Exploring unobserved heterogeneity in perinatal and neonatal mortality risks: The case of an Italian sharecropping community, 1900–39

Previous researchers have found that traditional determinants explain only a limited part of the variation in perinatal and infant mortality at the family level. In the study reported in this paper, we explored the factors that make the perinatal/neonatal death risk more heterogeneous across families. We estimated logistic regressions with cluster random effects at the maternal level, using data from the Italian village of Granarolo from 1900 to 1939. We estimated the effects of selected predictors on perinatal/neonatal mortality and unexplained inter-family variation. We found that non-rural skilled and lower-skilled workers experienced higher perinatal and neonatal mortality risks. Unexplained heterogeneity at the maternal level was lower for women living in sharecropper families than for those in landless labourer and non-rural worker families. Unexplained perinatal and neonatal mortality components were also due to socio-economic differences and were not necessarily related only to maternal biological features or shared genetic frailty.     

The Biodemography of Variation in Human Frailty

A population is composed of individuals who are heterogeneous in their susceptibility to death and disease. This heterogeneity is reflected in the age-specific incidence or mortality (hazard) function. This variation has typically been hidden--that is, not measured directly--and has generally been modeled in a purely empirical statistical way, because there is no theory in demography for the distribution of frailty. A substantial fraction of variation in frailty, however, has an underlying genetic basis, for which there is a formal theory. This theory, based on evolutionary biology and on the nature of mendelian transmission, provides prior constraints on the distribution of variation in the population as well as providing methods for identifying genes involved in many important diseases. The accumulating effects of environmental exposures with age are another major component of variation in frailty. In some important instances, this variation and its effect on the age-specific hazard function can also be understood in terms of cause-specific biological processes. These biological considerations may enable demographers to model frailty, and thus mortality, in a better way.     

Causes of Male Excess Mortality: Insights from Cloistered Populations

The degree to which biological factors contribute to the existence and the widening of mortality differences by sex remains unclear. To address this question, a mortality analysis for the years 1890 to 1995 was performed comparing mortality data on more than 11,000 Catholic nuns and monks in Bavarian communities living in very nearly identical behavioral and environmental conditions with life table data for the general German population. While the mortality differences between women and men in the general German population increased considerably after World War II, they remained almost constant among the members of Bavarian religious orders during the entire observation period, with slight advantages for nuns. Thus, the higher differences observable in the general population cannot be attributed to biological factors. The different trends in sex‐specific mortality between the general and the cloistered populations are caused exclusively by men in the general population who were unable to follow the trend in mortality reduction of women, nuns, and especially monks. Under the special environmental conditions of nuns and monks, biological factors appear to confer a maximum survival advantage for women of no more than one year in remaining life expectancy at young adult ages.     

Living and dying in the U.S.A.: Sociodemographic determinants of death among blacks and whites

This paper examines the demographic and social factors associated with differences in length of life by race. The results demonstrate that sociodemographic factors--age, sex, marital status, family size, and income--profoundly affect black and white mortality. Indeed, the racial gap in overall mortality could close completely with increased standards of living and improved lifestyles. Moreover, examining cause-specific mortality while adjusting for social factors shows that compared to whites, blacks have a lower mortality risk from respiratory diseases, accidents, and suicide; the same risk from circulatory diseases and cancer; and higher risks from infectious diseases, homicide, and diabetes. These results underscore the importance of examining social characteristics to understand more clearly the race differences in overall and cause-specific mortality.     

Why Is Infant Mortality Higher in Boys Than in Girls? A New Hypothesis Based on Preconception Environment and Evidence From a Large Sample of Twins

Infant mortality is higher in boys than girls in most parts of the world. This has been explained by sex differences in genetic and biological makeup, with boys being biologically weaker and more susceptible to diseases and premature death. At the same time, recent studies have found that numerous preconception or prenatal environmental factors affect the probability of a baby being conceived male or female. I propose that these environmental factors also explain sex differences in mortality. I contribute a new methodology of distinguishing between child biology and preconception environment by comparing male-female differences in mortality across opposite-sex twins, same-sex twins, and all twins. Using a large sample of twins from sub-Saharan Africa, I find that both preconception environment and child biology increase the mortality of male infants, but the effect of biology is substantially smaller than the literature suggests. I also estimate the interacting effects of biology with some intrauterine and external environmental factors, including birth order within a twin pair, social status, and climate. I find that a twin is more likely to be male if he is the firstborn, born to an educated mother, or born in certain climatic conditions. Male firstborns are more likely to survive than female firstborns, but only during the neonatal period. Finally, mortality is not affected by the interactions between biology and climate or between biology and social status.     

