Differential Mortality Research Articles

The Immigrant Mortality Advantage in Canada, 2001 and 2011

This study examines differential mortality between immigrant and native-born populations in Canada with respect to eighteen causes of death categories encompassing chronic and external types of mortality over two census periods, 2001 and 2011. The following interrelated questions are addressed: (1) what is the magnitude of the immigrant mortality advantage relative to native-born Canadians? (2) How does it change over time? (3) Is the migrant advantage uniform across all causes of death? (4) Does the advantage for immigrants prevail across all age groups? (5) Are immigrant men and women equally advantaged across causes of death? These queries are explored with multivariate analysis guided by a conceptual framework that specifies differential mortality as a function of nativity factors, health selection, and acculturation effects. It is shown that nativity status exerts a strong independent effect, and that over time, migrants experienced larger reductions in risk than did native-born Canadians. Further analysis revealed support for both health selection and acculturative explanations. Sex differences are found, with male immigrants enjoying a small but significant relative mortality advantage compared to immigrant females. The paper discusses these findings and closes with suggestions for further study.

Heterogeneity in the Health and Functional Capacity of Adults Aged 85+ as Risk for Mortality.

To examine whether older adults aged 85+, with different health and functional capacities, cluster in different ways and to demonstrate whether individuals within particular clusters report differential mortality risk. Retrospective cohort study. The Dynamic Analyses to Optimize Aging (DYNOPTA) project is a harmonization project of nine Australian longitudinal surveys of health and well-being in adults aged 50+ between 1991 and 2006. Participants were 685 older adults (female = 52%) living in the community and aged 85 to 103 at baseline who were followed until death or December 31, 2006, for survivors. Latent class analysis (LCA) analyzed self-reported information on physical health, mental health, and functional capacity to define homogeneous classes based on probable cognitive impairment and depression status, medical conditions, and number of activities of daily living and instrumental activities of daily living. LCA discriminated four classes reflecting two main survival patterns. Two classes reported half the median survival days; differences between these classes were related to high vs moderate depression and extent of functional limitations. Two classes reported better survival; differences between these classes were related to functional limitations, but both had low proportions with depression and dementia. The classes with shorter survival were associated with substantively higher rates of depression and dementia. Higher rates of baseline depression and dementia were unique characteristics of those individuals in the clusters that reported shorter survival. However, a substantial proportion of very old adults experience good mental health with better survival outcomes. J Am Geriatr Soc 67:1036-1042, 2019.

Differential disease incidence and mortality of inner and outer reef corals of the upper Florida Keys in association with a white syndrome outbreak

Differential disease incidence and mortality of inner and outer reef corals of the upper Florida Keys in association with a white syndrome outbreak

Phenotypic selection on ponderosa pine seed and seedling traits in the field under three experimentally manipulated drought treatments.

Drought‐related selection during seedling emergence and early development may play a strong role in adaptation. Yet this process is poorly understood and particularly so in relation to ongoing climate change. To evaluate drought‐induced differences in selection during early life stages, a total of 50 maternal families sampled from three climatically disparate ponderosa pine (Pinus ponderosa Doug.) populations were grown from seed in two common garden field experiments at a location that was warmer and drier than seed origins. Three drought treatments were imposed experimentally. Phenotypic selection was assessed by relating plant fitness measured as survival or unconditional expected height at age 3 to seed density (mass per unit volume), date of emergence, and timing of shoot elongation. In the year of emergence from seed, differential mortality was particularly strong and clearly indicated selection. In contrast, selection in subsequent years was far less pronounced. Phenotypes with high seed density, an intermediate but relatively early emergence date, and high 2nd‐year early‐season shoot elongation exhibited the greatest estimated fitness under drought. The form of selection varied among seed sources in relation to drought treatment. Selection was generally more acute in the cases of greatest difference between drought treatment and climatic patterns of precipitation at the site of seed origin. These results suggest that populations of ponderosa pine are differentially adapted to drought patterns associated with the climate of their origin. To the extent that the phenotypic traits examined are heritable or correlated with heritable traits, our results provide insight into how tree populations may evolve in response to drought.

