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PubMed2004

Worldwide variation in life-span sexual dimorphism and sex-specific environmental mortality rates.

In all human populations mean life span of women generally exceeds that of men, but the extent of this sexual dimorphism varies across different regions of the world. Our purpose here is to study, using global demographic and environmental data, the general tendency of this variation and local deviations from it. We used data on male and female life history traits and environmental conditions for 227 countries and autonomous territories; for each country or territory the life-span dimorphism was defined as the difference between mean life spans of women and men. The general tendency is an increase of life-span dimorphism with increasing average male-female life span; this tendency can be explained using a demographic model based on the Makeham-Gompertz equation. Roughly, the life-span dimorphism increases with the average life span because of an increase in the duration of expressing sex- and age-dependent mortality described by the second (exponential) term of the Makeham-Gompertz equation. Thus we investigated the differences in male and female environmental mortality described by the first term of the Makeham-Gompertz equation fitted to the data. The general pattern that resulted was an increase in male mortality at the highest and lowest latitudes. One plausible explanation is that specific factors tied to extreme latitudes influence males more strongly than females. In particular, alcohol consumption increases with increasing latitude and, on the contrary, infection pressures increase with decreasing latitude. This finding agrees with other observations, such as an increase in male mortality excess in Europe and Christian countries and an increase in female mortality excess in Asia and Muslim countries. An increase in the excess of female mortality may also be due to increased maternal mortality caused by an increase in fertility. However, this relation is not linear: In regions with the highest fertility (e.g., in Africa) the excess of female mortality is smaller than in regions with relatively lower fertility (e.g., in Asia). A possible explanation of this phenomenon is an evolutionary adaptation of women to the pressures of extremely high fertility by means of some reduction of their maternal mortality.

Age Factors↗
PubMed2005

Bayesian estimation of recent migration rates after a spatial expansion.

Approximate Bayesian computation (ABC) is a highly flexible technique that allows the estimation of parameters under demographic models that are too complex to be handled by full-likelihood methods. We assess the utility of this method to estimate the parameters of range expansion in a two-dimensional stepping-stone model, using samples from either a single deme or multiple demes. A minor modification to the ABC procedure is introduced, which leads to an improvement in the accuracy of estimation. The method is then used to estimate the expansion time and migration rates for five natural common vole populations in Switzerland typed for a sex-linked marker and a nuclear marker. Estimates based on both markers suggest that expansion occurred <10,000 years ago, after the most recent glaciation, and that migration rates are strongly male biased.

Animals↗
PubMed2004

Nucleotide variation at Msn and Alas2, two genes flanking the centromere of the X chromosome in humans.

The centromeric region of the X chromosome in humans experiences low rates of recombination over a considerable physical distance. In such a region, the effects of selection may extend to linked sites that are far away. To investigate the effects of this recombinational environment on patterns of nucleotide variability, we sequenced 4581 bp at Msn and 4697 bp at Alas2, two genes situated on either side of the X chromosome centromere, in a worldwide sample of 41 men, as well as in one common chimpanzee and one orangutan. To investigate patterns of linkage disequilibrium (LD) across the centromere, we also genotyped several informative sites from each gene in 120 men from sub-Saharan Africa. By studying X-linked loci in males, we were able to recover haplotypes and study long-range patterns of LD directly. Overall patterns of variability were remarkably similar at these two loci. Both loci exhibited (i) very low levels of nucleotide diversity (among the lowest seen in the human genome); (ii) a strong skew in the distribution of allele frequencies, with an excess of both very-low and very-high-frequency derived alleles in non-African populations; (iii) much less variation in the non-African than in the African samples; (iv) very high levels of population differentiation; and (v) complete LD among all sites within loci. We also observed significant LD between Msn and Alas2 in Africa, despite the fact that they are separated by approximately 10 Mb. These observations are difficult to reconcile with a simple demographic model but may be consistent with positive and/or purifying selection acting on loci within this large region of low recombination.

