THE EFFECT OF MEDICAID DENTAL COVERAGE ON DENTAL CARE UTILIZATION AMONG OLDER AMERICANS AHYUDA OH

Transcription

1 THE EFFECT OF MEDICAID DENTAL COVERAGE ON DENTAL CARE UTILIZATION AMONG OLDER AMERICANS by AHYUDA OH DAVID J. BECKER, CHAIR JUSTIN BLACKBURN ALLEN CONAN DAVIS JULIE LYNN LOCHER BISAKHA SEN A DISSERTATION Submitted to the graduate faculty of The University of Alabama at Birmingham, in partial fulfillment of the requirements for the degree of Doctor of Public Health BIRMINGHAM, ALABAMA 2014

2 Copyright by Ahyuda Oh 2014

3 THE EFFECT OF MEDICAID DENTAL COVERAGE ON DENTAL CARE UTILIZATION AMONG OLDER AMERICANS AHYUDA OH HEALTH CARE ORGANIZATION AND POLICY ABSTRACT This dissertation examines the impact of Medicaid dental coverage on dental care utilization and oral health outcome of low-income elderly and non-elderly adults, using a fixed-effects model with longitudinal data of all states and multiple years from the Behavioral Risk Factors Surveillance System (BRFSS). By exploiting within-state variation over time in adult Medicaid dental coverage, the study estimates the effects of Medicaid dental coverage on dental care utilization (i.e., dental visits and dental cleanings) and oral health outcome (i.e., tooth loss). The study evaluates the effects of Medicaid dental benefits with preventive dental services on each of the three dental outcomes as well. This study finds that Medicaid dental coverage has an effect on increase in dental visits for both low-income elderly and non-elderly adults. Among non-elderly adults, Medicaid dental coverage increases the likelihood of dental cleanings while it decreases the likelihood of tooth loss. Meanwhile, the study finds no significant evidence to support the effects of Medicaid dental coverage on dental cleanings and tooth loss of elderly adults. The estimated effects of Medicaid dental benefits with preventive dental services are analogous to the estimated effects of Medicaid dental coverage on the three dental outcomes. Even though the results show that Medicaid dental coverage is positively associated with dental care utilization among low-income adults, the magnitude of the iii

4 estimated effects is modest. This implies that public dental insurance expansion alone is not enough to succeed in promoting access to dental care of low-income adults. Increasing effect of Medicaid dental coverage on preventive dental care is only seen in non-elderly adults. This suggests further efforts to find out other significant factors affecting access to preventive dental care among the elderly population, who is rapidly growing and expected to make up a substantial part of the total U.S. population in the near future. Keywords: Medicaid dental coverage, dental care utilization, preventive dental care, lowincome adults, elderly adults, non-elderly adults iv

5 DEDICATION To God for guiding me to a new path of my life; To Dr. Hyunmi Kim for her encouragement and care; To Dr. M. Kim Oh and Dr. Shin J. Oh for their friendship and hospitality; To my family for supporting my decision to study abroad v

6 ACKNOWLEDGMENTS I would like to thank Dr. David J. Becker, who is my committee chair and advisor, for his guidance and advice over the past few years. He has helped me develop a rudimentary idea into a finished study. I would also like to thank my dissertation committee of Dr. Justin Blackburn, Dr. Allen Conan Davis, Dr. Julie Lynn Locher, and Dr. Bisakha Sen for sharing their time and ideas. vi

7 TABLE OF CONTENTS Page ABSTRACT... iii DEDICATION... v ACKNOWLEDGMENTS... vi LIST OF TABLES... ix LIST OF FIGURES... xii CHAPTER 1. INTRODUCTION BACKGROUND... 5 Dental Insurance Coverage of Elderly Adults in the United States... 5 Public Dental Insurance Coverage for Elderly Adults... 9 Aging and Oral Health Care Needs of the Elderly Population The Benefits of Preventive Dental Care Relationship Between Oral Health and General Health of the Elderly Factors Affecting Dental Care Utilization of Elderly Adults and the Role of Public Dental Insurance Coverage Prior Research on Adult Medicaid Dental Coverage Gaps in the Literature and Contribution of This Dissertation METHODOLOGY Conceptual Framework Research Questions Identification Strategy Difference-in-Differences Fixed Effects Study Design Population vii

8 Data Dual Eligibles Qualifying for Medicaid Benefits Variables Empirical Models Analysis of Non-Elderly Adults Descriptive Statistics EMPIRICAL RESULTS Effects of Medicaid Dental Coverage on Dental Visits of Elderly Adults Two by Two Difference-in-Differences Fixed-Effects Estimation with All States and Multiple Years Effects of Medicaid Dental Coverage on Dental Cleanings of Elderly Adults Two by Two Difference-in-Differences Fixed-Effects Estimation with All States and Multiple Years Effects of Medicaid Dental Coverage on Tooth Loss of Elderly Adults Two by Two Difference-in-Differences Fixed-Effects Estimation with All States and Multiple Years Effects of Medicaid Dental Coverage on Dental Visits of Non-Elderly Adults Two by Two Difference-in-Differences Fixed-Effects Estimation with All States and Multiple Years Effects of Medicaid Dental Coverage on Dental Cleanings of Non-Elderly Adults 99 Two by Two Difference-in-Differences Fixed-Effects Estimation with All States and Multiple Years Effects of Medicaid Dental Coverage on Tooth Loss of Non-Elderly Adults Two by Two Difference-in-Differences Fixed-Effects Estimation with All States and Multiple Years Summary of Empirical Results CONCLUSIONS LIST OF REFERENCES viii

