Health Affairs, 22, no. 4 (2003): 154-162 doi: 10.1377/hlthaff.22.4.154 © 2003 by Project HOPE	New Online   Senate Health Reform Bill   Rewarding Providers   Public Option Policy Brief   Health Reform & Abortion   Delivery System Reform

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Trends In Medication Use And Functioning Before Retirement Age: Are They Linked?

Abstract

 
This paper explores the extent to which changes in medication use during the 1990s are linked to improvements in functioning among Americans before they reach retirement age. Using two cross-sections from a survey of Americans ages 51–61, we examined changes between 1992 and 1998 in the prevalence of functional limitations and medication use associated with five chronic conditions: hypertension, diabetes, lung disease, stroke, and arthritis. We found no evidence linking increases in medication use to improvements in functioning. Instead, increases in educational attainment offset the negative effects of increases in obesity and arthritis over this period. Findings underscore the need for caution in projecting forward improvements in old-age functioning when considering the future of Medicare, Medicaid, and other programs that serve the elderly with disabilities.

To understand the consequences of disability declines for publicly financed programs, we need better insight into the causes of the trend. Current hypotheses may be classified broadly into long-term and shorter-term factors. Long-term factors might include better nutrition, improvements in the public health infrastructure, and widespread use of infectious disease treatments such as antibiotics. More recent explanations include changes in the socioeconomic status of older Americans, healthier lifestyles, increased use of assistive technologies, less restrictive environments, and better treatment of chronic diseases through medical procedures and medication use.

Indeed, use of medications has become an increasingly important aspect of health care for older Americans, and the development of drugs aimed at some of the more debilitating diseases of later life continues rapidly.³ Approximately nine out of ten older Americans take one or more prescription drugs daily.⁴ The 1980s and early 1990s saw major shifts in the classes of drugs prescribed for some of the more debilitating chronic conditions—for example, increased availability of nonsteroidal anti-inflammatory drugs for osteoarthritis and anti-rheumatic drugs for rheumatoid arthritis.⁵ New classes of psychotropic agents have become available to treat depression and other psychiatric conditions, which have been identified as a major cause of premature disability among the elderly.⁶ Drug treatments for diabetes and hypertension also expanded greatly during this period.⁷ Frank Lichtenberg has shown that people with prescriptions for newer medications have many fewer work disability days than do those taking older medications.⁸ Here we explore whether in 1992 and 1998 changes in medication use associated with five highly prevalent and often debilitating chronic conditions are linked to improvements in functioning among Americans of preretirement age.

Data And Approach

Top Data And Approach Study Results Discussion Editor's Notes NOTES

 
The 1992 (n = 9,573) and 1998 (n = 7,099) waves of the Health and Retirement Study (HRS) provide nationally representative cross-sections of the noninstitutionalized population ages 51–61 in those years. In both years respondents were instructed to report how much difficulty they had with various physical tasks (for example, reaching, stooping, and lifting) because of a health or physical problem.⁹ The survey also obtained information about height and weight (from which we calculated obesity) and the history of and current medication use for five chronic conditions: hypertension, diabetes, chronic lung disease, stroke, and arthritis.¹⁰

Reliability of self-reports. Previous studies generally show excellent agreement between administrative or medical records and self-reports for chronic conditions such as hypertension, diabetes, and stroke.¹¹ Studies of the reliability and validity of reported medication use are less common and with one exception involve foreign populations.¹² Moreover, a study of the influence of question structure on recall of medication use found that when questions were linked to specific conditions, as they are in the HRS, 88 percent of medications were accurately recalled.¹³

Analysis theory and structure. Our analysis draws upon a well-established depiction of the disablement process.¹⁴ Whether pathology and impairments lead to limitations in functioning is mediated in part by predisposing factors (such as demographic, social, and behavioral factors) and by intervening factors (such as medication use, medical care, and changes in behavior in response to diagnosis). Intervening factors are inserted during the disablement process, and the timing of their effects may be immediate, delayed, or cumulative.¹⁵

