This Article Abstract Full Text (PDF) Services Download to citation manager Citing Articles Citing Articles via HighWire PubMed PubMed Citation

Inner City, Middle-Aged African Americans Have Excess Frank and Subclinical Disability

¹ School of Medicine, Saint Louis University, St. Louis, Missouri.
² Geriatric Research, Education, and Clinical Center, VAMC, St. Louis, Missouri.
³ College of Public Health, University of Iowa, Iowa City.
⁴ School of Public Health, Saint Louis University, St. Louis, Missouri.
⁵ Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri.

Address correspondence to Douglas K. Miller, MD, Indiana University, Center for Aging Research, Regenstrief Institute, 1050 Wishard Blvd., RG-6, Indianapolis, IN 46202. E-mail: dokmille{at}iupui.edu

	Abstract

Top Abstract Methods Results Discussion References

 
Background. Healthy People 2010 seeks to decrease or eliminate the health disparities experienced by disadvantaged minority groups.

Methods. African American Health (AAH) is a population-based panel study of community-dwelling African Americans born between 1936 and 1950 from two strata. The first encompasses a poor, inner city area, and the second involves a suburban population with higher socioeconomic status. The authors recruited 998 participants (76% recruitment). Frank disability was assessed for 25 tasks and defined as inability or difficulty performing that task. Subclinical disability was assessed for 12 tasks and defined as no difficulty but a change in either manner or frequency of task performance. Frank disability prevalences were compared with national data for community-dwelling non-Hispanic white persons (NHW) and African American persons in the same age range.

Results. Compared with the suburban sample, the inner city group had a higher prevalence of frank disability for all 25 tasks (p <.05 for 16) and subclinical disability for 11 of the12 tasks (p <.05 for 5). Both strata had more frank disability compared with the national NHW population. The inner city area had higher frank disability proportions than did the national African American sample, whereas the suburban group had similar disability levels.

Conclusions. The AAH inner city group experiences more frank disability than other populations of African Americans and NHWs. The increased prevalence of subclinical disability in the inner city group compared with the suburban group suggests that the disparity in frank disability will continue. These findings indicate that African Americans living in poor inner city areas in particular need intensive and targeted clinical and public health efforts.

Beyond frank disability (i.e., having difficulty or inability performing a given task), there is increasing interest in the distribution and effect of "subclinical" [called "preclinical" by some authors (6,7)] disability on the health of populations (6–12). Although this concept has been measured in a variety of ways (6–8,12), in this study we determined that subclinical disability existed for a given task when the participant reported no difficulty with that task but had experienced either a decrease in the frequency or change in the method of performing that task as a result of health or physical problems (7). Defined in this way, subclinical disability is reliable (7) and has discriminatory validity in cross-sectional analyses (i.e., the measured functional status of those with subclinical disability falls between those having frank difficulty and those having neither task modification nor frank difficulty) (7,9) and predictive validity for incident mobility difficulty (10,11). Despite its utility for identifying persons at risk for developing frank disability, the differential prevalence of subclinical disabilities among racial and ethnic groups has not been explored, nor has the considerable diversity of socioeconomic status levels and the benefits and detriments that accrue from them been adequately considered (5,13–15).

The African American Health (AAH) study was designed to address the issues of disparity and diversity in both frank and subclinical disabilities among middle-aged African Americans. These issues are important because attainment of the goals of Healthy People 2010 (2) of reducing disability in the total population and diminishing health disparities experienced by disadvantaged minorities requires that we know when and where to concentrate prevention and treatment efforts. The AAH is a population-based panel study of African Americans born in the years 1936–1950 from two areas in metropolitan St. Louis with noticeably different socioeconomic circumstances. Thus, the AAH facilitates the assessment of differences in frank and subclinical disability across the range of socioeconomic status. Furthermore, the AAH enables the comparison of frank disability between the two AAH areas and national samples of non-Hispanic white persons (NHWs) and African Americans conducted at about the same time using rather similar measures. In these comparisons, our a priori hypothesis was that: (a) the relative prevalence of frank and subclinical disability would be greater in the inner city AAH area than in the suburban AAH area, (b) the relative prevalence of frank disability would be similar in the suburban AAH area to that in a national sample of African Americans, and (c) the relative prevalence of frank disability would be greater in both AAH groups than in the national sample of NHWs. Furthermore, we expected the prevalence of frank disability in this middle-aged cohort to be small but the prevalence of subclinical disability to be moderate.

