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The pilot projects are at the core of CDEHA’s past and planned activities. These projects are highly leveraged investments into aging research at Stanford, and they meet additional goals of the University and of the research community more generally. They develop the careers of junior investigators, they stimulate interest in aging research, and they encourage interdisciplinary collaboration. CDEHA investigators apply the perspectives of population studies, psychology, economics, statistics, genetics, and other disciplines, and the demography center grant has contributed to the growth of the number of individuals and disciplines involved in aging research at Stanford.
Additionally, the pilot projects are not merely exercises conducted to develop the careers of new investigators in aging research and to encourage interdisciplinary collaboration. They are also intended to have great intrinsic merit as research projects. They should represent the beginnings of highly promising research endeavors; in every case, we believe that the research should be conducted even if it did not provide the added benefits to our institution, to the young investigators, or to the general community of researchers on aging.
Seed Project Summaries:
This section describes the results and current status of the seed projects conducted since the inception of our Center. Supplement grant research is still largely in progress and updates about those projects will continue to be provided in our annual reports.
Explaining Changes in Disability Prevalence Among Younger and Older American Populations - Jay Bhattacharya, M.D., Ph.D., Principal Investigator; Alan Garber, Mentor [Awarded 2002]
In previous work, using data from the National Health and Interview Survey (NHIS), Lakdawalla, Bhattacharya, and Goldman found that the rate of severe disability (requiring assistance to perform basic activities of daily living) had increased between 1984 and 2000 for 25-year old to 55- year old populations in the U.S. In work funded by the Stanford demography center, Bhattacharya, et al. (2003) examined trends in chronic disease in younger populations as an explanation for the disability trends. Again using data from the NHIS, Bhattacharya, et al decomposed disability trends into three parts--one part attributable to changes in the prevalence of chronic disease, one part attributable to changes in the prevalence of disability among those with chronic disease, and a final part attributable to changes in the prevalence of disability among those with no chronic disease. For most age groups between 25 and 55, changes in the prevalence of chronic disease alone under-explain the total change in disability. For age groups above 55 (where there were declines in disability between 1984 and 1996), changes in prevalence of chronic disease alone under-explain the decline. On the other hand, changes in the prevalence of disability among those with a chronic condition explains most of the changes in disability prevalence. Among those with no chronic condition, disability rates actually fell. These conclusions are important because they suggest--contrary to prominent research by Autor and Duggan--that if rising disability in younger populations is due to moral hazard caused by the increasing generosity of disability assistance programs, the effects are limited to persons who have impaired health: Moral hazard affects the chronically ill in a fundamentally different way than it affects those with no chronic illness. Finally, if the increase in disability seen over these past two decades is permanent, great financial strain will be placed upon Medicare as these disabled populations enter old age.
Health Plan Choice Among the Elderly - M. Kate Bundorf, M.B.A., M.P.H., Ph.D., Principal Investigator; Alan Garber, Mentor [Awarded 2000]
Using point-in-time estimates from the Medicare Current Beneficiary Survey Cost and Use files from December 1992 and 1996, we examined changes in the duration of enrollment in both private plans and Medicaid coverage and found evidence of dramatic increases in switching behavior among those holding private plans. In 1992, 81% of private plans held by community dwelling Medicare beneficiaries age 65 and over were held for 12 months. In 1996, in contrast, only 60% of private plans were held for the entire year. While plans of all types were less likely to be held for 12 months in 1996 than in 1992, the percent change was greatest for Medicare HMOs (-40%). Medicaid coverage, in contrast, remained stable over the study period.
Racial Disparities in the Utilization of Emerging Medical Technologies during the 1990s - Peter W. Groeneveld, M.D., Principal Investigator; Alan Garber, Mentor [Awarded 2002]
Many studies have documented racial disparities in the use of many major medical procedures. However, it is unknown if rates of disparity have changed over time. Newer medical technologies may be utilized inequitably early in development with decreasing disparity in utilization as the technology diffuses and the volume increases. We examined discharge abstracts from a 20% random sample of elderly Medicare beneficiaries from 1989-1999 to measure overall procedure utilization among these patients. We used a modified version of the Agency for Healthcare Research and Quality's Clinical Classification System to identify 9 procedures that had expanded in use by at least 5% annually over this time period, and which had achieved substantial volume nationwide by the year 2000. We subsequently identified 11 comparable procedures which has modest (0-2.5%) annual growth in volume. After identifying diagnostic codes related to use of each procedure, we established 20 cohorts of patients (total N=9,851,866) who were potential candidates over the years 1989-2000. We performed multivariate logistic regression to determine if there were racial differences in procedure use within 90 days of hospital admission, and if such racial differences had changed over the 12-year study period. We noted significantly (p<0.01) lower procedure utilization rates in the year 2000 among black patients for five of nine emerging technologies, as well as for three of 11 established medical procedures. Among emerging technologies, only internal mammary artery coronary artery bypass grafting and cardiac electrophysiology studies showed significant trends of declining racial differences in utilization. Among established technologies, both spinal laminectomy and toe amputation occurred in more equivalent proportions of whites and blacks over time. Among elderly Medicare beneficiaries, lower technology utilization for blacks remains common for several medical procedures. However, substantial changes over time in the racial proportion of procedure use are uncommon. Reductions in racial differences in procedure utilization over time do not generally appear to be related to the growth rate of the technology.
