Cohort Life Tables Research Articles

Coccinellidae, Syrphidae and Aphidoletes are key mortality factors for Myzus persicae in tropical regions: A case study on cabbage crops

Natural factors regulate Myzus persicae populations in Brassicaceae crops. Ecological life table analysis is a robust tool that allows the estimation of the mortality caused by these factors. Here, we report the natural mortality of M. persicae caused by abiotic and biotic factors assessed by cohort life tables in cabbage crops. Together, these factors accounted for 94.6% mortality in M. persicae populations. The key mortality factor was predation by Coccinellidae larvae (Coccinella septempunctata, Cycloneda sanguinea, Eriopis connexa and Harmonia axyridis), Syrphidae (Allograpta exotica, Pseudodorus clavatus and Ocyptamus gastrostactus), and Aphidoletes sp. Other mortality factors included parasitism, rainfall, entomopathogens and physiological disturbance (e.g., incomplete molting). This information is essential to implement conservation measures of the main predators (key mortality factor) of M. persicae in cabbage crops.

VA3 - “It’s Tough to Make Predictions, Especially About the Future”: Comparing Life Expectancy Predictions Based on Period Versus Cohort Life Tables

Many cost-effectiveness models over a patient’s lifetime incorporate background mortality. Analysts often use recently available country life tables for these estimates, for example, those from the US Centers for Disease Control and Prevention (CDC). These period life tables that provide data on mortality rates (i.e., conditional survival probabilities) from a single year. As historical data, they may not take into account future reductions in mortality rates due to technological advancement and other factors. In contrast, the Social Security Administration’s (SSA) actuarial cohort life tables attempt to account for such mortality reductions by predicting the mortality rate at each age for a birth cohort over the course of their lifetime. The purpose of this analysis was to compare life expectancy predictions based on the 2010 CDC period life table versus the 2010 SSA cohort life table and discuss the implications. Based on the 2010 CDC period and SSA cohort life tables. We simulated the remaining life expectancies at birth and at age 65, undiscounted and discounted at 3%. The absolute difference in life expectancies (CDC versus SSA) increased with age. Undiscounted life expectancies at birth and at age 65 were 78.6 and 19.1 based on the CDC life table, lower by 5.4% (vs. 83.1) and by 14.3% (vs. 22.3) compared to SSA, respectively. Discounted life expectancies at birth and at age 65 were 30.4 and 14.1 from the CDC life table, lower by 1.6% (vs. 30.9) and 10.8% (vs. 15.8) compared on SSA-based estimates. At $150,000 per quality-adjusted life-year, CDC-based life expectancy underestimated value per individual by $75,000 at birth and $255,000 at age 65. In cost-effectiveness Markov models that consider background mortality, use of period rather than cohort models will generally underestimate life years gained. These differences can substantially lower the monetary value of health gains.

Comparison of statistical methods for calculating life expectancy after spinal cord injury.

Retrospective observational. To compare results of several different methods for calculating life expectancy in the same sample of people with spinal cord injury (SCI), and critically assess their advantages and disadvantages. Two spinal centres in Great Britain. Survival status of persons with traumatic SCI injured between 1943 and 2010 with follow-up to 2015 was determined. Standardised mortality ratios (SMRs) were calculated using age at injury and current (attained) age, and compared. Life expectancy was then estimated using the SMR methods and compared with the results of a method based on multivariate logistic regression of a person-year dataset. Life expectancy estimates calculated by applying SMRs based on current age to general population period (current) and cohort (projected) life tables were also compared. The estimated life expectancies were significantly higher when the SMRs were based on age at injury. They were also higher when a general population cohort life table was used, particularly for younger ages. With the exception of the ventilator-dependent group, the life expectancy estimates derived from logistic regression were slightly lower than those derived from SMRs based on current age and a general population period life table. The multivariate logistic regression of person-years method offers several advantages compared to the SMR method for calculating life expectancy after SCI, the main ones being: greater statistical power and precision with smaller sample sizes, the ability to include more predictive factors and to distinguish the otherwise confounded effects of current age, time post-injury, and calendar time.

