Mortality Patterns In Populations Research Articles

Exploration of Geographical Environmental Factors Influencing Regional Population Mortality Patterns inChina.

The regional population mortality patterns in China exhibit substantial geographical distribution characteristics. This paper aims to explore the impact and mechanisms of geographical environmental factors on regional population mortality patterns. This study first utilized the data from China's Seventh Population Census to obtain mortality patterns for the 31 provincial-level administrative regions. Subsequently, a functional regression method was employed to explore the geographical environmental driving factors of regional mortality patterns. The study provides a detailed explanation of the mechanisms and marginal contributions of key geographical environmental factors at different age groups. (1) The impact of geographical environmental factors on mortality patterns shows distinct phased characteristics. Mortality patterns before the age of 40 years are hardly influenced by geographical environmental factors, with a noticeable impact beginning at ages 40-69 years and reaching the maximum influence after the age of 70 years. (2) In mortality patterns at ages 40-69 years, average altitude have the most substantial impact, followed by extreme low-temperature days and PM2.5 concentration. In mortality patterns at ages 70-94 years, high-temperature days have the greatest influence, followed by the impact of SO2 concentration. (3) In comparisons based on gender, socioeconomic factors, and geographical environmental factors, gender and urban-rural differences have the most significant impact on regional population mortality patterns, followed by the influence of other socioeconomic factors, with geographical environmental factors having a relatively smaller impact.

IGF-1 induces sex-specific oxidative damage and mortality in a songbird

The insulin-like growth factor 1 (IGF-1) is a pleiotropic hormone that regulates essential life-history traits and is known for its major contribution to determining individual ageing processes. High levels of IGF-1 have been linked to increased mortality and are hypothesised to cause oxidative stress. This effect has been observed in laboratory animals, but whether it pertains to wild vertebrates has not been tested. This is surprising because studying the mechanisms that shape individual differences in lifespan is important to understanding mortality patterns in populations of free-living animals. We tested this hypothesis under semi-natural conditions by simulating elevated IGF-1 levels in captive bearded reedlings, a songbird species with an exceptionally fast pace of life. We subcutaneously injected slow-release biodegradable microspheres loaded with IGF-1 and achieved a systemic 3.7-fold increase of the hormone within the natural range for at least 24 h. Oxidative damage to lipids showed marked sexual differences: it significantly increased the day after the manipulation in treated males and returned to baseline levels four days post-treatment, while no treatment effect was apparent in females. Although there was no overall difference in survival between the treatment groups, high initial (pre-treatment) IGF-1 and low post-treatment plasma malondialdehyde levels were associated with enhanced survival prospects in males. These results suggest that males may be more susceptible to IGF-1-induced oxidative stress than females and quickly restoring oxidative balance may be related to fitness. IGF-1 levels evolve under opposing selection forces, and natural variation in this hormone’s level may reflect the outcome of individual optimization.

Rapid mortality transition of Pacific Islands in the 19th century.

The depopulation of Pacific islands during the 16th to 19th centuries is a striking example of historical mass mortality due to infectious disease. Pacific Island populations have not been subject to such cataclysmic infectious disease mortality since. Here we explore the processes which could have given rise to this shift in infectious disease mortality patterns. We show, using mathematical models, that the population dynamics exhibited by Pacific Island populations are unlikely to be the result of Darwinian evolution. We propose that extreme mortality during first-contact epidemics is a function of epidemiological isolation, not a lack of previous selection. If, as pathogens become established in populations, extreme mortality is rapidly suppressed by herd immunity, Pacific Island population mortality patterns can be explained with no need to invoke genetic change. We discuss the mechanisms by which this could occur, including (i) a link between the proportion of the population transmitting infectious agents and case-fatality rates, and (ii) the course of infection with pathogens such as measles and smallpox being more severe in adults than in children. Overall, we consider the present-day risk of mass mortality from newly emerging infectious diseases is unlikely to be greater on Pacific islands than in other geographical areas.

Life Expectancy and Cause of Death in Popular Musicians: Is the Popular Musician Lifestyle the Road to Ruin?