Our analysis involves four steps. We first present descriptive statistics on chronic conditions, medication use, and functioning in 1992 and 1998. We then show changes in the demographic composition of the preretirement-age population and in functioning for these subgroups. Next we present for the entire preretirement-age population and each chronic condition group the mean change in limitations between 1992 and 1998 based on a series of regression models.¹⁶ Our focus is on whether the change in functioning between 1992 and 1998 is attenuated once changes in other factors—namely, the demographic composition of the population (including age, sex, race, ethnicity, education, marital status, and ownership of liquid assets); the chronic disease profile (as measured by obesity [body mass index > 30] and indicators of the history of the five conditions of interest in this study); and the rate of medication use for the five conditions—are taken into account. Finally, to explore whether medications have become more effective over time in relation to functioning, we test whether improvements have been greater for groups who used medications than for those who did not.

Study Results

Top Data And Approach Study Results Discussion Editor's Notes NOTES

 
Prevalence data. Between 1992 and 1998 the reported prevalence of diabetes, stroke, and arthritis increased, but this change was statistically significant only for arthritis (Exhibit 1). The prevalence of obesity also increased dramatically, but reports of hypertension and lung disease declined.¹⁷

During the same period the average number of functional limitations reported by people ages 51–61 declined from 1.74 to 1.34 (p < .01) (Exhibit 2). Fewer limitations were reported by subgroups of respondents with hypertension, diabetes, stroke, and arthritis. Only people with lung disease did not report significantly fewer limitations in 1998 than in 1992.

Similar results are evident when we focus on subgroups of people with specific chronic conditions (Exhibit 5). For the five conditions considered here, we find statistically significant declines, ranging from 0.29 to 0.59, depending on the condition. Medication use alone does not explain these declines; however, when we control for shifts in the demo graphic and socioeconomic composition of the population, those shifts account for about half of the decline for arthritis and hypertension and nearly the entire decline for diabetes and stroke. Changes in the chronic-condition profile work in the opposite direction, offsetting some of the decline. For four of the five conditions, medication use does not further explain any of the declines. Only among those reporting a stroke does the coefficient on year attenuate when information about medication use is included (from –0.34 to –0.26), but neither effect is statistically different from finding no change.

Medication use and functional limitations. If changes in the type of medication—and consequently changes in the effectiveness of treatment—are contributing to improvements in functioning, we would expect to see greater improvements in functioning among those reporting medication use compared with those who are not using medications. We explore these relationships in Exhibit 6.

View larger version (33K): [in this window] [in a new window]   Exhibit 6 Mean Number Of Functional Limitations Among People Ages 51–61 Reporting Selected Chronic Conditions, By Medication Use, 1992 And 1998 SOURCE: Authors’ analysis of data from the Health and Retirement Study. NOTES: Significance tests compare number of functional limitations in 1992 and 1998 among people with a given chronic condition and medication status. Hypertension: no medication, p < .05; medication, p < .01. Diabetes: no medication, p < .01; medication, not significant. Lung disease: no medication and medication, not significant. Stroke: no medication and medication, not significant. Arthritis: no medication, p < .01; medication, p < .05.

Second, the improvements do not appear to be greater for those reporting medication use. For those reporting diabetes, only those not taking medications experienced improvements in functioning over time. For those reporting hypertension and arthritis, function ing improved about equally for people on medication and not on medication. When we controlled for additional factors related to medication use (not shown), these general patterns persisted.

Discussion

Top Data And Approach Study Results Discussion Editor's Notes NOTES

 
Like previous studies, our analysis provides support for the finding that functioning improved during the 1990s for Americans of preretirement age. During the same period re ports of medication use also increased dramatically for hypertension and diabetes. For lung disease, stroke, and arthritis, reports of medication use remained stable. Although there is clearly more medication use among this age group, we were unable to find statistical evidence linking medication use to improvements in functioning for the conditions considered here.