9 LIST OF TABLES Table Page 1 Dental Benefits Covered by Medicare Programs Previous Research that Evaluated the Effects of Medicaid Dental Coverage on Dental Care Utilization of Adults Adult Medicaid Dental Benefits by States and Years Oral Health Questionnaires Included in the Even-Year BRFSS Data from 2002 to Poverty Thresholds by Selected Family Size and Number of Dependent Children from 2002 to 2010 (Dollars) Summary of Dependent and Independent Variables The State-Level Variation Over Time in Adult Medicaid Dental Coverage by Whether or not Including More Than Emergency-Only Dental Services The State-Level Variation Over Time in Adult Medicaid Dental Coverage by Whether or not Preventive Dental Services Included in Dental Benefits Descriptive Statistics of Low-Income Elderly Adults in Treatment and Control Groups from 2004 and 2008 BRFSS Summary Statistics of Low-Income Non-Elderly Adults in Treatment and Control Groups from 2004 and 2008 BRFSS Summary Statistics of Low-Income Elderly and Non-Elderly Adults in 50 States and the District of Columbia from 2002, 2004, 2006, 2008, and 2010 BRFSS Estimated Effects of Expanding Medicaid Dental Coverage on Dental Visits of Low-Income Elderly Adults, Using Two by Two Difference-in-Differences Estimation ix

10 13 Estimated Effects of Medicaid Dental Coverage on Dental Visits of Low-Income Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Medicaid Dental Benefits with Preventive Dental Services on Dental Visits of Low-Income Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Expanding Medicaid Dental Coverage on Dental Cleanings of Low-Income Elderly Adults, Using Two by Two Difference-in-Differences Estimation Estimated Effects of Medicaid Dental Coverage on Dental Cleanings of Low- Income Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Medicaid Dental Benefits with Preventive Dental Services on Dental Cleanings of Low-Income Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Expanding Medicaid Dental Coverage on Tooth Loss of Low-Income Elderly Adults, Using Two by Two Difference-in-Differences Estimation Estimated Effects of Medicaid Dental Coverage on Tooth Loss of Low-Income Elderly Adults from the Fixed Effects Estimation with All States and Multiple Years Estimated Effects of Medicaid Dental Benefits with Preventive Dental Services on Tooth Loss of Low-Income Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Expanding Medicaid Dental Coverage on Dental Visits of Low-Income Non-Elderly Adults from Two by Two Difference-in-Differences Estimation Estimated Effects of Medicaid Dental Coverage on Dental Visits of Low-Income Non-Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Medicaid Dental Benefits with Preventive Dental Services on Dental Visits of Low-Income Non-Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years x

11 24 Estimated Effects of Expanding Medicaid Dental Coverage on Dental Cleanings of Low-Income Non-Elderly Adults from Two by Two Difference-in-Differences Estimation Estimated Effects of Medicaid Dental Benefits with Preventive Dental Services on Dental Cleanings of Low-Income Non-Elderly Adults from the Fixed Effects Estimation with All States and Multiple Years Estimated Effects of Medicaid Dental Coverage on Dental Cleanings of Low- Income Non-Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Expanding Medicaid Dental Coverage on Tooth Loss of Low-Income Non-Elderly Adults from Two by Two Difference-in-Differences Estimation Estimated Effects of Medicaid Dental Benefits with Preventive Dental Services on Tooth Loss of Low-Income Non-Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects of Medicaid Dental Coverage on Tooth Loss of Low-Income Non-Elderly Adults from the Fixed-Effects Estimation with All States and Multiple Years Estimated Effects on Dental Visits by Statistical Methods and Type of Dental Coverage Estimated Effects on Dental Cleanings by Statistical Methods and Type of Dental Coverage Estimated Effects on Tooth Loss by Statistical Methods and Type of Dental Coverage xi

12 LIST OF FIGURES Figure Page 1 Dental Coverage Rates Among Age Groups Trends in Dental Coverage of Children Aged Trends in Dental Coverage of Non-Elderly Adults Aged Trends in Dental Coverage of Elderly Adults Aged 65 and Over Percentage of Adults with No Natural Teeth, by Selected Age Groups All Types of Dental Visits During the Prior Year Among Dentate Persons Between 1997 and 2010, by Selected Age Groups A Conceptual Framework Used for the Analysis xii