Repurposed FDA-approved drugs targeting genes influencing aging can extend lifespan and healthspan in rotifers

Pharmaceutical interventions can slow aging in animals, and have advantages because their dose can be tightly regulated and the timing of the intervention can be closely controlled. They also may complement environmental interventions like caloric restriction by acting additively. A fertile source for therapies slowing aging is FDA approved drugs whose safety has been investigated. Because drugs bind to several protein targets, they cause multiple effects, many of which have not been characterized. It is possible that some of the side effects of drugs prescribed for one therapy may have benefits in retarding aging. We used computationally guided drug screening for prioritizing drug targets to produce a short list of candidate compounds for in vivo testing. We applied the virtual ligand screening approach FINDSITEcomb for screening potential anti-aging protein targets against FDA approved drugs listed in DrugBank. A short list of 31 promising compounds was screened using a multi-tiered approach with rotifers as an animal model of aging. Primary and secondary survival screens and cohort life table experiments identified four drugs capable of extending rotifer lifespan by 8–42%. Exposures to 1 µM erythromycin, 5 µM carglumic acid, 3 µM capecitabine, and 1 µM ivermectin, extended rotifer lifespan without significant effect on reproduction. Some drugs also extended healthspan, as estimated by mitochondria activity and mobility (swimming speed). Our most promising result is that rotifer lifespan was extended by 7–8.9% even when treatment was started in middle age.

The Cumulative Probability of Arrest by Age 28 Years in the United States by Disability Status, Race/Ethnicity, and Gender.

To estimate the cumulative probability (c) of arrest by age 28 years in the United States by disability status, race/ethnicity, and gender. I estimated cumulative probabilities through birth cohort life tables with data from the National Longitudinal Survey of Youth, 1997. Estimates demonstrated that those with disabilities have a higher cumulative probability of arrest (c = 42.65) than those without (c = 29.68). The risk was disproportionately spread across races/ethnicities, with Blacks with disabilities experiencing the highest cumulative probability of arrest (c = 55.17) and Whites without disabilities experiencing the lowest (c = 27.55). Racial/ethnic differences existed by gender as well. There was a similar distribution of disability types across race/ethnicity, suggesting that the racial/ethnic differences in arrest may stem from racial/ethnic inequalities as opposed to differential distribution of disability types. The experience of arrest for those with disabilities was higher than expected. Police officers should understand how disabilities may affect compliance and other behaviors, and likewise how implicit bias and structural racism may affect reactions and actions of officers and the systems they work within in ways that create inequities.

Demografía de brúquidos (coleoptera: bruchidae) asociados

Los brúquidos se alimentan principalmente de semillas de leguminosas, entre las cuales se encuentran algunos cultivos de importancia económica como el frijol (Phaseolus vulgaris L.), garbanzo (Cicer arietinum L.), lenteja (Lens culinaris Medik) y tamarindo (Tamarindus indica L.) entre otros, considerando al primero como la fuente principal de proteína en la dieta humana; sin embargo, Vigna unguiculata (L.) Walp, por sus propiedades nutritivas podría sustituir al frijol, pero su principal problema es la presencia de plagas, en particular los brúquidos, los cuales ocasionan pérdidas considerables en postcosecha, por lo que fue necesario conocer los parámetros poblacionales de Acanthoscelides obtectus (Say, 1831), Callosobruchus maculatus (Fabricius, 1775) procedente de dos hospederos diferentes y Zabrotes subfasciatus (Boheman, 1833) alimentados con V. unguiculata por medio de un estudio demográfico bajo condiciones controladas. Los parámetros poblacionales se estimaron con la técnica de tablas de vida de cohorte, la prueba de Log rank (p

Potential support ratios: Cohort versus period perspectives

The ‘prospective potential support ratio’ has been proposed by researchers as a measure that accurately quantifies the burden of ageing, by identifying the fraction of a population that has passed a certain measure of longevity, for example, 17 years of life expectancy. Nevertheless, the prospective potential support ratio usually focuses on the current mortality schedule, or period life expectancy. Instead, in this paper we look at the actual mortality experienced by cohorts in a population, using cohort life tables. We analyse differences between the two perspectives using mortality models, historical data, and forecasted data. Cohort life expectancy takes future mortality improvements into account, unlike period life expectancy, leading to a higher prospective potential support ratio. Our results indicate that using cohort instead of period life expectancy returns around 0.5 extra younger people per older person among the analysed countries. We discuss the policy implications implied by our cohort measures.

