Functional Health and Dental Service Use Among Older Adults

Journal ofcewntology: MEDICAL SCIENCES 1998, Vol. 53A, No. 6, M4I3-M4I8 Copyright 1998 by The Gerontological Society of America Functional Health and Dental Service Use Among Older Adults Teresa A. Dolan, 1 Chuck W. Peek, 2 Andreas E. Stuck, 3 and John C. Beck 4 "Department of Community Dentistry, University of Florida College of Dentistry, Gainesville. 2 Claude D. Pepper Center for Research on Oral Health in Aging, University of Florida College of Dentistry, Gainesville. 'Department of Geriatrics and Rehabilitation, Zieglerspital, Bern, Switzerland. 4 Multicampus Program in Geriatric Medicine and Gerontology, Department of Medicine, University of California, Los Angeles. Background. Although socioeconomic barriers to receiving adequate dental care have been well documented, physical frailty as a risk factor for not visiting the dentist has not been fully explored. This study prospectively examines the relationship between functional health and dental service use, taking into account sociodemographic characteristics, general and dental health status, and prior dental utilization behavior. Methods. Data from a randomized trial of a comprehensive geriatric assessment and prevention program in community-dwelling adults age 75+ years living in Santa Monica, CA, collected between 1988 and 1993, were analyzed. A series of discrete-time proportional hazards models were used to assess the effects of functional status, sociodemographic characteristics, and general health and dental health measures on dental service use. Results. Functional status was negatively associated with dental service use, and the conditional probability of a first visit to the dentist after baseline decreased over time. When additional measures of general health, dental health, and socioeconomic status were introduced, the effect of functional status was mitigated but remained significant. In the most fully specified model, which took dental visitation behavior prior to the beginning of the study into account, the effect of functional limitation remained significant. Conclusions. Even in this relatively well-educated group of older persons with higher than average dental service use, impaired functional status was associated with lower levels of dental service use over time. ORAL diseases are largely preventable if older adults practice effective self-care and have access to preventive and therapeutic dental services (1). Regular dental visits are an opportunity for early diagnosis, prevention, and treatment, as well as oral hygiene education. Adults who do not receive regular professional care can develop oral diseases that lead to the need for restorative dental care and eventual tooth loss (2). Socioeconomic risk factors associated with inadequate dental care have been well documented (3-10). Physical frailty, or impairment in functional abilities needed to live independently, has not been fully explored as an obstacle to receiving dental care and a cause of the subsequent development of oral diseases. At least two cross-sectional studies suggest a relationship between functional status, dental service utilization, and oral impairments. Analysis of the 1989 National Health Interview Survey data (11) showed that functionally impaired persons used dental services less frequently than the functionally nonimpaired. Jette and colleagues (12) found an association between physical disability and current dental caries and edentulism. They proposed that disabled older persons are at increased risk of oral disease because physical impairments may hinder their ability to maintain good oral hygiene or restrict their access to necessary dental treatment. However, the cross-sectional nature of this study limited the authors' ability to draw causal directions from their findings. The purpose of this study was to examine the association between functional health and dental service use, taking into account sociodemographic characteristics and general and dental health status. The prospective nature of the study permits an examination of the covariation of functional status and dental service use over time. In addition, the richness of the available data on each participant enabled us to control the influence of potentially confounding variables on the relationship between functional status and dental service use. METHODS The In-Home Preventive Care Program for Older Persons is a 5-year study, including a 3-year intervention period, to test the feasibility and assess the value of in-home comprehensive geriatric assessment and periodic follow-up as a strategy for delaying the onset of disability, reducing utilization of more costly health services, and improving the quality of life for frail elderly adults. A detailed description of the methodology employed in this study was previously reported (13). Briefly, eligible subjects were all noninstitutionalized elderly persons residing in Santa Monica, California, aged 75 years and older. Before randomization and M413

