This monograph introduces the Women's Health and Aging Study (WHAS). The WHAS, funded by the National Institute on Aging, is a prospective, observational study of 1,002 women age 65 years and older who were moderately to severely disabled, but not severely cognitively impaired, at study entry. These women represent the approximately one-third most disabled older women living in the community. This monograph presents comprehensive information on their physical disability; health status, including disease and physiologic measures; health care and service utilization; and their daily lives. It also describes the representative population of women age 65 years and older from which the WHAS study population was drawn. These data were obtained from November 1992 to February 1995 during the baseline recruitment and evaluation of WHAS participants.
The goal of the WHAS is to determine the causes and course of physical disability. Using data from the baseline assessment, presented in this monograph, and from followup assessments performed every 6 months over 3 years, the study will:
This introduction provides a framework for the data presented in this monograph, including the significance of disability for older adults and for older women in particular, an overview of the design and methods of the WHAS, and a description of the areas of unique data offered by this study.
The dramatic increases in life expectancy over the 20th century, the resulting increase in the older population, and the rising costs of long-term care have made age-associated disability and dependency matters of national concern. Overall, 40 percent of people age 70 years and older report limitations in their ability to carry on their usual activities (Cohen and Van Nostrand, 1995). According to the 1990 U.S. Census, among persons age 65 years and older, 16 percent have difficulty with basic mobility-related activities such as walking short distances, and 12 percent have difficulty with basic self-care tasks (LaPlante, 1993). Five to 8 percent of noninstitutionalized adults age 65 years and older receive help with one or more activities of daily living (ADLs) (Wiener et al., 1990). In addition to this disability in community-dwelling older adults, 7 percent of people age 65 years and older reside in a nursing home, including 8 percent of women and 5 percent of men (Feinleib et al., 1994). Ninety percent of these individuals are dependent in one or more ADLs (Hing et al., 1989). Clearly, disability and dependency are highly prevalent in older adults.
Disability in old age is associated with poor quality of life, dependence on formal and informal care providers, and often substantial medical and long-term care costs. In addition, disabled persons are at increased risk of other adverse health outcomes, including further declines in function (Branch et al., 1984; Manton, 1988), acute illnesses and injuries (Branch and Meyers, 1987; Fried and Bush, 1988), falls (Nevitt et al., 1989; Tinetti et al., 1986, 1988), recurrent hospitalization, and mortality (Branch, 1980; Corti et al., 1994; Koyano et al., 1986; Manton, 1988; Warren and Knight, 1982). The more severe the disability, the higher the risk of these outcomes. Successful prevention or delay of disability could make a substantial difference in health status and well-being, as well as in the care needs and care costs of the older population.
The high health care needs and costs of disabled older adults (Fried and Bush, 1988; Soldo and Manton, 1985) may result from the diseases that underlie disability, the severity of disease, and/or the presence of comorbid conditions. Recent research has added much to our understanding of the associations of specific diseases and comorbidity with physical disability. The major diseases reported to be associated with disability include heart disease, osteoarthritis, hip fracture, diabetes, intermittent claudication, stroke, chronic obstructive pulmonary disease, visual impairment, hearing impairment, depression, and cognitive impairment. Effective prevention requires an understanding of the types of disability caused by specific diseases, the mechanisms underlying the etiology of disability, the relationship between disease severity and the development and progression of disability, and the interactions of specific comorbid diseases.
The WHAS seeks to define these aspects of disability in older women for a number of reasons. Women make up the majority of the older population, represent a larger proportion of the total population at each higher age, report higher rates of physical disability, and spend more years in a disabled state. They also make up a substantially larger proportion of the nursing home population and are more vulnerable in terms of need for formal and informal care because of their higher rate of widowhood, especially at the oldest ages. The burden of disability in older women has wide-ranging and profound effects on older women themselves, their families, and the health care system. While it was recognized in designing this study that potentially valuable male-female comparisons are sacrificed by examining women only, and that certain findings on the causes and course of disability in women may not hold true in men, the magnitude of the problem in women and the analytic power gained by studying women only made this a compelling focus.
In 1991, the Institute of Medicine of the National Academy of Sciences published the priorities for a national agenda for aging research (Lonergan and Krevans, 1991). Its first priority in three of five areas included research "on the causes, prevention, management, and rehabilitation of disability," "on the most important social and psychological techniques to maintain and improve . . . level of functioning among older persons," and on "the factors that determine the need for and use of long-term care" (Lonergan and Krevans, 1991, pp.1826-1827). The data from this study will provide important information, with a breadth and level of detail generally not available, that will aid the policy and scientific communities in addressing these issues.