13 CHAPTER 1 INTRODUCTION Dental insurance coverage is an important determinant of dental care utilization and oral health (Bailit et al., 1985, Bendall and Asubonteng, 1995, Stancil et al., 2005). The lack of access to diagnostic and preventive dental services places individuals at risk of developing a range of oral health problems, such as dental caries, periodontal diseases, and tooth loss. Untreated dental diseases often lead to costly complications and have the potential to threaten general health and quality of life (Shay, 2002). Oral health deteriorates with age, and elderly adults (aged 65 and over) are particularly prone to oral health problems (USDHHS, 2000, Dye et al., 2012). The decline in job-based health care benefits at retirement leaves the majority of elderly Americans without dental insurance coverage (Manski et al., 2010). For the economically disadvantaged elderly, the impact of not having dental insurance coverage may be greater relative to affluent seniors. Whereas Medicare provides universal medical coverage for the over-65 population, there is no similar universal dental insurance coverage for elderly adults in the United States. Traditional Medicare does not pay for dental services, with the exception of medically necessary conditions (CMS, 2012). The medically necessary conditions are as follows: dental services as an integral part of a covered medical procedure (e.g., reconstruction of the jaw following accidental injury), extraction of teeth to prepare radiation therapy for cancers of the jaw, and oral examinations before kidney 1

14 transplantation or heart valve replacement. On the other hand, some state Medicaid programs provide dental benefits for low-income adults (Medicaid, 2012). Medicare beneficiaries can be dually eligible for Medicaid if they satisfy certain criteria of income and assets or have high medical expenses. Most dual eligibles receive a full range of Medicaid benefits covered by state Medicaid programs (CMS, 2004). In recent years, Medicaid dental coverage for adults has been the first target of cuts among states facing budget deficits (Shirk, 2010). To address disparities in dental care access among the lowincome elderly population, advocates have suggested a variety of new financing models, such as prepaid dental annuities for retirement (Anderson, 2005), Medicare Part D for dental care (Jones, 2005), the expansion of dental benefits through Medicare Advantage plans (Compton, 2005), and special care dentistry Act of 2011 (Engel and Schakowsky, 2011). While previous research suggests that dental insurance coverage alone does not ensure dental care use among the seniors (Branch et al., 1986, Gilbert et al., 1990), few studies have examined the effects of public dental insurance coverage on dental care utilization of the elderly population. Publicly funded dental coverage aims to improve access to oral health care of socioeconomically disadvantaged elderly adults. However, little work has examined its effects on their dental care utilization. Few empirical studies provide credible evidence for the causal effect of dental insurance coverage on the utilization of dental care services of adults. A remarkable exception is the work from the Rand Health Insurance Experiment (HIE), which found that increased beneficiary cost sharing led to reductions in dental services utilization and poor oral health, particularly for low-income patients (Bailit et al., 1985). A number of studies examined the impact of changes in Medicaid dental policies for adults on dental 2

15 care utilization and associated dental expenditures (Mullins et al., 2004, Pryor and Monopoli, 2005, Maiuro, 2011). However, most of these studies are descriptive analyses, which simply examined changes in dental care utilization before and after reduction in adult Medicaid dental benefits within a single state. Recently, two notable studies estimated the causal effect of Medicaid dental coverage on dental care utilization of nonelderly adults, using difference-in-differences (DD) methods. One is a study by Choi (2011), which examined differences in dental services use among selected states by exploiting state-level variation in Medicaid dental coverage between parents and childless adults (Choi, 2011). The other is a study by Nasseh and Vujicic (2013b), which compared dental care utilization of non-elderly adults in Massachusetts to that in eight control states before and after the Massachusetts health reform that included dental coverage expansion to adult Medicaid enrollees (Nasseh and Vujicic, 2013b). Although a DD approach yields a more unbiased estimate of causal effect of treatment, the validity of the DD estimate hinges upon the credibility of parallel trend assumption that the underlying trends of mean outcomes are identical for both treatment and control groups in the absence of treatment. The simple two by two DD setting (i.e., two groups and two time periods) is likely to misestimate treatment effects. With multiple groups and time periods, a more robust estimate can be produced. State Medicaid programs can choose not only to cover dental benefits for adults but also to include which type of dental services (Medicaid, 2012). This makes state Medicaid dental benefits for adults multidimensional. Different types of dental benefits may have a different impact on dental outcomes. Few studies investigated differential effects of adult Medicaid dental coverage by type of dental benefits. In addition, we know 3

16 of no prior work that investigated the causal relationship between Medicaid dental coverage and the utilization of dental care services among the elderly population. This dissertation examines how Medicaid dental coverage affects dental care utilization and oral health outcome of low-income adults in the United States, using nationally representative survey data from the Behavioral Risk Factors Surveillance System (BRFSS). The study adds to the existing literature by exploiting within-state variation over time in Medicaid dental coverage for adults. Using longitudinal data from all states and multiple years in a fixed-effects framework makes it possible to control for unmeasured or unobservable state- and year-specific factors, with identification of the effect of Medicaid dental coverage coming from states that change their Medicaid dental policies for adults over time. By exploiting state-level variation in type of dental benefits, this study examines the effects of Medicaid dental benefits with preventive dental services as well. The study revisits the work of Choi (2011) and of Nasseh and Vujicic (2013b) by estimating the effects of Medicaid dental benefits on dental care utilization and oral health outcome of low-income non-elderly adults, using a fixed-effects analysis as well as an alternative source of identification (i.e., longitudinal variation in Medicaid dental coverage for adults). Then the study extends the work to investigate the effects of adult Medicaid dental benefits on elderly dual-eligibles who are the main focus of this dissertation. 4

