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RESEARCH ARTICLE |
a Center for Health Care Research and Policy, Case Western Reserve University at MetroHealth Medical Center, Cleveland, Ohio
b Department of Medicine and Department of Epidemiology-Biostatistics, Case Western Reserve University School of Medicine, Cleveland, Ohio
c United States Quality Algorithms Center for Health Care ResearchTM, Atlanta, Georgia
d Departments of Neurology and Psychiatry, Case Western Reserve University School of Medicine and the Case Western Reserve University Alzheimer Center, University Hospitals of Cleveland, Ohio
David W. Baker, MetroHealth Medical Center, 2500 MetroHealth Drive, Rammelkamp 221, Cleveland, OH 44109-1998 E-mail: dwb{at}po.cwru.edu.
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Abstract |
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Methods. Home interviews were conducted with community-dwelling elderly persons (n = 2,774) to determine demographics, years of school completed, newspaper reading frequency, chronic diseases, and health status. Participants completed the Short Test of Functional Health Literacy in Adults (S-TOFHLA, range 0–100) and the Mini Mental State Examination (MMSE).
Results. Mean S-TOFHLA scores declined 1.4 points (95% CI 1.3–1.5) for every year increase in age (p < .001). After adjusting for sex, race, ethnicity, and education, the S-TOFHLA score declined 1.3 points (95% CI 1.2–1.4) for every year increase in age. Even after adjustment for performance on the MMSE, the S-TOFHLA score declined 0.9 points (95% CI 0.8–1.0) for every year increase in age (p < .001). Differences in newspaper reading frequency, visual acuity, chronic medical conditions, and health status, did not explain the lower literacy of older participants.
Discussion. Functional health literacy was markedly lower among older age groups even after adjusting for differences in MMSE performance, newspaper reading frequency, health status, and visual acuity. Future studies should prospectively examine whether functional literacy declines with age and whether this is explained by declines in cognitive function.
PREVIOUS studies have shown that reading skills are worse among older age groups (Gazmararian et al. 1999
; Kirsch, Jungeblut, Jenkins, and Kolstad 1993; Williams et al. 1995). In the National Adult Literacy Study (NALS), a cross-sectional study of the United States population, the proportion of Americans who read at the lowest reading level (level 1) increased from 16% among those 45–54 years old to 26% among those 55–64 years old, to 44% among those age 65 and older (Kirsch et al. 1993). Moreover, a recent cross-sectional study of community-dwelling elderly persons enrolled in a Medicare managed care program found that the negative association between reading skills and age persisted even beyond age 65 (Gazmararian et al. 1999). Poor reading skills among older populations has tremendous importance because of this group's high prevalence of chronic disease and their need to understand health-related information.
These cross-sectional studies suggest that reading ability may deteriorate with age. Reading is a complex cognitive process that requires adequate vision, concentration, word recognition, working memory, and information processing. Deficits in any of these areas may affect reading comprehension, and the prevalence of these problems may increase with age. For this project, we hypothesized that several specific health and behavioral domains could explain why older cohorts have worse reading ability: a higher prevalence of dementia or cognitive impairment, a higher prevalence of chronic diseases that may impair cognitive function, worse physical health, worse mental health, a higher prevalence of sensory impairment (i.e., worse visual acuity), and lower frequency of reading behaviors (i.e., less frequent reading of books and newspapers). The rationale for examining each of these will be briefly discussed.
The incidence and prevalence of dementia increases dramatically in those older than age 65 (Evans et al. 1989; Graham et al. 1997). Moreover, there is a substantial prevalence of cognitive impairment that is not due to dementia (Graham et al. 1997; Willis 1996). For example, the Canadian Study of Health and Aging (Graham et al. 1997) found that 16.8% of Canadians aged 65 and older had evidence of cognitive impairment that was not due to dementia, and the prevalence of this was twice that for all types of dementia combined (8.0%). Although individual word recognition may be relatively preserved even in patients with dementia (Cummings, Houlihan, and Hill 1986; Friedmann, Ferguson, Robinson, and Sunderland 1992; Fromm, Holland, Nebes, and Oakley 1991; O'Carroll 1995; Paque and Warrington 1995), true comprehension of written materials is a complex cognitive task that may be adversely affected by even mild degrees of cognitive impairment. Thus, the higher prevalence of dementia and cognitive impairment among older persons may explain much of their lower reading scores.