The study population for the WHAS was obtained by drawing a random sample from the Health Care Financing Administration's Medicare enrollment file for the 32,538 women residing in 12 contiguous Zip Code areas in Baltimore, Maryland (see Figures I.1 and I.2). This sampling frame represented all female Medicare beneficiaries as of September 1, 1992. An age-stratified (65-74, 75-84, 85 and older) random sample was selected, yielding 6,521 women for screening to determine study eligibility (see Appendix A for details on sampling). The Health Care Financing Administration sent a letter to each woman describing the study. Two weeks later the study Principal Investigator (Linda P. Fried) sent a second letter inviting their participation. A study interviewer contacted women in their homes to administer the screening questionnaire and determine study eligibility. Women residing in nursing homes at the time of contact and those no longer living in the catchment area were not eligible for screening. (Some women who were listed on the Medicare files were found to be deceased.) Of those sampled, 5,316 women were eligible for screening: 1,179 women could not be located or contacted, or refused screening, and 4,137 women were screened.
The screening interview was designed to identify the approximately one-third most disabled older women living in the community. The approach used was derived from previous research in which factor analyses indicated a clustering of difficulty in certain tasks, such that difficulty in one task was associated with difficulty in the other tasks in the group (Fried et al., 1994). It was found that physical disability can be usefully categorized into four domains consisting of related tasks primarily associated with: (1) mobility and exercise tolerance; (2) upper extremity function; (3) higher functioning tasks (a subset of instrumental activities of daily living, not including heavy housework); and (4) basic self-care tasks (a subset of non-mobility dependent ADLs). Using this domain-oriented approach, evaluation of population-based data (1984 National Health Interview Survey data from the Supplement on Aging) indicated that individuals who reported difficulty in two, three, or four domains represented one-third of persons residing in the community (WHAS Manual of Operations, 1993). This conceptual approach and empirical analysis provided the basis for defining study eligibility, based on self-report of difficulty in tasks in two or more domains of function (see Appendix B for screening instrument).
Details of screening and eligibility criteria are discussed in Chapter 1. In brief, of the 4,137 women age 65 years and older who were screened, 3,841 were able to complete the interview on their own, 1,409 met study eligibility criteria, and 1,002 agreed to participate in the study.
After signing an informed consent, study participants received an extensive interview in their homes. This interview ascertained many aspects of physical function and disability, including tasks affected, severity of difficulty or dependency, and adaptations to disabilities (Fried et al., 1991). Also assessed were history of physician diagnosis, symptoms and severity of over 20 diseases and conditions, current use of prescription and nonprescription medications, psychological functioning, social support and social networks, health-related behaviors, and health care and service utilization. The questionnaire for the baseline interview can be found in Appendix B. The interviewer also administered several performance-based measures of functioning (functional reach, lock and key, buttoning a blouse, using a telephone, visual memory, and block construction), and measured height, weight, and visual acuity (see Appendix C).
Two weeks later, by appointment, a trained nurse using a standardized protocol (see Appendix D) conducted a 4- to 5-hour examination of the study participant in her home. The goal of the examination was to validate the presence of specific diseases and physiologic states and to characterize their severity. The examination included the following: blood pressure and heart rate; anthropometry; electrocardiogram and auscultation of the heart and lungs; 4-hour ambulatory electrocardiogram; ankle:arm blood pressure ratio; assessment of musculoskeletal disease through examination of the joints and hand photographs; screening audiometry; and pulmonary function assessed statically using spirometry and dynamically using measurement of oxygen desaturation at rest and with exercise. The nurse also conducted the following performance-based measures in the home: semi-tandem, tandem, and side-by-side stands as measures of static postural stability; strength measures: grip, pinch, and lower extremity strength assessed by dynamometry and upper arm strength by lifting a 10-pound weight over the head; a 4-meter measured walk at usual and rapid pace; single and five repeated chair stands; Purdue Pegboard; and, for those eligible, a graded exercise test (seated step test) while monitored.
Through supplemental funding from Corning Clinical Laboratories, the study also performed phlebotomy on participants who signed a separate informed consent; approximately 75 percent agreed to the procedure. A trained phlebotomist visited the participant's home, by appointment, and phlebotomy was performed following a standardized protocol. After initial processing, Corning Clinical Laboratories analyzed fresh blood specimens for hematologic, biochemical, and hormonal characteristics of participants. Merck Research Laboratories provided support for the creation and maintenance of a blood repository.
