Jay S. Kaufman

Vulnerability to heat-related mortality: a systematic review, meta-analysis, and meta-regression analysis

Background: Addressing vulnerability to heat-related mortality is a necessary step in the development of policies dictated by heat action plans. We aimed to provide a systematic assessment of the epidemiologic evidence regarding vulnerability to heat-related mortality. Methods: Studies assessing the association between high ambient temperature or heat waves and mortality among different subgroups and published between January 1980 and August 2014 were selected. Estimates of association for all the included subgroups were extracted. We assessed the presence of heterogeneous effects between subgroups conducting Cochran Q tests. We conducted random effect meta-analyses of ratios of relative risks (RRR) for high ambient temperature studies. We performed random effects meta-regression analyses to investigate factors associated with the magnitude of the RRR. Results: Sixty-one studies were included. Using the Cochran Q test, we consistently found evidence of vulnerability for the elderly ages >85 years. We found a pooled RRR of 0.99 (95% confidence interval [CI] = 0.97, 1.01) for male sex, 1.02 (95% CI = 1.01, 1.03) for age >65 years, 1.04 (95% CI = 1.02, 1.07) for ages >75 years, 1.03 (95% CI = 1.01, 1.05) for low individual socioeconomic status (SES), and 1.01 (95% CI = 0.99, 1.02) for low ecologic SES. Conclusions: We found strongest evidence of heat-related vulnerability for the elderly ages >65 and >75 years and low SES groups (at the individual level). Studies are needed to clarify if other subgroups (e.g., children, people living alone) are also vulnerable to heat to inform public health programs.

From bad to worse: collider stratification amplifies confounding bias in the ''obesity paradox''

Smoking is often identified as a confounder of the obesity–mortality relationship. Selection bias can amplify the magnitude of an existing confounding bias. The objective of the present report is to demonstrate how confounding bias due to cigarette smoking is increased in the presence of collider stratification bias using an empirical example and directed acyclic graphs. The empirical example uses data from the Atherosclerosis Risk in Communities (ARIC) study, a prospective cohort study of 15,792 men and women in the United States. Poisson regression models were used to examine the confounding effect of smoking. In the total ARIC study population, smoking produced a confounding bias of <3 percentage points. This result was obtained by comparing the incidence rate ratio (IRR) for obesity from a model adjusted for smoking was 1.07 (95xa0% CI 1.00, 1.15) with one that did not adjust for smoking was 1.10 (95xa0% CI 1.03, 1.18). However, among smokers with CVD, the obesity IRR was 0.89 (95xa0% CI 0.81, 0.99), while among non-smokers with CVD the obesity IRR was 1.20 (95xa0% CI 1.03, 1.41). The empirical and graphical explanations presented suggest that the magnitude of the confounding bias induced by smoking is greater in the presence of collider stratification bias.

Secular Trends in Preeclampsia Incidence and Outcomes in a Large Canada Database: A Longitudinal Study Over 24 Years

BACKGROUNDnThe incidence of preeclampsia is increasing, but effects on women and infants are unclear. We measured the incidence of preeclampsia over time in a large Canadian population, and assessed trends in maternal and infant morbidity and mortality.nnnMETHODSnWe carried out a population-based study of 1,901,376 linked hospital discharge abstracts for all deliveries in the province of Quebec, Canada from 1989 through 2012. We computed the annual incidence of preeclampsia, and used log binomial models to determine associations with severe morbidity and mortality for preeclamptic vs nonpreeclamptic pregnancies. Main outcomes included maternal, fetal, and infant mortality, admission to intensive care, intubation, preterm delivery, growth restriction, cesarean delivery, transfusion, and severe medical complications.nnnRESULTSnThe incidence of preeclampsia increased from 26.4 per 1000 deliveries in 1989 to 50.6 in 2012. Maternal, fetal, and infant mortality decreased with time for preeclamptic but not for nonpreeclamptic pregnancies. By 2007-2012, risk for women with preeclampsia had declined for most maternal morbidities, except acute renal failure, which increased relative to no preeclampsia (risk ratio, 21.5; 95% confidence interval, 16.9-27.3). Risk of infant morbidity also decreased, but this coincided with an increase in the excess number of intubations and admissions for intensive care for preeclampsia relative to no preeclampsia.nnnCONCLUSIONSnThe incidence of preeclampsia increased during the study, but with little effect on the risk of maternal and infant morbidity and mortality. For most outcomes, the risk decreased relative to no preeclampsia, with more aggressive medical management over time.

