Effects of Alzheimer’s disease and related dementias on dental care usage and economic burden in older adults: a cross-sectional study

Abstract

Aim

Distinct subtypes of Alzheimer’s disease (AD) and related dementias (RD) might have different effects on dental care usage and economic burden. To determine the effects of AD and RD on specific types of dental care usage (preventive and treatment visits) and dental care costs from different payers (total and out-of-pocket costs).

Methods

A cross-sectional study was conducted using the Medicare Current Beneficiary Survey in 2016. This study identified 4268 community dwelling older adults with and without Alzheimer’s disease and related dementias (ADRD) from a nationally representative sample of Medicare beneficiaries. Dental care usage and costs are based on self-reported data. Preventive dental events included preventive and diagnosis events. Treatment dental events included restorative, oral surgery and other events.

Results

This study identified 4268 (weighted N=30 423 885) older adults, including 94.48% without ADRD, 1.90% with AD and 3.63% with RD. Compared with older adults without ADRD, those with AD had similar dental care usage, but those with RD were 38% less likely to have treatment visit (OR: 0.62; 95% CI: 0.41 to 0.94) and had a 40% reduced number of total treatment visits (incidence rate ratio: 0.60; 95% CI: 0.37 to 0.98). RD was not associated with dental care costs, but AD was associated with higher total costs (β: 1.08; 95% CI: 0.14 to 2.01) and higher out-of-pocket costs (β: 1.25; 95% CI: 0.17 to 2.32).

Conclusions

Patients with ADRD were more likely to have adverse dental care outcomes. Specifically, RD was associated with lower treatment dental care usage and AD was associated with higher total and out-of-pocket dental care costs. Effective patient-centred strategies should be used to improve dental care outcomes in patients with distinct subtypes of ADRD.

Strengths and limitations of this study.

• Data were from Medicare Current Beneficiary Survey (MCBS) which is a nationally representative, longitudinal survey of Medicare beneficiaries conducted by the Centers for Medicare and Medicaid Services.

• Respondents of MCBS reported detailed information on dental care events.

• Those enrolled in health maintenance organisations were excluded which otherwise may introduce bias.

• This study cannot identify all patients with Alzheimer’s disease and related dementias using Medicare claims.

• Dental care events were measured based on self-reports and indirect costs of dental care cannot be measured.

Introduction

Alzheimer’s disease and related dementias (ADRD) encompasses various dementia subtypes with differing aetiologies, namely Alzheimer’s disease (AD) and related dementias (RD).^1–3 ADRD affects 14% of older adults aged 71 and older in the USA.⁴ The economic burden of ADRD is substantial. Total direct healthcare costs of ADRD were US$290 billion, with out-of-pocket (OOP) costs estimated to be US$63 billion in 2019.⁴ Indirect costs, such as care provided by family and unpaid caregivers, are estimated to be US$234 billion.⁴ AD is the most common type of ADRD and affects 10% of the US population aged 71 and older.^{4 5} Oxidative and inflammatory damage in the ageing brain secondary to the accumulation of misfolded proteins (β-amyloid and tau) is the major pathology of AD.⁶ RD is another type of ADRD which encompasses vascular dementia, Lewy body dementia, frontotemporal lobar degeneration and dementia of mixed pathologies.^{3 4} Of these, vascular dementia is the second most common type of ADRD and affects 2.4% of the US population aged 71 and older.^{4 5 7} The pathology of vascular dementia is due to brain tissue damage induced by cerebrovascular disease.⁴ The clinical presentation of AD and RD differ in which memory impairment often occurs early in AD, whereas personality and/or behaviour changes present more commonly during the initial stages of RD.⁴

