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PubMed2000

A perspective on animal protein production in sub-Saharan Africa.

A large survey of animal protein production in sub-Saharan Africa was performed. The objective was to identify specific production needed to ensure sustainable development. Starting from data collection and analysis to gain control of this information, the study proposes possible paths of evolution for supply and demand for animal production. Africa will be the continent where the demand will grow the most (together with Asia), because of demography and urbanization. Urbanization will represent an extraordinary opportunity for the development of animal production. In 2020, the global demand will be 20 million tons per year (7.3 in 1994) for meat, 45 million tons for milk (18.6 in 1994) and 2.9 million tons for eggs (1.1 in 1994). Red meat, which now provides 55.6% of present meat consumption will satisfy only 36.5% in 2020. This underlines the immense effort needed to intensify ruminant production and/or to develop monogastric production. Consequently, there is a need in tropical animal health and research for better knowledge and control of monogastric diseases and particularly those linked to intensification. The development of peri-urban milk production will require particular attention to hemoparasitic diseases. Globally, there is an urgent need to set up projects for the development of animal production.

Africa South of the Sahara↗
PubMed2001

Origins of epidemiology.

In this paper we trace the history of epidemiology from 1800 to the present time. The history is highly selective because our purpose is to illuminate the evolving relationship of epidemiology with demography. We first describe the common "prehistory" of these two disciplines in the early nineteenth century, and then describe their divergence during three successive eras of epidemiology up to the end of the twentieth century. In the final section, we draw attention to exceptional individuals who bridged the two disciplines despite the historical trend in the other direction, and express our hope that recent signs of convergence in the face of globalization and the AIDS pandemic will be borne out during the coming decades.

Demography↗
PubMed2001

Demographers and the study of mortality: scope, perspectives, and theory.

Demographers have for a long time adopted an empirical approach to the study of the levels and trends of mortality, fertility, and population size. They depend for their analyses on data, usually collected until recent times by government and often for other purposes. Modern demography had its origins in Britain in the second half of the seventeenth century. The major focus of demographers has usually been on mortality, although fertility studies predominated in the 1960s and 1970s. Mortality decline in the West only became certain in the late nineteenth century. Until the 1960s the fastest mortality declines were for the young, but an unheralded mortality decline among the old thereafter became important. The world, especially in economically advanced countries, is faced with an increasingly high proportion of old people, explained largely, not by mortality decline, but by fertility decline. Explanations for the mortality transition place different emphases on the role of modern medicine, better nutrition, and behavioral and social change, particularly rising levels of education. Even among the old, at least until 85 years of age, there are wide differentials in mortality by educational level. Analysts have divided the mortality transition into stages: (1) high, pretransitional mortality, (2) early transitional mortality with the decline explained by the conquest of infectious disease, and (3) late transitional mortality largely attributable to degenerative disease. Some have now added stage (4), the reduction or delay in death from degenerative causes. Attempts have been made to effect the convergence of demographic and epidemiological approaches to the analysis of mortality, and they have been more successful in the case of medical demographic than in social demographic approaches.

Adult↗
PubMed2001

Social environment effects on health and aging: integrating epidemiologic and demographic approaches and perspectives.

This paper provides an overview of epidemiological and demographic research linking social characteristics of both individuals and communities to differences in both morbidity and mortality risks. Evidence is presented linking three broad aspects of the social environment to health--the network of personal social relationships within which most of us live our lives, individual socioeconomic status (SES), and community-level social characteristics. Large and consistent bodies of literature from both epidemiology and demography provide clear evidence for the generally health-promoting effects of personal social relationships and SES. The bulk of the evidence relates to mortality although both fields have begun to examine other health outcomes, including aspects of physical and cognitive functioning as well as disease outcomes. A smaller but growing body of community-level data, reflecting both the socioeconomic/resource characteristics of these broader communities and, more specifically, social features of these environments, also point to health impacts from these more macro level social environment characteristics. Much remains to be elucidated, however, concerning the actual mechanisms through which something as complex and multifaceted as SES "gets under the skin." This necessarily includes consideration of external characteristics of the environments (both physical and sociocultural) where people live and work, and individual characteristics, as well as possible interactions between these in producing the observed SES gradients in health and mortality. These questions concerning links between social environment conditions and health may be a particularly fruitful area of future collaboration, drawing on the shared interest of demographers and epidemiologists in understanding how different social conditions promote variation in distributions of better versus worse health outcomes within a population.