Similarly, the increasing prevalence of chronic diseases in late middle-age (National Center for Health Statistics 1999), particularly hypertension, could adversely affect the reading skills of older adults. Hypertension, diabetes, and hypercholesterolemia may all lead to cerebrovascular disease and stroke, which obviously can affect reading ability. Moreover, several studies have shown that individuals who have hypertension are more likely to have a decline in cognitive function, even in the absence of a stroke (Desmond, Tatemichi, Paik, and Stern 1993; Glynn et al. 1999; Tzourio, Dufouil, Ducimetiere, and Alperovitch 1999). Similarly, chronic obstructive pulmonary disease (COPD) can cause reduced blood oxygen levels, and this has been associated with worse cognitive function (Etnier et al. 1999). Thus, the higher prevalence of hypertension and other chronic diseases among older age groups could affect reading ability by negatively influencing cognition.
In addition, physical health status declines with age (Ware 1993). The worse physical health of the oldest old could affect their cognition (Hultsch, Hammer, and Small 1993) or decrease their ability to concentrate on complex cognitive tasks such as reading. Similarly, depression may impair concentration, and it also may be a risk factor for cognitive decline (Devanand et al. 1996). Thus, worse physical and mental health among older cohorts could contribute to the negative association between age and reading ability. In addition, several studies have shown that sensory impairments may affect cognition (Baltes and Lindenberger 1997; Lindenberger and Baltes 1994; Marsiske, Klumb, and Baltes 1997; Salthouse, Hancock, Meinz, and Hambrick 1996). For example, individuals in the Berlin Aging Study with worse visual acuity had lower perceived competence with basic activities of daily living (Marsiske et al. 1997). Corrected visual acuity has also been found to be associated with working memory, associative learning, and concept identification (Salthouse et al. 1996), leading investigators to postulate that all of these may be related to a general reduction in nervous system functioning. Thus, an increasing prevalence of sensory abnormalities among elderly persons could affect reading ability directly through decreased ability to read printed words or indirectly through an association with worse cognitive function.
Finally, some experts have suggested that reading ability may decline if people do not use their reading skills frequently enough. For example, after the NALS results were released in 1993, Secretary of Education Richard Riley commented that "Americans should consider going back to school and getting a tuneup" (Joseph 1993, p. A01). Support for the notion of "use it or lose it" comes from studies showing that individuals who continued to perform intellectually engaging activities had less cognitive decline (Hultsch, Hertzog, Small, and Dixon 1999). Therefore, if people tend to read less as they grow older, this could contribute to cognitive decline and worse reading scores among elderly persons. It is also possible that frequent reading could help preserve reading skills independently of any effect on cognition.
If the association between age and literacy is not explained by dementia, chronic medical problems, worse physical and mental health status, sensory impairments, or lack of use of reading skills, this suggests reading ability may decline as a consequence of the aging process itself. Studies have shown that the ability to complete complex cognitive tasks, especially those that require effortful processing of information, declines with age (Craik and Byrd 1982; Craik and Jennings 1992; Park 1999). We undertook this study to examine what cognitive, health, and behavioral factors were associated with functional health literacy among elderly persons and to determine whether the negative association between age and functional health literacy persists after adjusting for cognitive dysfunction (as measured by the Mini Mental State Examination [MMSE]; Folstein, Folstein, and McHugh 1975), chronic medical problems, physical functioning, mental health, corrected visual acuity, and self-reported frequency of reading the newspaper. Functional health literacy is the ability to read and comprehend health-related information such as prescription bottles, appointment slips, and instructions for procedures or diagnostic tests.
