.⁵ Some examples of developmental diagnoses are cerebral palsy, autism, and Down syndrome; examples of acquired disabilities include senility and disabilities secondary to a stroke.³

Diagnoses of IADDs have been found to be associated with poorer oral health status and outcomes.^3,6 Adults with IADDs have been reported to have a 56% through 92% prevalence of periodontal disease, score of 8 through 25 on the decayed, missing, and filled tooth index, and up to 73% prevalence of edentulism.^4,7,8 These conditions are also associated with decreased quality of life, including oral pain and psychological discomfort.^4,9 Poor oral health is associated with poor overall health, putting people with IADDs at additional risk of decreased health outcomes.^1,3,5,10 Oral health status for adults with IADDs has been well described, but the root causes for the disparities in status are not well understood.¹¹

Adults with IADDs may be susceptible to unmet oral health care needs, increased disability, and poorer quality of life.^3,5,9 The life span of adults with disabilities is expanding due to improvements in chronic health care management, so more adults with IADDs face these unmet needs.¹² Barriers to oral health care for adults with an IADD include poor access to care, insufficient education and training of dentists, limited behavior tolerance of patients, affordability of care, and lack of understanding about the need for care.^4,13–19 These barriers have been described in the literature, but have not been well investigated.^14–16 It is not understood how these barriers to care affect dental care use and frequency of dental visits for adults with an IADD.

Our aim was to assess the relationship between disability and oral health care use, with a special focus on those with IADDs.

We used data from the 2018 National Health Interview Survey (NHIS)²⁰ to answer the following question: What are the associations between disability status and use of dental services within 2 years for adults in the United States? We aimed to describe the distribution of function and independence-limiting disability diagnoses among adults and evaluate the association between IADD status and oral health care use within 2 years. We assessed population-based access to oral health care and the association of disability status with dental care use, which was measured as adults having seen a dentist within the past 2 years. We examined demographic characteristics and poverty status as potential confounders. Adults’ ability to afford oral health care, adults’ ability to respond to the survey on their own, and adults’ duration since their last physician visit were assessed as effect modifiers of the association between disability status and of oral health care use within 2 years.

METHODS

Study design

We used the 2018 NHIS Sample Adult Core questionnaire data set for this analytical cross-sectional study. It is publicly available and administered via the National Center for Health Statistics, Centers for Disease Control and Prevention.²⁰ We followed the Strengthening the Reporting of Observational Studies in Epidemiology guidelines for reporting observational studies.²¹

The NHIS is an annual cross-sectional complex sampling of all civilian noninstitutionalized people in the United States. The survey collects demographic, occupation and employment, health status, and health care use data to assess for health- and health care–related issues. There are separate surveys for adults and children, as well as household and family questionnaires. Adult data represented people 18 years and older, comprising 25,417 adults, and were weighted for analysis.

Exposure and outcome

All variables were categorized to evaluate for associations by means of odds ratios (ORs). Disability status, defined according to the specific diagnoses in NHIS, was categorized as diagnoses of IADDs with functional limitation, other disabilities with functional limitations, or no disabilities without functional limitations. For each diagnosis in NHIS, an adult could indicate that they experienced “functional limitation,” which was used to define the exposures of IADDs or other disability diagnoses. Diagnoses of IADDs included birth defect; developmental diagnosis; intellectual disability; stroke; senility, dementia or Alzheimer disease; depression; anxiety; emotional problem; and attention deficit disorder/attention-deficit/hyperactivity disorder, bipolar, schizophrenia, other mental problem, all causing problems with function. These diagnoses have been found to affect adult function and independence, which can affect their access to oral health care.³ Other disabilities included any other medical diagnosis indicated in the NHIS survey not included in IADD diagnoses with functional limitation due to that diagnosis.