	METHODS

Top Abstract Methods Results Discussion References

 
Study Sample
Recruitment involved multistage probability sampling of the community-dwelling population stratified from two catchment areas chosen to maximize socioeconomic contrasts. Sampling proportions were set to recruit approximately one half of the sample from each stratum to maximize the power of comparisons between them. Area 1 encompassed the same poor inner city area involved in a previous investigation of disability in older African Americans (5), and area 2 encompassed the nearby suburbs just northwest of the city of St. Louis. Approximately 98% of the population living in area 1 was African American, but area 2 was much more heterogeneous. Therefore, we identified block groups in area 2 that had at least 10% African Americans in the 1990 census using geographic information system data. Sampling involved random selection of first area segments within block groups and then housing units within each selected segment. Professional interviewers (two thirds of whom were African American) with extensive project-specific training contacted households in person. Within each noninstitutional housing unit, interviewers screened for eligibility criteria, which were self-reported black or African American race and birth date from January 1936 through December 1950. If the household contained two or more eligible persons, one of them was selected using Kish tables (16). Either during the initial visit or subsequently, interviewers informed eligible participants in detail about the AAH project and obtained informed consent from willing participants (no proxy consents were permitted).

As soon as possible after the enumeration process was completed, eligible participants received an extensive in-home evaluation that averaged 2.5 hours. The Mini-Mental State Examination (17) was performed early in the interview, and the three potential participants who scored less than 16 were excluded from further participation. This exclusionary criterion was based on information suggesting that persons with Mini-Mental State Examination scores of 16 or more have adequate decisional capacity to give informed consent, whereas those with scores less than 16 usually do not (18). Recruitment and baseline interviews were conducted between September 2000 and July 2001. The Saint Louis University's Institutional Review Board approved all AAH procedures and protocols.

Measures
We defined frank disability for a task as the participant's report of inability or difficulty performing that task. We measured seven basic activities of daily living (ADL) using the wording and method of the Second Longitudinal Study on Aging (19). The basic ADL scale score is the simple count of tasks with difficulty (bathing, dressing, eating, getting in and out of bed or a chair, walking across the room, getting outside, and using the toilet; range, 0–7). A simple count of difficulties with eight instrumental ADL tasks from the Second Longitudinal Study on Aging and Lawton (20) was also used (preparing meals, shopping for groceries, managing money, making telephone calls, performing light housework, performing heavy housework, getting to places beyond walking distance, and managing medications; range 0–8).

We separated nine items from the Nagi physical performance measure (21) into two sets, for which we obtained simple counts. Four items measured upper body functional tasks (sitting for 2 hours, reaching over one's head, reaching out as if to shake hands, and grasping an object; range 0–4). Five items tapped lower body functional tasks (walking one-quarter mile; walking up and down 10 steps without rest; standing for 2 hours; stooping, crouching, and kneeling; and lifting and carrying 10 pounds; range 0–5). A tenth functional task involved walking one-half mile [drawn from the modified Rosow-Breslau Scale (22)].

The presence or absence of subclinical disability was defined for three basic ADL tasks (bathing, dressing, and bed and chair transferring), three instrumental ADL tasks (meal preparation, light housework, heavy housework), three lower body functional tasks (walking up and down 10 steps; stooping, crouching, and kneeling; and lifting and carrying 10 pounds), and the Rosow-Breslau task (walking one-half mile). These 10 items represent different types of possible tasks and are comparable to previous items used by Fried and colleagues (7). For each task, participants who reported no inability and no difficulty in performing it were asked whether they had changed either the method or the frequency of performing the task "because of health or physical problems" since age 40 years. Participants who reported no difficulty performing a task but had modified task performance were classified as having subclinical disability for that task.

Comparison Groups
We used data from the year 2000 wave of interviews of the Health and Retirement Survey (HRS) (23,24) for persons born in 1936–1947 to construct national comparison samples. The HRS is a prospective, nationally representative panel study of the community-dwelling population born in those years. The HRS used the same data collection methods and asked questions about functional status that were substantially similar (but not always identical) as those posed in the AAH. Data were available from these cohorts for 1022 African Americans and 5474 NHWs.

After careful review of the wording of each task in AAH and the comparison cohort interview schedules, we concluded that the wording was equivalent or essentially equivalent for three basic ADLs, four instrumental ADLs, all three Nagi upper body tasks, and two lower body functional tasks. The AAH wording indicated a greater degree of difficulty for one basic ADL and one instrumental ADL task, and wording for the comparison cohorts indicated the greater degree of difficulty for two basic ADLs and one Nagi lower body functional tasks (Table 4).