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Methods |
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). New Prudential SeniorCare enrollees in Cleveland, Houston, Tampa, and South Florida (including Ft. Lauderdale and Miami) were eligible for participation. We sent a letter of introduction describing the study and ensuring confidentiality to each member who was at least 65 years of age 3 months after enrollment. One week later, interviewers called each enrollee to determine eligibility. Individuals who indicated they were not comfortable speaking either English or Spanish; were blind or had a severe vision problem that could not be corrected with glasses; or did not know what year or month it was, what state they lived in, what year they were born, or their address were ineligible. Eligible individuals who agreed to participate in the study completed a 1-h face-to-face interview in their home. The survey consisted of questions to determine demographics, self-rated health, chronic conditions, depression, social support, and health behaviors. We also asked respondents "how often do you read the newspaper?" and coded responses as never, once a month, once a week, two to four times per week, or five or more times per week. For analysis, we collapsed the intermediate categories to create categories of never, four times per week or less, and five or more times per week. We administered the MMSE using a standardized format with a maximum score of 30.
The last section of the survey assessed the enrollee's health literacy using the short version of the Test of Functional Health Literacy in Adults (S-TOFHLA; Baker, Williams, Parker, Gazmararian, and Nurss 1999). The S-TOFHLA uses actual materials that patients might encounter in the health care setting to test their reading ability. The reading comprehension section is a 36-item test using the modified Cloze procedure; that is, every fifth to seventh word in a passage is omitted and four multiple choice options are provided (Taylor 1953). Participants read the passage and select the multiple choice option that best completes the blank given the context of the surrounding phrases. The reading comprehension section measures the ability to read and understand prose passages selected from instructions for preparation for an upper gastrointestinal tract radiograph series, and the patient "Rights and Responsibilities" section of a Medicaid application. Readability levels of these passages on the Gunning-Fox index are grade 4.3 and 10.4, respectively.
The numeracy section of the S-TOFHLA is a 4-item measure using actual hospital forms and labeled prescription vials. It tests a patient's ability to comprehend directions on two prescription bottles, whether the blood glucose is within a normal range, and appointment instructions using an actual appointment slip. Participants are given a prop to read and then asked a question; they are allowed to look back at the prop for as long as they would like to answer the question. The numeracy score is multiplied by 7 (x 4 items) to create a score from 0 to 28, and each item in the reading comprehension is multiplied by 2 (x 36 items) to create a score from 0 to 72. The sum of the two sections yields the S-TOFHLA score, which ranges from 0 to 100. Scores from 0 to 55 indicate inadequate literacy; these individuals will often misread the simplest materials, including prescription bottles and appointment slips. Scores between 56 and 66 indicate marginal literacy, and scores from 67 to 100 indicate adequate literacy; the latter group will successfully complete most of the reading tasks required to function in the health care setting, although they may still misread the most difficult numerical information. The S-TOFHLA takes 12 min or less to administer, and it has been shown to have good internal consistency reliability (Cronbach's 
0.98 for all items combined) and validity compared to the long version of the TOFHLA (Parker, Baker, Williams, and Nurss 1995; Spearman's correlation 0.91) and the Rapid Estimate of Adult Literacy in Medicine (Davis et al. 1993; Spearman's correlation coefficient 0.80).
Prior to completing the S-TOFHLA section, we examined each enrollee's vision using the Rosenbaum Handheld Vision Chart. We administered the standard S-TOFHLA (12-point font) to those whose corrected vision was 20/50 or better. We administered the large print version (14-point font) of the S-TOFHLA to those whose vision was 20/70 to 20/100. We could not accurately assess the reading skills of those whose corrected vision was worse than 20/100 and excluded them from analysis (n = 71). We assigned a score of 0 to respondents who indicated that they could not read at all (n = 10). For analyses of the relationship between sensory impairment and reading ability, we classified vision as 20/50 or better versus 20/70 to 20/100.
To analyze the relationship between literacy and age, we determined mean S-TOFHLA scores for each age category (65–69; 70–74; 75–79; 80–84; 
85 years old). To eliminate the effect of any differences in education across age groups, we stratified analyses by the number of years of school completed (0–8, 9–11, 12 or GED, and > 12). We then determined mean MMSE scores for each age category, again with stratification by the number of years of school completed. We analyzed the statistical significance of differences in mean S-TOFHLA and MMSE scores across age groups using analysis of variance. We also analyzed bivariate analyses for mean S-TOFHLA scores and other patient characteristics using t tests and analysis of variance.