Aging↗
PubMed2001

Epidemiologic tools for today and tomorrow.

As the premier population sciences, epidemiology and demography face common challenges as the U.S. population ages, as the genomic revolution unfolds, and as computing power changes the scale of analysis by several orders of magnitude. Each discipline does need to develop new tools to address the changing research questions, and the best strategy for success includes increased collaboration between the disciplines. The paradigms of each discipline still offer important insights into the problems of both disciplines, so cross-training would be a simple step to begin enlarging the tool box for population science.

Adult↗
PubMed2000

Public policy on oral health and old age: a global view.

This paper reviews major trends in the global demography and oral health status of populations, the challenges faced in ensuring successful aging because of these trends, and basic principles to guide public policy responses. Virtually all populations in which the dental caries prevalence reached high levels in the first half of the 20th century have experienced large reductions. A feared increase of the disease in the developing world has been far less than expected. Some countries that did suffer large increases dating from the 1960s already have managed to return to their former low levels because of timely use of preventive measures. Improving oral hygiene and a consequent reduction in the occurrence and severity of periodontal diseases further bolster the mainly positive trend in global oral health. Only in the former socialist economies is oral health status worsening. These positive changes have brought the expectation that an intact and well-functioning dentition should last for life, no matter how extended the lifespan becomes. But these changes take us into "uncharted waters" and the most appropriate strategies for preserving health in old age are unknown because they have never been tried. However, public policies to support community awareness and acceptance of broad-based preventive behaviors to preserve oral health in old age are essential. Policies also must provide guidance on how to proceed when disabling disease occurs, provide for regular research and updating of information, and ensure access to cost-effective and high-quality services for all.

Aged↗
PubMed2006

The unusual genetics of human longevity.

In no species other than humans do cultural, social, and biological factors interact with each other in modulating complex phenotypes. Thus, the identification of genetic factors that affect human longevity is a true challenge. The model of centenarians provides us a unique opportunity to tackle this challenge. In this Perspective, we discuss some recent findings (the impact of geography and demography on the longevity phenotype, the relationship between longevity and homozygosity, the role of the nuclear-mitochondrial genome cross-talk) by which new ideas are suggested, such as the concept of a complex allele timing as a pivotal process in modulating the probability of achieving longevity.

Demography↗
PubMed1991

Census of single homeless people in Sheffield.

OBJECTIVE: To determine the number of single homeless people in Sheffield and to examine their demography and social and medical details. DESIGN: Census carried out between 8 am and 8 pm on one day. Participants completed a questionnaire designed to provide data relating to employment history, contact with welfare and health services, social state, prison history, medical history, and health state. SETTING: Sites in Sheffield identified by local workers as being places of residence of homeless people. SUBJECTS: 340 single homeless people. MAIN OUTCOME MEASURES: Self reported history of alcohol or drug misuse, existence of a chronic medical condition, and use of general practitioner and hospital services. RESULTS: The mean age of the population was 42.5 years and a quarter of the population were aged less than 30; there were 48 women. Significant differences were noted between men and women with respect to self reported psychiatric illness (77/266 men v 27/42 women), self reported alcoholism (83/273 v 4/44), prison history (152/255 v 8/41), and registration with a general practitioner (73/275 v 38/46). Various chronic medical conditions were reported, and the perceived health state of the population was low; 129 claimed to have been admitted to a psychiatric hospital. 220 people were registered with a general practitioner, and 179 claimed to see their doctor. Sixty five had attended or been admitted to a general hospital in the month preceding the study, 45 for accident and emergency services. CONCLUSIONS: The homeless in this population were younger than those found in previous studies. The prevalence of psychiatric illness was high in the population, and the overall health state was poor. Most subjects obtained health services from general practitioners.