A Review of Life Table Construction

Life table is the one of the oldest statistical techniques and is extensively used by medical statisticians and actuaries. It is also the scheme for expressing the form of mortality in terms of probabilities. The life table is constructed from census data and death registration data, it can also be constructed from vital registration or retrospective surveys. Generally, they are constructed for age, gender, ethnic groups and occupational groups and so on. Some classification of life table such as cohort or current life table which are classified according to the reference year, unabridged (complete) or abridge life table classified according to length of age interval and single or multiple decrement life table classified according to the number of characteristics considered were discussed in the article.

Lifetime Prevalence of Investigating Child Maltreatment Among US Children.

To estimate the lifetime prevalence of official investigations for child maltreatment among children in the United States. We used the National Child Abuse and Neglect Data System Child Files (2003-2014) and Census data to develop synthetic cohort life tables to estimate the cumulative prevalence of reported childhood maltreatment. We extend previous work, which explored only confirmed rates of maltreatment, and we add new estimations of maltreatment by subtype, age, and ethnicity. We estimate that 37.4% of all children experience a child protective services investigation by age 18 years. Consistent with previous literature, we found a higher rate for African American children (53.0%) and the lowest rate for Asians/Pacific Islanders (10.2%). Child maltreatment investigations are more common than is generally recognized when viewed across the lifespan. Building on other recent work, our data suggest a critical need for increased preventative and treatment resources in the area of child maltreatment.

Die Young or Live Long: Modeling Subjective Survival Probabilities

Modeling of subjective survival is critical to the use of mortality expectations in economic models and the life insurance industry. Subjective scaling factors that are used to adjust average survival probabilities for individual expectations are often based on a single observation of personal life expectancy and assumed to be constant for any projected target age. Using survey data on subjective survival probabilities over a range of target ages and from an array of age cohorts, we estimate individual subjective scalings of population mortality probabilities. We show that both cohort age and target age matter: comparing subjective survival probabilities with the cohort life table, we show that respondents are generally pessimistic about overall life expectancy, but are optimistic about their probability of surviving to advanced ages; and that older respondents in our middle-aged sample are more optimistic than younger ones. Hence, our data suggests that individuals tend to expect to either die young or to live long. We propose a new model to incorporate cohort- and target age-varying subjective survival beliefs and illustrate the effect of these variations on optimal life cycle consumption plans. The proposed model contributes to the explanation of both the retirement savings puzzle and conservative spending patterns in retirement.

Independent and combined effects of maternal smoking and solid fuel on infant and child mortality in sub-Saharan Africa.

To estimate the independent and combined risks of infant and child mortality associated with maternal smoking and use of solid fuel in sub-Saharan Africa. Pooled weighted data on 143 602 under-five children in the most recent demographic and health surveys for 15 sub-Saharan African countries were analysed. The synthetic cohort life table technique and Cox proportional hazard models were employed to investigate the effect of maternal smoking and solid cooking fuel on infant (age 0-11 months) and child (age 12-59 months) mortality. Socio-economic and other confounding variables were included as controls. The distribution of the main explanatory variable in households was as follows: smoking + solid fuel - 4.6%; smoking + non-solid fuel - 0.22%; no smoking + solid fuel - 86.9%; and no smoking + non-solid fuel - 8.2%. The highest infant mortality rate was recorded among children exposed to maternal smoking + solid fuel (72 per 1000 live births); the child mortality rate was estimated to be 54 per 1000 for this group. In full multivariate models, the risk of infant death was 71% higher among those exposed to maternal smoking + solid fuel (HR = 1.71, CI: 1.29-2.28). For ages 12 to 59 months, the risk of death was 99% higher (HR = 1.99, CI: 1.28-3.08). Combined exposures to cigarette smoke and solid fuel increase the risks of infant and child mortality. Mothers of under-five children need to be educated about the danger of smoking while innovative approaches are needed to reduce the mortality risks associated with solid cooking fuel.