Social security with differential mortality

This paper examines the welfare angle of Pay As You Go (PAYG) type social security under differential mortality among different income groups. Empirical evidence suggests that agents who have low income tend to start working earlier and have shorter longevity than those with middle or high income. Since a PAYG social security program collects payroll taxes whenever agents are working, and it pays retirement benefits as long as retirees are alive, each individual’s well being depends on how longthey contribute to and receive payments from this program as well as how much. Implications of the low income groups’ shorter longevity are examined both analytically and quantitatively. In the analytical part, in a simple two period partial equilibrium model, we observe that a social security program can have regressive outcome even though the benefits of the program are designed to be progressive. We also derive the conditions under which this can happen. Afterwards, we create a large scale quantitative OLG model calibrated to the US economy to compare aggregate and welfare implications of the US type PAYG, a non progressive PAYG, and a means tested pension program. Our results clearly indicate that incorporating differential mortality into the model changes the welfare implications of social security programs.

Migratory connectivity in the context of differential migration.

Understanding how breeding populations are spatially and temporarily associated with one another over the annual cycle has important implications for population dynamics. Migratory connectivity typically assumes that populations mix randomly; yet, in many species and populations, sex-, age- or other subgroups migrate separately, and/or spend the non-breeding period separated from each other-a phenomenon coined differential migration. These subgroups likely experience varying environmental conditions, which may carry-over to affect body condition, reproductive success and survival. We argue that environmental or habitat changes can have disproportional effects on a population's demographic rates under differential migration compared to random mixing. Depending on the relative contribution of each of these subgroups to population growth, environmental perturbations may be buffered (under-proportional) or amplified (over-proportional). Thus, differential migration may result in differential mortality and carry-over effects that can have concomitant consequences for dynamics and resilience of the populations. Recognizing the role of differential migration in migratory connectivity and its consequences on population dynamics can assist in developing conservation actions that are tailored to the most influential demographic group(s) and the times and places where they are at peril.

No evidence for prezygotic postcopulatory avoidance of kin despite high inbreeding depression.

Offspring resulting from mating among close relatives can suffer from impaired fitness through the expression of recessive alleles with deleterious effects. Postcopulatory sperm selection (a prezygotic mechanism of cryptic female choice) has been suggested to be an effective way to avoid inbreeding. To investigate whether postcopulatory female choice allows the avoidance of fertilization by close kin, we performed artificial inseminations in a promiscuous bird, the houbara bustard (Chlamydotis undulata undulata). Females were inseminated with a mix of sperm from triads of males, each constituted of a male genetically unrelated to the female, a first cousin and a half-sibling. When counting the number of eggs sired by unrelated males, cousins or half-siblings, we found a significant deviation from the expected random distribution, with more eggs sired by unrelated males. However, offspring sired by cousins, and especially by half-siblings suffered from high prehatching mortality, suggesting that the observed paternity skew towards unrelated males might reflect differential offspring mortality rather than sperm selection. In agreement with this hypothesis, within-triad siring success was similar for the three parental relatedness categories, but the relationship between siring and hatching success differed across categories. In clutches with high hatching success, unrelated males had the highest success while in clutches with high failure rate, half-siblings had the highest success. Offspring sired by half-siblings also suffered from reduced growth rate during the first three months and higher posthatching mortality. Hence, despite substantial fitness costs associated with fertilization by close relatives, females do not seem to select sperm of unrelated males.

Health Disparities and the Socioeconomic Gradient in Elderly Life-Cycle Consumption.

We quantify the importance of health disparities in explaining consumption differences at older ages by estimating a panel VAR model of elderly consumption, health, and mortality using data from the Health and Retirement Study. We use the estimated model and initial joint distribution of health and consumption to simulate elderly life-cycle paths and construct a measure of the net present value of expected remaining lifetime consumption at age sixty (NPVC). We first document a steep education gradient in elderly lifetime consumption. We then decompose the gradient in NPVC to quantify the effect of 1) differences in the health distribution at age sixty and 2) differential health and mortality transitions after age sixty. Our decomposition results suggest that roughly 10-12% of the education gradient in NPVC at age sixty could be closed by eliminating elderly health differences.

