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Biomedical subjects

K G Manton

Publications and source records attributed to K G Manton.

At least 91 records · Page 5Linked to original sources
PubMed1988

Racial differences in acute lymphocytic leukemia mortality and incidence trends.

Mortality and morbidity rates for childhood leukemia are examined with reference to time trends and racial differences. Prior to 1964, white and nonwhite children had very different acute lymphocytic leukemia (ALL) mortality rates. With the advent of successful chemotherapy, the mortality rate of ALL in white children has decreased resulting in virtually no racial differences in ALL mortality. The reasons for a stable ALL mortality rate in nonwhite children despite successful chemotherapy include poor access to health care, undefined socioeconomic factors and a biologically different type of ALL occurring in nonwhite children. Recent data from two cancer surveys (1969-1971, 1973-1976) reveal that nonwhite children have a lower incidence of ALL than white children. Underreporting in the nonwhite children could partly account for the difference, but other contributing factors might include a genetic predisposition, undefined socioeconomic influences, and perhaps, a viral agent. Further studies of the factors contributing to racial differences in ALL incidence and mortality are needed.

Adolescent↗
PubMed1988

A longitudinal study of functional change and mortality in the United States.

Studies of functional impairments in the U.S. elderly population have tended to rely on prevalence estimates from nationally representative health and institutional surveys. These prevalence estimates generally show higher rates of disability for females than males. Unfortunately, prevalence estimates can be misleading when one attempts to assess the risks of certain types of health event transitions for individuals. This study directly examined the individual transitions both into and out of functionally impaired states using longitudinal data from the 1982 and 1984 National Long Term Care Surveys (NLTCS). The data show that, even at very high levels of impairment, there are significant numbers of community residents who apparently manifest long-term improvement in functioning. The longitudinal data also show that the risks of becoming disabled are roughly the same for males and females. This suggests that sex differences in the national prevalence of disabilities arise from the greater longevity of females at any given level of age and functional impairment.

Activities of Daily Living↗
PubMed1988

Trends in US suicide mortality rates 1968 to 1982: race and sex differences in age, period and cohort components.

Interest has recently emerged in increases in suicide among US teenagers. Nonetheless suicide remains one of the major causes of death among the fastest growing components of the US population--the elderly. We examine the trends in US age-specific suicide rates for the period 1962 to 1981 for four elderly race and sex groups. The trends were analysed using a Poisson regression model which isolated the age, period, cohort effects for suicide mortality for demographic groups. Age, period and cohort effects all significantly contributed to these trends. The race and sex differences were largest for the age pattern of changes in suicide mortality. Of particular interest was the different contribution of each of these factors to recent increases in mortality at advanced ages for black males--a hitherto little recognized or studied trend.

Adult↗
PubMed1988

The global impact of noncommunicable diseases: estimates and projections.

With the aging of populations in developing countries there is both a demographic and an epidemiological transition which affects the impact of chronic degenerative diseases on the health status of the populations. Demographic transition takes place in countries where there are effective programmes of disease control which allow for survival during the early years of childhood and adolescence. This results in an increase in life expectancy which places larger proportions of the population in the age range (60 years and older) in which chronic degenerative diseases become the major determinants of health status. Epidemiological transition in diseases may also be brought about by shifts in social and economic patterns which favour detrimental changes in risk factors for the chronic degenerative diseases. Such changes may include health-related behaviour which augments dietary consumption of fats and alcohol, increases obesity, increases smoking and decreases physical activity. Such changes in risk-factor levels increase the prevalence of chronic degenerative diseases which manifest themselves at later ages, and for which early preventive actions could be cost-effective. In order to illustrate the impact of both demographic and risk-factor effects, analyses are made of the impact of increases in life expectancy on cause-specific mortality in both developing and developed countries. It is shown that there is great similarity in the effect of major noncommunicable diseases on the life expectancy of adults in both developed and developing countries. The major differences are seen to be in the proportions of deaths expected from such diseases as cancer, diabetes, heart disease, stroke and cirrhosis; but not in the distribution of age at death which is the better measure of disease impact. Demographic analyses, computing indirect estimates of mortality, also demonstrate that there are currently more chronic disease deaths in developing than developed countries and that as expectation of life increases in developing countries the global chronic disease burden will be greatly concentrated in the developing countries. Analyses of risk-factor reduction by feasible intervention strategies, e.g. smoking cessation campaigns, treatment of high blood pressure, using relationships between risk factors and diseases established in longitudinal studies carried out in developed countries, point out that the effect of risk-factor control in long-living populations can be hidden by the dependency of risk factors and various related causes of death, e.g. smoking has an impact on lung cancer, ischaemic heart disease and emphysema, but at different ages.(ABSTRACT TRUNCATED AT 400 WORDS)

Actuarial Analysis↗
PubMed1987

Debilitation's aftermath: stochastic process models of mortality.