The impact of smoke-free legislation on educational differences in birth outcomes

Background Smoke-free legislation may have positive effects on birth outcomes. Given that smoking and secondhand smoke during pregnancy vary with socioeconomic position, legislation may have greater effects in some socioeconomic groups. For this study, we evaluated the impact of a 2006 ban on smoking in public places in the Canadian province of Quebec on preterm birth, small-for-gestational-age birth and birth weight, and on educational differences in these birth outcomes. Methods We analysed data on singleton births in Quebec between 2003 and 2010. Logistic regression was used to model the association of smoke-free legislation with preterm birth (<37u2005weeks), very preterm birth (<34u2005weeks), small-for-gestational-age birth (<10th centile for gestational age and sex), low birth weight (<2500u2005g) and mean birth weight, adjusting for secular trends before and after legislation. Interaction terms were included to assess differential effects by level of maternal education. Results Smoke-free legislation was associated with average reductions of 3.1 preterm births (95% CI 0.1 to 6.0), 2.3 very preterm births (95% CI 0.9 to 3.7), 5.9 small-for-gestational-age births (95% CI 2.6 to 9.3) and 1.0 low birthweight infants (95% CI 0.4 to 1.6) per 1000 live births, as well as a 17.1u2005g increase in mean birth weight (95% CI 10.7 to 23.6). Legislation was associated with improved birth outcomes in all categories of maternal education. Conclusions Smoke-free legislation in Quebec was associated with reductions in preterm and small-for-gestational-age births, and an increase in birth weight. There was no compelling evidence that legislation impacted educational gradients in birth outcomes.

The Neighbourhood Built Environment and Trajectories of Depression Symptom Episodes in Adults: A Latent Class Growth Analysis.

Aim To investigate the effect of the neighbourhood built environment on trajectories of depression symptom episodes in adults from the general Canadian population. Research Design and Methods We used 10 years of data collection (2000/01-2010/11) from the Canadian National Population Health Study (n = 7114). Episodes of depression symptoms were identified using the Composite International Diagnostic Interview Short-Form. We assessed the presence of local parks, healthy food stores, fast food restaurants, health services and cultural services using geospatial data. We used latent class growth modelling to identify different trajectories of depression symptom episodes in the sample and tested for the effect of neighbourhood variables on the trajectories over time. Results We uncovered three distinct trajectories of depression symptom episodes: low prevalence (76.2% of the sample), moderate prevalence (19.2%) and high prevalence of depression symptom episodes (2.8%). The presence of any neighbourhood service (healthy food store, fast-food restaurant, health service, except for cultural service) was significantly associated with a lower probability of a depression symptom episode for those following a trajectory of low prevalence of depression symptom episodes. The presence of a local park was also a significant protective factor in trajectory groups with both low and moderate prevalence of depression symptom episodes. Neighbourhood characteristics did not significantly affect the trajectory of high prevalence of depression symptom episodes. Conclusions For individuals following a trajectory of low and moderate prevalence of depression symptom episodes, the neighbourhood built environment was associated with a shift in the trajectory of depression symptom episodes. Future intervention studies are recommended to make policy recommendations.

Estimating the Time-Varying Joint Effects of Obesity and Smoking on All-Cause Mortality Using Marginal Structural Models

Obesity and smoking are independently associated with a higher mortality risk, but previous studies have reported conflicting results about the relationship between these 2 time-varying exposures. Using prospective longitudinal data (1987-2007) from the Atherosclerosis Risk in Communities Study, our objective in the present study was to estimate the joint effects of obesity and smoking on all-cause mortality and investigate whether there were additive or multiplicative interactions. We fit a joint marginal structural Poisson model to account for time-varying confounding affected by prior exposure to obesity and smoking. The incidence rate ratios from the joint model were 2.00 (95% confidence interval (CI): 1.79, 2.24) for the effect of smoking on mortality among nonobese persons, 1.31 (95% CI: 1.13, 1.51) for the effect of obesity on mortality among nonsmokers, and 1.97 (95% CI: 1.73, 2.22) for the joint effect of smoking and obesity on mortality. The negative product term from the exponential model revealed a submultiplicative interaction between obesity and smoking (β = -0.28, 95% CI: -0.45, -0.11; P < 0.001). The relative excess risk of interaction was -0.34 (95% CI: -0.60, -0.07), indicating the presence of subadditive interaction. These results provide important information for epidemiologists, clinicians, and public health practitioners about the harmful impact of smoking and obesity.