Cohort Life Tables from Life Courses for the Municipality of Modena: New Data and New Analyses

The method used to construct cohort life tables starting from individual lives, which was shown to be valid in relation to small villages is also applicable to urban realities, albeit with prudence. Whenever it is necessary to select a sample, it is certainly expedient to stratify it on the basis of month of birth, after which the results may be considered reliable if the percentage of dates of death sourced is around 90%, and especially when numerous “last dates known to be alive” are available. The results also appear to be reliable in those cases in which the percentage of dates of death is lower, but it is good practice to ensure this by backing them up with those obtained by replacing the estimates based on the sample with other estimates based on data which may be sourced from the scientific literature. With more particular regard to the evolution of mortality in Modena district, it may be affirmed that this started to decline with the generations born at the end of the Nineteenth century, and therefore mainly in relation to improvements in public and private hygiene. During the Twentieth century, the industrialisation of the area appears to have had different consequences for males and females: the increase in life expectancy proved to be rather slower for the former.

More education, fewer divorces? Shifting education differentials of divorce in Taiwan from 1975 to 2010

Background: While social gradient in divorce has been explored in many Western societies, this issue has received less attention in Asia. Objective: Few existing studies offer evidence for how educational gradient in divorce shift from positive to negative in Asia. This study explores the changing divorce patterns by education for both sexes over the past four decades in Taiwan. Methods: Vital statistics of divorce since 1975 were used. Divorce rates were calculated and a synthetic cohort life table was also constructed to estimate the proportions of unions that remain intact with the duration-specific divorce rates observed in 2010. A separate life table estimating the actual marriage survivorship for the 1998 marriage cohort was also presented. Results: As Taiwan went through industrialization, the period findings show that a reversal in educational differential in divorce from positive to negative is observed for both sexes. Now the least educated men and women have become more vulnerable to union instability. Finally, synthetic cohort life table estimates indicate substantial educational differences in the proportions of recent marriages ending in divorce. Conclusions: The drastic increase in period divorce rates is accompanied by a reversal of educational gradient and expanding social inequality. Social gap in divorce rates expanded much faster among men than women across years. Given that remarriage rates for the disadvantaged are lower than the better educated, these patterns indicate that the disadvantaged is likely to spend an increasingly large proportion of their lives outside a marital union. Contribution: The divorce patterns revealed have critical implications for single-parent families, as well as family policies and social assistance.

Long-Term Survival Following Traumatic Brain Injury: A Population-Based Parametric Survival Analysis

Background: Long-term mortality may be increased following traumatic brain injury (TBI); however, the degree to which survival could be reduced is unknown. We aimed at modelling life expectancy following post-acute TBI to provide predictions of longevity and quantify differences in survivorship with the general population. Methods: A population-based retrospective cohort study using data from the Rochester Epidemiology Project (REP) was performed. A random sample of patients from Olmsted County, Minnesota with a confirmed TBI between 1987 and 2000 was identified and vital status determined in 2013. Parametric survival modelling was then used to develop a model to predict life expectancy following TBI conditional on age at injury. Survivorship following TBI was also compared with the general population and age- and gender-matched non-head injured REP controls. Results: Seven hundred and sixty nine patients were included in complete case analyses. The median follow-up time was 16.1 years (interquartile range 9.0-20.4) with 120 deaths occurring in the cohort during the study period. Survival after acute TBI was well represented by a Gompertz distribution. Victims of TBI surviving for at least 6 months post-injury demonstrated a much higher ongoing mortality rate compared to the US general population and non-TBI controls (hazard ratio 1.47, 95% CI 1.15-1.87). US general population cohort life table data was used to update the Gompertz model's shape and scale parameters to account for cohort effects and allow prediction of life expectancy in contemporary TBI. Conclusions: Survivors of TBI have decreased life expectancy compared to the general population. This may be secondary to the head injury itself or result from patient characteristics associated with both the propensity for TBI and increased early mortality. Post-TBI life expectancy estimates may be useful to guide prognosis, in public health planning, for actuarial applications and in the extrapolation of outcomes for TBI economic models.