Recent health trends in the Native American population

This paper reviews the changes in the health status of Native Americans since the mid-1950s, how the disease pattern differs from non-Natives, and regional differences within the Native American population. Despite some limitations, data from the Indian Health Service indicate that substantial decline in the infant mortality rate and mortality from such infectious diseases as tuberculosis and gastroenteritis has occurred. With the exception of cardiovascular diseases and cancer, the risk of death from most causes are higher among Native Americans than the total US population. Geographic variation in disease rates can be demonstrated, most notable in diabetes. The unique pattern of diseases among Native Americans reflect the interaction of environmental and genetic factors. Genetic susceptibility plays a significant role in some diseases, such as diabetes, while for others, the generally lower socioeconomic status, higher prevalence of certain health risk behaviors and lower utilization of preventive services in the Native American population are important determinants.     

A Comparison of US and Canadian Mortality in 1998

On average, Americans die earlier than Canadians. An estimate based on comparing the number of actual US deaths with the number that would have obtained had Canadian age‐ and sex‐specific death rates applied to the US population shows an excess number of US deaths in 1998 amounting approximately to 253,000. Excess US deaths were especially numerous among older women, middle‐aged men, and nonwhites. Circulatory diseases were the major cause of excess deaths. Prevalences of two of the major risk factors for circulatory deaths—smoking and hypertension—were higher in Canada than in the US. But obesity was higher in the US, suggesting a likely important role that obesity plays in higher mortality in the US relative to Canada. Comparisons of the level, age pattern, and causes of US and Canadian mortality, however, raise more questions than currently available data can answer.     

Social,behavioral, and biological factors,and sex differences in mortality

Few studies have examined whether sex differences in mortality are associated with different distributions of risk factors or result from the unique relationships between risk factors and mortality for men and women. We extend previous research by systematically testing a variety of factors, including health behaviors, social ties, socioeconomic status, and biological indicators of health. We employ the National Health and Nutritional Examination Survey III Linked Mortality File and use Cox proportional hazards models to examine sex differences in adult mortality in the United States. Our findings document that social and behavioral characteristics are key factors related to the sex gap in mortality. Once we control for women’s lower levels of marriage, poverty, and exercise, the sex gap in mortality widens; and once we control for women’s greater propensity to visit with friends and relatives, attend religious services, and abstain from smoking, the sex gap in mortality narrows. Biological factors—including indicators of inflammation and cardiovascular risk—also inform sex differences in mortality. Nevertheless, persistent sex differences in mortality remain: compared with women, men have 30% to 83% higher risks of death over the follow-up period, depending on the covariates included in the model. Although the prevalence ofriskfactors differs by sex, the impact of those riskfactors on mortality is similar for men and women.     

中国老年人虚弱指数与死亡风险及队列差异

利用中国老年人健康长寿影响因素调查（ CLHLS ）2002－2011年跟踪调查数据,通过多种健康指标构建中国老年人虚弱指数,运用增长曲线模型和Cox等比例风险函数的研究方法,对中国老年人虚弱指数和死亡风险及其队列差异进行了深入分析。研究发现,女性虚弱指数比男性高,增长速度也比男性快,但是死亡风险比男性低;出生较晚的队列与出生早的队列相比,虚弱指数会更高,他们的增长程度更快;受教育程度高的老年人虚弱指数低,但是其增长速度却比受教育程度低的老年人要高。     

Height, frailty, and the standard of living: modelling the effects of diet and disease on declining mortality and increasing height

Explanations of historical trends in both mortality and human height differ over the relative contributions of better nutrition and reduced exposure to disease. This paper explores theoretical models in which interactions between diet and disease determine both mortality and height. One model assumes that adult height is directly related to frailty, the relative risk of dying. The second model links frailty to differences between attained and potential height. Diet plays a small role in the transition to low mortality in the first model. The second model assigns a large role to diet in historical mortality trends, but implies that mortality will be unrelated to height in the future.     