M414 DOLANETAL. annually thereafter for 3 years, subjects were seen at home by trained interviewers, not involved in the intervention, who used a structured interview format. Participants were randomly assigned to one of two groups: a control group or an intervention group that received an annual in-home multidimensional assessment and follow-up visits every 3 months from a nurse practitioner. The nurse practitioner provided a comprehensive geriatric health assessment including an oral assessment in which they evaluated and targeted specific needs of participants in collaboration with geriatricians and other consultants as needed. Based on the oral assessment findings, intervention subjects were either: (a) told to continue with their usual oral health behaviors; (b) given advice for improved oral health behaviors; and/or (c) referred to a dentist for treatment. No dentist or dental hygiene services were provided as part of the intervention. Study Subjects A total of 414 individuals were enrolled; 317 remained at the conclusion of the study. A description of subject characteristics and attrition from the full panel is published elsewhere (14). Because the dental items were added to the baseline interview after 83 subjects were enrolled, a total of 331 subjects completed the dental interview items. Among these 331 subjects, 257 remained in the study at its conclusion. Of the remaining 257, 194 subjects provided usable responses to all dental items. Variables Dental service use. The dependent variable examined in this analysis reflects frequency of dental service use. At each annual interview, respondents were asked "When was the last time you saw a dentist? Was it: within the past 12 months; 1 to 2 years ago; 3 to 5 years ago; 6 to 10 years ago; or have you never received dental care?" Based on this information, an indicator of the dental service use was constructed for each interval (coded "1" if a dental visit occurred in a given 12-month interval and "0" if otherwise). A categorical variable was also used to indicate the interval in which the observation took place (regardless of whether an event occurred). Observation intervals were pooled to perform multivariate analyses. Functional status. A modified Kempen functional status scale (15) was used to measure functional ability at the beginning of each observation interval. This scale was based on a set of 12 items and measured difficulty performing basic as well as instrumental activities of daily living. This variable was treated as a continuous measure of functional ability ranging from 0 to 12. A higher score indicates a greater level of functional impairment. Sociodemographic characteristics. Four sociodemographic measures known to be associated with dental utilization were used to account for potentially confounding factors. Age was treated as a continuous variable and was measured in years. Gender was a dichotomous variable, coded "1" if the respondent was female and "0" if the respondent was male. Education was based on the highest grade of school completed (coded as "0" if 12th grade or less and "1" if the subject completed some education beyond high school). A dichotomous variable reflecting the respondents' satisfaction with their financial situation was constructed (coded "0" if subjects reported that they "can't make ends meet" or "have just enough money to get by" and "1" if they were financially comfortable). Gender, education, and financial satisfaction were treated as time-constant variables. General health status. A dichotomous indicator of general health status was coded "1" if the respondent rated his/her health as fair or poor and coded "0" if otherwise. A smoking behavioral measure was coded " 1" if the respondent ever smoked cigarettes on a regular basis and "0" if otherwise, and it was treated as a time-constant variable. Dental health status. Because the effect of functional status on dental service use could be confounded with other dental factors, we included two dental variables to control for the respondent's dental health status. A dichotomous indicator of problematic dental health measured at the beginning of each interval was coded "0" if the respondent rated his/her oral health as fair or poor and " 1" if otherwise. Edentulism was also treated as a dichotomous variable and was coded "0" if a respondent had no teeth at the time of the baseline interview and " 1" if otherwise. Intervention/control group. A dichotomous variable was coded "1" if the respondent was in the intervention group and "0" if the respondent was in the control group. Dental use prior to baseline. An issue that concerns most prospective studies is the history of behavior prior to the start of the study. Although these data do not possess a full history of dental use, self-reported frequency of dental visits prior to the baseline interview was available (coded "1" if the respondent had visited a dentist within the year before the baseline interview and "0" if otherwise). The majority (70.7%) reported having seen a dentist within the year preceding the baseline interview. Data Analysis The analytical strategy used in this research included sensitivity to potential bias resulting from selective or nonrandom attrition from the sample. Of the 331 individuals who completed the dental items of the baseline interview, 257 also completed the 36-month follow-up interview. The remaining 74 were treated as attrition from the sample- Thus, a dichotomous variable was coded "1" if the respondent participated in the baseline interview but dropped out of the study before the 36-month interview was administered and was coded "0" if the respondent participated in both the baseline and the 36-month follow-up interviews. A logistic regression model was estimated to identify factors associated with attrition. A series of discrete-time proportional hazards models (16,17) were used to assess the effects of functional status, sociodemographic characteristics, and general health and dental health measures on dental service use. The event of