Adolescent↗
PubMed1995

Using data from the 1991 census.

The 1991 census for England and Wales provides a substantial amount of data on demography, ethnicity, housing tenure, employment status, and other social factors for geographical areas ranging in size from enumeration districts upwards. Many in the health service and in the academic community are making use of the data in the 1991 census. However, users of census data need to be aware of the problems and limitations of these data, which include the format of the data, data modification and suppression, sampling error, and underenumeration. An important innovation of the 1991 census was that the census form included a question on the postcode of respondents; this allowed the Office of Population Censuses and Surveys to produce a postcode-enumeration district look up table which overcomes many of the problems previously encountered in trying to assign postcodes to enumeration districts. The new look up table also includes the grid reference of postcodes, and this will improve the geographical referencing of census data.

Data Collection↗
PubMed1997

Effectiveness of ambulance paramedics versus ambulance technicians in managing out of hospital cardiac arrest.

OBJECTIVE: To determine the effectiveness of extended trained ambulance personnel (paramedics) for the management of out of hospital cardiac arrest. METHODS: A retrospective cohort study of patients who suffered a cardiac arrest between 1 January 1992 and 31 July 1994, and who were transported to their local accident and emergency (A&E) department. Data were collected on basic demography, operational time intervals, and ambulance crew status. Further clinical data were collected, and outcome measures included status on arrival at A&E, status on leaving A&E (hospital admission), and status on leaving hospital. The data were analysed using univariate and multivariate techniques. RESULTS: Univariate analysis showed the likelihood of arriving in A&E with a return of spontaneous circulation was more than doubled among patients attended by a paramedic crew compared with those attended by technicians (relative risk = 2.48, 95% confidence interval 1.34 to 4.60). The likelihood of successful hospital admission was also significantly increased (RR = 1.92, 95% CI 1.13 to 3.27); however, beyond this point, further survival benefits appeared to be much smaller. Similar findings were revealed using multivariate analysis. Second level modelling revealed further possible differences between paramedic and technician crews according to type of incident. Patients successfully admitted to hospital who died before discharge remained severely disabled between admission and death. CONCLUSIONS: There are marked short term survival advantages after cardiac arrest associated with paramedic care, but these probably diminish rapidly over time.

Aged↗
PubMed1995

Genetic variation and aging.

Life span is subject to genetic modification in yeasts, nematodes, fruit flies, mice, humans, and other vertebrates and invertebrates. There are a few single-gene mutants known that extend life span in yeast and nematodes; in other experimental systems the character is treated quantitatively, and generally has a low to moderate heritability. Life span responds to artificial selection in Drosophila and Caenorhabditis. There are many candidate genes presently under investigation, including the anti-oxidizing enzymes and heat-shock proteins. The main evolutionary models of senescence are antagonistic pleiotropy and mutation accumulation, neither of which has substantial experimental support. The incorporation of analytical techniques from demography is playing an increasing role in research on aging.

Aging↗
PubMed2006

[Health care financing: is it enough and appropriate?].