Detailed descriptions of the examination instruments and procedures are provided in the relevant chapters of this monograph.
A core element of this study was to characterize the prevalence of the major chronic diseases in older adults, with comparably rigorous ascertainment for each disease. To accomplish this, algorithms were established for each of 16 diseases, utilizing state-of-the-art epidemiologic and clinical criteria for the presence of disease. These algorithms and appropriate references are found in Appendix E. Disease presence was validated through self-report of physician diagnosis of disease, reported symptoms, signs or physiologic measures obtained in the nurse's examination, and medication use. These data were supplemented, as necessary, with confirmation of diagnosis through questionnaires completed by the participant's primary care physician (see Appendix F) and with ongoing surveillance of medical records.
Finally, a small subset of WHAS participants were invited to participate in the Weekly Disability Substudy, a 6-month study aimed at characterizing short-term variability in function and testing the reliability of both self-report and performance indicators of functioning. The study was designed to select a sample of approximately 100 women, with equal numbers of subjects in each of nine cells defined by age (65-74, 75-84 and 85 years and older) and level of disability (two, three, or four domains of disability). The women were visited weekly over 6 months. Overall, 113 women, evenly distributed in the nine cells, agreed to participate in this substudy; 6 dropped out after the first interview and 8 had fewer than 5 visits, effectively creating a final substudy population of 99 women. During weekly interviews, women were asked about physical function and incident acute and chronic diseases or injuries. Selected performance-based tests of function also were administered.
No study has evaluated a representative sample of disabled older women living in the community in the breadth and depth attempted by the WHAS. It is hoped that the comprehensive information on the presence and severity of disease, obtained using physiologic and clinical measures, and the rich data characterizing the dimensions of functioning, will make it possible to unravel the complexities of functional decline in older women. In addition, the prospective component of the study (6-month followup interviews over 3 years) will characterize change in function and relate it to underlying changes in disease status, taking into account the impact of medical care, psychosocial factors, and important life events.
We expect this monograph to be of interest to a diverse group of people concerned with issues of aging, chronic disease, functional decline and disability, and provision of long-term care services. The data selected for presentation are relevant to those involved in population-based and clinical re- search, geriatric care, and policy development. The chapters that follow present the baseline descriptive data from the WHAS on the functioning, diseases and other health, psychosocial, service utilization, and demographic characteristics of the one-third most disabled older women living in the community, as well as data from the population from which the study participants were drawn. The WHAS provides unique data on the heterogeneity of function even within the most disabled segment of the population, as well as on adaptations to disability employed by these disabled older women. The in-home nurse's examination also provides substantial depth in terms of describing exercise tolerance and a range of physiologic and disease characteristics. Finally, these data offer important insight into the daily lives of the participants.
Chapter 1 describes the characteristics of the entire screened population, the screening methods and eligibility criteria, and comparisons between those women who were and were not eligible for the WHAS. Chapters 2, 3 and 4 describe the heterogeneity of functioning in older, disabled women through both self-report and performance-based measures, and through the compensations adopted to maximize function. Chapter 5 describes the day-to-day living circumstances and characteristics of these community-dwelling, disabled women. Chapter 6 provides data on health care utilization and coverage and receipt of preventive services in this population of women, who are likely to be among the greatest consumers of care. Chapter 7 provides extensive information on the instrumental and emotional support received by these disabled women. Chapter 8 describes psychosocial characteristics and perceived quality of life. Chapters 9 and 11 through 14 offer medical history, reported symptoms, and the results of physiologic measures obtained on home examination to characterize presence, manifestations, and severity of cardiovascular, pulmonary, musculoskeletal, and neurologic diseases, and of visual and hearing impairment. Chapter 10 describes exercise tolerance using both graded exercise testing and self-report, as well as distributions of body mass index and triceps skinfolds. Chapter 15 offers extensive data on medications used by these disabled older women with high rates of comorbidity. Finally, Chapter 16 provides insight into hematologic, biochemical, and thyroid function characteristics. Appendices provide technical details of the sample design and disease ascertainment methodology (Appendices A, E, and F). The full instruments of the WHAS are also included to facilitate their use by the scientific community, including screening and baseline questionnaires (Appendix B), and study protocols for the interviewer's objective assessment of physical function (Appendix C) and the nurse's physical examination (Appendix D).
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