Causes of death and mortality crossovers by race

Racial Differences in 1-Year Mortality after Hospitalization for Chronic Obstructive Pulmonary Disease in the United States

Rationale: One quarter of Medicare beneficiaries hospitalized for chronic obstructive pulmonary disease (COPD) die within 1 year. Although overall mortality rates are higher among White patients with COPD, racial and ethnic differences in the vulnerable period following hospitalization are unknown.Objectives: To determine the association between race and ethnicity and mortality following COPD hospitalization and to evaluate the extent to which differences are explained by clinical, geographic, socioeconomic, and post-acute care factors among Medicare beneficiaries in the United States.Methods: In this retrospective cohort study of Medicare beneficiaries hospitalized for COPD exacerbation, we constructed Cox regression models for 1-year mortality accounting for hospital-level clustering; sequentially adjusting for clinical, geographic, neighborhood socioeconomic, and post-acute care characteristics; and stratifying by sex and individual socioeconomic status.Results: Among 244,624 hospitalizations, Medicare beneficiaries of racial and ethnic minority groups had a lower risk of dying within 1 year of hospitalization than those of White race (hazard ratios, 0.78 [95% confidence interval, 0.75-0.80] for Black patients, 0.79 [0.76-0.82] for Hispanic patients, and 0.82 [0.77-0.86] for others). Differences in visits to physicians, attendance of pulmonary rehabilitation, and discharge disposition explained some of the mortality gap among dual-eligible beneficiaries but not among non-dual-eligible beneficiaries.Conclusions: Medicare beneficiaries of White race are at greater risk of mortality following COPD hospitalization compared with beneficiaries of minority race and ethnicity groups. Our findings should be interpreted in the context of the selection of a hospitalized population and a potentially incomplete assessment of illness severity in administrative data, and warrant further investigation.

Differences in survival and mortality in minority ethnic groups with dementia: A systematic review and meta-analysis

OBJECTIVES

Although there are disparities in both risk of developing dementia and accessibility of dementia services for certain minority ethnic groups in the United States and United Kingdom, disparities in survival after a dementia diagnosis are less well-studied. Our objective was to systematically review the literature to investigate racial/ethnic differences in survival and mortality in dementia.

METHODS

We searched Embase, Ovid MEDLINE, Global Health and PsycINFO from inception to November 2018 for studies comparing survival or mortality over time in at least two race/ethnicity groups. Studies from any country were included but analysed separately. We used narrative synthesis and random-effects meta-analysis to synthesise findings. The Newcastle-Ottawa Scale was used to assess quality and risk of bias in individual studies.

RESULTS

We identified 22 articles, most from the United States (n = 17), as well as the United Kingdom (n = 3) and the Netherlands (n = 1). In a meta-analysis of US studies, hazard of mortality was lower in Black/African American groups (Pooled Hazard Ratio = 0.86, 95% CI = 0.82-0.91, I²  = 17%, from four studies) and Hispanic/Latino groups (Pooled HR = 0.65, 95% CI = 0.50-0.84, I²  = 86%, from four studies) versus comparison groups. However, study quality was mixed, and in particular, quality of reporting of race/ethnicity was inconsistent.

CONCLUSION

Literature indicates that Black/African American and Hispanic/Latino groups may experience lower mortality in dementia versus comparison groups in the United States, but further research, using clearer and more and consistent reporting of race/ethnicity, is necessary to understand what drives these patterns and their implications for policy and practice.

Unobserved Population Heterogeneity and Dynamics of Health Disparities

BACKGROUND

A growing body of literature has reported widening educational health disparities across birth cohorts or time periods in the United States, but has paid little attention to the implication of mortality selection on the cohort trend in health disparities.

OBJECTIVE

This study investigates how changes in the variance of unobserved frailty over time may complicate the interpretation of cohort trends in health disparities and life expectancy.

METHODS

We use the microsimulation method to test the effect of mortality selection and further propose a counterfactual simulation procedure to estimate its contribution. Data used in the simulations are based on Panel Studies of Income Dynamics 1968-2013, National Health and Nutrition Examination Survey data 1999-2012, and National Health Interview Survey data 1986-2011.

RESULTS

Simulation shows that mortality selection may generate seemingly contradictory trends in health disparities and life expectancy across birth cohorts at the group and individual level. Life expectancy can change even when individual mortality curve is fixed. In the absence of a change in the causal effect of education on mortality at the individual level, an educational life expectancy gap can change across cohorts as a result of the change in frailty variance. Empirical analysis shows that mortality selection accounts for a sizeable amount of contribution to the widening educational life expectancy gap from the 1950s to 1960s birth cohorts in the United States.

