Showing papers by "Goodarz Danaei published in 2014"

Global Sodium Consumption and Death from Cardiovascular Causes

Abstract: BACKGROUND High sodium intake increases blood pressure, a risk factor for cardiovascular disease, but the effects of sodium intake on global cardiovascular mortality are uncertain. METHODS We collected data from surveys on sodium intake as determined by urinary excretion and diet in persons from 66 countries (accounting for 74.1% of adults throughout the world), and we used these data to quantify the global consumption of sodium according to age, sex, and country. The effects of sodium on blood pressure, according to age, race, and the presence or absence of hypertension, were calculated from data in a new meta-analysis of 107 randomized interventions, and the effects of blood pressure on cardiovascular mortality, according to age, were calculated from a meta-analysis of cohorts. Cause-specific mortality was derived from the Global Burden of Disease Study 2010. Using comparative risk assessment, we estimated the cardiovascular effects of current sodium intake, as compared with a reference intake of 2.0 g of sodium per day, according to age, sex, and country. RESULTS In 2010, the estimated mean level of global sodium consumption was 3.95 g per day, and regional mean levels ranged from 2.18 to 5.51 g per day. Globally, 1.65 million annual deaths from cardiovascular causes (95% uncertainty interval [confidence interval], 1.10 million to 2.22 million) were attributed to sodium intake above the reference level; 61.9% of these deaths occurred in men and 38.1% occurred in women. These deaths accounted for nearly 1 of every 10 deaths from cardiovascular causes (9.5%). Four of every 5 deaths (84.3%) occurred in low- and middle-income countries, and 2 of every 5 deaths (40.4%) were premature (before 70 years of age). The rate of death from cardiovascular causes associated with sodium intake above the reference level was highest in the country of Georgia and lowest in Kenya. CONCLUSIONS In this modeling study, 1.65 million deaths from cardiovascular causes that occurred in 2010 were attributed to sodium consumption above a reference level of 2.0 g per day. (Funded by the Bill and Melinda Gates Foundation.)

Selection bias in rheumatic disease research

Abstract: The validity of research into risk factors for the development of rheumatic conditions and their sequelae can be threatened by selection bias. In this Review, the authors outline potentially major selection bias issues in rheumatic disease research and suggest approaches which could be used to help limit the impact of these biases on future research. The identification of modifiable risk factors for the development of rheumatic conditions and their sequelae is crucial for reducing the substantial worldwide burden of these diseases. However, the validity of such research can be threatened by sources of bias, including confounding, measurement and selection biases. In this Review, we discuss potentially major issues of selection bias—a type of bias frequently overshadowed by other bias and feasibility issues, despite being equally or more problematic—in key areas of rheumatic disease research. We present index event bias (a type of selection bias) as one of the potentially unifying reasons behind some unexpected findings, such as the 'risk factor paradox'—a phenomenon exemplified by the discrepant effects of certain risk factors on the development versus the progression of osteoarthritis (OA) or rheumatoid arthritis (RA). We also discuss potential selection biases owing to differential loss to follow-up in RA and OA research, as well as those due to the depletion of susceptibles (prevalent user bias) and immortal time bias. The lesson remains that selection bias can be ubiquitous and, therefore, has the potential to lead the field astray. Thus, we conclude with suggestions to help investigators avoid such issues and limit the impact on future rheumatology research.

Incidence of Adult-onset Asthma After Hypothetical Interventions on Body Mass Index and Physical Activity: An Application of the Parametric G-Formula

Abstract: High body mass index (BMI) (calculated as weight (kg)/height (m)(2)) is associated with increased asthma risk, but uncertainty persists about the role of physical activity. We estimated the independent and joint associations of hypothetical interventions on BMI and physical activity with the risk of adult-onset asthma in 76,470 asthma-free women from the Nurses' Health Study who were followed between 1988 and 1998. Information about asthma, BMI, physical activity, and other factors was updated every 2 years. We used the parametric g-formula to estimate the 10-year asthma risk in the following 4 scenarios: no intervention, 5% BMI reduction in a 2-year period for those who were overweight or obese, at least 2.5 hours/week of moderate-to-vigorous physical activity, and both of the previous 2 interventions. At baseline, women had a mean age of 55 (standard deviation, 7) years and a mean BMI of 25.4 (standard deviation, 4.8). Median time spent in physical activity was 0.7 hours/week. During follow-up, 1,146 women developed asthma. The 10-year asthma risk under no intervention was 1.5%. Compared with no intervention, the population risk ratios were 0.96 (95% confidence interval (CI): 0.93, 0.99) under the BMI intervention, 0.96 (95% CI: 0.81, 1.10) under the physical activity intervention, and 0.92 (95% CI: 0.78, 1.06) under the joint intervention. Interventions on BMI and physical activity may have a modest impact on the risk of adult-onset asthma in this population of US women.

Scaling-up access to family planning may improve linear growth and child development in low and middle income countries.