Limitations. This study is limited in several important respects. First, our analysis is limited to reports of medication use associated with only five chronic conditions. It may be that medication use for other disease processes has played an integral role in improving functioning. For example, pharmacological treatment of depression has increased markedly during the 1990s.¹⁸ Medications aimed at relieving gastrointestinal discomfort, the symptoms of menopause (primarily in the form of estrogen therapy), and back pain also clearly have implications for quality of life but were beyond the scope of this study.

Second, we have not considered medical treatments beyond pharmacological agents. For example, surgical treatments for vision loss because of cataracts and glaucoma and for hip and knee replacements have also increased dramatically over the past decade. If the relative importance of medical treatment to recent trends in old-age functioning is to be fully understood, further study of the contribution of these important procedures is warranted.

Third, data limitations kept us from addressing what types of medications people were using in each year. However, we did not find evidence consistent with aggregate improvements in the effectiveness of medication for the five conditions considered here.

Fourth, our analysis focuses on people ages 51–61. But the largest improvements in functioning have been observed for much older people.¹⁹ It may be that the beneficial effects of medication use in midlife are not fully apparent until later in life. Follow-up analyses with future waves of the HRS could provide valuable insight into the cumulative benefits of medication use in midlife.

Finally, and perhaps most importantly, because of changes in question wording in the data we drew upon, we excluded from our measure of functioning several mobility items that are typically included in functional limitation scales (for example, walking one or several blocks, or climbing one or several flights of stairs). It may be that medication use has a greater effect on mobility than on other body functions included here. As newer data become available to examine the link between medication use and mobility-related impairments, this question should be addressed.

Education factor. Notwithstanding these limitations, our analysis suggests that changes in the rate of medication use and its effectiveness do not appear to be driving recent improvements in functioning at ages 51–61. Instead we find, consistent with previous studies, that increases in educational attainment appear to be an important factor.²⁰ Had years of schooling not increased, functioning would have improved only half as much as it did from 1992 to 1998. Educational levels among older Americans will continue to increase over the next several decades, but not at the rates observed during the 1980s and early 1990s.²¹ Taken together, these findings underscore the need for caution in projecting forward improvements in old-age functioning when considering the future of Medicare, Medicaid, and other programs that serve the older population with disabilities.

Obesity. Also noteworthy are the large increases in some of the most disabling conditions in this preretirement-age group. Notably, obesity increased more than 25 percent in just six years. Other studies have confirmed an obesity epidemic occurring in the United States that reaches down the age spectrum, affecting one in four of America’s children.²² Obesity has been linked not only to disability but also to costly conditions such as heart disease, stroke, and diabetes. Studies of the implications of impending increases in obesity for future disability rates and related medical costs are clearly a critical next step.

Narrowed racial gap. Although most demographic groups reported improvements in functioning between 1992 and 1998, non-whites—a group well documented to be disadvantaged in terms of late-life health—did not experience such gains. In further analyses (not shown), we explored whether this lack of improvement could be attributed to disproportionately low medication use but found the opposite: For the five conditions considered here, nonwhites had higher rates of medication use relative to whites, even after we controlled for other health and socioeconomic differences across these groups. These findings may signal yet another cautionary note: The recent narrowing of the racial gap in old-age disability may yet again reverse course as the remaining members of the birth cohorts considered here (1931–1947) enter old age.²³

Future research agenda. Finally, our analysis suggests that researchers may need to refocus their search for the causes of recent improvements in late-life functioning. While our findings do not rule out substantial future contributions of pharmaceuticals to the quality of life of older persons, researchers may do well to focus on other factors, particularly those linked to educational attainment.

Editor's Notes

Top Data And Approach Study Results Discussion Editor's Notes NOTES

 
Vicki Freedman is the director and Hakan Aykan, a policy analyst, at the Polisher Research Institute, Madlyn and Leonard Abramson Center for Jewish Life (formerly, Philadelphia Geriatric Center), in Horsham, Pennsylvania.

This research was funded by a supplement from the Office of the Assistant Secretary for Planning and Evaluation, U.S. Department of Health and Human Services, to the National Institute on Aging, Grant no. R01 14346. The views expressed are those of the authors alone and do not reflect the opinions of the funding agencies.