Does a combination of lifestyle pressures and personality, as reflected in genre, lead to the early death of popular musicians? We explored overall mortality, cause of death, and changes in patterns of death over time and by music genre membership in popular musicians who died between 1950 and 2014. The death records of 13,195 popular musicians were coded for age and year of death, cause of death, gender, and music genre. Musician death statistics were compared with age-matched deaths in the US population using actuarial methods. Although the common perception is of a glamorous, free-wheeling lifestyle for this occupational group, the figures tell a very different story. Results showed that popular musicians have shortened life expectancy compared with comparable general populations. Results showed excess mortality from violent deaths (suicide, homicide, accidental death, including vehicular deaths and drug overdoses) and liver disease for each age group studied compared with population mortality patterns. These excess deaths were highest for the under-25-year age group and reduced chronologically thereafter. Overall mortality rates were twice as high compared with the population when averaged over the whole age range. Mortality impacts differed by music genre. In particular, excess suicides and liver-related disease were observed in country, metal, and rock musicians; excess homicides were observed in 6 of the 14 genres, in particular hip hop and rap musicians. For accidental death, actual deaths significantly exceeded expected deaths for country, folk, jazz, metal, pop, punk, and rock.

Evolution of aging: individual life history trade-offs and population heterogeneity account for mortality patterns across species.

A broad range of mortality patterns has been documented across species, some even including decreasing mortality over age. Whether there exist a common denominator to explain both similarities and differences in these mortality patterns remains an open question. The disposable soma theory, an evolutionary theory of aging, proposes that universal intracellular trade-offs between maintenance/lifespan and reproduction would drive aging across species. The disposable soma theory has provided numerous insights concerning aging processes in single individuals. Yet, which specific population mortality patterns it can lead to is still largely unexplored. In this article, we propose a model exploring the mortality patterns which emerge from an evolutionary process including only the disposable soma theory core principles. We adapt a well-known model of genomic evolution to show that mortality curves producing a kink or mid-life plateaus derive from a common minimal evolutionary framework. These mortality shapes qualitatively correspond to those of Drosophila melanogaster, Caenorhabditis elegans, medflies, yeasts and humans. Species evolved in silico especially differ in their population diversity of maintenance strategies, which itself emerges as an adaptation to the environment over generations. Based on this integrative framework, we also derive predictions and interpretations concerning the effects of diet changes and heat-shock treatments on mortality patterns.

Performance of the Tariff Method: validation of a simple additive algorithm for analysis of verbal autopsies

BackgroundVerbal autopsies provide valuable information for studying mortality patterns in populations that lack reliable vital registration data. Methods for transforming verbal autopsy results into meaningful information for health workers and policymakers, however, are often costly or complicated to use. We present a simple additive algorithm, the Tariff Method (termed Tariff), which can be used for assigning individual cause of death and for determining cause-specific mortality fractions (CSMFs) from verbal autopsy data.MethodsTariff calculates a score, or "tariff," for each cause, for each sign/symptom, across a pool of validated verbal autopsy data. The tariffs are summed for a given response pattern in a verbal autopsy, and this sum (score) provides the basis for predicting the cause of death in a dataset. We implemented this algorithm and evaluated the method's predictive ability, both in terms of chance-corrected concordance at the individual cause assignment level and in terms of CSMF accuracy at the population level. The analysis was conducted separately for adult, child, and neonatal verbal autopsies across 500 pairs of train-test validation verbal autopsy data.ResultsTariff is capable of outperforming physician-certified verbal autopsy in most cases. In terms of chance-corrected concordance, the method achieves 44.5% in adults, 39% in children, and 23.9% in neonates. CSMF accuracy was 0.745 in adults, 0.709 in children, and 0.679 in neonates.ConclusionsVerbal autopsies can be an efficient means of obtaining cause of death data, and Tariff provides an intuitive, reliable method for generating individual cause assignment and CSMFs. The method is transparent and flexible and can be readily implemented by users without training in statistics or computer science.

A New Model of Ageing and Mortality

ABSTRACTThe Nested Binomial Model presented in this paper is a new approach to modelling mortality and survival in humans and other species that seeks to reconcile individual life course risk trajectories and those population mortality patterns that arise from inter-individual heterogeneity. In describing individual trajectories it partitions mortality risk into two main elements: ‘redundancy’ and ‘interactive risk'. Interactive risk is volatile, increasing or decreasing with time and circumstance, while redundancy is a quantity which declines in a linear and largely invariable fashion throughout life. Although a biological correlate for redundancy is not identified, this assumption allows strikingly realistic modelling of mortality and survival curves, late-life mortality deceleration, Strehler-Mildvan correlation, mortality plateaux and slowing of mortality. Simple assumptions with regard to heterogeneity of parameters within the model allow close approximation to the entire human mortality curve, and provide a rationale for observed and otherwise paradoxical population mortality phenomena. As such, it fulfils biodemographic criteria for a comprehensive theory of ageing. Future challenges are to reconcile its theoretical structure with empirical findings in the biology of ageing and to render it in a form that can become a usable actuarial tool.