Older adults have an increased risk of dental health problems.⁸ Common dental problems reported in older adults include dental caries, periodontal disease and xerostomia.⁸ It is estimated that coronal caries affect up to 96%, xerostomia affects 29% to 57% and moderate or severe periodontal disease affects 53% of seniors.^{8 9} Since Medicare does not cover routine dental care, those with limited or no dental insurance can incur significant cost-sharing, which might result in foregoing necessary dental care.¹⁰ Only 29% of older adults have dental insurance and only 66% have visited a dentist in the past 12 months in the USA.¹¹ In 2016, the average cost-sharing of dental care was US$469 among Medicare beneficiaries, with 19% spending more than US$1000 on dental care.¹⁰

Poor dental health is associated with an increased risk of ADRD. Recent studies have indicated the association between ADRD and chronic periodontitis.^{12 13} Porphyromonas gingivalis, a key pathogen in chronic periodontitis, has been implicated as an important risk factor for the development of AD.^{14 15} After infecting the oral cavity, P. gingivalis can spread to the brain through various pathways such as infecting monocytes followed by brain recruitment,^{16 17} directly infecting and causing damage to the endothelial cells that protect the blood-brain barrier¹⁸ or infecting and spreading through cranial nerves like the olfactory or trigeminal nerves to reach the brain.¹⁹ Gingipains (cysteine proteases produced by P. gingivalis) was shown to be associated with the promotion of tau tangle formation which underlies the pathogenesis of AD.¹⁴ Other dental risk factors associated with developing ADRD include tooth loss and suboptimal dental health behaviours.^20–23

Evidence also suggests that ADRD is a risk factor for poor dental health. Individuals with ADRD are more likely to have dental problems such as higher plaque accumulation, dental caries and severe periodontal disease.^21–24 Poor dental health observed in patients with ADRD might be due to the greater functional dependence, increasing age and frailty and comorbidities and medications associated with ADRD.²⁴ The level of cognitive function has been inversely associated with dental care usage, with patients with ADRD found to have a lower likelihood of attending regular preventive dental visits.^{25 26} A significant decline in the rate of dental visits following dementia diagnosis was also observed, especially in those with mixed dementia and Lewy body dementia.²⁷ However, other studies did not find an association between ADRD and dental care usage.²⁸ With regards to dental care costs, existing studies did not find an association between ADRD and cost-sharing on dental care.²⁹

Despite the high prevalence of ADRD, limited studies have assessed the impact of ADRD on dental care outcomes. Existing studies have not examined the relationship between different subtypes of ADRD and dental care outcomes. Furthermore, existing studies have not differentiated various types of dental care visits and costs from different payers. Having a comprehensive understanding of the relationship between ADRD and dental care usage and costs can better target quality improvement efforts to improve dental care outcomes in patients with ADRD. To fill the gap in the literature, the objectives of this study were to determine the effects of AD and RD on specific types of dental care usage (preventive and treatment visits) and costs from different payers (total and OPP costs).

Methods

Data source

This is a cross-sectional study using the Medicare Current Beneficiary Survey (MCBS) in 2016. MCBS is a nationally representative, longitudinal survey of Medicare beneficiaries conducted by the Centers for Medicare and Medicaid Services.³⁰ MCBS collects extensive information on individual demographic and social characteristics, health and functional status, medical and prescription drug usage and costs and is linked to Medicare administrative and claims data. Dental care events are not included in Medicare claims because most of them are not covered under Medicare. However, respondents of MCBS reported detailed information on dental care events, including expenditures with different payment sources.³¹ Thus, the linked data are appropriate for this study.

Study population

This study included Medicare beneficiaries who were 65 years or older, had continuous coverage of Medicare Part A and B, and lived in community settings. Those enrolled in health maintenance organisations were excluded. Older adults without ADRD (reference group) were compared with those with ADRD (including AD and RD) in this study.

Measurement

AD and RD were measured based on the relevant 10th revision of the International Statistical Classification of Diseases and Related Health Problems codes from Medicare claims. Dental care events were measured based on self-reports and classified as preventive/diagnosis events and definitive treatment events. Preventive/diagnosis events can be further classified as preventive events (cleaning) and diagnosis events (examination and X-ray). Definitive treatment events can be further classified as restorative events (bridge, crown, bonding and filling), oral surgery events (extraction and surgery) and other treatment events (orthodontics, periodontics, root canal and other). Dental care usage was measured by any dental care visit and total dental care visits in a given year. Dental care costs were measured by total dental care costs and OOP dental care costs in a given year. Covariates considered in this study were age, gender, race, education, marital status, income, residence, census region, comorbidity, caregiver and dental insurance and measured based on self-reports and Medicare administrative and claims data.