17 CHAPTER 2 BACKGROUND Dental Insurance Coverage of Elderly Adults in the United States The loss of employer-sponsored dental insurance coverage and the decline in incomes associated with retirement can undermine the ability of seniors to pay for their needed dental care (Manski et al., 2010, Manski et al., 2011, Manski et al., 2012). According to the 1999 National Health Interview Survey, more than a half of dentate adults (i.e., those with natural teeth) aged 55 and older reported that they could not see a dentist due to costs, although they perceived dental care needs (Macek et al., 2004). Approximately twenty-four percent of persons aged 65 and over have private dental insurance, which is far lower than the rates among children (54%) and workingage adults (60%) (Manski and Brown, 2007). In the past several decades, industries have curtailed retiree health benefits, which has contributed to the low rate of dental insurance coverage among the elderly population (KFF, 2012b). A report from the Agency for Healthcare Research and Quality showed that elderly adults paid more than seventy-five percent of their dental costs out-of-pocket, whereas other age groups paid about fifty percent (Brown and Manski, 2004). There was also considerable variation in public dental insurance coverage by age. While more than twenty-six percent of children or adolescents had public dental coverage, less than six percent of non-elderly adults had it in 2004 (Manski and Brown, 5

18 2007). The 2004 Medical Expenditure Panel Survey showed that 6.1% of those aged 65 to 74 and 6.5% of those aged 75 and over had public dental coverage. Overall, more than sixty-five percent of older Americans had no dental insurance, in marked contrast to the rates of non-elderly population without dental insurance: around thirty-four percent of non-elderly adults and less than twenty percent of children/adolescents. Figure 1 presents differences in the rates of persons with dental insurance coverage across age groups by type of dental coverage. The abrupt increase in the rate of no dental coverage around retirement age is the mirror of the sharp drop in private dental insurance. 80% 70% 60% 50% 40% 30% 20% Private Public No insurance 10% 0% <6 6 to to to to to 74 >74 years old Note: Adapted from Medical Expenditure Panel Survey 2004 (Manski and Brown, 2007) Figure 1. Dental coverage rates among age groups 6

19 Over the past several years, there has been a significant change in the prevalence in dental insurance coverage among selected age groups (Nasseh and Vujicic, 2013a). In their paper, Nasseh and Vujicic pointed out that a constant expansion of public dental insurance over a decade has contributed to a significant reduction in the percentage of children (aged 2-18) with no dental coverage (Figure 2). Between 2001 and 2011, the rate of non-elderly adults (aged 19-64) with private dental coverage decreased from 62% to 56%. A large part of the drop could be offset by the increased rate of public dental coverage from 6.5% in 2000 to 10% in 2011 (Figure 3). The authors also found that the percentage of elderly adults (aged 65 and over) with private dental coverage slightly rose from 24% in 2001 to 26% in 2011, whereas there was no considerable change in the rates of public dental coverage during the same periods (Figure 4). 70% 60% 50% 40% 30% 20% Private Public No insurance 10% 0% Note: Adapted from Medical Expenditure Panel Survey (MEPS) (Nasseh and Vujicic, 2013a) Figure 2. Trends in dental coverage of children aged

20 70% 60% 50% 40% 30% 20% Private Public No insurance 10% 0% Note: Adapted from MEPS (Nasseh and Vujicic, 2013a) Figure 3. Trends in dental coverage of non-elderly adults aged % 70% 60% 50% 40% 30% 20% Private Public No insurance 10% 0% Note: Adapted from MEPS (Nasseh and Vujicic, 2013a) Figure 4. Trends in dental coverage of elderly adults aged 65 and over 8

21 Public Dental Insurance Coverage for Elderly Adults Traditional Medicare does not cover dental services other than a few specific severe dental conditions (CMS, 2012). While some Medigap plans provide health services that neither Medicare Part A nor Part B covers, they include no dental benefits. As of March 2010, approximately twenty-five percent of Medicare beneficiaries (11.1 million) had health benefits through private Medicare Advantage plans (Gold et al., 2010b). Fifty-five percent of Medicare Advantage plans provided some form of preventive dental services including a limited number of oral exams, dental cleanings, or x-rays. However, none of those plans offered restorative dental care, such as fillings, crowns, or dentures (Gold et al., 2010a). Table 1 summarizes dental services covered under Medicare programs. While state Medicaid programs are required to cover dental services for children, dental benefits are optional for adult beneficiaries including the elderly (Medicaid, 2012). As a result, only a small fraction (6.3%) of community-dwelling older adults have public dental insurance coverage (Manski and Brown, 2007). In addition, Medicaid dental policy for adults varies widely across states in populations covered, coverage limitation, copayment/prior approval requirement, and so on. According to the 2003 survey conducted by Oral Health America (OHA, 2003), in twenty states, Medicaid programs for adults covered only emergency-related dental services, such as pain/infection reliefs and tooth extractions. Six states provided no Medicaid dental benefits for adults. While twenty states covered partial dental benefits for their adult Medicaid beneficiaries, only five states provided full dental coverage. 9

