Eric Stallard

Bio: Eric Stallard is an academic researcher from Duke University. The author has contributed to research in topics: Population & Life expectancy. The author has an hindex of 40, co-authored 143 publications receiving 7704 citations. Previous affiliations of Eric Stallard include Durham University & Population Research Institute.

The impact of heterogeneity in individual frailty on the dynamics of mortality.

Abstract: Life table methods are developed for populations whose members differ in their endowment for longevity. Unlike standard methods, which ignore such heterogeneity, these methods use different calculations to construct cohort, period, and individual life tables. The results imply that standard methods overestimate current life expectancy and potential gains in life expectancy from health and safety interventions, while underestimating rates of individual aging, past progress in reducing mortality, and mortality differentials between pairs of populations. Calculations based on Swedish mortality data suggest that these errors may be important, especially in old age.

Chronic disability trends in elderly United States populations: 1982–1994

Abstract: Statistically significant declines in chronic disability prevalence rates were observed in the elderly United States population between the 1982 and 1989 National Long Term Care Surveys (NLTCS). The 1994 NLTCS was used to investigate whether disability rate declines continued to 1994. The 1982, 1984, 1989, and 1994 NLTCS employ the same sample design and instrumentation so that trends in disability can be estimated with minimal sampling and measurement bias. Age (5-year categories from 65 to >95)-specific rates were calculated for the 1982 NLTCS and applied to United States Census Bureau estimates of the 1994 population to calculate chronic disability prevalence rates adjusted for aging in the United States population aged >65. The 1982 age standardized rates were compared with 1994 NLTCS estimates. The prevalence of disability estimated for 1994 (21.3%) was 3.6% lower than the 1982 age standardized rate (24.9%)—a highly significant reduction (t = −8.5; P ≪ 0.0001). Of the 3.6 percentage point decline in prevalence, 1.7% occurred in the 5 years between 1989 and 1994—compared with the 1.9% decline in the 7 years between 1982 and 1989. Both declines are significant. Because of the shorter time period, the per year decline in disability prevalence from 1989 to 1994 was greater than that from 1982 to 1989. Given the higher acute and long-term care service needs of the disabled elderly population, Medicare, Medicaid, and private health expenditures may be dramatically lower than if declines had not occurred.

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.

Abstract: 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.

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

Abstract: To develop a model to estimate the degree of unobserved heterogeneity in morality risks in a population, it is necessary to specify two types of functions, one describing the age-specific rate of increase of mortality risks for individuals and the other describing the distribution of mortality risks across individuals. There has been considerable interest in the question of how sensitive the estimates of heterogeneity are to the choices of these functions. To explore this question, high-quality data were obtained from published Medicare mortality rates for the period 1968–1978 for analysis of 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).

Limits to human life expectancy: evidence prospects and implications.

Abstract: Identifying limits to human life expectancy and life span is difficult because survival is determined by the individuals physiology exogenous influences and their interaction over time. To explore theoretical limits the authors examine the life expectancy of selected populations with good health behavior and apply a multivariate risk-factor model to longitudinal data. The risk-factor model and the population data produce consistent estimates of a lower bound of the theoretical limit to human life expectancy. The results suggest that such limits may be higher than estimates obtained by extrapolating human mortality trends which necessarily are dependent on historical conditions. The investigation emphasizes the need to use information on individual physiological processes and health changes prior to death in addition to mortality or endpoint data in making estimates. The low-risk populations studied are from the United States and Japan. (SUMMARY IN FRE AND SPA) (EXCERPT)

Approximate inference in generalized linear mixed models

Abstract: Statistical approaches to overdispersion, correlated errors, shrinkage estimation, and smoothing of regression relationships may be encompassed within the framework of the generalized linear mixed model (GLMM). Given an unobserved vector of random effects, observations are assumed to be conditionally independent with means that depend on the linear predictor through a specified link function and conditional variances that are specified by a variance function, known prior weights and a scale factor. The random effects are assumed to be normally distributed with mean zero and dispersion matrix depending on unknown variance components. For problems involving time series, spatial aggregation and smoothing, the dispersion may be specified in terms of a rank deficient inverse covariance matrix. Approximation of the marginal quasi-likelihood using Laplace's method leads eventually to estimating equations based on penalized quasilikelihood or PQL for the mean parameters and pseudo-likelihood for the variances. Im...

A life course approach to diet, nutrition and the prevention of chronic diseases.

Abstract: Objective: To briefly review the current understanding of the aetiology and prevention of chronic diseases using a life course approach, demonstrating the lifelong influences on the development of disease. Design: A computer search of the relevant literature was done using Medline-‘life cycle’ and ‘nutrition’ and reviewing the articles for relevance in addressing the above objective. Articles from references dated before 1990 were followed up separately. A subsequent search using Clio updated the search and extended it by using ‘life cycle’, ‘nutrition’ and ‘noncommunicable disease’ (NCD), and ‘life course’. Several published and unpublished WHO reports were key in developing the background and arguments. Setting: International and national public health and nutrition policy development in light of the global epidemic in chronic diseases, and the continuing nutrition, demographic and epidemiological transitions happening in an increasingly globalized world. Results of review: There is a global epidemic of increasing obesity, diabetes and other chronic NCDs, especially in developing and transitional economies, and in the less affluent within these, and in the developed countries. At the same time, there has been an increase in communities and households that have coincident under- and over-nutrition. Conclusions: The epidemic will continue to increase and is due to a lifetime of exposures and influences. Genetic predisposition plays an unspecified role, and with programming during fetal life for adult disease contributing to an unknown degree. A global rise in obesity levels is contributing to a particular epidemic of type 2 diabetes as well as other NCDs. Prevention will be the most cost-effective and feasible approach for many countries and should involve three mutually reinforcing strategies throughout life, starting in the antenatal period.

Regression analysis of count data

Abstract: Three nonlinear count models, Poisson R.egression (PR), Negative Binomial Regression (NBR), and Generalized Poisson Regression (GPR) are used for assessing the effects of risk factors on agricultural injuries from farm injury data. A sample of 1,322 respondents who participated in the farm safety/injury baseline survey in nine rural counties in Alabama and Mississippi, aged 18 years and older are considered for analysis. The dispersion parameter estimates and their standard errors for GPR models were consistently smaller than that of NBR models. Estimated dispersion parameters in the NBR and GPR models were positive and significantly different from zero. Estimated goodness-of-fit measures showed that GPR models outperformed the NBR and PR models.