CONTRIBUTION

We demonstrate mortality selection can complicate the cohort trend in health disparities and life expectancy and propose a counterfactual simulation method to evaluate its contribution.

Multidimensional Mortality Selection: Why Individual Dimensions of Frailty Don't Act Like Frailty

Theoretical models of mortality selection have great utility in explaining otherwise puzzling phenomena. The most famous example may be the Black-White mortality crossover: at old ages, Blacks outlive Whites, presumably because few frail Blacks survive to old ages while some frail Whites do. Yet theoretical models of unidimensional heterogeneity, or frailty, do not speak to the most common empirical situation for mortality researchers: the case in which some important population heterogeneity is observed and some is not. I show that, when one dimension of heterogeneity is observed and another is unobserved, neither the observed nor the unobserved dimension need behave as classic frailty models predict. For example, in a multidimensional model, mortality selection can increase the proportion of survivors who are disadvantaged, or "frail," and can lead Black survivors to be more frail than Whites, along some dimensions of disadvantage. Transferring theoretical results about unidimensional heterogeneity to settings with both observed and unobserved heterogeneity produces misleading inferences about mortality disparities. The unusually flexible behavior of individual dimensions of multidimensional heterogeneity creates previously unrecognized challenges for empirically testing selection models of disparities, such as models of mortality crossovers.

Temporal trends and black-white disparity in mortality among hospitalized persons living with HIV in the United States

We sought to determine whether black-white gap in mortality exists among hospitalized HIV-positive patients in the United States (US). We hypothesized that in-hospital mortality (IHM) would be similar between black and white HIV-positive patients due to the nationwide availability of HIV services.Our analysis was restricted to hospitalized HIV-positive patients (15-49 years). We used the National Inpatient Sample (NIS) that covered the period from January 1, 2002 to December 31, 2014. We employed joinpoint regression to construct temporal trends in IHM overall and within subgroups over the study period. We applied multivariable survey logistic regression to generate adjusted odds ratios (OR) and 95% confidence intervals (CI).The total number of HIV-related hospitalizations and IHM decreased over time, with 6914 (3.9%) HIV-related in-hospital deaths in 2002 versus 2070 HIV-related in-hospital deaths (1.9%) in 2014, (relative reduction: 51.2%). HIV-related IHM among blacks declined at a slightly faster rate than in the general population (by 56.8%, from 4.4% to 1.9%). Among whites, the drop was similar to that of the general population (51.2%, from 3.9% to 1.9%). Although IHM rates did not differ between blacks and whites, being black with HIV was independently associated with a 17% elevated odds for IHM (OR = 1.17; 95% CI = 1.11-1.25).In-hospital HIV-related deaths continue to decline among both blacks and whites in the US. Among hospitalized HIV-positive patients black-white disparity still persists, but to a lesser extent than in the general HIV population. Improved access to HIV care is a key to eliminating black-white disparity in HIV-related mortality.

Reflections on telomere dynamics and ageing-related diseases in humans

Epidemiological studies have principally relied on measurements of telomere length (TL) in leucocytes, which reflects TL in other somatic cells. Leucocyte TL (LTL) displays vast variation across individuals—a phenomenon already observed in newborns. It is highly heritable, longer in females than males and in individuals of African ancestry than European ancestry. LTL is also longer in offspring conceived by older men. The traditional view regards LTL as a passive biomarker of human ageing. However, new evidence suggests that a dynamic interplay between selective evolutionary forces and TL might result in trade-offs for specific health outcomes. From a biological perspective, an active role of TL in ageing-related human diseases could occur because short telomeres increase the risk of a category of diseases related to restricted cell proliferation and tissue degeneration, including cardiovascular disease, whereas long telomeres increase the risk of another category of diseases related to increased proliferative growth, including major cancers. To understand the role of telomere biology in ageing-related diseases, it is essential to expand telomere research to newborns and children and seek further insight into the underlying causes of the variation in TL due to ancestry and geographical location.

This article is part of the theme issue ‘Understanding diversity in telomere dynamics’.

Can Survival Bias Explain the Age Attenuation of Racial Inequalities in Stroke Incidence?: A Simulation Study

BACKGROUND

In middle age, stroke incidence is higher among black than white Americans. For unknown reasons, this inequality decreases and reverses with age. We conducted simulations to evaluate whether selective survival could account for observed age patterning of black-white stroke inequalities.