5-Aminolevulinate Synthetase↗
PubMed2000

Smoking prevalence in 2010: why the healthy people goal is unattainable.

OBJECTIVES: This study examined the changes in smoking initiation and cessation needed to realize the Healthy People 2010 national adult smoking prevalence objective (13%). METHODS: Using data from the National Health Interview Surveys, we calculated smoking prevalence over time with a dynamic population demographics model, examining the effects of changes in smoking initiation and cessation. RESULTS: The draft objective is unattainable solely through decreases in smoking initiation. It could be achieved through smoking cessation alone only if cessation rates immediately increased by a factor of more than 3.5. Assuming plausible decreases in initiation and increases in cessation, the draft objective is virtually unattainable. CONCLUSIONS: The health objectives should challenge the status quo but be achievable. Formal analysis often can assist in establishing reasonable objectives.

Adult↗
PubMedDate not supplied

Health-based risk adjustment: is inpatient and outpatient diagnostic information sufficient?

Adequate risk adjustment is critical to the success of market-oriented health care reforms in many countries. Currently used risk adjusters based on demographic and diagnostic cost groups (DCGs) do not reflect expected costs accurately. This study examines the simultaneous predictive accuracy of inpatient and outpatient morbidity measures and prior costs. DCGs, pharmacy cost groups (PCGs), and prior year's costs improve the predictive accuracy of the demographic model substantially. DCGs and PCGs seem complementary in their ability to predict future costs. However, this study shows that the combination of DCGs and PCGs still leaves room for cream skimming.

Capitation Fee↗
PubMed2002

Health-related quality of life before and after solid organ transplantation. Measurement consideration, reported outcomes, and future directions.

The initial focus in organ transplantation clinical research was demonstrating acceptable technical and survival outcomes. Both patient and graft survival have reached well-documented, laudable levels, and solid organ (liver, heart, kidney, lung) transplantation procedures are now relatively common. As with any complex medical procedure that entails relatively high risk, financial costs, and life-long follow-up care, reliable and valid assessments of the "quality" of the extended life years are of interest to patients, their families, policy makers, and payers. This review focuses on health-related quality of life (HRQOL) and functional performance in adults following solid organ transplantation, with an emphasis on: 1) instruments and methods; 2) outcomes in liver, heart, kidney, and lung transplant recipients; and 3) future research directions. Practical considerations for developing longitudinal HRQOL assessment strategies are reviewed. The current emphasis on modeling demographic and clinical factors that promote or limit optimal HRQOL is illustrated. These lines of research will help identify potential interventions designed to promote better HRQOL in organ transplant recipients.

Health Status↗
PubMed2003

How important are intergenerational cycles of teenage motherhood in England and Wales? A comparison with France.

Teenage fertility has fallen substantially in every Western European country except the United Kingdom. This article examines the hypothesis that repetition of teenage motherhood from mother to daughter is a major cause of the UK being the exception. A simple demographic model of fertility across generations is estimated with comparable data from England and Wales and France. The main finding is that mother-daughter repetition can account for only a minor part of the total difference in teenage childbearing between the two countries, especially over the long term. The higher teenage childbearing in England and Wales of those whose mothers began childbearing after their teenage years dominates.

Adolescent↗
PubMed2005

Provincial mortality in South Africa, 2000--priority-setting for now and a benchmark for the future.

