Biomedical subjects

K G Manton

Publications and source records attributed to K G Manton.

At least 55 records · Page 3Linked to original sources

PubMed1994

Home health and skilled nursing facility use: 1982-90.

In this article, analyses are made of home health and skilled nursing facility (SNF) use for the period 1982-90 using Medicare records linked to data on community and institutional residents from the National Long-Term Care Surveys (NLTCSs) of 1982, 1984, and 1989. The combined survey and administrative data analyses are performed to ascertain how the chronic health and functional characteristics of community and institutional residents using Medicare-reimbursed services changed during the period. During this period, changes had been made in the Medicare system that affected the use of services for persons with specific health and functional problems.

Activities of Daily Living↗

PubMed1993

Methods for combining ancillary data in stochastic compartment models of cancer mortality: generalization of heterogeneity models.

"We present a mortality model where nationally representative survey data on risk factor distributions are combined with data on cohort mortality rates to increase information, i.e., a fixed marginal risk factor distribution is combined with a cohort model representing unobserved individual risk heterogeneity. The model is applied to lung cancer mortality in nine U.S. white male cohorts aged 30 to 70 in 1950 and followed 38 years. Estimates of the cohort specific proportions of smokers were made from the National Health Interview Survey. Comparisons are made for models with different patterns of changes with age of individual heterogeneity." (SUMMARY IN FRE)

Americas↗

PubMed1993

Estimates of change in chronic disability and institutional incidence and prevalence rates in the U.S. elderly population from the 1982, 1984, and 1989 National Long Term Care Survey.

The U.S. elderly (65+) and oldest-old (85+) populations are growing rapidly which, combined with their high per capita acute and long-term care needs, will increase total U.S. health care needs. Also important in determining needs is how health and function change as mortality declines in the elderly population. Recent increases in adult life expectancy have been due to declines in stroke and heart disease mortality. There is controversy, however, about how those declines relate to the health and function of survivors. We examined changes in the prevalence and incidence of chronic disability using the 1982, 1984, and 1989 National Long Term Care Surveys. The total prevalence of U.S. chronically disabled community-dwelling and institutionalized elderly populations declined from 1984 to 1989, overall, for each of three age strata and after mortality adjustment. These changes varied over level of disability. Factors contributing to these changes, including measurement, are reviewed.

Activities of Daily Living↗

PubMed1993

Forecasts of active life expectancy: policy and fiscal implications.

Age-related changes in functional status can be summarized by active life expectancy (ALE) measures. ALE is useful in assessing efforts to improve function and in determining a population's service needs. ALE disaggregates total life expectancy (TLE) into components representing degree and type of impairment. We illustrate the calculation of two ALE measures and their relations to health inputs and service use. First, scores are calculated from 27 measures of function for persons 65 and over, as reported in the National Long Term Care Survey (NLTCS). The scores are then used to calculate the two ALE measures. Results are compared to ALE calculated from the 1982, 1984, and 1989 NLTCS.

Activities of Daily Living↗

PubMed1993

Changes in the use of personal assistance and special equipment from 1982 to 1989: results from the 1982 and 1989 NLTCS.

Analysis of data from the 1982, 1984 and 1989 National Long-term Care Surveys suggests that long-term care use is changing. Between 1982 and 1989, equipment use by persons with light physical impairment, or to supplement personal assistance for the severely disabled, increased. Over this same period, there was a decline in the use of personal assistance as the sole modality to deal with chronic impairments. Since equipment costs are nonrecurrent, whereas personal assistance costs are recurrent, this finding has implications for long-term care policy.

Activities of Daily Living↗

PubMed1993

A multivariate analysis of disability and health, and its change over time in the National Channeling Demonstration data.

The Channeling Demonstration examined the effects of case management interventions on a variety of outcomes. In the study, longitudinal data were collected from interviews of cases and controls. A multivariate procedure applied to this data identified groups with specific health profiles. Six profiles described health variation over individuals, and time, according to likelihood ratio statistics. Six sets of life tables were calculated, one for each health profile, to estimate the average duration of service use and the "follow-up" services used. A number of differences, and changes, in service use between the six groups were significant.

Activities of Daily Living↗

PubMed1993

Social/health maintenance organization and fee-for-service health outcomes over time.

Evaluating the performance of long-term care (LTC) demonstrations requires longitudinal assessment of multiple outcomes where selective mortality and disenrollment, if not accounted for, can give the appearance of reduced (or enhanced) efficacy. We assessed outcomes in social/health maintenance organizations (S/HMOs) and Medicare fee-for-service (FFS) care using a multivariate model to estimate active life expectancy (ALE). S/HMO enrollees and samples of FFS clients in four sites were analyzed and outcome differences assessed for a 3-year period. Results provide insights into S/HMO performance under different conditions and, more generally, into evaluating LTC demonstrations without randomized client and control groups.

Activities of Daily Living↗

PubMed1993

Use of Medicare services before and after introduction of the prospective payment system.