22 Table 1. Dental benefits covered by Medicare programs Medicare programs Original Medicare Covered services Dental services that are an integral part of a covered procedure, such as reconstruction of the jaw following accidental injury Extraction of teeth to prepare radiation therapy for cancers of the jaw Oral examinations before kidney transplantation or heart valve replacement Excluded services Routine dental care: oral exams, dental screenings, and dental cleanings Restorative care: fillings, crowns, bridges, and root canals Extraction of teeth Dentures Medigap Medicare Advantage Plans No dental benefits Some plans provide limited preventive dental benefits, such as dental exams, cleaning, or x-rays Note: Adapted from Centers for Medicare and Medicaid Services (CMS, 2012, Huang et al., 2012) Aging and Oral Health Care Needs of the Elderly Population As of 2011, a huge cohort of Americans known as baby boomers began to reach retirement age. According to the 2010 Census, thirteen percent of the U.S. population was age 65 and older (Howden and Meyer, 2011). By 2030, the elderly population is projected to account for approximately twenty percent of the U.S. 10

23 population (Passel and Cohn, 2008). It is also expected that the number of older Americans will increase by eighty percent from 40.2 million in 2010 to 72 million in 2030 (Vincent and Velkoff, 2010). During the past several decades, dental conditions of older adults have changed dramatically. The proportion of elderly adults who have maintained their own natural teeth has been growing (Burt and Eklund, 2005). An increase in the number of elderly people with more retained teeth involves an increase in oral health care needs for preventive and other dental treatments rather than denture care (Reinhardt and Douglass, 1989, Ettinger, 1993). In the United States, the proportion of edentulous adults (i.e., those who lost all their natural teeth) has declined (USDHHS, 2000). Among younger Medicare beneficiaries aged years, the rate of complete tooth loss has fallen nearly in half over the past few decades (Figure 5). More retention of their natural teeth as people age may put older adults at a continual risk of dental caries and periodontal disease, which results in an increased need for oral health care among the elderly (Douglass et al., 1998). According to the National Health and Nutrition Examination Survey, the prevalence of dental caries among older adults aged 55 to 74 years has increased, whereas a reverse trend has been found in other younger groups (USDHHS, 2000). The prevalence of untreated dental caries has increased among older African and Hispanic Americans as well as low-income older adults with less education (Chalmers and Ettinger, 2008). The prevalence of periodontal disease also increases with age. A study found that periodontal disease ranged from about twenty-four percent in young adults aged years to seventy percent in elderly adults aged 65 and over (Eke et al., 2012). 11

24 50% 45% 40% 35% 30% 25% 20% % 10% 5% 0% 18 to to to to 74 yrs old Note: Adapted from National Center for Health Statistics 1975 and 1996 (USDHHS, 2000) Figure 5. Percentage of adults with no natural teeth, by selected age groups Despite a significant improvement in the oral health of Americans (Dye et al., 2007), there are still substantial differences in access to dental care and oral health status across demographic subgroups (Stanton and Rutherford, 2003, Haley et al., 2008). While approximately thirteen percent of adolescents (aged 12-19) have untreated dental caries, twenty percent of the elderly (aged 65 and over) have it (Dye et al., 2012). Forty-one percent of the low-income elderly (i.e., those with household incomes below 100% of the federal poverty level, FPL) have untreated dental caries, a rate which is nearly three times higher than that of older adults with greater than 200% of the FPL of household incomes (Dye et al., 2012). More than seventy percent of elderly adults (aged 65 and over) have periodontal disease and sixty-four percent of those have either moderate or severe periodontal disease (Eke et al., 2012). Older people at the lowest socioeconomic status 12

25 are more likely to have severe periodontal disease (USDHHS, 2000). Meanwhile, a study points out that the majority of periodontal disease among older adults is mild or moderate, which can be treated through simple scaling and dental cleanings by general dentists and dental hygienist (Boehm and Scannapieco, 2007). More of today s seniors have their natural teeth, but lack dental insurance coverage to take care of it (Wu et al., 2012). The National Health Interview Survey showed that the dental care utilization rate of children has steadily increased by more than five-percentage points from 71.8% in 1997 to 77.0% in 2000, which has been in part driven by the expansion of public dental insurance coverage for children (Wall et al., 2012). On the other hand, among the dentate persons (i.e., those with their own natural teeth), dental visits of elderly adults aged 65 and over has decreased by 4.8 percentage points from 74.4% in 1997 to 69.6% in 2010 (Figure 6) (Wall et al., 2012). Roughly onethird (28.2%) of poor older adults (i.e., those in families with household income below 100% of the FPL) have at least one dental visit during a year, which is just half the rate (60%) of older adults with high family incomes (i.e., those in families with household income over 400% of the FPL) (Manski and Brown, 2007). With increasing dental care demands and limited access to dental care among economically disadvantaged older adults, a rising number of voices have advocated for the expansion of publicly funded dental coverage (Compton, 2005, Jones, 2005). 13

26 90% 80% 70% 60% 50% 40% % 20% 10% 0% 2 to to yrs old and over Note: Adapted from National Health Interview Survey 1997 and 2010 (Wall et al., 2012) Figure 6. All types of dental visits during the prior year among dentate persons between 1997 and 2010, by selected age groups The Benefits of Preventive Dental Care Preventive dental care refers to several kinds of work to keep one s teeth and gums healthy, such as tooth brushing, dental flossing, regular dental check-ups, and annual dental cleanings performed by a dental professional. In particular, routine checkups and dental cleanings enable early diagnosis and treatment of dental problems. This prevents a patient from suffering serious complications and helps avoid costly nonpreventive dental procedures. According to a longitudinal study that examined the trends in dental care utilization of insured patients from 1980 through 1995, there was a clear pattern of increase in preventive dental services use including oral examinations and dental cleanings but decline in restorative dental procedures (Eklund et al., 1997). 14