Abstract: BACKGROUND: A large literature has indicated a robust association between birth spacing and child survival but evidence on the association of birth timing with physical growth in low and middle income countries (LMICs) remains limited. METHODS AND RESULTS: Data from 153 cross-sectional Demographic and Health Surveys (DHS) across 61 LMICs conducted between 1990 and 2011 were combined to assess the association of birth timing with child stunting (height-for-age z-score <-2). A total of 623789 children of birth order 1-5 contributed to the maternal age analysis while the birth spacing dataset consisted of 584226 children of birth order 2 and higher. Compared to 27-34 year old mothers maternal age under 18 years was associated with a relative stunting risk of 1.35 (95% CI: 1.29-1.40) for firstborn children whereas the relative risk was 1.24 (95% CI: 1.19-1.29) for mothers aged 18-19 years. The association of young maternal age with stunting was significantly greater for urban residents and those in the top 50% of household wealth. Birth intervals less than 12 months and 12-23 months had relative risks for stunting of 1.09 (95% CI: 1.06-1.12) and 1.06 (95% CI: 1.05-1.06) as compared to a 24-35 month inter-pregnancy interval respectively. The strength of both teenage pregnancy and short birth interval associations showed substantial variation across WHO region. We estimate that 8.6% (6.9-10.3%) of stunted cases in the South Asian DHS sample would have been averted by jointly eliminating teen pregnancies and birth intervals less than 24 months while only 3.6% (1.5-5.7%) of stunting cases would have prevented in the Middle East and North Africa sample. CONCLUSIONS: Postponing the age of first birth and increasing inter-pregnancy intervals has the potential to significantly reduce the prevalence of stunting and improve child development in LMICs.

Bayesian Estimation of Population-Level Trends in Measures of Health Status

Abstract: Improving health worldwide will require rigorous quantification of population-level trends in health status. However, global-level surveys are not available, forcing researchers to rely on fragmentary country-specific data of varying quality. We present a Bayesian model that systematically combines disparate data to make country-, region- and global-level estimates of time trends in important health indicators. The model allows for time and age nonlinearity, and it borrows strength in time, age, covariates, and within and across regional country clusters to make estimates where data are sparse. The Bayesian approach allows us to account for uncertainty from the various aspects of missingness as well as sampling and parameter uncertainty. MCMC sampling allows for inference in a high-dimensional, constrained parameter space, while providing posterior draws that allow straightforward inference on the wide variety of functionals of interest. Here we use blood pressure as an example health metric. High blood pressure is the leading risk factor for cardiovascular disease, the leading cause of death worldwide. The results highlight a risk transition, with decreasing blood pressure in high-income regions and increasing levels in many lower-income regions.

Supplementation with multivitamins and vitamin A and incidence of malaria among HIV-infected Tanzanian women.

Abstract: Introduction: HIV and malaria infections occur in the same individuals, particularly in sub-Saharan Africa. We examined whether daily multivitamin supplementation (vitamins B complex, C, and E) or vitamin A supplementation altered malaria incidence in HIV-infected women of reproductive age. Methods: HIV-infected pregnant Tanzanian women recruited into the study were randomly assigned to daily multivitamins (B complex, C, and E), vitamin A alone, both multivitamins and vitamin A, or placebo. Women received malaria prophylaxis during pregnancy and were followed monthly during the prenatal and postpartum periods. Malaria was defined in 2 ways: presumptive diagnosis based on a physician’s or nurse’s clinical judgment, which in many cases led to laboratory investigations, and periodic examination of blood smears for malaria parasites. Results: Multivitamin supplementation compared with no multivitamins significantly lowered women’s risk of presumptively diagnosed clinical malaria (relative risk: 0.78, 95% confidence interval: 0.67 to 0.92), although multivitamins increased their risk of any malaria parasitemia (relative risk: 1.24, 95% confidence interval: 1.02 to 1.50). Vitamin A supplementation did not change malaria incidence during the study. Conclusions: Multivitamin supplements have been previously shown to reduce HIV disease progression among HIV-infected women, and consistent with that, these supplements protected against development of symptomatic malaria. The clinical significance of increased risk of malaria parasitemia among supplemented women deserves further research, however. Preventive measures for malaria are warranted as part of an

The Effect of HIV and the Modifying Effect of Anti-Retroviral Therapy (ART) on Body Mass Index (BMI) and Blood Pressure Levels in Rural South Africa