Dr. Groeneveld completed his M.S. in Health Services Research in June, 2003, and is now an Assistant Professor of Medicine at the University of Pennsylvania School of Medicine in Philadelphia, and a Staff Physician at the Philadelphia VA Medical Center’s Center for Health Equity Research and Promotion.
Racial and Gender Differences in Refusal of Coronary Angiography - Paul A. Heidenreich, M.D., M.S., Principal Investigator; Mark McClellan, Mentor [Awarded 2000]
Racial and gender differences in the use of cardiovascular procedures are well documented. This study conducted a cohort analysis of non-federal acute care hospitals in the United States to determine the effect of patient refusal on racial and gender differences in coronary angiography utilization. In-hospital use and refusal of coronary angiography adjusted for patient comorbidities, severity of infarction, hospital, physician, and socio-economic status. 124,691 patients of age 65 or older admitted to hospitals performing coronary angiography were identified using the Cooperative Cardiovascular Project Database, which includes nearly all Medicare beneficiaries admitted with an acute myocardial infarction (MI) from February 1994 through July 1995. Out of the sample, 53,671 (43%), patients underwent angiography and 2,881 (2.4%) patients refused during hospitalization. Patients refusing angiography were more likely to be female (odds ratio 1.37, 95% confidence interval 1.23 – 1.53), black (odds ratio 1.26 versus whites, 1.02-1.56), and older (odds ratio 2.25 per 10 year increase, 2.05-2.43) when compared to patients that received angiography. Angiography use was less for blacks (odds ratio 0.78, 0.72-0.83) compared with whites, and for women (odds ratio 0.83, 0.80-0.86) compared with men. Increased refusal explained 6% of the difference in angiography use between whites and blacks and 16% of the difference between males and females. Patients who refused were twice as likely to die during the year following MI (31% vs. 16%), but this mortality difference disappeared after adjustment for patient characteristics. We found that elderly females and black patients are more likely to refuse angiography than are male and white patients. However, patient refusal is relatively uncommon and accounts for only a small fraction of the racial and gender differences in angiography utilization after MI.
This research was also supported by Dr. Heidenreich’s Career Development Award from the Veterans Affairs Health Services Research and Development Service.
Remembering Health Decisions - Mara Mather, Ph.D., Principal Investigator; Laura Carstensen, Mentor [Awarded 2000]
Contrary to popular stereotypes, aging is associated with improved emotional well-being, rather than increased depression. This enhancement in emotional well-being is associated with a greater focus on emotional goals as people age. We hypothesized that older adults’ greater focus on emotional regulation would lead them to engage in more memory distortion that supports decisions they made than among younger adults. Thus, in this study, we investigated whether older adults’ memories for health care choices are more gratifying than those of younger adults. Studies with younger adults reveal that they tend to remember their choices as being better than they actually were. These younger participants were asked to make memory attributions about features from previously considered options (e.g., was "easily discouraged" associated with the first job candidate, the second job candidate, or is it a new feature?). They attributed more positive features to the option they had chosen and more negative features to the option they had rejected. This choice-supportive asymmetry was evident both among those old features correctly attributed and those attributed to the wrong option. Choice-supportive asymmetries even occurred among those new features that were misattributed to one of the options. Younger participants ranged in age from 18 to 35 (M=25.4, N=108) and older participants ranged in age from 60 to 94 (M=73.1, N=103). Participants made four choices based on 2-option choice scenarios. We gave participants memory tests for the choice options either ten minutes or two days after they completed their choices. Half of the participants first listed all the features they could remember from the choice options and then completed a source identification test. The other half of the participants received the source identification test first, followed by the recall test. This repeated testing factor allowed us to see how one retrieval attempt might influence later retrieval attempts. We found that older adults were more choice supportive in their source attributions than younger adults. Furthermore, older adults were also more choice supportive in their free recall of the options than younger adults were. Older adults remembered the decision scenarios in a more positive light overall. Both recall and recognition (derived from the source attribution test) measures revealed that, in comparison with what older adults remember, a larger proportion of what younger adults remembered from the decision was negative.