27 Although the effects of preventive dental services on oral health outcomes and dental expenditure savings have not been proved completely, recently there have been two noticeable studies that examined the clinical and economical impacts of preventive dental care for adults. One is a randomized controlled trial study, which found that patients in the Caries Management System (CMS) providing preventive dental care were significantly less likely to have afflicted teeth relative to those who only got the usual care for dental problems. (Warren et al., 2010). The study also found that the CMS is most cost-effective in patients with a high risk of developing dental caries. By analyzing the Medicare Current Beneficiary Survey data, Moeller and colleagues (2010) showed that Medicare beneficiaries who received preventive dental services had fewer dental visits for costly non-preventive procedures and less dental expenditures compared to those who had dental visits for caring of existing dental problems (Moeller et al., 2010). They concluded that preventive dental services coverage through Medicare could improve the oral health of older adults and reduce the costs of expensive non-preventive dental procedures for the dentate persons (i.e., those who have natural teeth). Relationship Between Oral Health and General Health of the Elderly With insufficient production of saliva, there is a high risk for new and recurrent dental caries as well as a variety of oral infections (Turner and Ship, 2007). Older adults are prone to reduced salivary flow, or dry mouth, often caused by side effects of medications (Narhi, 1994, Sreebny and Schwartz, 1997, Bergdahl and Bergdahl, 2000, Ship et al., 2002). According to a recent survey, forty-one percent of communitydwelling Medicare beneficiaries take five or more prescription medications, including 15

28 diuretics, anti-hypertensives, anti-inflammatories, and antidepressants, all of which are known to interfere with salivary gland function (Wilson et al., 2007). This condition increases the likelihood of having oral health problems for the elderly who have more retained natural teeth in particular. Uncontrolled dental caries and periodontal diseases can cause pain, difficulty in eating and speaking, as well as serious systemic complications including infective endocarditis and aspiration pneumonia. Poor oral health is strongly associated with a poor diet in the elderly (Moynihan, 2007). Both reduced chewing ability and oral pain due to tooth loss and dental diseases can cause changes in food selection and nutrient intake, which consequently affects general health and quality of life among elderly adults. Deteriorating oral health conditions might lead to decrease in cognitive ability (Osterberg et al., 1990). Pain, chewing difficulty, and unpleasant look caused by oral disease and tooth loss may also affect negatively the emotional and psychological quality of older adults lives (Strauss and Hunt, 1993). The American Heart Association concluded there is no evidence of a causal relationship between periodontal disease and cardiovascular disease (Lockhart et al., 2012). However, research continues to suggest a link between poor oral health and systemic diseases, such as diabetes mellitus, infective endocarditis, and aspiration pneumonia among the older adult population. All of these conditions can lead to serious general health conditions and incur considerable health care costs (Taylor et al., 2000, Shay, 2002, Azarpazhooh and Leake, 2006, Lamster et al., 2008). In cost-effective ways, regular oral hygiene procedures administered by dental professionals are recommended to 16

29 help minimize oral infections and then reduce the risk of systemic complications due to oral bacteria or inflammation (Grossi et al., 1997, Adachi et al., 2002, Shay, 2002). To summarize, a downward trends in tooth loss among the elderly population will increase dental care needs for preventive and other dental services rather than denture care of older adults who are at risk of developing dental caries and periodontal diseases. It will also profoundly change their oral health care needs from pain management, extraction, and dentures to diagnostic and preventive dental services including dental exams and professional dental cleanings. Oral health may affect general health so that the mouth cannot be separated from the body as a whole. Given the association between poor oral hygiene and the risk of systemic disease, good oral health care for the elderly, through effective and inexpensive preventive dental services, can play an important role in managing their medical conditions and general health. Factors Affecting Dental Care Utilization of Elderly Adults and the Role of Public Dental Insurance Coverage While many scholars have examined on the factors influencing dental care utilization, only a few studies have concentrated on the elderly population. In addition, they showed mixed results depending on research methods and sample data. Because a regular dental visit is associated with preventing dental problems as well as maintaining good oral health, a dental visit in the previous year is frequently used to measure dental care utilization in the studies (Thomson et al., 2010). A study by Conrad found that dental care utilization of elderly adults aged 65 and older was significantly related to the cost of dental services, and they were specifically price-sensitive to some dental procedures such as oral exams, dental cleanings, fillings 17