METHODS

We simulated birth cohorts of 20,000 blacks and 20,000 whites with survival distributions based on US life tables for the 1919-1921 birth cohort. We generated stroke incidence rates for ages 45-94 years using Reasons for Geographic and Racial Disparities in Stroke (REGARDS) study rates for whites and setting the effect of black race on stroke to incidence rate difference (IRD) = 20/10,000 person-years at all ages, the inequality observed at younger ages in REGARDS. We compared observed age-specific stroke incidence across scenarios, varying effects of U, representing unobserved factors influencing mortality and stroke risk.

RESULTS

Despite a constant adverse effect of black race on stroke risk, the observed black-white inequality in stroke incidence attenuated at older age. When the hazard ratio for U on stroke was 1.5 for both blacks and whites, but U only directly influenced mortality for blacks (hazard ratio for U on mortality =1.5 for blacks; 1.0 for whites), stroke incidence rates in late life were lower among blacks (average observed IRD = -43/10,000 person-years at ages 85-94 years versus causal IRD = 20/10,000 person-years) and mirrored patterns observed in REGARDS.

CONCLUSIONS

A relatively moderate unmeasured common cause of stroke and survival could fully account for observed age attenuation of racial inequalities in stroke.

The Methuselah Effect: The Pernicious Impact of Unreported Deaths on Old-Age Mortality Estimates

We examine inferences about old-age mortality that arise when researchers use survey data matched to death records. We show that even small rates of failure to match respondents can lead to substantial bias in the measurement of mortality rates at older ages. This type of measurement error is consequential for three strands in the demographic literature: (1) the deceleration in mortality rates at old ages; (2) the black-white mortality crossover; and (3) the relatively low rate of old-age mortality among Hispanics, often called the "Hispanic paradox." Using the National Longitudinal Survey of Older Men matched to death records in both the U.S. Vital Statistics system and the Social Security Death Index, we demonstrate that even small rates of missing mortality matching plausibly lead to an appearance of mortality deceleration when none exists and can generate a spurious black-white mortality crossover. We confirm these findings using data from the National Health Interview Survey matched to the U.S. Vital Statistics system, a data set known as the "gold standard" (Cowper et al. 2002) for estimating age-specific mortality. Moreover, with these data, we show that the Hispanic paradox is also plausibly explained by a similar undercount.

Racial disparities in adult all-cause and cause-specific mortality among us adults: mediating and moderating factors

BACKGROUND

Studies uncovering factors beyond socio-economic status (SES) that would explain racial and ethnic disparities in mortality are scarce.

METHODS

Using prospective cohort data from the Third National Health and Nutrition Examination Survey (NHANES III), we examined all-cause and cause-specific mortality disparities by race, mediation through key factors and moderation by age (20-49 vs. 50+), sex and poverty status. Cox proportional hazards, discrete-time hazards and competing risk regression models were conducted (N = 16,573 participants, n = 4207 deaths, Median time = 170 months (1-217 months)).

RESULTS

Age, sex and poverty income ratio-adjusted hazard rates were higher among Non-Hispanic Blacks (NHBs) vs. Non-Hispanic Whites (NHW). Within the above-poverty young men stratum where this association was the strongest, the socio-demographic-adjusted HR = 2.59, p < 0.001 was only partially attenuated by SES and other factors (full model HR = 2.08, p = 0.003). Income, education, diet quality, allostatic load and self-rated health, were among key mediators explaining NHB vs. NHW disparity in mortality. The Hispanic paradox was observed consistently among women above poverty (young and old). NHBs had higher CVD-related mortality risk compared to NHW which was explained by factors beyond SES. Those factors did not explain excess risk among NHB for neoplasm-related death (fully adjusted HR = 1.41, 95 % CI: 1.02-2.75, p = 0.044). Moreover, those factors explained the lower risk of neoplasm-related death among MA compared to NHW, while CVD-related mortality risk became lower among MA compared to NHW upon multivariate adjustment.

CONCLUSIONS

In sum, racial/ethnic disparities in all-cause and cause-specific mortality (particularly cardiovascular and neoplasms) were partly explained by socio-demographic, SES, health-related and dietary factors, and differentially by age, sex and poverty strata.