Dr. Mather is currently an Assistant Professor of Psychology at the University of California, Santa Cruz. Her seed research was also supported by NIA grant R01-8816, awarded to Laura L. Carstensen.
Potential Cost Effectiveness of Genetic Screening for Sudden Cardiac Death - Gillian D. Sanders, Ph.D., Principal Investigator; Mark Hlatky, Mentor [Awarded 2002]
Recent advances in genomics have identified mutations in cardiac sodium channels that predispose affected people to cardiac arrhythmia and sudden cardiac death (SCD). Given the likely high costs of both genetic testing and subsequent treatment, and the uncertain effectiveness of these measures in preventing cardiac morbidity and mortality, the cost-effectiveness of using such genetic tests is very uncertain. We modified a previously developed Markov model to assess the cost effectiveness of screening the general population for a SCD-related mutation and prophylactically implanting an implantable cardioverter defibrillator (ICD) in those patients who tested positive. Based on a recently published variant of SCN5A sodium channel that may elevate the risk of SCD, our analysis assumed a mutation prevalence of 13% with an associated 8.7 relative risk of arrhythmic mortality. Consistent with existing genetic tests, our hypothetical test had a clinical sensitivity and specificity of 89% and 99% respectively, and cost $400. Sudden cardiac, nonsudden cardiac, and noncardiac death reflected mortality rates in the general US population. ICD implantation cost $30,000 and reduced arrhythmic mortality by 60%. The strategy of testing 55-year olds from the general population for a SCD-related mutation and implanting an ICD in those who tested positive (12.4% of population) resulted in an average life expectancy of 15.74 years at a cost of $55,350. Members of the population in the no-test strategy had both a lower life expectancy (15.59 years) and lifetime cost ($48,600). The incremental cost effectiveness of the genetic testing strategy was $47,012/LY compared to no testing. The genetic testing strategy remained below $50,000/LY as long as the genetic test cost less than $900. Our results are sensitive to both the prevalence of the mutation and the relative risk of arrhythmic mortality associated with a positive mutation. If the mutation is prevalent in 5% of the population, the relative risk would need to be greater than 5.1 or 10 to reach $100,000/LY and $50,000/LY respectively. If the relative risk of arrhythmic mortality associated with a mutation is less than 4.0, genetic testing for the mutation would not become economically favorable even if the mutation was prevalent in 30% of the population. The cost-effectiveness of genetic screening for sudden cardiac death is highly sensitive to both the prevalence and relative risk associated with the mutation. Given initial epidemiological data, the identification of SCD-related mutations is plausible. Although our work models a hypothetical genetic test, our model allows us to readily assess the value of using a genetic test or prognostic marker in a cohort of patients as such markers become available.
Dr. Sanders recently accepted a tenure-track position as an Associate Professor at the Duke University Clinical Research Institute in Durham, North Carolina.
Uxorilocal Marriage, Old-Age Security, and Son Preference in Rural China - Li Shuzhuo, Ph.D., Principal Investigator; Marcus Feldman, Mentor [Awarded 2000]
This project studied the generational patterns and trends in uxorilocal marriage, the predictors for this type of union, and related policies in three counties in western and central China that affect old-age security. Cluster sampling with at least 500 couples in each county was employed. The strict population-control policy in China has resulted in below-replacement fertility and exacerbated the age-old preference for sons. Because of the population policy increasing proportions of rural couples do not have a son, which by tradition jeopardizes their old-age security. As a substitute, in some places, couples are opting to live alongside son-in-laws, representing a dramatic shift in Chinese rural marriage customs. Determinants of uxorilocal marriage vary by county and include educational attainment, belonging to a large family, age at marriage, marriage arrangement, adoption status, a couple's parental marriage type, sibling composition, and their attitudes towards uxorilocal marriage. We also find that community and government initiatives are necessary to promote the acceptance and practice of uxorilocal marriage in rural China so as to provide old-age security for couples without a son, and consequently to mitigate strong son preference.