FUNCTIONAL HEALTH AND DENTAL SERVICE USE M415 interest in this analysis is the initial dental visit after baseline. All study participants to whom the dental component of the survey was administered (n = 331) constituted the "risk group" for dental visitation. Respondents remained in the risk group until a dental visit was reported or until censoring occurred. Censoring occurred if: (a) the subject was lost to follow-up, (b) there was not sufficient information to determine whether a dental visit took place, or (c) the end of the 36-month observation period was reached. The dependent variable used in this investigation was a dichotomous indicator coded " 1" if a dental visit occurred during an interval and coded "0" if otherwise. The person-intervals contributed by respondents remaining in the risk group for each observation interval were pooled, and a series of logistic regression models were used to estimate the effect of model variables on experiencing an event. The first of these models included the Kempen functional status scale and a set of dichotomous variables representing the observation intervals. In the second model, the sociodemographic characteristics, general health status measures, dental health status measures, and the intervention indicator were added to determine whether any of these factors affected the relationship between functional status and dental service use. Finally, the measure of dental use prior to baseline was included in the third model as a control for left censoring. RESULTS This sample is characterized by relatively high levels of dental service use (Figure 1). More than 7 in 10 older adults (70.7%) reported a dental visit within a year prior to the baseline interview. Figure 1 shows that this trend continued during the first year of the study. Of the 331 respondents who constitute the study sample, 201 (60.7%) had a dental visit during the first year of the study. Among those who did not see a dentist in the first year of the study, the proportion of subjects reporting a dental visit in the second and third intervals was much lower. Among the 75 individuals who entered the second year of the study without reporting a dental visit (55 were either lost to follow-up between baseline and year 1 or did not provide sufficient information to determine if a dental visit had occurred), 21 (28.0%) had a dental visit during the second observation interval. Likewise, among the 40 individuals who entered the third year of the study without reporting a dental visit (14 were either lost to follow-up between years 1 and 2 or did not provide sufficient information to determine if a dental visit had occurred), 6 (15.0%) had a dental visit during the third observation interval. The distribution of the Kempen functional status scale (Table 1) was skewed toward the "healthy" extreme, suggesting that most elders in this sample were relatively free of functional limitation. However, the mean score of 2.50 (SD = 1.9) on the Kempen functional status scale was evidence of functional limitation among some study participants. The majority of respondents (72.2%) rated their dental health as good or better and only 17.1% of the sample reported being edentulous at baseline. This compares to a national edentulism rate of about 43.9% for this age group (18). The mean age of the respondents was 80.9 years (SD = 3.9) indicating that the oldest old were adequately represented in these data. As would be expected in a sample of elderly persons, most respondents were female (69.8%). The older adults in this sample had relatively high levels of education. Only 28.9% were dissatisfied with their financial status. About a third of respondents (35.8%) rated their general health as fair or poor. Over half of the sample (58.3%) smoked on a regular basis at some point their lives. Attrition In the logistic regression model used to determine the factors associated with leaving the dental sample, four variables were associated with attrition from the study: age, self-perceived health, edentulism, and frequency of dental use prior to baseline (Table 2). Older respondents and those who perceived their general health as fair or poor were significantly more likely to drop out. Conversely, older adults who were edentulous at baseline and those who had a dental visit within a year prior to the baseline interview were significantly less likely to exit the study. The Kempen functional status scale was not a predictor of attrition. The pre- Dental Visit (n=201) Dental Visit (n=21) Dental Visit (n=6) Baseline Sample ("Risk Group") N=331 No Visit (n=75) No Visit (n=40) No Visit (n=27) Missing Data (n=55) Missing Data (n=14) Missing Data (n=7) Baseline Year 1 Year 2 Year 3 Figure 1. Timing of the first dental visit after the baseline interview.