Trends in neonatal mortality in Nigeria and effects of bio-demographic and maternal characteristics.

BackgroundNigeria’s efforts to reduce under-five mortality has been biased in favour of childhood mortality to the neglect of neonates and as such the literature is short of adequate information on the determinants of neonatal mortality. Whereas studies have shown that about half of infant deaths occur in the neonatal period. Knowledge of the determinants of neonatal mortality are essential for the design of intervention programes that will enhance neonatal survival. Therefore, this study was conducted to investigate the trends and factors associated with neonatal mortality in Nigeria.MethodsThis was a retrospective analysis of the reproductive history data collected in the Nigeria Demographic and Health Surveys (NDHS) for 1990, 2003, 2008 and 2013. Neonatal mortality rates were estimated as the probability of dying before 28 completed days using synthetic cohort life table techniques. Univariate and multiple Cox proportional hazards regression models were used to explore the effects of selected maternal and bio-demographic variables on neonatal mortality. The Hazard Ratio (HR) and its 95% Confidence Interval (CI) were estimated to prioritize obtained significant factors.ResultsNigeria neonatal mortality rate stagnated at 41 per 1000 live births between 1990 and 2013. There were rural-urban and regional differences with more deaths occurring in rural areas and northern regions. In 1990, antenatal care (HR = 0.76; CI = 0.61-0.95), facility delivery (HR = 0.69; CI = 0.53-0.90) and births interval less than 24 months (HR = 1.67; CI = 1.41-1.98) were significantly associated with neonatal deaths. Factors identified from the 2013 data were antenatal care (HR = 0.76; CI = 0.61-0.95), birth interval less than 24 months (HR = 1.67; CI = 1.41-1.98), delivery at health facility (HR = 0.69; CI = 0.53-0.90), and small birth size (HR = 1.72; CI = 1.39-2.14).ConclusionThere was little improvement in neonatal survival in Nigeria between 1990 and 2013. Bio-demographic and health care related characteristics are significant determinants of neonatal survival. Family planning should be intensified while government should improve the quality of maternal and child health services to enhance the survival of neonates.

Demographic Parameters of Nezara viridula (Heteroptera: Pentatomidae) Reared on Two Diets Developed for Lygus spp.

Two artificial diets developed for rearing Lygus spp., a fresh yolk chicken egg based-diet (FYD) and a dry yolk chicken egg based-diet (DYD), were evaluated as an alternative food source for rearing the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae). Survival to adult was 97.3 and 74.67%, respectively, on the fresh and dry yolk diets. Insects fed FYD had 100% survival of nymphs from first through fourth instars. Adult development was significantly shorter on FYD (30.37 ± SE 0.30 d) as compared with DYD (32.77 ± SE 0.16 d). Increased male and female longevity, higher fecundity, and larger egg mass sizes were also observed with N. viridula-fed FYD. However, fertility and hatchability was higher on DYD. A complete cohort life table was constructed to describe the development of N. viridula on both diets.

Cohort life tables for a population of the soft-shell clam, Mya arenaria L., in the White Sea

The Mya arenaria generation in the White Sea was observed for almost the whole life cycle (around 25 years). Using the data on this generation dynamics, the cohort life table was built. The main purpose of the research is analysis of age-specific mortality in this soft-shell clam population. The mortality rate was found to change more than tenfold throughout the study period. No regular changes in its value were observed. Periods of low mortality alternated with periods of much higher mortality. Several reasons for the increase in M. arenaria mortality rate during its life cycle are proposed: (a) living in the surface sediment layer at early stages of life cycle (unstable environment, high mortality of non-viable clams, predator impact); (b) intense intraspecific relationships in dense aggregations of young clams; (c) increased intraspecific competition during periods of the rapid individual growth; (d) ageing (clam mortality increases with older age—achievement of an average and a maximum lifespan).

Cumulative risks of foster care placement for Danish children.

Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster care placement in other countries, which makes it difficult to gauge the degree to which factor foster care placement is salient in other contexts. In this article, we provide companion estimates to those provided in recent work on the US by using Danish registry data and synthetic cohort life tables to show how high and unequally distributed the cumulative risk of foster care placement is for Danish children. Results suggest that at the beginning of the study period (in 1998) the cumulative risk of foster care placement for Danish children was roughly in line with the risk for American children. Yet, by the end of the study period (2010), the risk had declined to half the risk for American children. Our results also show some variations by parental ethnicity and sex, but these differences are small. Indeed, they appear quite muted relative to racial/ethnic differences in these risks in the United States. Last, though cumulative risks are similar between Danish and American children (especially at the beginning of the study period), the age-specific risk profiles are markedly different, with higher risks for older Danish children than for older American children.

The prevalence of confirmed maltreatment among US children, 2004 to 2011.

Child maltreatment is a risk factor for poor health throughout the life course. Existing estimates of the proportion of the US population maltreated during childhood are based on retrospective self-reports. Records of officially confirmed maltreatment have been used to produce annual rather than cumulative counts of maltreated individuals. To estimate the proportion of US children with a report of maltreatment (abuse or neglect) that was indicated or substantiated by Child Protective Services (referred to as confirmed maltreatment) by 18 years of age. The National Child Abuse and Neglect Data System (NCANDS) Child File includes information on all US children with a confirmed report of maltreatment, totaling 5,689,900 children (2004-2011). We developed synthetic cohort life tables to estimate the cumulative prevalence of confirmed childhood maltreatment by 18 years of age. The cumulative prevalence of confirmed child maltreatment by race/ethnicity, sex, and year. At 2011 rates, 12.5% (95% CI, 12.5%-12.6%) of US children will experience a confirmed case of maltreatment by 18 years of age. Girls have a higher cumulative prevalence (13.0% [95% CI, 12.9%-13.0%]) than boys (12.0% [12.0%-12.1%]). Black (20.9% [95% CI, 20.8%-21.1%]), Native American (14.5% [14.2%-14.9%]), and Hispanic (13.0% [12.9%-13.1%]) children have higher prevalences than white (10.7% [10.6%-10.8%]) or Asian/Pacific Islander (3.8% [3.7%-3.8%]) children. The risk for maltreatment is highest in the first few years of life; 2.1% (95% CI, 2.1%-2.1%) of children have confirmed maltreatment by 1 year of age, and 5.8% (5.8%-5.9%), by 5 years of age. Estimates from 2011 were consistent with those from 2004 through 2010. Annual rates of confirmed child maltreatment dramatically understate the cumulative number of children confirmed to be maltreated during childhood. Our findings indicate that maltreatment will be confirmed for 1 in 8 US children by 18 years of age, far greater than the 1 in 100 children whose maltreatment is confirmed annually. For black children, the cumulative prevalence is 1 in 5; for Native American children, 1 in 7.

Natural humic substances effects on the life history traits of Latonopsis australis SARS (1888) (Cladocera – Crustacea)

Cultivation medium is one of the first aspects to be considered in zooplankton laboratory cultivation. The use of artificial media does not concern to reproduce natural conditions to the cultivations, which may be achieved by using natural organic compounds like humic substances (HS). This study aimed to evaluate the effects of a concentrate of dissolved organic carbon (DOC) from the Negro River (NR1NR, for Negro River.1) and an extraction of humic acids (HA) from humus produced by Eisenia andrei on the life history traits of laboratory-based Latonopsis australis SARS (1888). A cohort life table approach was used to provide information about the effectiveness of NR and HA as supplements for the artificial cultivation of L. australis. Additionally, we seek to observe a maximization of L. australis artificial cultivation fitness by expanding the range of HS concentrations. The first experiment demonstrated that the females of L. australis reared under NR10 (mgDOCL−1) may have experienced an acceleration of the population life cycle, as the females have proportionally reproduced more and lived shorter than controls. By contrast, the use of the HA did not improve life history traits considered. The expansion of the concentration range (5, 10, 20 and 50mgDOCL−1) corroborated the patterns observed on the first assay. Results for the fitness estimates combined with shorter lifespans than controls demonstrated trade-offs between reproductive output and female longevity reared under NR conditions, with NR20 been suggested as the best L. australis cultivation medium. This response might be associated with hormone-like effects.