INTRODUCTION: The object of this short paper is to present the results of Spanish public health care expenditures projections until 2013 according to the expected impact of the main demographic and technological health cost drivers. MATERIAL AND METHODS: Future annual health expenditures are estimated using a simple method based on the decomposition of the past main growth factors in two scenarios. The main cost drivers considered were the following: demography, which includes the increasing number of people and the impact of population ageing; the increase in the price of health care inputs above the general price level; and the impact of changes in medical practice related with expanding medical technology. RESULTS AND DISCUSSION: In 2013, public health care expenditure may be around 5.7% and 6% of gross domestic product (GDP); that is, at least, between 0.24 and 0.53 additional GDP points will be spent on public health care. The main factor responsible for the future expenditure increase will continue to be the increase in the average health service intensity, followed by demographic factors. In the base-case scenario, public expenditure increase until 2013 will be compatible with a real 2.5% annual increase in consumption of non-health goods and services. In order to finance the future costs, the Spanish population will have to devote to public health expenditure less than 7% of income increase until 2013. CONCLUSION AND PERSPECTIVES: Despite being important, the expected Spanish GDP growth until 2013 may be enough to finance the increase in public health expenditure as a result of the impact of demographic changes. Expanding medical technology is expected to continue being the main driver of future costs.

Age Distribution↗
PubMed1998

Carotid endarterectomy among Medicare beneficiaries: a statewide evaluation of appropriateness and outcome.

BACKGROUND AND PURPOSE: We sought to examine the appropriateness and the surgical outcomes of carotid endarterectomy (CE) in unselected community hospitals to identify opportunities for improvement. METHODS: We performed a retrospective review of all CEs performed on Medicare beneficiaries in Georgia in 1993 (n = 1945). Conclusions regarding appropriateness were based on current guidelines as interpreted by a physician reviewer and were supported by the aggregate results of structured, blinded overreading by clinicians with relevant expertise. Adverse outcomes were confirmed and rated as to severity by a physician. Outcomes were correlated with demography, vascular anatomic findings, comorbidity, surgical techniques, and hospital characteristics. RESULTS: The majority of the patients (51%) were asymptomatic at presentation. CEs were performed appropriately in 96.1% of the cases in accordance with current guidelines. There was no significant difference in the rate of appropriateness between the symptomatic (96%) and the asymptomatic patients (96.4%). Survival without stroke or myocardial infarction (MI) was 94.3%. The 30-day mortality was 1.9%; moderate to severe strokes occurred in 1.8%, stroke-related death in 0.7%, MI in 1.1%, and MI-related death in 0.5%. Those hospitals performing <10 CEs in the observed year had a statistically significant higher morbidity and mortality as well as an increase in less severe complications such as hematomas, wound dehiscence, wound infection, and pneumonia than did hospitals with higher volume of CEs.. Older patients and women had statistically significantly higher morbidity and mortality. Patients with a Charlson Severity Index score of > or =1 had a risk for adverse outcomes 3.4 times higher than patients with a score of 0 after adjustment for age and sex. CONCLUSIONS: The great majority of CEs performed in Georgia on Medicare patients were appropriate, according to current guidelines. Slightly more than half of the patients were asymptomatic as defined in the Asymptomatic Carotid Atherosclerosis Study. In hospitals performing <CEs in the index year, we noted higher morbidity and mortality, as well as an increase in less severe complications. This relationship between the volume of surgery and outcome was confirmed in the analysis of the 30-day mortality for all Medicare cases (n = 10,569) performed in Georgia from 1991 to 1995. This was the most important opportunity for improvement identified in this study. In view of the increased use of CE, it is important to continue to monitor the patterns of practice for this procedure to improve outcomes.

Age Factors↗
PubMed1998

Epidemiology of carotid endarterectomy among Medicare beneficiaries: 1985-1996 update.

BACKGROUND AND PURPOSE: This article describes changes in the rate and outcome of carotid endarterectomies among Medicare beneficiaries. METHODS: We analyzed International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes as shown on Medicare bills to calculate carotid endarterectomy frequency, rate, and perioperative mortality by patient demography and hospital characteristics. RESULTS: After initially peaking at 61273 procedures (20.6 per 10000 beneficiaries) in 1985, the frequency of carotid endarterectomy among Medicare beneficiaries declined to 46571 (14.3 per 10000) in 1989 and then rose to 108275 (28.6 per 10000) in 1996. Patients were predominantly aged 65 to 74 years, male, and white; surgery occurred mainly in large, urban, nonprofit, and teaching hospitals. Perioperative mortality declined from 3.0% in 1985 to 1.6% in 1996. CONCLUSIONS: The frequency and rate of carotid endarterectomy showed prompt response to reports from clinical trials. Perioperative mortality both improved and converged over time but did not attain the rates reported by the trials. Patients aged 85+ years suffered twice the average perioperative mortality.