LONGEVITY‐RELATED OPTIONS FOR SOCIAL SECURITY: A MICROSIMULATION APPROACH TO RETIREMENT AGE AND MORTALITY ADJUSTMENTS

We consider the distributional implications of Social Security policy changes in the context of increases in life expectancy and differential mortality. Using a robust microsimulation model, we examine how several options for raising the retirement age, including a scenario that applies a mortality adjustment in combination with such policies, affect different types of individuals and households. Policy changes are simulated for Social Security beneficiaries in 2030 using the Modeling Income in the Near Term (MINT) microsimulation model. The analysis shows that increasing either the age at which individuals receive their full retirement benefit alone or the early eligibility and full retirement ages together result in across-the-board reductions in benefit levels. The policies are projected to result in slightly higher poverty, but the expected rise is sharper among groups known to experience higher rates of mortality, as well as many disadvantaged groups. Analysis of a hypothetical adjustment to offset the historical impacts of differential mortality by lifetime earnings on lifetime benefit receipt, when combined with these retirement age increases, shows varied results. While some groups of individuals experience sharper reductions in median monthly benefits, the adjustment has an offsetting and protective effect for the benefits of disadvantaged groups when combined with options that would raise the retirement age. This combined package of policies, as well as simulations that incorporate a behavioral adjustment in benefit claiming ages, result in an increase of less than one percentage point in the average poverty rate.

Habitat-dependent movement rate can determine the efficacy of marine protected areas.

Theoretical studies of marine protected areas (MPAs) suggest that more mobile species should exhibit reduced local effects (defined as the ratio of the density inside vs. outside of the MPA). However, empirical studies have not supported the expected negative relationship between the local effect and mobility. We propose that differential, habitat-dependent movement (i.e., a higher movement rate in the fishing grounds than in the MPA) might explain the disparity between theoretical expectations and empirical results. We evaluate this hypothesis by building two-patch box and stepping-stone models and show that increasing disparity in the habitat-specific movement rates shifts the relationship between the local effect and mobility from negative (the previous theoretical results) to neutral or positive (the empirical pattern). This shift from negative to positive occurs when differential movement offsets recruitment and mortality differences between the two habitats. Thus, local effects of MPAs might be caused by behavioral responses via differential movement rather than by, or in addition to, reductions in mortality. In addition, the benefits of MPAs, in terms of regional abundance and fishing yields, can be altered by the magnitude of differential movement. Thus, our study points to a need for empirical investigations that disentangle the interactions among mobility, differential movement, and protection.

Similar cranial trauma prevalence among Neanderthals and Upper Palaeolithic modern humans

Neanderthals are commonly depicted as leading dangerous lives and permanently struggling for survival. This view largely relies on the high incidences of trauma that have been reported1,2 and have variously been attributed to violent social behaviour3,4, highly mobile hunter-gatherer lifestyles2 or attacks by carnivores5. The described Neanderthal pattern of predominantly cranial injuries is further thought to reflect violent encounters with large prey mammals, resulting from the use of close-range hunting weapons1. These interpretations directly shape our understanding of Neanderthal lifestyles, health and hunting abilities, yet mainly rest on descriptive, case-based evidence. Quantitative, population-level studies of traumatic injuries are rare. Here we reassess the hypothesis of higher cranial trauma prevalence among Neanderthals using a population-level approach-accounting for preservation bias and other contextual data-and an exhaustive fossil database. We show that Neanderthals and early Upper Palaeolithic anatomically modern humans exhibit similar overall incidences of cranial trauma, which are higher for males in both taxa, consistent with patterns shown by laterpopulations of modern humans. Beyond these similarities, we observed species-specific, age-related variation in trauma prevalence, suggesting that there were differences in the timing of injuries during life or that there was a differential mortality risk of trauma survivors in the two groups. Finally, our results highlight the importance of preservation bias in studies of trauma prevalence.

Morphological Variability Among Broods of First-Stage Blue Crab (Callinectes sapidus) Zoeae.