National Trends in the Use of Recommended Cardiac Medications, 1990-2001 - Randall S. Stafford, M.D., Ph.D., Principal Investigator; Mary Goldstein, Mentor [Awarded 2001]
Previous studies indicate that recommended cardiac medications are underutilized among the elderly. To evaluate recent trends, we examined longitudinal national data on the outpatient use of warfarin in atrial fibrillation, beta-blockers and aspirin in coronary artery disease, and ACE inhibitors in congestive heart failure. We used the IMS Health, National Disease and Therapeutic Index (NDTI) for 1990-2001 and the National Ambulatory Medical Care Surveys (NAMCS) for 1990-1999 to follow nationally representative samples of outpatient visits. For visits by patient with atrial fibrillation (total N=14,634 visits), coronary artery disease (N=35,295), and congestive heart failure (N=33,008), we examined trends in the proportion of visits with the selected medications reported. Warfarin use in atrial fibrillation increased from 12% in 1990 to 41% in 1995 to 58% in 2001 in NDTI; a similar moderation of recent increase was seen in NAMCS. For coronary artery disease in NDTI, beta blocker use increased slowly from 19% in 1990 to 20% in 1995 then to 40% in 2001; NAMCS showed this same pattern. Aspirin use in coronary artery disease in NDTI increased from 18% in 1990 to 19% in 1995 to 38% in 2001; NAMCS, however, showed lower use rates. For NDTI, ACE inhibitor use in congestive heart failure increased from 24% in 1990 to 36% in 1996, but increased to only 39% by 2001, a general pattern also seen in NAMCS. Both national datasets demonstrate increased use of recommended cardiac medications. Use remains lower than expected, however, and some increases have slowed. Substantial public health benefits would result from further adoption of these effective therapies.
The Stanford Survey of Health Care and the Internet - Todd H. Wagner, Ph.D., Principal Investigator; Laurence Baker, Mentor [Awarded 2001]
The Internet is an important source of health information and a tool for interaction and communication between patients, their families and friends, and the health care delivery system. Older adults, who are more likely to have health concerns and to interact more frequently with the health care system than younger individuals, have the potential to benefit significantly from greater use of information technologies. Prior surveys suggest that the prevalence of Internet use among older adults is much lower compared to younger age groups. One study found that the prevalence of Internet use among children and teenagers is over 75%, plateaus at higher levels among adults age 21 to 49, and declines steadily at older ages to about 10% by age 80. These numbers suggest that Internet applications for health may not be accessible to older populations who could potentially benefit from them. We surveyed 8,935 adults aged 21 and over, oversampled for older adults, and drawn from a survey research panel of over 60,000 households, to examine between the relationship between age and self-reported Internet use for health. We measured self-reported Internet use; Internet and email use for health care among Internet users; and effects of Internet use on health care knowledge, decisions, and utilization. We compared differences in these measures by age, adjusting for sex, income, education, self-reported health status, and urban residence. We found that adults 70 and over were less likely than younger individuals to use the Internet at all. Of those who used the Internet, 29% of those 70 and over reported using the Internet for health information compared to 40% of 21-69 year olds (p=.008). Respondents 60 and older were 2-3 times as likely to report purchasing a prescription using the Internet than those 21-59 (p<.001). Perceptions about the effects that Internet use had on health and health care use did not differ by age. These findings suggest low rates of Internet use for health care, particularly among adults aged 70+. Internet use for health among older adults is lower than among younger adults, but among those who use the Internet for health, the perceived benefits are similar.
This research was also supported by funding from the Department of Veterans Affairs, and the Stanford University Office of Technology and Licensing.
Similar Physiology but Different Determinants? Comparing the Dimensionality and Determinants of Physical Functioning Among Community-dwelling Older Adults in China and the United States - LiJing L. Yan-Li, M.P.H., Ph.D., Principal Investigator; Marcus Feldman, Mentor [Awarded 2000]
Using data from the China Health and Nutrition Survey 1993 (N=2,014 for ages 50+, and N=656 for ages 65+; community dwelling), and from the U.S. National Long Term Care Survey 1994 (N=4,731 ages 65+; Medicare population in a detailed community sample only), ordinary least squares (OLS) regressions showed similar dimensionality of functioning measures across countries and cultures with a common physiological basis, but different impacts of potential determinants (age and gender; marital status, race, and residence; education and income; drinking and smoking; and cultural and reporting factors in self-rated health). In the United States, self-reported health status is the most important predictor of functional limitations in the elderly U.S. population. These activities of daily living, including climbing stairs, eating without help, and lifting 10 pounds, are influenced much less by socioeconomic characteristics such as gender, marital status, and income.
Dr. Yan-Li is now a researcher at Northwestern University.
Supported by funding from the National Institute on Aging (NIA)
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