Black or African American↗
PubMed1993

The social effects and institutional structure of immigration in New Zealand in the 1980s.

"The aim of this paper is to facilitate an understanding and explanation of the social effects of immigration in New Zealand during the 1980s. Working within the framework of social demography...this objective will be pursued in two stages. First, a concise overview will be given of some of the more commonly known social effects that can be related to the composition and volume of immigration. Second, to gain a deeper appreciation of the causes of change, attention will be directed to the nature and operation of what has been described as the 'institutional structure of immigration'...."

Demography↗
PubMed1981

Estimation of place-to-place migration flows from net migration totals: a minimum information approach.

"A truism in demography has been that net migration may be derived from information on gross place-to-place flows, but that gross place-to-place flows cannot be inferred back from information on the net population movements in a system. Some recent work on maximum entropy and minimum information models, however, suggests a possible means for estimating just such as set of place-to-place flows. The net migration constrained model presented here could prove particularly useful for updating detailed migration matrices on the basis of current net migration estimates, and could even provide some clues as to the nature of the still poorly understood relationship between gross and net migration. Performance of the model is demonstrated using flow matrices from the 1960 and 1970 U.S. Censuses.

Americas↗
PubMed1999

The demographic transition then and now: processes, perspectives, and analyses.

Fifty years have passed since the post-World War II development of demography as an academic field. During this time, one of the central focuses of research has been the study of demographic and fertility transitions. The authors review a selection of research developments and analytic issues that have appeared in the literature. After presenting, in roughly chronological order, the general development of this research work, they raise questions concerning theory and methodology. In doing so, they argue that some research directions have been overemphasized to the neglect of others.

Demography↗
PubMed2006

Mixing of propagules from discrete sources at long distance: comparing a dispersal tail to an exponential.

BACKGROUND: Rare long distance dispersal events impact the demography and the genetic structure of populations. When dispersal is modelled via a dispersal kernel, one possible characterisation of long-distance dispersal is given by the shape of the tail of the kernel, i.e. its type of decay. This characteristic is known to directly act on the speed and pattern of colonization, and on the spatial structure of genetic diversity during colonization. In particular, colonization waves behave differently depending on whether the kernel decreases faster or slower than an exponential (i.e. is thin-tailed vs. fat-tailed). To interpret and extend published results on the impact of long-distance dispersal on the genetic structure of populations, we examine a classification of dispersal kernels based on the shape of their tails and formally demonstrate qualitative differences among them that can influence the predicted diversity of a propagule pool sampled far from two distinct sources. RESULTS: We show that a fat-tailed kernel leads asymptotically to a diverse propagule pool containing a balanced mixing of the propagules from the two sources, whereas a thin-tailed kernel results in all propagules originating from the closest source. We further show that these results hold for biologically relevant distances under certain circumstances, and in particular if the number of propagules is large enough, as would be the case for pollen or seeds. CONCLUSION: To understand the impact of long-distance dispersal on the structure and dynamics of a metapopulation, it might be less important to precisely estimate an average dispersal distance than to determine if the tail of the dispersal kernel is fatter or thinner than that of an exponential function. Depending solely on this characteristic, a metapopulation will behave similarly to an island model with a diverse immigrant pool or to a stepping-stone model with migrants from closest populations. Our results further help to understand why thin-tailed dispersal kernels lead to a colonization wave of constant speed, whereas fat-tailed dispersal kernels lead to a wave of increasing speed. Our results also suggest that the diversity of the pollen cloud of a mother plant should increase with increasing isolation for fat-tailed kernels, whereas it should decrease for thin-tailed kernels.

Demography↗