M416 DOLANETAL. Table 1. Sample Characteristics at Baseline, at the Year 1, Year 2 and Year 3 Follow-Up Interviews Baseline Year 1 Year 2 Year 3 Functional Health Status Kempen scale score, mean (SD) Physical Health Status Fair or poor self-rated health (%) Ever smoked (%) Dental Health Status Fair/poor self-rated dental health (%) Edentulism (yes = 1) Socioeconomic Characteristics Age, mean (SD) Women (%) Any college (%) Dissatisfied with finances (%) Member of intervention group (%) Dental visit in previous year (%) 2.5 (1.9) 31.7 58.3 27.8 17.5 80.9 (3.9) 69.8 52.3 28.9 50.8 70.7 2.5 (2.0) 3.0 (2.4) 3.1 (2.5) 28.6 81.7(3.8) 29.3 82.7 (3.8) 27.9 83.6 (3.8) 72.8 71.0 70.4 Table 2. Logistic Regression Model of Attrition* on Socioeconomic Characteristics and Health and Dental Health Measures (n = 319)t Predictor Variables! Intercept Overall Health Status Functional status (Kempen scale) Self-rated health (fair or poor = 1) Emotional health (Yesavage depression scale) Ever smoked (yes = 1) Dental Health Status Self-rated dental health (fair or poor = 1) Recent dental visit (yes = 1) Edentulism (yes = 1) Socioeconomic Characteristics Age Gender (women = 1) Education (any college = 1) Dissatisfaction with finances (yes = 1) Member of intervention group (yes = 1) Model x 2 DF Logistic Regression Coefficients -7.11911.109.68011.042 -.093.186 -.70111-1.11811.07311 -.037.156.111 -.369 36.0# *Attrition refers to loss to follow-up during the 36-month observation period. ftwelve cases were omitted from the attrition analysis because one or more predictor variables had missing data. JPredictors of attrition were measured during the baseline interview. Dental visit in year prior to baseline interview. II.05 >p>.01. #p<.001. dictors of attrition (poor self-rated general health, recent dental visit, age, and edentulism) suggest that the composition of the sample changed over time. The greater likelihood of respondents in poor health to leave the sample 12 resulted in a disproportionately healthy sample over time. Following the same logic, the relative proportion of regular users of dental services, younger subjects, and edentulous subjects in the sample increased over time. Discrete-Time Proportional Hazards Models The results of the discrete-time proportional hazards models are presented in Table 3. Model 1 of Table 3 included functional status as measured by the Kempen functional status scale as the only explanatory variable. Functional status exhibited a negative association with dental service use. The coefficient for the Kempen Scale, b = -0.187, indicates that every point increase in this scale (indicative of declining functional ability) results in a change in the hazard ratio of experiencing a dental visit in a particular time interval by 0.83 (e- 187 =.829; p <.001). Given the interval-level nature of the measure of functional ability, the influence of functional limitation on the odds of visiting a dentist was consequential over the range of functional abilities. For instance, the inter-quartile range of the Kempen Scale (3 points) represents a hazard ratio of approximately 3.5. The conditional probability of a first visit to the dentist after baseline also decreases with time. The first dental visit beyond the baseline interview is significantly less likely to be observed in the second or third 12-month interval than in the first year of the study. This mirrors the pattern of events shown in Figure 1, i.e., the majority of respondents who received dental care during the 3-year study did so in the first year. In Model 2 of Table 3, additional measures of general health were introduced along with measures of dental health, socioeconomic status, and intervention group membership. The addition of these variables mitigates the effect of functional status on dental service use. The coefficient for the Kempen functional status scale changed from b ~ -0.187 (in Model 1) to b = -0.138 (in Model 2), but remained significant (p <.05). Rating one's health as fair or poor, edentulism, and dissatisfaction with one's financial situation were associated with less frequent dental service

FUNCTIONAL HEALTH AND DENTAL SERVICE USE M417 Table 3. Discrete-Time Hazards Model of Dental Visit on Functional Status (Kempen Score), Socioeconomic Characteristics, and Health, and Dental Health Measures Predictor Variables Intercept Timing of Dental Visit 0-12 months 13-24 months 25-36 months Functional Health Status Functional status (Kempen scale) Physical Health Status Self-rated health (fair or poor = 1) Ever smoked (yes = 1) Dental Health Status Self-rated dental health (fair or poor = 1) Edentulism (yes = 1) Sociodemographic Characteristics Age Gender (women = 1) Education (any college = 1) Dissatisfaction with finances (yes= 1) Member of intervention group (yes=l) Recent dental visit (yes = 1) Model x 2 Model DF Model 1.914t -1.299* -2.195* -.187* 57.1* 3 Model 2 4.761* -.765* -1.502* -.138* -.6861.037 -.090-1.479* -.050.585*.164 -.506*.540* 113.6* 12 Model 3 3.117 -.458-1.064 -.168t -.679*.044.198-1.126* -.041.145 -.068 -.482.421 1.843* 162.2* Notes: These results are based on 427 intervals generated by the 331 study participants. *.01 >/?