A stochastic differential equation model is developed to clarify the interaction of debilitation, recuperation, selection, and aging. The model yields various insights about the lingering mortality consequences of disasters such as wars, famines, and epidemics that may weaken the survivors. A key result is that debilitation and selection are interdependent: debilitation that increases population heterogeneity will result in subsequent selection; selection, by altering the distribution of population heterogeneity, will influence the impact of debilitating events.

Aging↗
PubMed1987

Suicide in middle age and later life: sex and race specific life table and cohort analyses.

Cross-temporal data on suicide for the period 1962 to 1981 from the National Center for Health Statistics were analyzed. These data were used to estimate period and cohort suicide rates for the four middle-aged and elderly groups (ages 45 to 64, 65 to 74, 75 to 84, and 85 and older) by sex and race. Statistical procedures included multiple decrement life table analyses and cause elimination life table analyses for each year 1968 to 1981. Results from an age, period, cohort analysis of cohort trends 1962 to 1981 also were presented. The analysis showed that suicide continues to be a serious problem in later life especially among the "oldest-old" (those aged 85 and over) and among nonwhite males. It also showed important differences in cohort risks that may strongly affect future suicide risks among elderly adults.

Actuarial Analysis↗
PubMed1987

A multidimensional approach to case mix for home health services.

Developing a case-mix methodology for home health services is more difficult than developing one for hospitalization and acute health services, because the determinants of need for home health care are more complex and because of the difficulty in defining episodes of care. To evaluate home health service case mix, a multivariate grouping methodology was applied to records from the 1982 National Long-Term Care Survey linked to Medicare records on home health reimbursements. Using this method, six distinct health and functional status dimensions were identified. These dimensions, combined with factors describing informal care resources and local market conditions, were used to explain significant proportions of the variance (r2 = .45) of individual differences in Medicare home health reimbursements and numbers of visits. Though the data were not collected for that purpose, the high level of prediction strongly suggests the feasibility of developing case-mix strategies for home health services.

Diagnosis-Related Groups↗
PubMed1987

The linkage of health status changes and disability.

Forecasting health and functional status changes in elderly populations is a difficult task because forecasting must describe the linkage of chronic morbidity, and its progression, with different levels and types of disability. In this paper we present a model which links morbidity and disability and, with the use of multiple survey and epidemiological data sources, provide estimates of the long-term reduction in chronic disability that would result from changing the prevalence of specific chronic diseases by the control of major risk factors. The results show that many of the diseases which are currently the principal target of primary prevention have more impact upon mortality, and overall life expectancy, than they do on the age at onset of chronic disability. Thus, in order to increase the average number of years that elderly persons can expect to live with less disability, or less severe forms of disability, new prevention strategies and techniques may have to be developed.

Adult↗
PubMed1987

Health differentials between blacks and whites: recent trends in mortality and morbidity.

Black Americans continue to have large numbers of premature and excess deaths, measured against white experience, from seven major causes. Major differences in chronic disease, disability and case fatality rates persist despite similarities in the amount of health care received; the nature and quality of care is likely to be dissimilar. Epidemiological and clinical evidence suggests various strategies to reduce these differentials through well-designed public health efforts at prevention. These will have to deal with harsh realities of sociocultural, economic, and political contexts.

Black or African American↗
PubMed1987

Statistically adjusted estimates of geographic mortality profiles.

The spatial variation of site-specific cancer mortality rates at the county or state economic area level can provide a) insights into possible etiologic factors and b) the basis for more detailed epidemiologic studies. One difficulty with such studies, especially for rare cancer types, is that unstable local area rate estimates, resulting from small population sizes, can obscure the underlying spatial pattern of disease risk. This paper presents a methodology for producing more stable rate estimates by statistically weighting the local area rate estimate toward the experience at the national level. The methodology is illustrated by the analysis of the spatial variation of two cancer types, bladder and lung, for U.S. white males over the three decades 1950-79.

Age Factors↗
PubMed1987

A study of somatization disorder in a community population utilizing grade of membership analysis.