The time lapse since the adults’ last dental visits was dichotomized into less than or equal to 2 years and greater than 2 years for dental care use outcomes. Healthy People 2030 has a goal of increasing the proportion of people who used the oral health care system within the past year.²² However, according to Healthy People 2020, fewer than 45% of people older than 2 years visited a dentist within the past year in 2007 and, according to the Centers for Disease Control and Prevention, substantial disparities in access to oral health care exist among people of different racial and ethnic groups, socioeconomic groups, and education levels for oral health care.^22,23 Therefore, we dichotomized the study outcome of dental care use into time frames of less than or equal to 2 years and greater than 2 years since the last dental visit to capture a broader and more conservative reference of timely dental care use. Age was categorized into groups 18 through 25 years, 26 through 44 years, 45 through 64 years, and 65 years and older. Adults’ regions were reported according to categories provided in the data set, which were Northeast, Midwest, South, and West. Race or ethnicity was categorized into non-Hispanic White, non-Hispanic Black, non-Hispanic other, or Hispanic. Adult proxy status was dichotomized into self and alternate, ability to afford oral health care was dichotomized to yes or no, and time lapse since the last medical visit was dichotomized to less than or equal to 2 years or greater than 2 years to match the time lapse for dental care use.

The foci of this study were the exposure of disability status (IADD or other disability, both with functional limitation or no disability) and the outcome of dental care use within 2 years (≤ 2 years or >2 years). In the 2018 NHIS,²⁰ the following 2 questions were asked regarding use of oral health care services: “About how long has it been since you last saw a dentist? Include all types of dentists, such as orthodontists, oral surgeons, and all other dental specialists, as well as dental hygienists” and “During the past 12 months, was there any time when you needed any of the following [dental care, including check ups], but didn’t get it because you couldn’t afford it?”

The specific diagnoses that defined disability status were used to focus on the impact of a diagnosis of IADD on dental care use within 2 years. These diagnoses were also determined on the basis of the review of literature, citing people with IADD as having higher risk of inferior oral health outcomes than the general population.^3,14–16

Data analysis

Data analyses were completed using statistical software (SAS, Version 9.4; SAS Institute). For analyses, P values of .05 or less were considered statistically significant. Descriptive analyses of the study population and logistic regression analyses were implemented to examine the association between disability status and duration since the last dental visit. The crude association between disability and duration was assessed via Pearson χ² test with categorical variables of disability status and dental care use within 2 years. Weighted multiple logistic regression was used to test the association between disability status and dental care use, controlling for age group, sex, race or ethnicity, geographic region, and poverty status, using NHIS person file for poverty status measure for sample adults.

Among the 25,417 adults surveyed in the United States, 1,528 (6%) had received a diagnosis of IADD, 9,346 (37%) had received a diagnosis of a non-IADD with functional limitation (other disability), and 14,543 (57%) had no disability and no functional limitation. Dental care use data were missing for 322 sample adults (1.3%). Among adults who had received a diagnosis of IADD, 519 (34.4%) had not seen a dentist within the past 2 years and 990 (65.6%) had seen a dentist within 2 years. Among adults with other disabilities, 2,485 (26.9%) had not seen a dentist within the past 2 years and 6,741 (73.1%) had seen a dentist within 2 years. Among adults with no disabilities, 2,652 (18.5%) had not seen a dentist within the past 2 years and 11,708 (81.5%) had seen a dentist within 2 years. Sample adults with unknown dental care use (1.3%) were excluded from the analysis, as dental care use was the outcome of interest. The final analytical file included 23,884 adults, after excluding nonresponders for the could not afford care (n = 194), dental care use (n = 322), medical care use (n = 316), and poverty status (n = 1,182) variables (Figure).

Figure.

Flowchart of methods and inclusion for diagnoses of intellectual, acquired, or developmental disabilities (IADDs). Limitation with function includes difficulties with at least one of the following activities due to a specific condition: any difficulty walking a quarter mile; walking up 10 continuous steps without rest; standing or sitting continuously for 2 hours; stooping or bending or kneeling; reaching above one’s head; using fingers to grasp or handle small objects; lifting or carrying 10 pounds; maneuvering large objects; going out and running errands (shopping, going to the movies); participating in social activities; or relaxing at home (reading or sewing and so forth).²⁰ Diagnosis of IADD includes attention deficit disorder/attention-deficit/hyperactivity disorder, bipolar disorder, schizophrenia, other mental problem, birth defect, developmental diagnosis (for example, cerebral palsy), senility, dementia, Alzheimer disease, intellectual disability, mental retardation, depression, anxiety, emotional problem, or stroke.