>.05. Dental visit in year prior to baseline interview. use. Conversely, being female and being a member of the intervention group were associated with a higher likelihood of visiting a dentist. Model 3 of Table 3 added an indicator of whether the respondent visited a dentist during the year prior to the baseline interview. This measure of previous dental service use had a dramatic influence on the likelihood of experiencing a dental visit during the observation period. The coefficient b = 1.843 translates into an hazard ratio of 6.31 (e 1843 = 6.309; p <.001), indicating that a respondent with a recent dental visit was more than six times as likely to visit a dentist during the study than a respondent who had not had a recent dental visit. Despite the explanatory power of past service use, however, the effect of functional limitation on dental service use remained significant. Additional models with interaction terms were estimated (results not shown) to determine whether the effects of functional ability on dental utilization varied by membership in the intervention group or by prior utilization patterns. None of the interaction terms significantly improved the fit of the models to the data. 13 DISCUSSION To the best of our knowledge, this is the first prospective study of the relationship of functional health status to dental utilization behaviors. We estimated a series of discretetime proportional hazards models to assess the effects of functional status, other measures of general health, dental health, and socioeconomic characteristics on the conditional probability of a first visit to the dentist after baseline during a 36-month observation period. Functional status was negatively associated with dental service use, and the likelihood of visiting a dentist decreased over time. This relationship remained significant when additional measures of general health, dental health, socioeconomic status, and previous dental service use were introduced. It should be noted that the respondent with a recent dental visit at baseline was six times as likely to visit a dentist during the study than a respondent who had not reported a recent visit. Findings from our research support the hypothesis that functional impairments are negatively associated with recent dental service use, even after taking into account known correlates of dental service utilization. Thus, the correlation of poor dental health with functional limitation observed by Jette and colleagues (12) can probably be explained, at least in part, by underutilization of dental services by functionally impaired older people. In addition, general health problems and resultant higher medical care utilization may "crowd out" dental use, either because the medical problems are treated as a higher priority, or because dealing with medical problems leaves too little time, financial resources, or energy to seek dental care (19). Identifying barriers to dental care is an important step toward overcoming poor oral health outcomes including pain, discomfort, and poor oral function commonly experienced by older adults. Members of the intervention group were more likely to report a dental visit over the 36-month observation period. Due to sample size limitation, it is not possible to explore whether the use of dental services could be improved in both well-functioning and functionally impaired older people. However, the fact that nurse practitioners, as part of their comprehensive preventive intervention, also gave advice to patients on how to overcome access barriers (e.g., they recommended the use of transportation services) favors the conclusion that access barriers in functionally impaired older people can at least in part be overcome. As compared with the U.S. population of persons 75 years old or older living at home, the study group had a higher education level, a lower mortality rate, and a lower rate of acute care hospital admissions, with a higher proportion of persons living alone (20,21). The study group also reported higher rates of dental service use in comparison to the U.S. population (18,22). The higher dental utilization rate is consistent with lower rates of edentulism, higher education level, and perhaps selection bias. Individuals who are willing to participate in a study of this type are probably more likely to practice preventive behaviors including seeking regular dental care (23). Yet, even in this relatively well-educated group of older persons with higher than average dental use, impaired functional status acted as a barrier preventing dental visits. Thus, it is likely that in

M418 DOLANETAL less-educated older populations or those with lower than average dental use, underuse of dental services among older persons with functional impairments would be even more prevalent than in this study. ACKNOWLEDGMENTS The project described was supported by the Agency for Health Care Policy and NIH research grant numbers R03 HS08124-01 and HS00086, the W.K. Kellogg Foundation, the Swiss National Science Foundation grant #4032-35637, and the Senior Health and Peer Counseling Center, Santa Monica, CA. The authors acknowledge the numerous investigators and participants for their help in carrying out this study, including Mike Miller and Dan Nissen from the University of Florida; Kathryn Atchison from the University of California, Los Angeles; Harriet Aronow, Kristiana Raube, Andrea Steiner, Christophe J. Bula, Kathryne Barnowski, Marcia Gold, Karen Yuhas, Pat McDonough, Rosane Nisenbaum, Laurence Z. Rubenstein, and Cathy A. Alessi from the University of California, Los Angeles and the Senior Health and Peer Counseling Center, Santa Monica, CA. Address correspondence to Teresa A. Dolan, DDS, MPH, University of Florida College of Dentistry, JHMHC Box 100405, Gainesville, FL 32610-0405. E-mail: tdolan@dental.ufl.edu REFERENCES 1. U.S. Preventive Services Task Force. Guide to Clinical Preventive Services. 2nd ed. Baltimore, MD: Williams and Wilkins; 1996. 2. U.S. Department of Health and Human Services PHS. Healthy People 2000, National Health Promotion and Disease Prevention Objectives. Publication No. (PHS) 91-50212. Washington, DC: Public Health Service; 1991. 3. Dolan TA, Corey CR, Freeman HE. Older Americans' access to oral health care. J Dent Ed. 1988;52:637-642. 4. Douglas CW, Cole KA. Utilization of dental services in the United States. / Dent Ed. 1979;43:223-238. 5. Anatczak A, Branch L. Perceived barriers to the use of dental services in the elderly. Gerodontics. 1985;1:194-198. 6. Kiyak HA. 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