Statistical analysis

Basic characteristics of respondents with and without ADRD were compared using the χ² test. Logistic regressions were used to analyse binary data on dental care visits. Negative binomial regressions were used to analyse count data on total dental care visits. Generalised linear models, with log link and gamma distribution, were used to analyse cost data on dental care costs. Survey sampling weights were applied to generate national estimates. Statistical analyses were conducted using SAS V.9.4 (SAS Institute, Cary, North Carolina, USA).

Patient and public involvement

Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Results

A total of 4268 (weighted N=30 423 885) older adults were included in this study. Among them, 94.48% were not diagnosed with ADRD and 5.52% were patients diagnosed with ADRD, including 1.90% patients with AD and 3.63% patients with RD. Compared with older adults without ADRD, those with AD and RD were more likely to be older (p<0.0001), be women (p=0.0061), have a lower level of education (p<0.0001), be widowed (p=0.0002), have lower income (p<0.0001), have more comorbidities (p<0.0001), have caregivers (p<0.0001) and not have dental insurance (p=0.0022) (table 1).

Table 1.

Characteristics of older adults with and without Alzheimer’s disease and related dementias (weighted N=30 423 885)

Characteristics	ADRD status
	No ADRD (reference)	AD subgroup	RD subgroup	P value
	%	%	%
Age				<0.0001
65–74	62.60	11.23	21.67
75–84	27.37	40.11	41.43
85+	10.03	48.66	36.90
Gender				0.0061
Male	46.59	31.39	40.35
Female	53.41	68.61	59.65
Race				0.1618
Non-Hispanic white	80.97	74.18	76.36
Non-Hispanic black	7.07	11.01	10.37
Hispanic	5.72	8.84	8.57
Other	6.25	5.98	4.70
Education				<0.0001
Less than high school	12.66	29.51	25.35
High school graduate	23.62	30.35	24.16
Some college	25.88	16.96	22.64
College graduate	37.83	23.18	27.84
Marital status				0.0002
Married	58.31	53.91	45.61
Widowed	22.03	35.43	39.04
Single	19.66	10.66	15.35
Income				<0.0001
<US$10 000 per year	7.26	12.69	12.32
US$10 000–19 999 per year	16.23	27.63	24.03
US$20 000–39 999 per year	26.17	28.65	27.56
≥US$40 000 per year	50.33	31.03	36.09
Residence				0.3911
Metropolitan	75.98	81.05	68.42
Non-metropolitan	24.02	18.95	31.58
Census region				0.4232
Northeast	17.47	16.71	19.96
Midwest	20.97	19.30	20.66
South	39.34	45.22	45.19
West	22.22	18.77	14.18
CCI				<0.0001
0	44.83	14.26	16.66
1	17.69	23.91	14.82
2	12.01	18.63	11.19
3+	25.46	43.21	57.33
Caregiver				<0.0001
No	67.13	22.71	40.26
Yes	32.87	77.29	59.74
Dental insurance				0.0022
No	76.69	77.88	88.06
Yes	23.31	22.12	11.94

AD, Alzheimer’s disease; ADRD, Alzheimer’s disease and related dementias; CCI, Charlson Comorbidity Index; RD, related dementias.