We tested for effect modification with ability to afford oral health care, proxy status, and duration since the last physician visit in the multivariable model. In prior studies, these covariates had been found to modify the association between disability status and dental care use.^3,15,16

Confounding was evaluated by means of percentage of change of the log transformed OR, adjusting for the specified covariate, with a difference of 10% from the crude association to the adjusted log OR and a P value of <.20 for the association between the covariate and duration since last dental visit. Final modeling by means of weighted multiple logistic regression was stratified according to the adult’s ability to afford oral health care and was controlled for age group, sex, race, and poverty status.

RESULTS

There were fewer adults aged 18 through 25 years (13.3%) than 26 through 44 years (32.8%), 45 through 64 years (33.3%), and 65 years and older (20.6%). Men accounted for 48.3% of adults, and women accounted for 51.7% of adults. Most adults were non-Hispanic White (63.1%) compared with non-Hispanic Black (11.7%), non-Hispanic other (8.9%), or Hispanic (16.3%). Adults were distributed among the following 4 regions: Northeast (17.3%), Midwest (21.9%), South (36.9%), and West (23.8%). These data were the weighted overall findings, not reported in Table 1.

Table 1.

Weighted prevalence of disability according to demographic characteristics.

VARIABLE	IADD,* %	OTHER DISABILITY,† %	NO DISABILITY,‡ %	ASSOCIATION WITH DISABILITY, P VALUE, χ2
Age Group, Y				<.01
18–25	4.6	10.7	84.7	NA§
26–44	5.4	7.6	77.0	NA
45–64	5.9	38.9	55.1	NA
≥ 65	7.1	61.8	31.1	NA
Sex				<.01
Male	5.2	32.2	62.6	NA
Female	6.7	40.6	52.7	NA
Race or Ethnicity				<.01
Non-Hispanic White	5.9	39.9	54.2	NA
Non-Hispanic Black	6.6	36.2	57.2	NA
Non-Hispanic other	6.5	28.1	65.4	NA
Hispanic	5.5	25.8	68.6	NA
Region				<.01
Northeast	5.7	38.2	56.1	NA
Midwest	6.3	38.3	55.4	NA
South	6.0	36.7	57.3	NA
West	6.0	34.3	59.7	NA
Dental Care Use, Y				<.01
≤ 2	5.1	34.7	60.2	NA
> 2	9.2	43.9	46.9	NA

^*IADD: Intellectual, acquired, or developmental disability (includes adults with diagnoses of birth defect, developmental diagnosis, intellectual disability, stroke, senility, depression, anxiety, or emotional problem, all indicating with functional limitation from adult National Health Interview Survey (NHIS).²⁰

^†Other disability includes adults indicating any medical diagnoses with functional limitation, not included in IADD from adult NHIS.

^‡No disability includes all adults who did not indicate medical diagnoses with functional limitation from adult NHIS.

^§NA: Not applicable.

Age group, sex, race or ethnicity, and region were highly associated with disability status as well as time lapse since last dental visit. The proportion of adults with IADD increased as age increased, from 4.6% among those aged 18 through 25 years to 7.1% among those 65 years and older. More women had diagnoses of IADDs and other disabilities than men (6.7% vs 5.2% for IADD, 40.6% vs 32.2% for women) (Table 1).

Nearly all adults (96.9%) responded for themselves, and 1.5% relied on an alternate respondent (1.5% missing). In terms of ability to afford care, 87.7% were able to afford oral health care and 11.5% were unable to afford oral health care. Most adults (91.4%) reported visiting a physician within the last 2 years compared with 7.2% who had not (1.2% missing). Ability to afford oral health care was the only 1 of these 3 covariates that was a significant effect modifier of the association between disability status and dental care use (P < .01).