To determine what factors explained the negative association between S-TOFHLA scores and age, we conducted hierarchical linear regression modeling. For this, we conducted a series of linear regression models. We included variables based on previous literature or a priori hypotheses, as described in the introduction, and included the variables regardless of statistical significance. The baseline model included age alone. The second model added gender, race, and years of school completed. In the third model, we added the MMSE score as an independent variable, and the fourth model added health indicator variables for chronic diseases, physical functioning and mental health, and vision. We included the following chronic medical conditions: hypertension, diabetes, coronary artery disease, chronic obstructive pulmonary disease (COPD, including chronic bronchitis, emphysema, or asthma), and prior stroke. We measured physical functioning using the SF-36 physical functioning subscale, a 10-item measure ranging from 0 to 100 that captures physical limitations, (with 100 indicating no physical limitations; Ware 1993). We measured mental health using the SF-36 mental health subscale, a five-item measure ranging from 0 to 100 that captures self-reported mood and anxiety (with 100 indicating perfect mental health; Ware 1993). We entered vision as an indicator variable for 20/70 to 20/100 vision. The fifth and final model added newspaper reading frequency. As we added additional variables into successive models, we analyzed (a) the statistical significance of the new variables in the model and (b) whether the relationship between the S-TOFHLA score and age changed compared to the previous model. For all analyses, we used a p value of .05 to determine statistical significance.
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Results |
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The mean age of participants was 73.1 (± 6.3), 58.9% were women, 84.1% were White, and 31.7% did not complete high school. Two thirds (67.9%) said they read the newspaper five times per week or more, but 8.5% said they never read the newspaper. A total of 46.4% had hypertension, 14.7% had diabetes, 23.1% had coronary artery disease, 13.4% had chronic obstructive pulmonary disease, 8.8% had suffered a stroke, and 11.0% had vision of 20/70 or 20/100. The mean physical functioning score on the SF-36 (± SD) was 72.9 (27.2), and the mean mental health score was 81.3 (18.2). Older age groups were more likely to be women, White, and have less than a high school education, poor vision, and worse physical functioning and mental health scores. Cognitive function was also substantially lower for older participants. The mean MMSE scores (± SD) for the five age groups were 26.5 (2.8), 26.0 (3.1), 25.5 (3.1), 24.9 (3.4), and 23.5 (4.1) for participants aged 65–69, 70–74, 75–79, 80–84, and 85 or older respectively (p < .001). Chronic disease prevalence and frequency of reading the newspaper were similar across age groups, although the proportion of participants who said they never read the newspaper increased with age.
There were dramatic differences in functional health literacy across age groups. Mean S-TOFHLA scores were 81.9, 75.6, 69.9, 60.8, and 48.6 for participants aged 65–69, 70–74, 75–79, 80–84, and 85 or older, respectively (p < .001). When stratified by the number of years of school completed, all educational strata showed similar differences in mean S-TOFHLA scores across age groups (Fig. 1). Performance on the MMSE was also highly correlated with functional health literacy (Spearman correlation coefficient 0.58). The mean S-TOFHLA scores (± SD) by MMSE quartiles (highest to lowest) were 89.8 (13.1), 79.3 (20.2), 72.2 (22.8), and 47.2 (27.4). Functional health literacy was also positively associated with self-reported frequency of reading a newspaper. The mean S-TOFHLA score (± SD) was 52.1 (30.8) for those who said they never read the newspaper, 70.4 (25.8) for those who read the newspaper less than four times per week, 77.1 (23.9) for those who read the newspaper five or more times per week, respectively (p < .001). Individuals who reported hypertension, diabetes, and a history of a stroke also had slightly lower S-TOFHLA scores, although participants with chronic obstructive pulmonary disease had slightly higher scores. Blacks and Hispanics had lower mean S-TOFHLA scores than Whites, but there was no difference between men and women.