OBJECTIVE: The case mix-adjusted pattern of use of health care services, especially posthospital care, is compared before and after the introduction of Medicare's Prospective Payment System (PPS). DATA SOURCES: The 1982 and 1984 National Long Term Care Surveys (NLTCS) linked to Medicare administrative records 1982-1986 provide health and health service use data for 12-month periods before and after the introduction of PPS. STUDY DESIGN: Case-mix differences between pre- and post-periods are controlled by using the Grade of Membership model to identify health groups from the NLTCS data. Differences in timing (e.g., hospital length of stay) were controlled using life table models estimated for each health group, that is, service use patterns pre- and post-PPS are compared within groups. PRINCIPAL FINDINGS: Hospital LOS and admission rates declined post-PPS. Changes in the timing and location of death occurred but, overall, mortality did not increase. Changes in post-acute care service use by elderly, chronically disabled Medicare beneficiaries were observed: home health service use increased overall and among the unmarried disabled population. CONCLUSIONS: PPS did not adversely affect quality of care as reflected in mortality or in hospital readmissions. Moreover, the differential use of post-acute care, and changes in hospital LOS by health group, indicate that the system responded, specific to marital status and age, to the severity of needs of chronically disabled persons.

Age Factors↗

PubMed1992

Projecting the future size and health status of the U.S. elderly population.

"A projection model based on a multivariate continuous state, stochastic process is presented. The model allows multiple time-varying covariates to be used so parameters can be estimated from time series information on health changes and mortality, and their interaction. Health changes are simulated by altering parameters controlling the age trajectory and diffusion of risk factor means, variances, and covariances....By increasing the information used in projections it may be possible to better (a) anticipate the state of health at extreme ages, (b) forecast changes in health at specific ages over time, (c) stimulate the effects of specific interventions, and (d) determine the sensitivity of outcomes to a range of interventions."

Adult↗

PubMed1992

Risk factor dynamics, mortality and life expectancy differences between eastern and western Finland: the Finnish Cohorts of the Seven Countries Study.

Prior studies have not accounted for male mortality being higher in east than west Finland. Efforts to identify the mechanisms producing higher mortality in the east, due primarily to cardiovascular diseases (CVD), initially focused on a search for new risk factors. An alternate approach is to examine the assumptions of the analysis. This was investigated using a model which described (a) changes in risk factors over time, (b) dependency of risk factor effects on age, and (c) interactions and nonlinear effects of risk factors on mortality. The model was applied to 25-year follow-up data from cohorts of eastern (N = 823) and western (N = 888) Finnish men using pulse pressure, diastolic blood pressure, body mass index, total cholesterol, vital capacity index, cigarette smoking, and heart rate as risk factors. At age 40, men in the west had a life expectancy 2.4 years higher. Of the difference 29% (0.7 years) was associated with area differences in risk factor means, variances, and their change with age. The remainder, 1.7 years, was associated with age differences in the relation of risk factor interactions to CVD mortality. Possible reasons for these differences, such as joint elevation of several risk factors inducing rapid progression of atherogenesis, are discussed. No significant area differences were observed for mortality from either cancer or other causes.

Adult↗

PubMed1992

Analysis of underwriting factors for AAPCC (adjusted average per capita cost).

The adjusted average per capita cost (AAPCC) formula is used to determine payment to health maintenance organizations (HMOs) by Medicare. The four original underwriting factors (i.e., age, sex, institutional status, and welfare status) for the AAPCC were calibrated from the Current Medicare Surveys for 1974-76. Those factors have been updated by various actuarial adjustments. Revised calculations of the AAPCC underwriting factors are presented using survey data from the 1984 National Long-Term Care Survey and expenditure data from the Medicare Part A and Part B bill files. Also examined is the effect on the underwriting factors of chronic functional disability, defined as having one or more chronic limitations in activities of daily living. Comparison of alternative underwriting factors is conducted by simulating the dollar impact on payment to HMOs for select enrollee populations.

Actuarial Analysis↗

PubMed1992

Forecasting health: data needs and implications for model structure.

An agenda for analysing data on the health and functioning of the elderly must indicate new types of data to be collected, innovations in data collection strategies and new methods for analysis and forecasting. The required research agenda is broad and will require inputs from investigators in a number of disciplines. The data and methods required will need to be developed in order to reflect national, regional and local variations in the health phenomena under study; they will also have to be responsive to these variations. In the end, however, if the investment is to be most useful, it must be integrated into simulation and forecasting models, the mechanics of which are based on individual-level processes and not on the elements of the service system.

Breast Neoplasms↗

PubMed1992

Demographics (1950-1987) of breast cancer in birth cohorts of older women.

The effects of screening on breast cancer mortality, incidence, and prevalence were investigated using a general forecasting and simulation model. First, a biologically motivated model of disease incidence and mortality was fit to the breast cancer mortality experience of 15 U.S. White female birth cohorts followed for a 38-year period. The model assumed that breast cancer was the result of two different diseases. The first, or "premenopausal" disease, tends to have strong associations with the family history of disease and to be histologically more aggressive. The second, "postmenopausal" disease, occurs at more advanced ages, is apparently less strongly linked to family history, and is less aggressive with different histological characteristics (e.g., positive estrogen receptor status). Those results were used to forecast the effects of screening on the stage at diagnosis to simulate a screening program which reduced late-stage diagnoses by 50%. This produced large reductions in breast cancer mortality--an impact larger for disease associated with late age of onset.