Adults with an IADD were 2.29 times as likely to have had no dental visit in the last 2 years than adults with no disabilities (95% CI, 1.96 to 2.67) and those with other disabilities were 1.5 times as likely to have had no visit (95% CI, 1.41 to 1.66) (Table 2).

Table 2.

Weighted unadjusted crude association between disability status and having more than 2 years since the dental visit.

	PREVALENCE OF DENTAL USE, %
DISABILITY STATUS	≤2 y	>2 y	CRUDE ODDS RATIO (95% CI)	P VALUE
Intellectual, Acquired, or Developmental Disability	66.2	33.8	2.29 (1.96 to 2.67)	<.01
Other Disability	74.6	25.4	1.53 (1.41 to 1.66)	<.01
No Disability	81.9	18.1	1.00 [Reference]	Not applicable

Adults’ ability to afford oral health care is an effect modifier of the association between disability status and dental care use (Table 3). Modeling including the ability to afford oral health care as an effect modifier yielded the results that adults with an IADD who were able to afford oral health care were 1.73 times as likely as those without disabilities to have had no dental visit within the last 2 years (95% CI, 1.47 to 2.14), but those with an IADD who could not afford oral health care were 1.21 times as likely as those without disabilities to have had no dental visit in the last 2 years (95% CI, 0.88 to 1.67). Similarly, adults with other disabilities who were able to afford oral health care were 1.36 times as likely as those without disabilities to have had no dental visit in the last 2 years (95% CI, 1.23 to 1.50) compared with 1.05 times for those who could not afford oral health care (95% CI, 0.84 to 1.31).

Table 3.

Weighted multivariable association^* between disability status and dental use, stratified according to ability to afford oral health care.

DISABILITY STATUS	ADJUSTED ODDS RATIO (95% CI)	P VALUE†
Able to Afford Oral Health Care
Intellectual, acquired, or developmental disabilities	1.73 (1.47 to 2.14)	<.01
Other disability	1.36 (1.23 to 1.50)	<.01
No disability	1.00 [Reference]	Not applicable
Unable to Afford Oral Health Care
Intellectual, acquired, or developmental disabilities	1.21 (0.88 to 1.67)	.27
Other disability	1.05 (0.84. to 1.31)	.69
No disability	1.00 [Reference]	Not appicable

^*Adjusted for age group, sex, race and ethnicity, and poverty status.

^†P value for interaction between disability status and dental care use and ability to afford oral health care was <.01.

DISCUSSION

To our knowledge, our study is the only analysis to investigate the effect of disability on oral health care use for adults with disabilities in the following 3 distinct categories: IADDs, other disabilities with functional limitations, and no disabilities. Our results showed that there are significant implications of a diagnosis of an IADD that limits a person’s independence or function on that person’s use of oral health care. Adults with IADDs are less likely to visit a dentist than those with other disabilities or no disabilities. However, for adults who cannot afford oral health care, oral health care use is not statistically different for adults with disabilities compared with adults without disabilities. A separate analysis of nonresponse revealed that participants with no poverty status data were no more likely to have an IADD than were those who responded to the poverty status items.

Although to our knowledge there are no other studies that address the association between adults’ disability statuses and ability to afford oral health care and their dental care use, the findings from our study are consistent with those from researchers who investigated and assessed the barriers that impact dental care use for adults with disabilities.^{6,14,16,24,25} Adults with IADDs are often insured via Medicaid for medical and dental coverage.⁷ This coverage is widely variable according to state, including reimbursement rate and extent of coverage. Some states have more robust dental coverage in their Medicaid programs, and some states offer none. Medicaid dental coverage may help improve access to oral health care in states with a high density of dentists and strong Medicaid coverage.²⁶ However, dental providers may choose not to participate in the Medicaid program, owing to limited coverage and reimbursement, which then limits the financial feasibility of adults with IADDs and other disabilities to be able to afford necessary oral health care.^2,4,18,27 Without accepted insurance, oral health care represents considerable out-of-pocket costs. These costs may be untenable for adults with function- and independence-limiting conditions, which may impede their ability to work or earn an income, inhibiting dental care use. The disproportionate barriers to oral health care for adults with IADDs, especially those who are covered via Medicaid, could be improved with more closely integrated medical and oral health care, which could prevent differences in medical vs dental visits.