External morphology has been shown to influence predation and locomotion of decapod larvae and is, therefore, directly related to their ability to survive and disperse. The first goal of this study was to characterize first-stage blue crab zoeal morphology and its variability across larval broods to test whether inter-brood differences in morphology exist. The second was to identify possible correlations between maternal characteristics and zoeal morphology. The offspring of 21 individuals were hatched in the laboratory, photographed, and measured. Zoeae exhibited substantial variability, with all metrics showing significant inter-brood differences. The greatest variability was seen in the zoeal abdomen, rostrum, and dorsal spine length. A principal component analysis showed no distinct clustering of broods, with variation generally driven by larger zoeae. Using observed morphology, models of drag induced by swimming and sinking also showed significant inter-brood differences, with a maximum twofold difference across broods. In contrast to trends in other decapod taxa, maternal characteristics (female carapace width and mass and egg sponge volume and mass) are not significant predictors of zoeal morphology. These results suggest that brood effects are present across a wide range of morphological characteristics and that future experiments involving Callinectes sapidus morphology or its functionality should explicitly account for inter-brood variation. Additionally, inter-brood morphological differences may result in differential predation mortality and locomotory abilities among broods.

Chronic exposure to copper and zinc induces DNA damage in the polychaete Alitta virens and the implications for future toxicity of coastal sites

Copper and zinc are metals that have been traditionally thought of as past contamination legacies. However, their industrial use is still extensive and current applications (e.g. nanoparticles and antifouling paints) have become additional marine environment delivery routes. Determining a pollutant's genotoxicity is an ecotoxicological priority, but in marine benthic systems putative substances responsible for sediment genotoxicity have rarely been identified. Studies that use sediment as the delivery matrix combined with exposures over life-history relevant timescales are also missing for metals. Here we assess copper and zinc's genotoxicity by exposing the ecologically important polychaete Alitta virens to sediment spiked with environmentally relevant concentrations for 9 months. Target bioavailable sediment and subsequent porewater concentrations reflect the global contamination range for coasts, whilst tissue concentrations, although elevated, were comparable with other polychaetes. Survival generally reduced as concentrations increased, but monthly analyses show that growth was not significantly different between treatments. The differential treatment mortality may have enabled the surviving worms in the high concentration treatments to capture more food thus removing any concentration treatment effects for biomass. Using the alkaline comet assay we confirm that both metals via the sediment are genotoxic at concentrations routinely found in coastal regions and this is supported by elevated DNA damage in worms from field sites. However, combined with the growth data it also highlights the tolerance of A. virens to DNA damage. Finally, using long term (decadal) monitoring data we show stable or increasing sediment concentrations of these metals for many areas. This will potentially mean coastal sediment is a significant mutagenic hazard to the benthic community for decades to come. An urgent reappraisal of the current input sources for these ‘old pollutants’ is, therefore, required.

Differential Mortality of North Atlantic Bivalve Molluscs During Harmful Algal Blooms Caused by the Dinoflagellate, Cochlodinium (a.k.a. Margalefidinium) polykrikoides

Blooms of the dinoflagellate, Cochlodinium (a.k.a.Margalefidinium) polykrikoides, have had deleterious effects on marine life across the Northern Hemisphere and, since the early 1990s, have become more frequent and widespread. While the toxic effects of C. polykrikoides have been well-described for finfish, the effects on bivalve molluscs are poorly understood, particularly in ecosystem and aquaculture settings. The purpose of this study was to characterize the comparative effects of C. polykrikoides blooms on North Atlantic bivalves and to identify the environmental factors that influence its toxic effects. The growth and survival of two age-classes (first- and second-year) of the northern quahog (Mercenaria mercenaria), the bay scallop (Argopecten irradians), and the eastern oyster (Crassostrea virginica) were quantified in surface deployments and at depth during annual bloom events in multiple locations across eastern Long Island (NY, USA), capturing a natural gradient in C. polykrikoides. In two consecutive years, scallops deployed within surface locations experienced significant mortality (75–100%) during short-term (1–2 weeks) but intense (> 1.5 × 104 cells mL−1) C. polykrikoides blooms. Conversely, scallops deployed at depth and clams and oysters deployed at either the surface or at depth were more resistant to blooms. First-year oysters and scallops that survived blooms displayed significant reductions in growth rates, while clams and older scallops and oysters did not. Results suggest that blooms of C. polykrikoides pose significant age- and species-specific threats to native and cultured bivalve shellfish and that shellfish deployed in surface waters are at greater risk during blooms than those deployed at depth.