30 (Conrad, 1983). Using a path analysis, Evashwick and colleagues found that older adults dental visit was positively associated with education level, having a regular dentist, and perceived dental care needs that measured by having dental problems or dentures (Evashwick et al., 1982). They pointed out that perceived dental care needs was the most significant factor affecting dental visits. The findings from the study also showed that none of the following factors had a significant effect on dental care utilization of the elderly: age, gender, annual income, transportation, and Medicaid insurance coverage. Locker and colleagues found that dental insurance coverage had no independent effect on the utilization of dental services among the elderly (Locker et al., 1989). According to Manski and colleagues 2004 paper, among older adults aged 55 years or older, those who have natural teeth, are female, are a non-hispanic White, have higher education, have higher income, and have private dental insurance coverage were significantly more likely to have a dental visit (Manski et al., 2004). They stressed that having natural teeth was the strongest determinant of a dental visit. They also found that elderly people aged 65 to 74 were significantly more likely to have a dental visit than those aged 55 to 64. They inferred that more spare time and disposable income after retirement might have allowed those around retirement age to receive dental care more. They also added that such a tendency could wither as time passes on. There is a study showing that limitations in activities of daily living (ADL) are negatively associated with dental care utilization among the elderly (Sugihara et al., 2010). A few studies found that smokers were less likely to see a dentist compared to non-smokers (Mucci and Brooks, 2001, Drilea et al., 2005). On the other hand, Lee and colleagues examined not only the effects of individual factors but also the effects of 18

31 community factors on older adults dental care utilization (Lee et al., 2014). They found that a higher dentist-to-population ratio at the county level was associated with the increased likelihood of dental care utilization among the elderly aged 65 and over. In terms of individual factors, they found that those who are female, are married, have higher income, have higher education, and have private dental insurance are more likely to see a dentist. Collectively, perceived dental care needs, having natural teeth, gender, education, income, and private dental insurance are strongly associated with the increased likelihood of dental care utilization among the elderly. Race/ethnicity, marital status, activity limitation, smoking habits, having a regular dental care source, and dentist-to-population ratio are also positively related to elderly adults dental care utilization. In contrast, older adults with public dental insurance coverage are less likely to have a dental visit compared to those with private dental insurance coverage and even relative to those without any dental insurance coverage oftentimes. The finding from a study by Branch and colleagues showed that Medicaid coverage was negatively associated with dental care utilization of older persons aged 70 and over (Branch et al., 1986). In 2004, forty-three percent of the elderly population had a dental visit. While sixty-five percent of those who had private dental insurance coverage visited a dentist, those with public dental insurance coverage (37%) and those with no dental insurance coverage (26%) were less likely to see a dentist (Manski and Brown, 2007). The majority of elderly patients visiting a dentist received both preventive (dental cleaning, fluoride, sealant, and so on) and diagnostic (oral exams and x-ray) dental services (Macek et al., 2004, Manski and Brown, 2007). Although dental insurance coverage has been found to 19

32 be one of the key factors influencing dental care utilization (Bendall and Asubonteng, 1995), this might not be as true for older adults with public dental insurance coverage. Otherwise, research methods used in the previous studies were not good enough to estimate the effects of public dental insurance coverage on dental care utilization. Prior Research on Adult Medicaid Dental Coverage Whether or not state Medicaid programs provide dental benefits for adults has been a topic of argument. While one of the principal objectives of expanding public dental insurance coverage is to increase access to dental care of low-income people, a small number of studies have examined the effects of Medicaid dental benefits on dental service utilization of adult beneficiaries. According to their research methods and types of dental policy changes, the studies have been classified into three groups (Table 2). Key findings and limitations of the studies are discussed below. Table 2. Previous research that evaluated the effects of Medicaid dental coverage on dental care utilization of adults Research Simple before-and-after design Design Studies Group 1 Group 2 Difference-indifferences Group 3 Mullins et al. (2004) Pryor and Monopoli (2005) Maiuro (2011) Lee et al. (2012) Choi (2011) Wallace et al. (2011) Nasseh and Vujicic (2013b) Objectives To evaluate the impact of reducing Medicaid dental benefits for adult beneficiaries To examine the effect of increases in Medicaid reimbursement rates for dental care To compare differences in dental services utilization between adult Medicaid beneficiaries 20

33 To compare differences in dental services utilization before and after Medicaid dental policy changes To compare differences in dental care utilization between pre- and postchange periods with dental benefits and those without it To estimate the impact of increase in dental benefits on dental care use Major Findings Medicaid dental benefit cuts reduced dental care utilization of adults and then resulted in expenditure savings to state Medicaid programs After increasing reimbursement rate of dental services, dental care utilization of adults increased Medicaid dental benefits are positively associated with dental care utilization of adult enrollees Limitations Possible alternative explanations for their findings because there are no control groups to compare with No specific findings on the elderly population A study by Wallace et al. was conducted in a single state Unobservable omitted variable bias Issues on the quality of control groups No specific findings on the elderly population The studies in the first group evaluated the impact of reducing or eliminating Medicaid dental coverage for adult enrollees, using a simple comparison of dental care utilization before and after changes in adult Medicaid dental policies within a single state (Mullins et al., 2004, Pryor and Monopoli, 2005, Maiuro, 2011). They compared differences in dental claims or expenditures before- and after-cuts in Medicaid dental coverage for adult beneficiaries. The major findings of these studies showed that the Medicaid dental benefit cuts drastically reduced dental claims and then resulted in 21