Abstract: Background The trajectory of body-mass index (BMI) in long-term HIV patients on antiretroviral therapy (ART) compared with the non-HIV population has been poorly studied. Methods Methods In 2003 and 2010, height, weight, and blood pressure measurements were recorded in a subset (n=505) of the population in KwaZulu-Natal, South Africa—a region with a very high prevalence of HIV (30%) and intensive ART rollout since 2004. Difference analysis was used to study change in BMI and blood pressure over time in HIV-negative patients, HIV-positive patients who had been on ART for 0– + ART 0– ; n=62), HIV patients who had been on ART for 2–5 years (HIV + ART 2–5 years ; n=44), and HIV-positive patients who were not on ART (HIV + ART − ; n=52). Multinomial logistic regression models were used to assess change in the risk of obesity and hypertension. Findings The HIV-negative and HIV-positive groups were both overweight at baseline (mean BMI 29·5, 95% CI 28·8–30·3; and 27·5, 25·9–29–3, respectively). The HIV-negative group was obese in 2010 (mean BMI >30); all other groups remained in the overweight range (25 0– group was −5·21 (95% CI −7·53 to −2·89; p=0·001). This difference in change in BMI was attenuated by increased ART use, with a difference in BMI change between the HIV − and the HIV + ART 2–5 group of −1·07 (95% CI −2·5 to 0·361; p=0·086), suggesting a U-shaped association of BMI with ART use. The difference in change in BMI between the HIV + ART − and the HIV + ART 0– group was −4·14 (95% CI −6·76 to −1·53; p=0·002). The HIV + ART − group had the highest average systolic blood pressure in 2003. Compared with the HIV − group, the overall systolic blood pressure in the HIV + ART − group significantly declined by −7·55 mm Hg (95% CI −13·2 to −1.90; p=0·009). The effect of the dose of ART on systolic blood pressure change was not significant (p=0·853). Interpretation Short-term ART exposure (0– Funding None.

Bayesian Estimation of Population-Level Trends in Measures of Health Status

Abstract: Improving health worldwide will require rigorous quantification of population-level trends in health status. However, global-level surveys are not available, forcing researchers to rely on fragmentary country-specific data of varying quality. We present a Bayesian model that systematically combines disparate data to make country-, region- and global-level estimates of time trends in important health indicators. The model allows for time and age nonlinearity, and it borrows strength in time, age, covariates, and within and across regional country clusters to make estimates where data are sparse. The Bayesian approach allows us to account for uncertainty from the various aspects of missingness as well as sampling and parameter uncertainty. MCMC sampling allows for inference in a high-dimensional, constrained parameter space, while providing posterior draws that allow straightforward inference on the wide variety of functionals of interest. Here we use blood pressure as an example health metric. High blood pressure is the leading risk factor for cardiovascular disease, the leading cause of death worldwide. The results highlight a risk transition, with decreasing blood pressure in high-income regions and increasing levels in many lower-income regions.

Abstract P163: Racial Disparities In Coronary Heart Disease Risk Among United States Adults

Abstract: Introduction: Health disparities remain pervasive in US and eliminating such disparities is one of the overarching goals of the Healthy People 2020 agenda. Previous studies have assessed the disparities in risk of coronary heart disease (CHD) mortality by race/ethnicity, but most of them only focused on the average CHD risk without taking into account the full risk distribution which would enable analysis of specific high-risk sub-groups. In this study, we estimated the 10-year risk distribution of CHD mortality based on 5 leading modifiable risk factors in US (i.e. smoking, adiposity, high blood pressure, serum cholesterol and blood glucose). We quantified the racial disparities in absolute CHD risk while accounting for full risk distribution. Methods: We included 3866 individuals aged 45 to 74 years, who were black or white, non-pregnant, free of CHD and had measurements of all 5 risk factors from 6 consecutive 2-year cycles of the National Health and Nutrition Examination Survey 1999-2010. We used mortality data from National Center for Health Statistics to estimate the cause-age-sex-race specific mortality in 2010. We also obtained hazard ratios of the selected 5 risk factors on CHD mortality from large meta-analyses of epidemiological studies. We predicted the 10-year risk of CHD death for each individual by simulating their survival process from 2010 to 2020 incorporating competing risks by death from other correlated causes. To assess health disparities, we compared the 5th, 25th, 50th, 75th and 95th percentile of the predicted risks between black and white by age and sex. Results: More than half of the black and white population aged 45 to 74 years had a low 10-year risk of CHD death (< 2%). The age-sex-race specific distributions of 10-year CHD risk were right-skewed with a large proportion of population on the low risk tail. Comparing to white, black had similar shape of CHD risk distributions, but higher risk levels at all percentiles across age and sex groups. In 55-64 ages where CHD was the major cause of death, the median of CHD risk for black males was 2.9% (interquartile range (IQR) 1.7% - 4.4%), which was 0.7% larger than that for white males (2.2%, IQR 1.4% - 3.3%). This risk difference was similar in females: the median CHD risk for black females was 1.6% (IQR 0.9% - 2.4%) and 0.9% for white females (IQR 0.5% - 1.5%). The disparities became larger on the high risk tail (95th percentile of predicted risk), where black had 2.7% higher risk for male and 2.3% for female in 55-64 ages. In older age groups (65-74 ages), such difference increased to 3.5% for both male and female. Conclusions: This analysis showed a skewed 10-year CHD risk distribution in US. The racial disparities are larger in the high risk sub-groups compared to those in the center of the risk distribution, indicating that the high risk subgroups should be the target population of intervention that aims to reduce health disparities in US.