NOTES

Top Data And Approach Study Results Discussion Editor's Notes NOTES

 

1. D.M.Cutler, "Declining Disability among the Elderly," Health Affairs (Nov/Dec 2001): 11–27; and V.A.Freedman, L.G. Martin, and R.F. Schoeni, "Recent Trends in Disability and Functioning among Older Adults in the United States: A Systematic Review," Journal of the American Medical Association 288, no. 24 (2002): 3137–3146.[Abstract/Free Full Text]
2. B.H.Singer and K.G. Manton, "The Effects of Health Changes on Projections of Health Service Needs for the Elderly Population of the United States," Proceedings of the National Academy of Sciences USA 95 (1998): 15618–15622[Abstract/Free Full Text]; and V.A.Freedman and L.G. Martin, "Understanding Trends in Functional Limitations among Older Americans," American Journal of Public Health 88, no. 10 (1998): 1457–1462.[Abstract/Free Full Text]
3. D.K.Cherry, C.W. Burt, and D.A. Woodwell, "National Ambulatory Medical Care Survey: 1999 Summary," Advance Data no. 322, 17 July 2001, www.cdc.gov/nchs/data/ad/ad322.pdf (9 April 2003); and J.Morley, "Drugs, Aging, and the Future" (editorial), Journal of Gerontology: Medical Sciences 51, no. 1 (2002): M2–M6.
4. J.Rogowski, L.A. Lillard, and R. Kington, "The Financial Burden of Prescription Drug Use among Elderly Persons," Gerontologist 37, no. 4 (1997): 475–482.[Abstract]
5. J.F.Fries et al., "Reduction in Long-Term Disability in Patients with Rheumatoid Arthritis by Disease-Modifying Antirheumatic Drug-Based Treatment Strategies," Arthritis Rheumatology 39, no. 4 (1996): 616–622; M.M.Ward and J.F. Fries, "Trends in Antirheumatic Medication Use among Patients with Rheumatoid Arthritis, 1981–1996," Journal of Rheumatology 25, no. 3 (1998): 408–416; and Y.Zhang et al., "Estrogen Replacement Therapy and Worsening of Radiographic Knee Osteoarthritis: The Framingham Study," Arthritis Rheumatology 41, no. 10 (1998): 1867–1873.[CrossRef]
6. A.Luisi, N.J. Owens, and A.L. Hume, "Drugs and the Elderly," in Clinical Aspects of Aging, 5th ed., ed. J.J. Gallo et al. (Baltimore: Lippinott Williams and Wilkins, 1999), chap. 5; and C.Boult et al., "Chronic Conditions That Lead to Functional Limitation in the Elderly," Journal of Gerontology: Medical Sciences 49, no. 1 (1994): M28–M36.
7. Luisi et al., "Drugs and the Elderly."
8. F.R.Lichtenberg, "Are the Benefits of Newer Drugs Worth Their Cost? Evidence from the 1996 MEPS," Health Affairs (Sep/Oct 2001): 241–251.
9. Minor wording differences existed between the 1992 and 1998 surveys with respect to functional limitation items. However, our analysis of the 1994 wave of the HRS, which asked both sets of questions for a randomly selected group of respondents (N = 595), suggested a lack of sensitivity to such wording changes for the seven items included here: sitting for about two hours; getting up from a chair after sitting for long periods; lifting or carrying weights over ten pounds; stooping, kneeling, or crouching; picking up a dime from a table; reaching or extending arms above shoulder level; and pulling or pushing large objects. These seven items scale into a single factor with high internal consistency (Cronbach’s alpha = .80) and good predictive validity. We also explicitly accounted for the influence of wording changes in an alternative set of estimates and tests. Because substantive conclusions were not affected by these corrections, we present the more straightforward uncorrected estimates here. More details are available from the authors upon request; send e-mail to Vicki Freedman at vfreedman{at}abramsoncenter.org