A new multivariate analytical technique for the analysis of medical classification, Grade of Membership analysis, is utilized to examine somatization disorder in a community population. The authors examine whether somatic symptoms will cluster into a clinical syndrome resembling somatization disorder, as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), if no prior assumptions are made about the inter-relationship of somatic symptoms or their clustering into clinical syndromes. Using respondents in the US National Institute of Mental Health Epidemiologic Catchment Area project of the Piedmont Region of North Carolina, Grade of Membership analysis was applied to all respondents reporting 3 or more somatic symptoms from the somatization disorder section of the Diagnostic Interview Schedule. Seven 'pure' types, roughly analogous to clusters in cluster analysis emerged from the analysis. One 'pure' type in the analysis is nearly identical to DSM-III somatization disorder and is associated with demographic characteristics found among patients with DSM-III somatization disorder. The results indicate that symptoms associated with somatization disorder cluster in a highly predictable fashion and represent a strong validation of the natural occurrence of an entity resembling somatization disorder.

Adult↗
PubMed1986

Dependent competing risks: a stochastic process model.

Analyses of human mortality data classified according to cause of death frequently are based on competing risk theory. In particular, the times to death for different causes often are assumed to be independent. In this paper, a competing risk model with a weaker assumption of conditional independence of the times to death, given an assumed stochastic covariate process, is developed and applied to cause specific mortality data from the Framingham Heart Study. The results generated under this conditional independence model are compared with analogous results under the standard marginal independence model. Under the assumption that this conditional independence model is valid, the comparison suggests that the standard model overestimates by 4% the effect on life expectancy at age 30 due to the hypothetical elimination of cancer and by 7% the effect for cardiovascular/cerebrovascular disease. By age 80 the overestimates were 11% for cancer and 16% for heart disease. These results suggest the importance of avoiding the marginal independence assumption when appropriate data are available--especially when focusing on mortality at advanced ages.

Adolescent↗
PubMed1986

Compartment model approaches for estimating the parameters of a chronic disease process under changing risk factor exposures.

Compartment model approaches have been proposed for the analysis of the age incidence of specific types of cancer. These models represented the age increases in incidence as the result of a compound hazard function where individual level risks were described by the Weibull hazard function and where the population level hazard rate is a continuous mixture of the Weibull hazards. These formulations assumed that the mixing function, which described differences in risk due to different exposure histories, was constant after the age at which the model was first applied. In this paper we show how the mixing distribution can be allowed to change with time reflecting changing exposures. The model is fitted to U.S. lung cancer mortality data where for recent male cohorts there appear to be changing patterns of exposure possibly related to recent declines in male smoking. The implications for future lung cancer mortality trends in the United States are discussed.

Adult↗
PubMed1986

Alternative models for the heterogeneity of mortality risks among the aged.

The authors examine how sensitive the estimates of heterogeneity in the mortality risks in a population are to the choices of two types of function, "one describing the age-specific rate of increase of mortality risks for individuals and the other describing the distribution of mortality risks across individuals." U.S. data from published Medicare mortality rates for the period 1968-1978 are used to analyze total mortality among the aged. "In addition, national vital statistics data for the period 1950-1977 were used to analyze adult lung cancer mortality. For these data, the estimates of structural parameters were less sensitive to reasonable choices of the heterogeneity distribution (gamma vs. inverse Gaussian) than to reasonable choices of the hazard rate function (Gompertz vs. Weibull)."

Adult↗
PubMed1986

Cause specific mortality patterns among the oldest old: multiple cause of death trends 1968 to 1980.

Trends in sex specific mortality from six conditions (hip fracture, septicemia, pneumonia, cancer, heart disease, and stroke) were examined for the period 1968 to 1980 to determine if recent increases in life expectancy at advanced ages were associated with significant shifts in the pattern of cause specific mortality at those ages. Changes in life table parameters were assessed both at birth and age 85 to determine if the relative significance of certain conditions had increased or decreased at advanced ages. In particular, I examined whether three conditions (hip fracture, septicemia, pneumonia), often viewed as being associated with mortality among debilitated persons, had increased in the proportion of deaths they affected at advanced ages and if there had been changes in the mean age at death for persons with these conditions. I also examined trends in the mortality rates of three conditions (heart disease, stroke, cancer) that often are viewed as primary disease processes with high mortality risks. Overall there seemed to be little evidence that mortality for conditions associated with a debilitation had increased markedly at later ages.

Actuarial Analysis↗