Epidemiological evaluation of death risk from cardiovascular diseases among Polish population of working age

"The aim of the study was an evaluation of death risk among men and women of working age exposed to cardiovascular risk factors. The survey covered random samples of the population living in the regions of Wroclaw and Ciechanow, [Poland,] including families of all who died from cardiovascular diseases in 1988.... The results of demographic analyses [indicate] that social factors exerting a negative effect on health behaviours are responsible for high mortality in males. Moreover, difficulties of Polish life place additional stress on male population.... For each from among 18 analysed factors the risk of death from cardiovascular diseases was several times higher in exposed males than in females."     

A Case for Developing Community Drug Indicators

The EU Action Plan on Drugs (2005?C2008) calls for member states of the European Union to provide information on five key epidemiological indicators. These are: general population surveys, prevalence and patterns of problem drug use, drug related infectious diseases, drug related deaths and mortality of drug users, and demand for drug treatment. The goal is to improve the comparability of data across the Member States, which is a central task of the EMCDDA (European Monitoring Centre for Drugs and Drug Addiction). Ireland has made progress on a national level in meeting this obligation. Currently the core information systems used to monitor the drugs problem in Ireland and to inform policy making are in the health and law enforcement areas including treatment, mortality and crime data. The dominance of such objective indicators and treatment outcome measures has contributed to obscuring the view of communities experiencing drugs problems on a day to day basis. The data are summations of the individual experience of drug problems and contribute little to understanding the broader question of how drug problem effect communities. This article draws on a community drugs study to review the contribution of traditional indicators of drug problems and consider some of the limitations of this data. It then presents an analysis of community data to identify possible community indicators of drug problems.     

Is 60 the New 50? Examining Changes in Biological Age Over the Past Two Decades

Increasing life expectancy has been interpreted as improving health of a population. However, mortality is not always a reliable proxy for the pace of aging and could instead reflect achievement in keeping ailing people alive. Using data from NHANES III (1988–1994) and NHANES IV (2007–2010), we examined how biological age, relative to chronological age, changed in the United States between 1988 and 2010, while estimating the contribution of changes in modifiable health behaviors. Results suggest that biological age is lower for more recent periods; however, the degree of improvement varied across age and sex groups. Overall, older adults experienced the greatest improvement or decreases in biological age. Males, especially those in the youngest and oldest groups, experienced greater declines in biological age than females. These differences were partially explained by age- and sex-specific changes in behaviors, such as smoking, obesity, and medication use. Slowing the pace of aging, along with increasing life expectancy, has important social and economic implications; thus, identifying modifiable risk factors that contribute to cohort differences in health and aging is essential.     

New insights into the Far Eastern pattern of mortality

Some of the highest levels of excess mortality of males found anywhere in the world were present in several Far Eastern populations during the 1960s and 1970s but have progressively disappeared since that time. This study uses cause-of-death data to determine the diseases responsible for the existence and attenuation of these sex differences in Hong Kong, Singapore, and Taiwan. The results indicate that respiratory tuberculosis is the single most important underlying cause of the existence and attenuation of the pattern, that the role of liver diseases is not clear cut, and that other causes (such as cardiovascular diseases) are also important. A review of numerous risk factors yields no compelling reason why these populations experienced such large sex differences in mortality. However, it seems likely that public health and biomedical improvements (particularly those related to the reduction in mortality from tuberculosis) played a critical role in the attenuation of the Far Eastern mortality pattern.     

Religious attendance and mortality: Implications for the black-white mortality crossover

This study investigates the relationships among religious attendance, mortality, and the black-white mortality crossover. We build on prior research by examining the link between attendance and mortality while testing whether religious involvement captures an important source of population heterogeneity that contributes to a crossover Using data from the Established Populations for Epidemiologic Studies of the Elderly, we find a strong negative association between attendance and mortality. Our results also show evidence of a racial crossover in mortality rates for both men and women. When religious attendance is modeled in terms of differential frailty, clear gender differences emerge. For women, the effect of attendance is race- and age-dependent, modifying the age at crossover by 10 years. For men, however; the effect of attendance is not related to race and does not alter the crossover pattern. When other health risks are modeled in terms of differential frailty, wefind neither race nor age-related effects. Overall, the results highlight the importance of considering religious attendance when examining racial and gender differences in age-specific mortality rates.     