	RESULTS

Top Abstract Methods Results Discussion References

 
By design, approximately one half of the AAH participants came from each strata (463 and 535, respectively; Table 1). The recruitment proportion of eligible participants was 77% in area 1 and 75% in area 2. The inner city sample was slightly older, more likely to live alone, and poorer compared with the suburban sample. Overall, 46.8% of the AAH cohort had one or more frank disabilities and one or more subclinical disabilities, 12.7% had one or more frank disabilities but no subclinical disabilities, 19.1% had one or more subclinical disabilities but no frank disability, and only 21.4% had neither type of disability. Women were more likely to have one or more frank disabilities (62.3% vs 55.5% for men, p <.05) and to have more subclinical disabilities (70.4% vs 59.7% for men, p <.001). The youngest participants were least likely to have either frank or subclinical disability, but even in this group, the prevalences were high. For example, 49.6% of AAH participants born in the years 1946–1950 had one or more frank disabilities compared with 65.5% of AAH participants born in the years 1936–1945, and 57.4% of the younger AAH participants had one or more subclinical disabilities compared with 71.1% of the older AAH participants.

Comparisons between the AAH and the national African Americans population were more mixed. Except when the task question was phrased to indicate a greater degree of difficulty in the national data, the inner city sample showed consistently higher proportions of frank disability. Eight of these differences were statistically significant, and some of the differences were remarkable (e.g., walking across a room). Overall, the AAH suburban sample was similar to the national African American sample, with significantly increased disability for the suburban group for two tasks and for the national sample for four tasks. Differences in wording may help explain some of the anomalies. For dressing, the national sample was asked whether they had "any difficulty with dressing, including putting on shoes and socks?" [emphasis added], whereas AAH participants were simply asked whether they had any difficulty dressing. In the lower body functional tasks, the comparison group was asked whether they had "any difficulty with lifting or carrying weights over 10 pounds, such as a heavy bag of groceries?" [emphasis added], whereas AAH participants were asked whether they had any difficulty lifting or carrying something "as heavy as 10 pounds?" [emphasis added]. (The exact questions for AAH and the comparison group are available from the authors by request.) Logistic regression adjusting for age and sex generally confirmed the chi-square results, with three additional inner city AAH to national African American contrasts becoming statistically significant. The excess disability in the inner city AAH group ranged from 62% (shop) to 166% (grasp or handle), whereas the adjusted odds ratios for the suburban group ranged from 1.70 to 0.53.

	DISCUSSION

Top Abstract Methods Results Discussion References

 
For the most part, our a priori hypothesis was confirmed. The inner city AAH group had considerably more frank disability and somewhat more subclinical disability compared with the AAH suburban group. The inner city AAH population also had more frank disability than either the national black or NWH population, whereas the AAH suburban population had disability levels similar to the national sample of black persons and greater than NHW levels. The observed levels of frank disability, however, were higher than we expected in this relatively young cohort. For example, 59% of the AAH cohort (mean age, 56.8 years) had at least one frank disability compared with 63% in the older, primarily white convenience sample of Fried and colleagues (mean age, 73.3 years) (7). In fact, 30%–50% of the AAH group reported difficulty performing six tasks (heavy housework, walking one-quarter or one-half mile, walking up and down stairs, standing for 2 hours, and stooping, crouching, and kneeling). As expected, the levels of subclinical disability were generally moderate, ranging from nearly 10% for two tasks in the suburban AAH group to 35%–40% for three tasks in the inner city AAH group.

Combined with findings of previous research (5), our study results suggest that inner city, middle-aged African Americans experience excess frank disability and that this disability is evident at a surprisingly young age. The excess subclinical disability in the inner city AAH group compared with the suburban group suggests that this disparity in frank disability will continue. At this point, we cannot determine whether the excess frank and subclinical disability is caused by biomedical factors, cultural differences (e.g., diet or differential meaning of the questions), socioeconomic factors, or differential migration patterns. However, we plan to explore most of these possibilities in our longitudinal follow-up study.

This study has limitations. The AAH cohort included only two areas of St. Louis with differing socioeconomic circumstances and therefore is not representative of the entire metropolitan area. Neither does it include African Americans living in other large metropolitan areas or performance-based measures of functional status. Thus, the findings we report here may not directly apply to other urban African American populations or to performance-based functional status measures. However, in our previous study of older inner city African Americans, disadvantage in measured physical functions paralleled the disadvantage seen in self-reported functions (5). We could only compare persons born in the years 1936–1947 with the national samples, although it is unlikely that the additional three cohort years would have changed the data in any substantial way. Furthermore, the way that the disability questions were worded in AAH and the comparison cohorts was not identical for all tasks, and the differences in wording likely affected some of the findings. Despite these differences in wording, the HRS is the most comparable cohort with available data. In addition, the pattern of findings across all tasks was consistent enough to support our hypothesis of excess disability compared with NHWs nationally and excess disability in the inner city group compared with the national African American sample.