Among older adults without ADRD, 56.32% had at least one dental visit. Specifically, 51.68% had at least one preventive/diagnosis visit and 27.29% had at least one definitive treatment visit. Compared with older adults without ADRD, those with AD had similar dental care visit (OR: 0.90; 95% CI: 0.50 to 1.64), preventive/diagnosis visit (OR: 1.03; 95% CI: 0.53 to 2.01) and definitive treatment visit (OR: 0.78; 95% CI: 0.45 to 1.36) (figure 1A). Older adults with RD had similar dental care visit (OR: 0.81; 95% CI: 0.55 to 1.19) and preventive/diagnosis visit (OR: 0.88; 95% CI: 0.59 to 1.31), but were 38% less likely to have definitive treatment visit (OR: 0.62; 95% CI: 0.41 to 0.94) than those without ADRD (figure 1B). In addition, older adults with RD were 33% less likely to have diagnosis visit (OR: 0.67; 95% CI: 0.45 to 0.98) and 42% less likely to have restorative visit (OR: 0.58; 95% CI: 0.39 to 0.88) (figure 1B).

Figure 1.

The impact of Alzheimer’s disease and related dementias on dental care visit. (A) The impact of Alzheimer’s disease on any dental care visit. (B) The impact of related dementias on any dental care visit. (C) The impact of Alzheimer’s disease on total dental care visits. (D) The impact of related dementias on total dental care visits. AD, Alzheimer’s disease; ADRD, Alzheimer’s disease and related dementias; IRR, incidence rate ratio; RD, related dementias. Covariates controlled: age, gender, race, education, marital status, income, residence, census region, comorbidity, caregiver and dental insurance.

The total number of dental care visits were 1.60 (SD=0.05) on average in older adults without ADRD, including 1.06 (SD=0.04) total preventive/diagnosis visits and 0.59 (SD=0.04) total definitive treatment visits. Compared with older adults without ADRD, those with AD had similar total dental care visits (incidence rate ratio (IRR): 0.99; 95% CI: 0.66 to 1.48), total preventive/diagnosis visits (IRR: 1.00; 95% CI: 0.65 to 1.55) and total definitive treatment visits (IRR: 1.14; 95% CI: 0.58 to 2.27) (figure 1C). Older adults with RD had similar total dental care visits (IRR: 0.79; 95% CI: 0.59 to 1.06) and total preventive/diagnosis visits (IRR: 0.84; 95% CI: 0.67 to 1.06), but had a 40% reduced number of total definitive treatment visits (IRR: 0.60; 95% CI: 0.37 to 0.98) than those without ADRD (figure 1D). In addition, older adults with RD had a 36% reduced number of total diagnosis visits (IRR: 0.74; 95% CI: 0.56 to 0.99) and had a 44% reduced number of total restorative visits (IRR: 0.56; 95% CI: 0.34 to 0.94) (figure 1D).

Among older adults without ADRD, the total dental care costs were US$694.50 (SD=US$65.19) on average. Specifically, the total preventive/diagnosis costs were US$338.47 (SD=US$31.81) and total definitive treatment costs were US$388.30 (SD=US$58.10) on average. Compared with older adults without ADRD, those with AD had higher total dental care costs (β: 1.08; 95% CI: 0.14 to 2.01), similar total preventive/diagnosis costs (β: 0.79; 95% CI: −0.38 to 1.96) and higher total definitive treatment costs (β: 1.55; 95% CI: 0.60 to 2.49) (figure 2A). In addition, older adults with AD had higher total restorative costs (β: 1.57; 95% CI: 0.48 to 2.62), higher total oral surgery costs (β: 2.20; 95% CI: 0.88 to 3.52) and higher total other treatment costs (β: 1.87; 95% CI: 0.32 to 3.42) (figure 2A). Older adults with RD had similar total dental care costs (β: −0.34; 95% CI: −0.86 to 0.18), similar total preventive/diagnosis costs (β: −0.36; 95% CI: −0.78 to 0.05) and similar total definitive treatment costs (β: −0.05; 95% CI: −0.96 to 0.87) (figure 2B).

Figure 2.

The impact of Alzheimer’s disease and related dementias on dental care costs. (A) The impact of Alzheimer’s disease on total dental care costs. (B) The impact of related dementias on total dental care costs. (C) The impact of Alzheimer’s disease on out-of-pocket dental care costs. (D) The impact of related dementias on out-of-pocket dental care costs. AD, Alzheimer’s disease; ADRD, Alzheimer’s disease and related dementias; OOP, out-of-pocket; RD, related dementias. Covariates controlled: age, gender, race, education, marital status, income, residence, census region, comorbidity, caregiver and dental insurance.