In a 2015 study within an affluent metropolitan community, investigators surveyed parents and caregivers of children with special needs aged 3 through 26 years and found that 34% of respondents indicated that the most limiting barrier to oral health care was finding a dentist willing to treat their child.²⁴ The second most prevalent barrier (18%) to oral health care was finances, and the third most prevalent barrier (14%) identified was wait time.²⁴ This study applied to children mainly, but parents of adults with special needs aged 18 through 26 years were also included. Although IADDs are only a subset of special needs, adults with IADDs experience similar barriers as children and adults with more broad special needs, which contributes to the limited dental care use that adults with IADD face.

In Australia, special care dentistry is a recognized dental specialty and in the United States it is not. In a qualitative study among dentists and oral health care professionals, investigators found that providers may want to help patients of this population, but they find patients with IADDs more difficult to treat.²⁵ Providers broadly lacked the training, experience, and support to routinely and adequately provide care for these patients. Adults with IADDs present a specific challenge to oral health care providers, as they may be unable to behaviorally tolerate care, follow instructions, or transfer to a dental chair.^4,15 However, it is telling that even in a country in which special care dentistry is a recognized specialty there is a reported lack of education, experience, training, and support for dentists to treat patients with disabilities, which creates a dental workforce barrier to provide care for these patients.²⁵

Our study does have some limitations. NHIS data are self-reported and are difficult to validate. NHIS does not directly assess for or measure need for oral health care, provision of dental treatment, or dental outcomes. Due to the cross-sectional design, there is no ability to assess temporality or cause and effect. We did not consider dentist-based factors, such as geographic location or timeliness of appointments, or patient-based factors, such as patient or caregiver knowledge or motivation to address limited dental care use.

Despite these limitations, we provided a broad, publicly accessible, generalizable overview of the state of dental care use across the United States. The use of NHIS data provides a population-based overview of the duration since adults’ most recent dental visits, and clear associations are able to be assessed between dental care use and disability diagnosis status and the impact of the ability to afford oral health care. Our study is reproducible and allows inferences to be drawn about dental care use for adults with IADD compared with other disabilities, which can help target future studies that may be able to improve access and oral health outcomes. Although we cannot provide any inference about oral health care need and the temporality of oral health care, we found a clear and significant association between disability and limited use of oral health care.

PRACTICAL IMPLICATIONS

Our results showed that barriers to oral health care exist for adults with IADDs and may be beneficial in advocacy to improve the condition and well-being of adults with IADDs. Our study can help guide future research to understand the specific patient and clinician-centered issues that limit patient use, as well as hinder providers from being able to treat these patients.

Practitioners can use our study to better understand the impact of receiving a diagnoses of IADD on oral health care use, incorporate methods and equipment to facilitate the care of adults with IADDs more broadly, and increase their capacity to treat adults with IADDs and other disabilities. Similarly, dentists could become Medicaid providers to facilitate their treatment of adults with IADDs and other disabilities. They could implement the data to advocate for increased funding for programs targeting adults with IADDs, including broader Medicaid coverage, as well as increased benefits to remove some of the financial burden of oral health care from the patient and improve access to care more broadly.

CONCLUSIONS

Adults with disabilities are a faction of patients that face disproportionate difficulties in accessing care. This impeded access can contribute to decreased health outcomes, which can lead to increased disability, increased health care costs, and decreased quality of life. It is imperative to address these issues to decrease the burden of oral disease among adults with IADDs and work to improve the overall health status of adults with disabilities.

ABBREVIATION KEY

IADD

Intellectual acquired or developmental disability

NA

Not applicable

NHIS

National Health Interview Survey