10. The HRS also asked about heart disease in both years, but the wording of these questions differed between 1992 and 1998, so the condition, albeit important, is not considered here. For arthritis, survey respondents were asked if they ever had or if a doctor ever told them that they had arthritis. For all other conditions, they were asked to report whether a doctor ever told them that they had the given condition. Medication-use questions were tailored to each condition as follows. Hypertension: Are you currently taking any medication for the condition? Diabetes: Do you now use medication that you swallow or insulin injections to treat or control your diabetes? Stroke: Are you taking any medications because of the stroke and its complications? Lung disease and arthritis: Are you currently taking any medication or other treatments for the condition?
11. See, for example, T.L.Bush et al., "Self-Report and Medical Record Report Agreement of Selected Medical Conditions in the Elderly," American Journal of Public Health 79, no. 11 (1987): 1554–1556; R.Kehoe et al., "Comparing Self- Reported and Physician-Reported Medical History," American Journal of Epidemiology 139, no. 8 (1994): 813–818[Abstract/Free Full Text]; and L.M.Martin et al., "Validation of Self-Reported Chronic Conditions and Health Services in a Managed Care Population," American Journal of Preventive Medicine 18, no. 3 (2000): 215–218.[CrossRef][Web of Science][Medline]
12. See Kehoe et al., "Comparing Self-Reported and Physician-Reported Medical History."
13. O.H.Klungel et al., "Influence of Question Structure on the Recall of Self-Reported Drug Use," Journal of Clinical Epidemiology 53, no. 3 (2000): 273–277.[CrossRef][Web of Science][Medline]
14. L.M.Verbrugge and A. Jette, "The Disablement Process," Social Science and Medicine 38, no. 1 (1994): 1–14.
15. Here we ignore these circularities; however, we also examined panel-based evidence about changes between 1994 and 2000, using information about medication use and other predictors from 1992 and 1998, respectively. Changes in functioning between 1994 and 2000 were much smaller, and the role of medication use was not appreciably different than the results presented here.
16. Here we present results from ordinary least squares regression; however, our findings are robust to a variety of alternative models including Poisson, negative binomial, and lognormal specifications.
17. For similar results from other national surveys, see V.A.Freedman and L.G. Martin, "Contribution of Chronic Conditions to Aggregate Changes in Old-Age Functioning," American Journal of Public Health 90, no. 11 (2000): 1755–1760[Abstract/Free Full Text]; and K.G.Manton, E. Stallard, and L. Corder, "Changes in Morbidity and Chronic Disability in the U.S. Elderly Population: Evidence for the 1982, 1984, and 1989 National Long Term Care Surveys," Journal of Gerontology: Social Sciences 50B, no. 4 (1995): S194–S204.
18. M.Olfson et al., "National Trends in the Outpatient Treatment of Depression," Journal of the American Medical Association 287, no. 2 (2002): 203–209.[Abstract/Free Full Text]
19. See Freedman and Martin, "Understanding Trends in Functional Limitations."
20. V.A.Freedman and L.G. Martin, "The Role of Education in Explaining and Forecasting Trends in Functional Limitations among Older Americans," Demography 36, no. 4 (1999): 461–473; [Web of Science][Medline]R.F.Schoeni, V.A. Freedman, and R.B. Wallace, "Persistent, Consistent, Widespread, and Robust?" Journal of Gerontology: Social Sciences 56B, no. 4 (2001): S206–S218; and T.Waidmann and K. Liu, "Disability Trends among the Elderly and Implications for the Future," Journal of Gerontology: Social Sciences 55B, no. 5 (2000): S298–S307.
21. Freedman and Martin, "The Role of Education."
22. A.H.Mokdad et al., "The Continuing Epidemics of Obesity and Diabetes in the United States," Journal of the American Medical Association 286, no. 10 (2001): 1195–1200.[Abstract/Free Full Text]
23. K.G.Manton and X. Gu, "Changes in the Prevalence of Chronic Disability in the United States Black and Nonblack Population above Age Sixty-five from 1982 to 1999," Proceedings of the National Academy of Sciences 98 (2001): 6354–6359.[Abstract/Free Full Text]

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