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Discussion |
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The persistent association between older age and worse functional health literacy in multivariate analysis raises the possibility that the lower reading ability of older cohorts is due to age-related changes in cognitive function that are not captured by the MMSE. Previous research has shown that the ability to perform cognitive tasks requiring effortful or controlled processing of information declines markedly with age (Craik and Byrd 1982; Craik and Jennings 1992; Park 1999). During these tasks, there is a conscious search for information from memory, active mental manipulation of information, and conscious attempts to solve a problem. The ability to complete these tasks may be related to an individual's working memory, which is the capacity to process, store, and retrieve information (Park 1999; Baddeley 1992). Moreover, older adults have more difficulty completing tasks that require reasoning or inferences from information presented to them (Salthouse 1992). Reading comprehension of health-related material such as the prescription bottles used in the S-TOFHLA is likely to place significant demands on all of these mental faculties. Age-related declines in cognitive function, even in the absence of dementing illnesses, may explain the association between increasing age and lower functional health literacy.
There are other possible explanations for our findings. First, older individuals perform cognitive tasks more slowly (Salthouse 1996), and this could have affected our measurements of functional health literacy. Because the reading comprehension portion of the S-TOFHLA is timed, part of the relationship between age and functional health literacy could have resulted from older participants being unable to complete the test in the allotted time. To evaluate this possibility, we conducted two additional analyses using only (a) the numeracy items (which had no time limit) and (b) the first reading comprehension passage (which consisted of only 16 items written at a forth-grade level). Both of these found a similar relationship between age and reading ability, indicating that this was not due to differences in the speed of completing the tasks. It is also possible that older individuals became fatigued by the interview conducted prior to administering the S-TOFHLA. The average time to complete the interview and the S-TOFHLA was 58 min for those aged 85 and older compared to 53 min for those aged 65–69, so it appears unlikely that our findings are explained to a large degree by differences in the time required to complete the interview and resultant fatigue.
This study has several important limitations. First, only 37% of all new enrollees participated in the study, and those who did not had slightly higher socioeconomic status based on their ZIP code. Although this implies that individuals with limited literacy are probably over-represented in our study, this should not bias our estimates of the relationship between age and functional health literacy unless the association between literacy and age is different among individuals who did not participate. Second, because this was a cross-sectional analysis we cannot reliably determine whether there is a causal relationship between increasing age and declining literacy. Third, this study was not designed to examine whether the age-related differences in reading ability result from declines in working memory. The MMSE items used in this analysis are coarse indicators of cognitive impairment, and additional studies are needed to examine the relationship between working memory and reading ability. Longitudinal studies of changes in individuals' reading ability and working memory will probably be essential to untangle this relationship.
Although prospective studies are needed to determine whether an individual's reading ability declines with age even in the absence of dementing illness, our results suggest that many middle-age adults with adequate or marginal functional health literacy may have progressive worsening of their reading ability that will make it increasingly difficult for them to understand typical written health-related information as they age. This has tremendous implications for our ability to instruct older adults about proper health behaviors, about vaccinations for pneumonia and influenza, about screening for breast cancer and osteoporosis, about management of chronic diseases such as congestive heart failure, or about how to choose a health care plan. Although much has been learned about how to communicate more effectively with older adults (Park 1999), it is vital to further our understanding of this area, to develop innovative patient education tools, and to implement these in hospitals, clinics, and doctors' offices.
If this apparent decline in reading ability with age reflects a more general diminution in information-processing and is not due to medical conditions, then the problem of communicating health information to older adults will not go away even with better prevention and control of cerebrovascular and dementing illnesses. Nevertheless, a decline in reading ability, like declines in cognition, may not be inevitable. Our finding that individuals who said they read the newspaper more frequently had better functional health literacy should raise a glimmer of hope that continued use of reading skills may help preserve literacy. Although functional health literacy was negatively associated with age even for individuals who read the newspaper on most days, longitudinal studies with much more detailed measures of reading behaviors are needed to determine whether frequent reading can prevent or slow declines in literacy. Previous studies suggest that continued involvement in intellectual and social activities may prevent cognitive decline (Bassuk, Glass, and Berkman 1999; Hultsch et al. 1999), and some studies suggest that even short-term behavioral training may be able to prevent or slow cognitive decline (Plemons, Willis, and Baltes 1978). In addition to improving cognitive function or slowing decline, these strategies could also help preserve reading ability.
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Acknowledgments |
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Received for publication January 5, 2000. Accepted for publication July 11, 2000.
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; n = 998), 9–11 yr (
; n = 526), and 0–8 yr (
; n = 352). The bars indicate standard errors.