Black-White Disparities in Adult Mortality: Implications of Differential Record Linkage for Understanding the Mortality Crossover

Mortality rates among black individuals exceed those of white individuals throughout much of the life course. The black-white disparity in mortality rates is widest in young adulthood, and then rates converge with increasing age until a crossover occurs at about age 85 years, after which black older adults exhibit a lower mortality rate relative to white older adults. Data quality issues in survey-linked mortality studies may hinder accurate estimation of this disparity and may even be responsible for the observed black-white mortality crossover, especially if the linkage of surveys to death records during mortality follow-up is less accurate for black older adults. This study assesses black-white differences in the linkage of the 1986-2009 National Health Interview Survey to the National Death Index through 2011 and the implications of racial/ethnic differences in record linkage for mortality disparity estimates. Match class and match score (i.e., indicators of linkage quality) differ by race/ethnicity, with black adults exhibiting less certain matches than white adults in all age groups. The magnitude of the black-white mortality disparity varies with alternative linkage scenarios, but convergence and crossover continue to be observed in each case. Beyond black-white differences in linkage quality, this study also identifies declines over time in linkage quality and even eligibility for linkage among all adults. Although linkage quality is lower among black adults than white adults, differential record linkage does not account for the black-white mortality crossover.

Uncrossing the U.S black-white mortality crossover: the role of cohort forces in life course mortality risk

In this article, I examine the black-white crossover in U.S. adult all-cause mortality, emphasizing how cohort effects condition age-specific estimates of mortality risk. I employ hierarchical age-period-cohort methods on the National Health Interview Survey-Linked Mortality Files between 1986 and 2006 to show that the black-white mortality crossover can be uncrossed by factoring out period and cohort effects of mortality risk. That is, when controlling for variations in cohort and period patterns of U.S. adult mortality, the estimated age effects of non-Hispanic black and non-Hispanic white U.S. adult mortality risk do not cross at any age. This is the case for both men and women. Further, results show that nearly all the recent temporal change in U.S. adult mortality risk was cohort driven. The findings support the contention that the non-Hispanic black and non-Hispanic white U.S. adult populations experienced disparate cohort patterns of mortality risk and that these different experiences are driving the convergence and crossover of mortality risk at older ages.

Socioeconomic status and the Black-White mortality crossover

OBJECTIVES

We investigated associations among age, race, socioeconomic status (SES), and mortality in older persons and whether low SES contributes to the Black-White mortality crossover (when elevated age-specific mortality rates invert).

METHODS

We used panel data from the North Carolina Established Populations for Epidemiologic Studies of the Elderly to test the main and interactive effects of SES on mortality.

RESULTS

Discrete-time hazard models showed that the association between low education and mortality did not vary by race or age and was only significant for men. For women, the effect of low income diminished with age and had little impact on the crossover. For men, low income varied by race and age, altering the Black-White crossover and producing low-high income crossovers at advanced ages.

CONCLUSIONS

Low education and income were associated with increased mortality risk for older adults, but only low income had a differential impact on the Black-White mortality crossover. A primary route to reducing mortality differentials in later life is to prevent the disproportionate selective mortality of Blacks and the poor earlier in the life course.

Mortality resulting from congenital heart disease among children and adults in the United States, 1999 to 2006

BACKGROUND

Previous reports suggest that mortality resulting from congenital heart disease (CHD) among infants and young children has been decreasing. There is little population-based information on CHD mortality trends and patterns among older children and adults.

METHODS AND RESULTS

We used data from death certificates filed in the United States from 1999 to 2006 to calculate annual CHD mortality by age at death, race-ethnicity, and sex. To calculate mortality rates for individuals ≥1 year of age, population counts from the US Census were used in the denominator; for infant mortality, live birth counts were used. From 1999 to 2006, there were 41,494 CHD-related deaths and 27,960 deaths resulting from CHD (age-standardized mortality rates, 1.78 and 1.20 per 100,000, respectively). During this period, mortality resulting from CHD declined 24.1% overall. Mortality resulting from CHD significantly declined among all race-ethnicities studied. However, disparities persisted; overall and among infants, mortality resulting from CHD was consistently higher among non-Hispanic blacks compared with non-Hispanic whites. Infant mortality accounted for 48.1% of all mortality resulting from CHD; among those who survived the first year of life, 76.1% of deaths occurred during adulthood (≥18 years of age).

CONCLUSIONS

CHD mortality continued to decline among both children and adults; however, differences between race-ethnicities persisted. A large proportion of CHD-related mortality occurred during infancy, although significant CHD mortality occurred during adulthood, indicating the need for adult CHD specialty management.