Aged↗

PubMed1991

Blood pressure and mortality risk in the elderly.

Blood pressure was assessed between 1981 and 1983 in all persons over age 65 years in three communities (East Boston, Massachusetts; New Haven, Connecticut; and Iowa and Washington countries, Iowa), and cause-specific mortality was monitored annually over the subsequent 5 years as part of the National Institute on Aging-sponsored Established Populations for Epidemiologic Studies of the Elderly. Each community had 80% or more participation: in East Boston, 3,809 persons with 903 deaths, in New Haven, 2,812 persons with 804 deaths, and in Iowa, 3,673 persons with 763 deaths. At 2 years, odds of death from all causes were higher in the low (less than 130 mmHg) than the middle (130-159 mmHg) systolic blood pressure group for persons aged 65-79 years in all three populations. By 5 years, cardiovascular death increased with increasing systolic pressure in all three communities and reached significance in Iowa. Cancer death was highest in the low systolic pressure stratum in all three centers. All-cause, cardiovascular death, and cancer mortality was highest in the low (less than 75 mmHg) diastolic blood pressure group in East Boston, even at 5 years. Blood pressures obtained 9 years earlier in 2,079 (68%) of the East Boston participants showed a significantly higher risk of cardiovascular death with increasing systolic pressure and no relation between diastolic pressure and mortality risk. In the elderly, excess mortality at lower levels of blood pressure during early follow-up may in part be due to the effects of illness and disability present at baseline. This may obscure the usual rise in mortality with increasing systolic pressure. There is no consistent relation between diastolic pressure and mortality.

Aged↗

PubMed1991

Analyses of black and white differentials in the age trajectory of mortality in two closed cohort studies.

We examine the relationship of age to mortality in blacks and whites in two cohort studies, the 20-year follow-up of the Evans County, Georgia. Study population and the 25-year follow-up of the Charleston Heart Study population. We conducted analyses with two parametric forms of hazard models (Gompertz and Weibull) for total mortality experience and considered the fit of the two hazard models in each study both separately and with the data pooled. We evaluated the robustness of conclusions about differences in the age pattern of mortality for blacks and whites by comparing results from the two hazard models. Where the tests were non-nested, we used an information-based statistic (AIC) to compare the fit of the models to the data. Results were robust to the selection of the hazard function, that is both models provided evidence that mortality rates at younger ages were lower for white than black females but that mortality rates increased more rapidly with age for white females. The absolute differences and the differences in the rates of increase were in the same direction, but smaller, for males. Though both models represented the general features of mortality patterns, the information statistic suggested better performance of the Gompertz function. The Gompertz function was also less sensitive to the initial age of determination of mortality exposure.

Adult↗

PubMed1991

Grade of Membership generalizations and aging research.

The Grade of Membership (GOM) model is a general multivariate procedure for analyzing high dimensional discrete response data. It does this by estimating, using maximum likelihood principles, two types of parameters. One describes the probability that a person who is exactly like one of the K analytically defined types has a particular response on a given variable. The second describes each individual's degree of membership in each of the K types. This "partial" membership score reflects the logic of the fuzzy partitions (rather than of discrete groups) that are employed in the analyses. By modifying the probability structure of the basic model we show how the procedure can be applied to a number of different types of data and analytic problems. The utility of the different GOM models for different types of aging research is discussed.

Aging↗

PubMed1991

Cross-sectional estimates of active life expectancy for the U.S. elderly and oldest-old populations.

Estimates are made of active life expectancy for the U.S. elderly and oldest-old populations using data from the 1982 and 1984 National Long Term Care Surveys. In the calculation of active life expectancy a multivariate analysis of 27 measures of functioning was used to define scores to decompose total life expectancy by type and level of disability. These analyses showed significant differences in active life expectancy for males and females. Though a higher proportion of male life expectancy at age 65 was "active," females had larger absolute amounts of active life expectancy. By age 85, in contrast, males had a higher absolute amount of active life expectancy. In addition, calculations were performed with the disability associated with cognitive impairment eliminated in order to illustrate the sensitivity of active life expectancy to changes in morbidity.

Activities of Daily Living↗

PubMed1991

Cancer mortality, aging, and patterns of comorbidity in the United States: 1968 to 1986.

Cancer is often reported as contributing to the risk of noncancer causes of death. The age variation of these reports was studied using U.S. data on all causes of death listed on death certificates for 1968 to 1986. The occurrence of cancer as a nonunderlying cause of death increased with age and was higher for treatable and slowly growing tumor types. These patterns persisted even if the cancer manifested changes in occurrence. Nonunderlying occurrences were highest in the 85 to 94 age group and were correlated with cancer survival. This suggests increased importance of cancer as a cause of death and a comorbid condition among oldest-old persons. The high rate of occurrence as an associated cause of death suggests that if life expectancy increases due to declines in circulatory and other chronic disease mortality, cancer could become the preeminent cause of death in the United States.

Age Factors↗