BACKGROUND: Cause-of-death statistics are an essential component of health information. Despite improvements, underregistration and misclassification of causes make it difficult to interpret the official death statistics. OBJECTIVE: To estimate consistent cause-specific death rates for the year 2000 and to identify the leading causes of death and premature mortality in the provinces. METHODS: Total number of deaths and population size were estimated using the Actuarial Society of South Africa ASSA2000 AIDS and demographic model. Cause-of-death profiles based on Statistics South Africa's 15% sample, adjusted for misclassification of deaths due to ill-defined causes and AIDS deaths due to indicator conditions, were applied to the total deaths by age and sex. Age-standardised rates and years of life lost were calculated using age weighting and discounting. RESULTS: Life expectancy in KwaZulu-Natal and Mpumalanga is about 10 years lower than that in the Western Cape, the province with the lowest mortality rate. HIV/AIDS is the leading cause of premature mortality for all provinces. Mortality due to pre-transitional causes, such as diarrhoea, is more pronounced in the poorer and more rural provinces. In contrast, non-communicable disease mortality is similar across all provinces, although the cause profiles differ. Injury mortality rates are particularly high in provinces with large metropolitan areas and in Mpumalanga. CONCLUSION: The quadruple burden experienced in all provinces requires a broad range of interventions, including improved access to health care; ensuring that basic needs such as those related to water and sanitation are met; disease and injury prevention; and promotion of a healthy lifestyle. High death rates as a result of HIV/AIDS highlight the urgent need to accelerate the implementation of the treatment and prevention plan. In addition, there is an urgent need to improve the cause-of-death data system to provide reliable cause-of-death statistics at health district level.

Adult↗
PubMed1989

[Forecasting health personnel needs on the basis of long-term developmental trends in relation to the standardized results].

The author compares the results of prognostic work conducted with the help of a demographic model of personnel based on the long-term development of the age structure of workers or on assumptions in the plan and add gradually revealed quantified factors which influence the numbers and the structure of workers, with results obtained by calculation of norms of workers for the network of health institutions. The author evaluates the possibilities and applicability of the two approaches.

Czechoslovakia↗
PubMed1993

Self-injurious behaviour (SIB)--from definition to human rights.

This article is part of a special section on 'self-injurious behaviour and autism' and is mainly based on a book edited by Luiselli, Matson and Singh (1992) addressing empirical data on self-injurious behaviour and mental retardation from a behavioural perspective. Within the overview of the book some information on autism is also presented and critically discussed. Self-injurious behaviour is a poorly understood phenomenon and problematic in many ways; its definition is not easy; little is known about the causes and neuroscientific models. Demographic data are scarce and functional analysis and interventions (behavioural techniques, medication, education) need to be further developed, under the protection of human rights committees.

Autistic Disorder↗
PubMed1977

[The problem of economic and population development (author's transl)].

The question is raised whether the apparent complexity and differentiation excludes chance. Generally a chance occurrence is without prior determination. The laws established by economics and demography with mathematical methods are therefore not capable to determine all facts because of their hypothetical arrangement. Reality can only be expressed in a categorical judgment. It is possible to arrive from hypothetical judgments--when there is A so there is B to an existence of a categorical B. Any theory of economic balance and any calculation in a demographic model to arrive at a balanced population development are methods which correlate facts with facts and allow conclusions when the correlation is actually existent. However, no conclusion as to the idea of determination of the generative behavior by economic production can be arrived at. Revorsely the conclusion that sociologie developments and generative behavior are completely independant of economic production is not possible. Hypothetical type of thinking in a model does not exclude chance and each fact has an element of chance in it. This appears to be a heuristic circle. Noncircular conclusions for the practice of life in order to advise, decide and act, do not exist without assumptions and without value judgments. In order to influence the development of the population continued scientific reflection, observation and argumentation is necessary. Correct technical functioning is translated into social realms. New reflections and interpretations are constantly required.

Economics↗
PubMedDate not supplied

[Evaluation of the dynamics of mortality over short time intervals].

Discusses the problem of assessing the time course of demographic values for short periods of time under conditions when stable long-term tendencies are absent. The author proposes to solve this problem by an extra analysis of alternative demographic models, e.g. Brass model. The method is illustrated by data for the Saratov district.

Data Collection↗
PubMed1998

Risk adjustment of mental health and substance abuse payments.