In addition, we could not identify public use datasets that contained middle-aged persons who were living in poor, inner city areas (either black or white) and asked disability questions similar to our own. Perhaps NHWs and other racial-ethnic groups living in poor, inner city areas also experience the same excess disability we identified here in area 1 of the AAH cohort, but there is no way to know for sure. Nevertheless, this fact does not change our main conclusion that inner city, middle-aged African Americans represent a pocket of excess disability and therefore offer an important target for intensive clinical and public health efforts to improve racial disparities. At the same time, the excess disability reported by the suburban AAH group compared with the age-matched national NHW sample emphasizes again the importance of addressing disparity throughout the African American population. Finally, this study used cross-sectional data rather than longitudinal information. However, we will continue to follow this cohort, evaluate the effects of socioeconomic status on health over time, and report the findings.

Conclusion
As a group, the inner city cohort is experiencing excess frank and subclinical disability as they begin to enter their senior years. As next steps, we plan to evaluate the aspects of poorer socioeconomic status that appear to generate the differences in health status in the two areas in both cross-sectional and longitudinal analyses. In particular, we are interested in the impact conferred by personal resources versus those conferred by block or community-level assets. At the same time, we will evaluate the biomedical concomitants of disability development. Our overall goal is to identify critical transition points in the disability process so that interventions can be designed to prevent or reverse these transitions. Our findings also suggest that African Americans living in poor inner city areas need more intensive and targeted clinical and public health efforts.

	Acknowledgments

 
Supported by grant RO1 AG10436 from the National Institute on Aging.

Presented in part at the 55th Annual Scientific Meeting of the Gerontological Society of America, November 25, 2002, Boston, Massachusetts.

The Health and Retirement Study is a cooperative agreement between the Institute for Social Research at the University of Michigan and the National Institute on Aging. Financial support for the project is provided by the National Institute on Aging, with supplementary funding provided by the U.S. Social Security Administration.

Dr. Douglas K. Miller is now with Indiana University, Center for Aging Research, Regenstrief Institute.

	Footnotes

 
Decision Editor: Larry E. Johnson, MD, PhD

Received May 21, 2003

Accepted December 30, 2003

	References

Top Abstract Methods Results Discussion References

 

1. U. S. Department of Health and Human Services. Healthy People 2000: National Health Promotion and Disease Prevention Objectives. DHHS Publication (PHS) 91-50212. Washington, DC: U.S. Government Printing Office, 1991.
2. U. S. Department of Health and Human Services. Healthy People 2010. McLean, VA: International Medical Publishing, 2000.
3. Satcher D, Hull FL. The weight of an ounce. JAMA. 1995;273:1149-1150.[Abstract/Free Full Text]
4. National Center for Health Statistics. Healthy People 2000 Final Review. Hyattsville, MD: Public Health Service, 2001;365–368.
5. Miller DK, Carter ME, Miller JP, et al. Inner-city older blacks have high levels of functional disability. J Am Geriatr Soc. 1996;44:1166-1173.[Medline]
6. Fried LP, Herdman SJ, Kuhn KE, Rubin G, Turano K. Preclinical disability. Hypotheses about the bottom of the iceberg. J Aging Health. 1991;3:285-300.[Abstract/Free Full Text]
7. Fried LP, Bandeen-Roche K, Williamson JD, et al. Functional decline in older adults: expanding methods of ascertainment. J Gerontol A Biol Sci Med Sci. 1996;51:M206-M214.
8. Binder EF, Schechtman KB, Ehsani AA, et al. Effects of exercise training on frailty in community-dwelling older adults: results of a randomized, controlled trial. J Am Geriatr Soc. 2002;50:1921-1928.[Medline]
9. Fried LP, Young Y, Rubin G, Bandeen-Roche K, Group WICR. Self-reported preclinical disability identifies older women with early declines in performance and early disease. J Clin Epidemiol. 2001;54:889-901.[Medline]
10. Fried LP, Bandeen-Roche K, Chaves PH, Johnson BA. Preclinical mobility disability predicts incident mobility disability in older women. J Gerontol A Biol Sci Med Sci. 2000;55:M43-M52.
11. Chaves PH, Garrett ES, Fried LP. Predicting the risk of mobility difficulty in older women with screening nomograms: the Women's Health and Aging Study II. Arch Intern Med. 2000;160:2525-2533.[Abstract/Free Full Text]
12. Hazuda HP, Gerety MB, Lee S, Mulrow CD, Lichtenstein MJ. Measuring subclinical disability in older Mexican Americans. Psychosom Med. 2002;64:520-530.[Abstract/Free Full Text]
13. Berkman CS, Gurland BJ. The relationship between ethnoracial group and functional level in older persons. Ethn Health. 1998;3:175-188.[Medline]
14. Robbins AS, Whittemore AS, Thom DH. Differences in socioeconomic status and survival among white and black men with prostate cancer. Am J Epidemiol. 2000;151:409-416.[Abstract/Free Full Text]
15. Cross CK, Harris J, Recht A. Race, socioeconomic status, and breast carcinoma in the U.S: What have we learned from clinical studies? Cancer. 2002;95:1988-1999.[Medline]
16. Kish L. Survey Sampling. New York: Wiley & Sons, 1965.
17. Folstein MF, Folstein SE, McHugh PR. ‘Mini-Mental State.’ A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189-198.[Medline]
18. Molloy DW, Silberfeld M, Darzins P, et al. Measuring capacity to complete an advance directive. J Am Geriatr Soc. 1996;44:660-664.[Medline]
19. National Center for Health Statistics. Data File Documentation, National Health Interview Second Supplement on Aging, 1994 (machine readable data file and documentation). Hyattsville, MD: National Center for Health Statistics, 1998.
20. Lawton MP, Brody EM. Assessment of older people: self-maintaining and instrumental activities of daily living. Gerontologist. 1969;9:179-186.[Medline]
21. Nagi SZ. An epidemiology of disability among adults in the United States. Milbank Q. 1976;54:439-467.
22. Guralnik JM, LaCroix AZ, Branch LG, Kasl SV, Wallace RB. Morbidity and disability in older persons in the years prior to death. Am J Public Health. 1991;81:443-447.[Abstract/Free Full Text]
23. The Institute for Social Research. Health and Retirement Study, 2000 Core, Final, Version 2.0, October 2002. Ann Arbor, MI: University of Michigan. Data Description and Organization, 2002.
24. The Institute for Social Research. The Health and Retirement Study: A Longitudinal Study of Health, Retirement, and Aging. Available at: HRSONLINE.ISR.UMICH.EDU/META/2000/CORE/DESC/HRS00DD.PDF, 2003. Accessed December 29, 2004.