Comparison of black-white disparities in preterm birth between Canada and the United States

Background: A higher risk of preterm birth among black women than among white women is well established in the United States. We compared differences in preterm birth between non-Hispanic black and white women in Canada and the US, hypothesizing that disparities would be less extreme in Canada given the different historical experiences of black populations and Canada’s universal health care system. Methods: Using data on singleton live births in Canada and the US for 2004–2006, we estimated crude and adjusted risk ratios and risk differences in preterm birth (< 37 wk) and very preterm birth (< 32 wk) among non-Hispanic black versus non-Hispanic white women in each country. Adjusted models for the US were standardized to the covariate distribution of the Canadian cohort. Results: In Canada, 8.9% and 5.9% of infants born to black and white mothers, respectively, were preterm; the corresponding figures in the US were 12.7% and 8.0%. Crude risk ratios for preterm birth among black women relative to white women were 1.49 (95% confidence interval [CI] 1.32 to 1.66) in Canada and 1.57 (95% CI 1.56 to 1.58) in the US (p value for heterogeneity [pH] = 0.3). The crude risk differences for preterm birth were 2.94 (95% CI 1.91 to 3.96) in Canada and 4.63 (95% CI 4.56 to 4.70) in the US (pH = 0.003). Adjusted risk ratios for preterm birth (pH = 0.1) were slightly higher in Canada than in the US, whereas adjusted risk differences were similar in both countries. Similar patterns were observed for racial disparities in very preterm birth. Interpretation: Relative disparities in preterm birth and very preterm birth between non-Hispanic black and white women were similar in magnitude in Canada and the US. Absolute disparities were smaller in Canada, which reflects a lower overall risk of preterm birth in Canada than in the US in both black and white populations.

Place and health in diabetes: the neighbourhood environment and risk of depression in adults with Type 2 diabetes

Depression is a common co‐illness in people with diabetes. Evidence suggests that the neighbourhood environment impacts the risk of depression, but few studies have investigated this effect in those with diabetes. We examined the effect of a range of neighbourhood characteristics on depression in people with Type 2 diabetes.

Simple Estimation of Patient-Oriented Effects From Randomized Trials: An Open and Shut CACE

In randomized controlled trials, the intention-to-treat estimator provides an unbiased estimate of the causal effect of treatment assignment on the outcome. However, patients often want to know what the effect would be if they were to take the treatment as prescribed (the patient-oriented effect), and several researchers have suggested that the more relevant causal effect for this question is the complier average causal effect (CACE), also referred to as the local average treatment effect. Sophisticated approaches to estimating the CACE include Bayesian and frequentist methods for principal stratification, inverse-probability-of-treatment-weighted estimators, and instrumental-variable (IV) analysis. All of these approaches exploit information about adherence to assigned treatment to improve upon the intention-to-treat estimator, but they are rarely used in practice, probably because of their complexity. The IV principal stratification estimator is simple to implement but has had limited use in practice, possibly due to lack of familiarity. Here, we show that the IV principal stratification estimator is a modified per-protocol estimator that should be obtainable from any randomized controlled trial, and we provide a closed form for its robust variance (and its uncertainty). Finally, we illustrate sensitivity analyses we conducted to assess inference in light of potential violations of the exclusion restriction assumption.

Do Socioeconomic Inequalities in Neonatal Mortality Reflect Inequalities in Coverage of Maternal Health Services? Evidence from 48 Low- and Middle-Income Countries.

ObjectivesTo examine socioeconomic and health system determinants of wealth-related inequalities in neonatal mortality rates (NMR) across 48 low- and middle-income countries.MethodsWe used data from Demographic and Health Surveys conducted between 2006 and 2012. Absolute and relative inequalities for NMR and coverage of antenatal care, facility-based delivery, and Caesarean delivery were measured using the Slope Index of Inequality and Relative Index of Inequality, respectively. Meta-regression was used to assess whether variation in the magnitude of NMR inequalities was associated with inequalities in coverage of maternal health services, and whether country-level economic and health system factors were associated with mean NMR and socioeconomic inequality in NMR.ResultsOf the three maternal health service indicators examined, the magnitude of socioeconomic inequality in NMR was most strongly related to inequalities in antenatal care. NMR inequality was greatest in countries with higher out-of-pocket health expenditures, more doctors per capita, and a higher adolescent fertility rate. Determinants of lower mean NMR (e.g., higher government health expenditures and a greater number of nurses/midwives per capita) differed from factors associated with lower NMR inequality.ConclusionsReducing the financial burden of maternal health services and achieving universal coverage of antenatal care may contribute to a reduction in socioeconomic differences in NMR. Further investigation of the mechanisms contributing to these cross-national associations seems warranted.