A gender comparison of HIV and drug use across the rural-urban continuum

Despite the central role of women drug users in escalating AIDS statistics, there is still a limited number of studies that examine the roles of gender and drug use type in HIV seroprevalence. This lacuna in the research literature has led to significant gaps in researchers' understanding of how and to what extent women may differ in their drug-using and HIV risk behaviors compared to their better-studied male counterparts. This study, derived from a sample of 3,555 out-of-treatment drug users residing in three South Florida urban and rural communities, attempts to compare the drug usage and needle and sexual risk behaviors of male and female drug users that put them at risk for HIV infection. The overall seropositivity rate for women drug users was 26.5% compared to 19.5% for their male counterparts. Results of multivariate analyses indicate that females compared to males were 1.4 times more likely to be HIV seropositive. Risk behaviors associated with this elevated seropositivity include living arrangements, homeless status, drug use, sexual trading behaviors, and history of STDs. Furthermore, there was a strong linear relationship between drug use type and HIV seroprevalence among women drug users. Compared to those who were neither crack smokers nor injectors of illicit drugs, those who were crack smokers only were 2 times more likely to be HIV seropositive, while those who were both crack smokers and injectors were 5 times more likely to be HIV seropositive, and those who were injectors only were 6 times more likely to be HIV seropositive. These findings indicate that among women, drug abuse and its associated risk behaviors, increase the vulnerability of this population for HIV and thus render them an extremely important priority population on which to focus HIV prevention and public health efforts and programs.     

Drug dependency and HIV testing among state prisoners

HIV and drug use are higher among prisoners than the general US population. This study examines drug dependency/use and differences between prisoners who volunteered for HIV testing and those who did not in a less densely populated state. It was hypothesized that prisoners who volunteered for an HIV test were engaged in more drug use and other risky behaviors than those who did not. Survey data were collected from 600 randomly selected inmates (567 males and 33 females) from 15 state prisons. Subjects were male (95%), white (63%), never married (43%), and 44% volunteered for an HIV test since entering prison. Ninety-two percent of inmates met DSM criteria for drug dependence in their lifetime. Those who volunteered for HIV testing were 2.6 times more likely to ever have used PCP; 1.5 times more likely to ever have used cocaine; 1.4 times more likely to ever have had a problem with drugs; 1.3 times more likely to have used opiates, and 1.6 times more likely to report having been sexually or physically abused. Implications for interventions are discussed.     

Recent trends in multiple-caused mortality 1968 to 1982: Age and cohort components

Declines in mortality at advanced ages have been observed recently in the United States. These declines have been related to a reduction in the risk of major circulatory diseases, such as stroke and heart disease. In this paper we examine the contribution of two additional major factors in those declines. The first is the effect of conditions associated with circulatory diseases. This effect can be examined by using multiple-cause mortality data in which all conditions reported by the physician on the death certificates are recorded. The second is the contribution of cohort mortality differentials to temporal changes. If major cohort differentials are identified, we may be able to determine if recent declines in mortality are likely to continue-and to what levels. Such insights would be useful both in improving projections of the size and age structure of the U.S. elderly population and its entitlement groups and in helping to identify future patterns of needs for preventive and other health services.     

Taking the Lab to the Field: Monitoring Reproductive Hormones in Population Research

The incorporation of biological measures in social science research allows for the development of robust models, with greater explanatory power. By analyzing the underlying proximate causes of fertility and mortality, biodemographers have been able to model demographic patterns more accurately. Recent technological advances are making possible the analysis of biological samples collected using minimally invasive methods. Methods and techniques are discussed that can be used for estimating hormonal, particularly reproductive hormone, levels in large‐scale population studies in which thousands of samples could be collected. Sample collection methods and techniques reviewed include blood spots, urine samples, and saliva samples. The collection of biological samples is associated with serious ethical concerns. The article discusses the issue of asymmetries in technology between developing and developed countries, emphasizing the need for capacity building and information transfer. Illustrative contributions of biological data are presented.