This article has been cited by other articles:

				C. A. Reyes-Ortiz, K. Eschbach, D. D. Zhang, and J. S. Goodwin Neighborhood Composition and Cancer among Hispanics: Tumor Stage and Size at Time of Diagnosis Cancer Epidemiol. Biomarkers Prev., November 1, 2008; 17(11): 2931 - 2936. [Abstract] [Full Text] [PDF]

				D. K. Miller, F. D. Wolinsky, E. M. Andresen, T. K. Malmstrom, and J. P. Miller Adverse Outcomes and Correlates of Change in the Short Physical Performance Battery Over 36 Months in the African American Health Project J. Gerontol. A Biol. Sci. Med. Sci., May 1, 2008; 63(5): 487 - 494. [Abstract] [Full Text] [PDF]

				M. Schootman, E. M Andresen, F. D Wolinsky, T. K Malmstrom, J P. Miller, and D. K Miller Neighbourhood environment and the incidence of depressive symptoms among middle-aged African Americans J Epidemiol Community Health, June 1, 2007; 61(6): 527 - 532. [Abstract] [Full Text] [PDF]

				F. D. Wolinsky, T. R. Miller, T. K. Malmstrom, J. P. Miller, M. Schootman, E. M. Andresen, and D. K. Miller Four-Year Lower Extremity Disability Trajectories Among African American Men and Women J. Gerontol. A Biol. Sci. Med. Sci., May 1, 2007; 62(5): 525 - 530. [Abstract] [Full Text] [PDF]

				M. Schootman, E. M. Andresen, F. D. Wolinsky, T. K. Malmstrom, J. P. Miller, and D. K. Miller Neighborhood Conditions and Risk of Incident Lower-Body Functional Limitations among Middle-aged African Americans Am. J. Epidemiol., March 1, 2006; 163(5): 450 - 458. [Abstract] [Full Text] [PDF]

				E. M. Andresen, T. K. Malmstrom, D. K. Miller, and F. D. Wolinsky Reliability and Validity of Observer Ratings of Neighborhoods J Aging Health, February 1, 2006; 18(1): 28 - 36. [PDF]

				E. M. Andresen and D. K. Miller The Future (History) of Socioeconomic Measurement and Implications for Improving Health Outcomes Among African Americans J. Gerontol. A Biol. Sci. Med. Sci., October 1, 2005; 60(10): 1345 - 1350. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Services Download to citation manager Citing Articles Citing Articles via HighWire PubMed PubMed Citation