This study used 1992 and 1993 data from private employers to compare the performance of various risk adjustment methods in predicting the mental health and substance abuse expenditures of a nonelderly insured population. The methods considered included a basic demographic model, Ambulatory Care Groups, modified Ambulatory Diagnostic Groups and Hierarchical Coexisting Conditions (a modification of Diagnostic Cost Groups), as well as a model developed in this paper to tailor risk adjustment to the unique characteristics of psychiatric disorders (the "comorbidity" model). Our primary concern was the amount of unexplained systematic risk and its relationship to the likelihood of a health plan experiencing extraordinary profits or losses stemming from enrollee selection. We used a two-part model to estimate mental health and substance abuse spending. We examined the R2 and mean absolute prediction error associated with each risk adjustment system. We also examined the profits and losses that would be incurred by the health plans serving two of the employers in our database, based on the naturally occurring selection of enrollees into these plans. The modified Ambulatory Diagnostic Groups and comorbidity model performed somewhat better than the others, but none of the models achieved R2 values above .10. Furthermore, simulations based on actual plan choices suggested that none of the risk adjustment methods reallocated payments across plans sufficiently to compensate for systematic selection.

Actuarial Analysis↗
PubMed2005

Modeling association among demographic parameters in analysis of open population capture-recapture data.

We present a hierarchical extension of the Cormack-Jolly-Seber (CJS) model for open population capture-recapture data. In addition to recaptures of marked animals, we model first captures of animals and losses on capture. The parameter set includes capture probabilities, survival rates, and birth rates. The survival rates and birth rates are treated as a random sample from a bivariate distribution, thus the model explicitly incorporates correlation in these demographic rates. A key feature of the model is that the likelihood function, which includes a CJS model factor, is expressed entirely in terms of identifiable parameters; losses on capture can be factored out of the model. Since the computational complexity of classical likelihood methods is prohibitive, we use Markov chain Monte Carlo in a Bayesian analysis. We describe an efficient candidate-generation scheme for Metropolis-Hastings sampling of CJS models and extensions. The procedure is illustrated using mark-recapture data for the moth Gonodontis bidentata.

Animals↗
PubMed2003

HIV and population dynamics: a general model and maximum-likelihood standards for east Africa.

In high-prevalence populations, the HIV epidemic undermines the validity of past empirical models and related demographic techniques. A parsimonious model of HIV and population dynamics is presented here and fit to 46,000 observations, gathered from 11 East African populations. The fitted model simulates HIV and population dynamics with standard demographic inputs and only two additional parameters for the onset and scale of the epidemic. The underestimation of the general prevalence of HIV in samples of pregnant women and the fertility impact of HIV are examples of the dynamic interactions that demographic models must reproduce and are shown here to increase over time even with constant prevalence levels. As a result, the impact of HIV on population growth appears to have been underestimated by current population projections that ignore this dynamic.

Adolescent↗
PubMedDate not supplied

A structural model of the relationships among stage of disease, age, coping, and psychological adjustment in women with breast cancer.

The present study used structural equation modeling to examine the relationships among disease stage (i.e. Stage II versus Stage IV), age, coping style, and psychological adjustment in 100 women diagnosed with breast cancer. Five separate models were examined: a full model, a mediational model, a demographic-disease model, a coping style model, and a regression model The analyses revealed that the present data best fit the mediational model in which age and stage of disease were not directly associated with psychological adjustment but, instead, were mediated by coping style (chi 2(25) = 45.776, AASR = 0.05, CFI = 0.94). The mediational model accounted for 56% of the variance in psychological adjustment. In particular, the model showed that younger women and women with an earlier disease stage used greater levels of the coping strategy characterized as a fighting spirit and lower levels of the coping strategies characterized as hopelessness/helplessness, anxious preoccupation, and fatalism which, in turn, were related to better psychological adjustment. Overall, these findings may offer an explanation for the conflicting findings regarding the relationship between age, stage of disease, and psychological adjustment to breast cancer by illustrating that coping strategies may be an essential mediating factor; in turn, a mediating model of psychological adaptation may offer useful information for clinicians as they implement interventions designed to improve patients coping efforts.

Adaptation, Psychological↗