Indexes of natural selection in Kharkiv population

Aim. Reproductive behavior of women has particular importance in the reproduction of the population and depends on cultural characteristics and religious views. Number of birth and medical abortions become artificially regulated; nevertheless selection in human populations does not disappear. Therefore, the aim of this task to study the direction and intensity of indexes of natural selection and the dynamics of the gene pool in the Kharkiv population for two adjacent generations. Methods. The material was collected in 2017. Anonymous questionnaires were conducted for women in postreproductive age. The questionnaire includes questions which reflect a woman's gynecological and obstetrical anamnesis. The number of pregnancies and their outcomes was calculated: medical and spontaneous abortions, ectopic pregnancies, number of stillbirths and live births. Results. In one generation, the total selection index decrease from 0.29 to 0.28, while the differential fertility index is much higher than the differential mortality index. The average number of pregnancies and medical abortions reduced in the younger generation with statistically significant difference. Conclusions. The Kharkov population is characterized by a narrow type of reproduction. The dynamics of Crow's indexes are in line with global trends. From the older generation to the younger the total selection index decreases gradually.Keywords: reproductive characteristics,Kharkov population, Crow's index, selection, generations.

Extreme flooding decreases stream consumer autochthony by increasing detrital resource availability

Abstract Extreme disturbances, those high magnitude events that are statistically rare in a particular system, may affect consumer resource use through multiple mechanisms, such as differential consumer mortality and modified resource availability and quality. Documenting the ecological importance of these rare events is difficult, but essential, as the frequency of extreme events is predicted to increase under many climate change scenarios. We quantified changes in stream insect resource use following intense, nonseasonal flooding in the Rocky Mountains of northern Colorado during September 2013. We hypothesised that taxonomic identity, functional feeding group membership and disturbance‐caused alterations in resource quantity and quality (C:N ratios) would determine consumer reliance on autochthonous and allochthonous resources and community structure following the disturbance. In summer 2014, we collected basal resources and stream insects for carbon, nitrogen and deuterium bulk stable isotope analysis, and community composition. Basal resource quantity and quality (C:N ratios) were collected at seven headwater streams along a 2013 flood intensity gradient. Using stable isotope mixing models, we analysed consumer autochthony. We also used baseline community composition data from 2011 to compare functional feeding group abundance prior to and following the flood events. We found that consumer resource use was primarily associated with detrital resource quantity, which was positively correlated with disturbance intensity and elevation. Functional feeding group membership did not predict resource use. However, consumers in functional feeding groups did experience differential mortality following flooding. Herbivore relative abundance significantly declined along the disturbance gradient, and predator relative abundance generally declined across all streams from 2011 to 2014. Our results suggest that changes in resource quantity from extreme disturbances can be associated with shifts in consumer resource use. Following this flood event, detritus standing stocks increased, resulting in a concomitant increase in consumer reliance on allochthonous sources.