34 expenditure savings to state Medicaid programs. Each of these studies used a simple prepost design on a single state without a control group to compare with. The sharp drop in Medicaid dental claims after the dental cuts does not necessarily mean people having dental problems went without dental care. Individuals may pay for dental services out of pocket, go to emergency departments, or find free clinics. It is insufficient to simply compare dental claims and expenditures before and after the dental cuts for understanding the role of Medicaid dental insurance coverage in making a decision to seek dental care. Although public dental insurance coverage allows improvement in access to dental care for low-income people, actual dental visits cannot happen without a sufficient participation of dental care providers who are willing to take care of Medicaid patients. Low Medicaid reimbursement rates for dental care is one of important reasons for dental care providers low participation in state Medicaid programs (Borchgrevink et al., 2008). Lee and colleagues examined the effects of increase in reimbursement rates for Medicaid dental benefits on adults dental care utilization (Lee et al., 2012). The study compared dental claims among adults before and after the increase in Medicaid reimbursement rate for dental services on a single state. The study found that the percentage of adults who received at least one dental service rose following the increase in Medicaid payment rate. However, the findings from the study also showed that adults dental care utilization have constantly grown over time. Like the studies in the first group, Lee and colleagues did not use a control group to make it possible to distinguish the effect of Medicaid reimbursement rates from secular trends in dental care utilization before and after change in Medicaid dental policy. Considering the sample in the study that comprises of parents 22

35 and relative caregivers eligible for Medicaid coverage, its results cannot be simply applicable to the elderly population. Another single-state study (Wallace et al., 2011), which employed a more persuasive research design, examined the effects of eliminating Medicaid dental coverage on dental-related emergency department (ED) visit and dental care needs among adult beneficiaries. The authors compared Medicaid adult enrollees who lost dental benefits with those who retained dental coverage. Using a difference-in-differences approach, the study found that adult enrollees who lost dental benefits were more likely to use emergency department for dental care and to have unmet dental care needs rather than those who retained dental coverage. A particularly relevant study by Choi (2011) used the Behavioral Risk Factor Surveillance System (BRFSS) data to examine the causal relationship between Medicaid dental benefits and dental care utilization among low-income adults (Choi, 2011). In 2002, twenty-six states and the District of Columbia did not cover dental care for adult Medicaid beneficiaries, while sixteen states provided adult Medicaid dental benefits to low-income adults with children but not to childless adults. In the study, low-income adults are defined as those with less than $10,000 of annual household income. With variations in Medicaid eligibility and Medicaid dental coverage for adults across states, the author located treatment and control groups. Using a difference-in-differences approach, the study compared dental care utilization of low-income parents in states with no adult dental benefits to those in states with adult dental benefits only for parents. The author explained that in the comparison childless adults were used as a control group for explaining an unmeasured or unobservable state-level variation that might affect dental 23

36 service utilization. In order to control for state-specific characteristics, the study included average water fluoridation rate and dentist-to-patient ratio in the regression. The results from the study showed that Medicaid dental coverage was significantly associated with a 7.4- to 9.9-percentage point increase in the likelihood of visiting a dentist within the previous year among low-income adults. By analyzing nationally representative survey data that exploited state-level variation in adult Medicaid dental benefits, the study by Choi (2011) provided reasonably compelling estimates of the causal effects of Medicaid dental benefits on low-income non-elderly adults dental care utilization. In order to estimate an unbiased effect of Medicaid dental benefits, it would be necessary to find the most comparable treatment and control groups. The study asserted that there was no big difference in observable characteristics except the eligibility in adult Medicaid dental benefits between treatment and control groups across states. It appears to be reasonable to think that the two groups with very similar observable characteristics may also have common unobservable characteristics. However, the similarity in the limited number of observables does not rule out the possibility of differences in unobservable factors that might influence dental care utilization. Using data from the BRFSS, a recent study by Nasseh and Vujicic (2013b) investigated the impact of expanding dental benefits to poor adults aged (i.e., those with less than 100% of the federal poverty level of annual household income), which is carried out as a part of Massachusetts health reform in 2006 (Nasseh and Vujicic, 2013b). They performed a difference-in-differences analysis to compare dental care utilization of adults in Massachusetts to that in eight control states before and after the health reform. 24

37 They also conducted a difference-in-difference-in-differences framework to measure differential effects of expanding Medicaid dental benefits on poor and non-poor adults. The study found that dental care utilization of adults in Massachusetts increased by 2.9 percentage points after the expansion of Medicaid dental coverage compared to that in control states. The study also found that dental care utilization of poor adults in Massachusetts increased by percentage points after the health reform relative to dental care utilization of non-poor adults. The study by Choi (2011) excluded adults aged 56 and older from the sample because, without the exclusion, parents would be much younger than childless adults. Only non-elderly adults (aged 19-64) are included in the work by Nasseh and Vujicic (2013b). Thus, the study findings are not applicable to the elderly population, which is the main focus of this dissertation. Gaps in the Literature and Contribution of This Dissertation Despite the previous studies that investigated the impact of Medicaid dental insurance coverage on dental care utilization of adult beneficiaries, there exist unfilled gaps in the literature. First of all, most studies focused on examining the effects of Medicaid dental coverage on a bundle of dental care utilization that is usually measured in dental visits or dental expenditure. There are a variety of dental services depending on its purpose from preventive dental care to advanced restorative treatments. Preventive dental care is considered an efficient and effective way to maintain good oral health and to avoid expensive restorative dental treatments. To understand how differently dental insurance 25