The OOP dental care costs were US$526.36 (SD=US$53.48) on average in older adults without ADRD, including US$239.86 (SD=US$25.86) OOP preventive/diagnosis costs and US$313.27 (SD=US$52.13) OOP definitive treatment costs. Compared with older adults without ADRD, those with AD had higher OOP dental care costs (β: 1.25; 95% CI: 0.17 to 2.32), similar OOP preventive/diagnosis costs (β: 0.99; 95% CI: −0.57 to 2.55) and higher OOP definitive treatment costs (β: 1.55; 95% CI: 0.58 to 2.53) (figure 2C). In addition, older adults with AD had higher OOP restorative costs (β: 1.24; 95% CI: 0.17 to 2.32), higher OOP oral surgery costs (β: 2.07; 95% CI: 0.81 to 3.32) and higher OOP other treatment costs (β: 2.34; 95% CI: 0.81 to 3.87) (figure 2C). Older adults with RD had similar OOP dental care costs (β: −0.46; 95% CI: −1.09 to 0.18), similar OOP preventive/diagnosis costs (β: −0.37; 95% CI: −0.84 to 0.10) and similar OOP definitive treatment costs (β: 0.18; 95% CI: −0.95 to 1.32) (figure 2D).

Discussion

Overall, ADRD had an impact on dental care outcomes. Cognitive impairment and associated deterioration in executive functioning, memory and attention can significantly reduce an individual’s ability to perform home dental care and attend regular dental visits.^{21 25} This is because unlike eating and other basic activities of daily living, maintaining proper dental care is a higher level skill acquired through learning.³² Therefore, patients with ADRD can encounter challenges in initiating, planning, sequencing and carrying out dental care activities.³² Patients with ADRD might also have difficulties expressing their dental care needs and remembering their dental care appointments, which can contribute to reductions in the frequency of dental care visits and treatments.³²

This study found that AD did not impact dental care usage but RD was associated with reduced definitive treatment dental care usage. Existing studies have reported discordant results on the association between ADRD and dental care usage. Delavande et al found no difference in the likelihood of dental care visits with ADRD.²⁸ This is consistent with our findings when we studied total dental care visits. However, when we compared specific types of dental care visits, we found that RD was associated with reduced definitive treatment visits. This finding is consistent with Fereshtehnejad et al’s study, which found a significant decline in different types of dental care visits among individuals with Lewy body dementia and dementia of the mixed pathology.²⁷ This might be due to the earlier onset of behaviour changes in RD, which can result in individuals refusing to open mouth during dental visits or biting those who attempt to perform their dental care. Furthermore, the motor impairment associated with Lewy body dementia and dementia of the mixed pathology, such as tremors or facial musculature rigidity, can make dental care and treatments challenging therefore further reducing its usage.

We found that AD was associated with increased definitive treatment dental care costs but RD was not associated with increased dental care costs. Limited evidence exists assessing the impact of ADRD on dental care costs. Dwibedi et al found that OOP spending on dental care was similar between older adults with and without ADRD.²⁹ Although we found no difference in total dental care costs with RD, our results revealed higher dental care costs with AD, mainly definitive treatment costs. This is because we assessed AD and RD separately, and therefore, were able to highlight the differences in dental care costs between these two subtypes.²⁹ The earlier onset of memory impairment with AD, might more negatively impact their ability to remember and perform regular dental hygiene. Therefore, patients with AD need for more intensive dental care treatment as evidenced by the higher definitive treatment costs spent on restoration, oral surgery and other treatments.