Sex hormones and incident dementia in older men: The health in men study

BackgroundLow circulating testosterone has been associated with dementia in older men but existing evidence from prospective studies is inconsistent. MethodsWe conducted a prospective longitudinal study of 4069 community-dwelling older men free of dementia aged 71–88 years at baseline. The main objective of the study was to determine if men with low circulating sex hormones were more likely to develop dementia over time. The main biochemical exposures of interest were collected at baseline between 2001 and 2004 and men were assessed for incident dementia via an electronic health records database to the 31 st of December 2013. ResultsDementia developed in 499 men over a median of 10.5 years (range 9.4–12.2 years). The risk of developing dementia increased with decreasing total (hazard ratio [HR] 1.14, 95% confidence interval [95%CI] 1.03–1.26 per standard deviation decrease) and calculated free testosterone (HR 1.18, 95%CI 1.06–1.31 per standard deviation decrease) after adjustment for age, baseline cognitive function, depression, body mass, hypertension, cardiovascular disease and total plasma homocysteine. Men in the lowest quartiles of total (adjusted HR 1.39, 95%CI 1.04–1.85) and calculated free testosterone (adjusted HR 1.43, 95%CI 1.08–1.90) had increased risk of developing dementia compared to those in the highest quartiles. ConclusionsLower plasma total and calculated free testosterone were associated with increased risk of developing dementia independent of relevant measured clinical and biochemical factors and was not explained due to differential mortality in those with lower testosterone levels. The association between low testosterone and dementia is biologically plausible but data on the role of testosterone treatment in preventing dementia is lacking and adequately powered trials in men at risk would be welcome.

Reproducible Peak Clusters on Differential Mouse Mortality Curves and Their Relation to the Gompertz Model.

It is shown that differentiation of mouse mortality curves (number of animals that died at a certain age plotted versus their lifespan) results in the appearance of eight clearly distinguished clusters of peaks corresponding to increased mortality rates. Smoothing of the original mortality curves and subsequent transformation of the differential mortality curves according to the Gompertz model makes the peaks and the corresponding clusters less pronounced and drives the logarithm of the force mortality curve toward a straight line. The positions of the clusters on the lifespan axis (expressed in days) were calculated as weighted means by dividing the sum of the products of multiplication of the peak heights and their position on the lifespan axis by the sum of the peak heights within a cluster. To prove that the peaks and their clusters are not random, we have demonstrated that the positions of the clusters on the lifespan axis do not depend on the extent of mortality curve smoothing or the group of mice analyzed.

Impact of time since diagnosis and mortality rate on cancer‐associated venous thromboembolism: the Scandinavian Thrombosis and Cancer (STAC) cohort

Background Venous thromboembolism (VTE) is a common complication in cancer, and studies have suggested that aggressive cancers create the highest risk of VTE. However, competing risk by death may result in overestimation of VTE risk in patients with cancers associated with high mortality. Therefore, we estimated the risk of VTE by cancer site, accounting for the differential mortality between cancers. Methods The Scandinavian Thrombosis and Cancer cohort included 144 952 participants followed from 1993-1997 to 2008-2012. Incidence rates, cause-specific hazard ratios (HRs) and subdistribution HRs (SHRs) were assessed for overall cancer and by cancer site according to time intervals since cancer diagnosis. Results During follow-up, 14 272 subjects developed cancer, and 567 had cancer-related VTE. In cause-specific analyses, the VTE risk was highest in the first 6 months after cancer diagnosis (HR 17.5, 95% confidence interval [CI] 15.1-20.3), and declined rapidly thereafter. However, when mortality was taken into account, the risk was similar in the periods 6 months before (SHR 4.8, 95% CI 3.6-6.4) and 6 months after (SHR 4.6, 95% CI 3.9-5.4) cancer diagnosis. The range of the 2-year cumulative VTE incidence rates was substantially narrowed for all cancer sites after competing risk by death was taken into account (from 1-10% to 1-4%). Conclusion VTE risk by cancer site was influenced by the mortality rate and the time since cancer diagnosis. Our findings suggest that the cancer itself is a major contributor to VTE risk, and that competing risk by death should be taken into account when VTE risk in cancer is explored.

The distribution of pension wealth in Europe

Abstract The present study estimates pension wealth inequality among elderly households for 26 EU countries by exploiting cross-sections of the EU Statistics on Income and Living Conditions survey. To assess the role of life expectancy inequalities on pension wealth, this study estimates life tables per educational level with auxiliary data in order to capture socio-economic status (SES). This procedure also distinguishes mortality estimates by sex, birth cohort, and year. The results indicate that differential mortality due to SES increases pension wealth inequality. In most of the countries, this effect has decreased between 2006 and 2014, which means that SES inequalities in mortality are less important in explaining today’s pension wealth inequality. Gini re-centered influence function (RIF) regressions confirm the diminishing influence of tertiary education on pension wealth inequality.