Age-standardisation of relative survival ratios of cancer patients in a comparison between countries, genders and time periods

A recent method of age-standardisation of relative survival ratios for cancer patients does not require calculation of age-specific relative survival ratios, as ratios of age-specific proportions between the standard population and study group at the beginning of the follow-up are used to substitute the original individual observations. This method, however, leads to direct age-standardisation with weights that are different for each patient group if the general population mortality patterns for the groups are different. This is the case in international comparisons, and in comparisons between genders and time periods. The magnitude of the bias caused by the differences in general population mortality is investigated for comparisons involving European countries and the USA. Patients in each country are assumed to have exactly the same age-specific relative survival ratios as those diagnosed in Finland in 1985–2004. An application of a properly functioning age-standardisation method should then give exactly equal age-standardised relative survival ratios for each country. However, the recent method shows substantial differences between countries, with highest relative survival for populations, where the general population mortality in the oldest ages is the highest. This source of error can thus be a serious limitation for the use of the method, and other methods that are available should then be employed.

Interaction between physical activity and diet: implications for blood pressure management in primary care.

This review summarises the evidence for the effectiveness of primary care based interventions of diet and physical activity aimed at reducing blood pressure. As blood pressure rises so does the risk of heart disease and stroke. There is a large literature on the effects on blood pressure of changing various aspects of diet either as single nutrient interventions, patterns of food consumption, or the addition of dietary supplements (potassium, magnesium, and fish oil). Controlled trials have been undertaken to assess the relative benefits of lifestyle changes in activity (walking etc) compared with more structured exercise programmes. There is sufficient evidence to suggest that changes in diet and activity under controlled conditions can reduce blood pressure and delay or reduce the need for drug treatment in subjects who are hypertensive. What is less clear is how to achieve these lifestyle changes in the primary care setting as part of routine clinical management. There have been a number of systematic reviews undertaken to evaluate the evidence. The interventions were either delivered alone or in combination with other advice, either with or without aids, and by various practice nurse staff (GP, nurse, dietitian); follow-up varied from 3 months to a year. Compliance with the advice was generally not measured. The variability in the quality of the studies and interventions made it difficult to draw conclusions: any effects seen tended to be small. Equivocal results (non statistically significant reductions) should not be considered as proof of no effect without careful consideration of the effects of chance, bias and confounding, and without better measures of compliance. There is little debate that, under investigator control, blood pressure can be reduced by changes in diet and activity. Changes to a 'healthy' diet (low in total and saturated fat; energy intake balanced with expenditure to maintain or achieve optimal body weight; low in salt: high in fruits, vegetables, legumes; and whole grains) and increases in modest levels of physical activity (walking etc) would be expected to reduce blood pressure by between two and four mmHg. A shift in the population distribution of this order would be expected to have a substantial impact on population mortality patterns and could be achieved cost-effectively in primary care.

Does grazing reduce survival of indigenous perennial grasses of the semi‐arid woodlands of western New South Wales?

Abstract Exclosures were used to examine the impact of grazing upon the mortality patterns of populations of six indigenous grass species. The experiment compared unfenced areas with areas from which either sheep only or sheep, rabbits and kangaroos were excluded. There were large interspecific differences in mortality patterns, with Stipa nitida and Aristida browniana having relatively high mortality rates and Eragrostis eriopoda having relatively low mortality rates. Grazing‐induced mortality was observed in treatment areas that were grazed by sheep, rabbits and kangaroos and in areas grazed only by rabbits and kangaroos. The short‐lived S. nitida appears less likely to suffer grazing‐induced mortality than species of intermediate longevity such as Monachather paradoxa. These observations help explain the decline in endemic perennial grasses that has taken place in the vegetation of western New South Wales since European settlement. Management of these rangelands to encourage these grasses must consider total grazing pressure and not simply the impact of livestock.