The association between ADRD and adverse dental care outcomes highlights the importance of optimising dental care in this population. Dental professionals can assist patients with ADRD to optimise their dental care outcomes. First and foremost, dental professionals need to be aware of ADRD’s impact on dental health and be equipped to manage these patients. Caregivers have identified that dental professionals’ lack of skills and knowledge in treating patients with ADRD is a barrier to access dental care.³³ Even implementation of simple behaviour management and communication techniques can be helpful in reducing behavioural issues during dental visits, which in turn can improve dental care usage among patients with RD.³³ Dental professionals should also proactively inquire about barriers in maintaining dental hygiene with patients with ADRD and advise individualised strategies to help them overcome these challenges. Furthermore, dental professionals should regularly reinforce the importance of preventive dental care to patients with ADRD and their caregivers. As patients often have multiple care tasks to manage, being reminded of the importance of dental health maintenance in reducing future dental problems can help them prioritise and adhere to routine dental visits.³³ Since preventive dental treatment has been associated with lower subsequent dental costs, attending regular preventive dental visits might help in reducing the increased dental treatment costs associated with AD.³⁴ Methods that can be adopted to assist patients with AD in reducing dental care costs include ensuring that all dental treatments are necessary by carefully assessing the benefits and risks of these treatments while considering the patients’ goals of care and ADRD severity. Caregivers have reported that having receptive and transparent communication with the patients’ dental professionals can mitigate some of the cost barriers.³³

Patients with ADRD and their caregivers have a major responsibility in maintaining the patients’ dental health. Strategies that patients and caregivers can implement include proactively informing their dental professionals of their ADRD diagnosis. This would allow the dental office to better prepare for the appointment. Patients at earlier stages of ADRD should volunteer potential dental issues and challenges in performing regular dental care activities to their dental professionals. Because patients at more advanced stages of ADRD might be unable to express dental issues directly, caregivers should proactively look for indirect signs suggestive of dental discomfort (eg, eating habit changes and weight loss, frequent facial wincing and cupping of face and bad breath).³³ Caregivers can advocate for these patients’ dental health issues and assist them in making an informed decision around their dental care by accompanying patients to their dental visits.

Policymakers have an important role in improving dental care outcomes in patients with ADRD. Current policy limitations that preclude patients with ADRD from achieving optimal dental health include the lack of dental insurance coverage in Medicare. Having dental insurance is associated with increased dental care usage among older adults.²⁶ However, only 29% of the US older adults have dental insurance despite the greater need in this population.¹¹ Policymakers should consider providing Medicare dental insurance covering preventive dental care services. This could increase preventive dental care visits and reduce future treatment dental care visits and costs.

This study has a few limitations. First, this study cannot identify all patients with ADRD using Medicare claims. Patients with ADRD who did not seek care and those who are undiagnosed would not have been captured using claims. Second, dental care events were measured based on self-reports. Although respondents collected dental care bills, some dental care events might still have been missed. Third, this study only examined direct costs of dental care. Indirect costs of dental care (eg, caregiver productivity loss) cannot be measured in this study.

Conclusions

This study found that patients with ADRD were more likely to have adverse dental care outcomes. Specifically, RD was associated with lower treatment dental care usage and AD was associated with higher total and OOP dental care costs. Different stakeholders, including dental professionals, patients, caregivers and policymakers, should adopt effective patient-centred strategies to improve dental care outcomes in patients with ADRD. Targeted efforts should be implemented to optimise dental care in distinct subtypes of ADRD. Healthcare decision-makers should consider dental coverage all Medicare recipients, and not just for the dementia population. Dental coverage is provided by most Medicare Advantage plans, thus creating a double standard of care within the Medicare population.

Data availability statement

Data may be obtained from a third party and are not publicly available. Data may be obtained from a third party and are not publicly available. No data are available. The Medicare Current Beneficiary Survey is maintained by the Centers for Medicare and Medicaid Services and contains identified data. These data can be accessed only by certified personnel.

Ethics statements

Patient consent for publication

Not applicable.

Ethics approval

This study was approved by the University of Tennessee Health Science Center Institutional Review Board (19-07057-NHSR). Data were anonymised before the authors accessed them for the purpose of this study.