Modifiable risk factors, cardiovascular disease, and mortality in 155 722 individuals from 21 high-income, middle-income, and low-income countries (PURE): a prospective cohort study

BACKGROUND

Global estimates of the effect of common modifiable risk factors on cardiovascular disease and mortality are largely based on data from separate studies, using different methodologies. The Prospective Urban Rural Epidemiology (PURE) study overcomes these limitations by using similar methods to prospectively measure the effect of modifiable risk factors on cardiovascular disease and mortality across 21 countries (spanning five continents) grouped by different economic levels.

METHODS

In this multinational, prospective cohort study, we examined associations for 14 potentially modifiable risk factors with mortality and cardiovascular disease in 155 722 participants without a prior history of cardiovascular disease from 21 high-income, middle-income, or low-income countries (HICs, MICs, or LICs). The primary outcomes for this paper were composites of cardiovascular disease events (defined as cardiovascular death, myocardial infarction, stroke, and heart failure) and mortality. We describe the prevalence, hazard ratios (HRs), and population-attributable fractions (PAFs) for cardiovascular disease and mortality associated with a cluster of behavioural factors (ie, tobacco use, alcohol, diet, physical activity, and sodium intake), metabolic factors (ie, lipids, blood pressure, diabetes, obesity), socioeconomic and psychosocial factors (ie, education, symptoms of depression), grip strength, and household and ambient pollution. Associations between risk factors and the outcomes were established using multivariable Cox frailty models and using PAFs for the entire cohort, and also by countries grouped by income level. Associations are presented as HRs and PAFs with 95% CIs.

FINDINGS

Between Jan 6, 2005, and Dec 4, 2016, 155 722 participants were enrolled and followed up for measurement of risk factors. 17 249 (11·1%) participants were from HICs, 102 680 (65·9%) were from MICs, and 35 793 (23·0%) from LICs. Approximately 70% of cardiovascular disease cases and deaths in the overall study population were attributed to modifiable risk factors. Metabolic factors were the predominant risk factors for cardiovascular disease (41·2% of the PAF), with hypertension being the largest (22·3% of the PAF). As a cluster, behavioural risk factors contributed most to deaths (26·3% of the PAF), although the single largest risk factor was a low education level (12·5% of the PAF). Ambient air pollution was associated with 13·9% of the PAF for cardiovascular disease, although different statistical methods were used for this analysis. In MICs and LICs, household air pollution, poor diet, low education, and low grip strength had stronger effects on cardiovascular disease or mortality than in HICs.

INTERPRETATION

Most cardiovascular disease cases and deaths can be attributed to a small number of common, modifiable risk factors. While some factors have extensive global effects (eg, hypertension and education), others (eg, household air pollution and poor diet) vary by a country's economic level. Health policies should focus on risk factors that have the greatest effects on averting cardiovascular disease and death globally, with additional emphasis on risk factors of greatest importance in specific groups of countries.

FUNDING

Full funding sources are listed at the end of the paper (see Acknowledgments).

Joint association of urinary sodium and potassium excretion with cardiovascular events and mortality: prospective cohort study

OBJECTIVE

To evaluate the joint association of sodium and potassium urinary excretion (as surrogate measures of intake) with cardiovascular events and mortality, in the context of current World Health Organization recommendations for daily intake (<2.0 g sodium, >3.5 g potassium) in adults.

DESIGN

International prospective cohort study.

SETTING

18 high, middle, and low income countries, sampled from urban and rural communities.

PARTICIPANTS

103 570 people who provided morning fasting urine samples.

MAIN OUTCOME MEASURES

Association of estimated 24 hour urinary sodium and potassium excretion (surrogates for intake) with all cause mortality and major cardiovascular events, using multivariable Cox regression. A six category variable for joint sodium and potassium was generated: sodium excretion (low (<3 g/day), moderate (3-5 g/day), and high (>5 g/day) sodium intakes) by potassium excretion (greater/equal or less than median 2.1 g/day).

RESULTS

Mean estimated sodium and potassium urinary excretion were 4.93 g/day and 2.12 g/day, respectively. After a median follow-up of 8.2 years, 7884 (6.1%) participants had died or experienced a major cardiovascular event. Increasing urinary sodium excretion was positively associated with increasing potassium excretion (unadjusted r=0.34), and only 0.002% had a concomitant urinary excretion of <2.0 g/day of sodium and >3.5 g/day of potassium. A J-shaped association was observed of sodium excretion and inverse association of potassium excretion with death and cardiovascular events. For joint sodium and potassium excretion categories, the lowest risk of death and cardiovascular events occurred in the group with moderate sodium excretion (3-5 g/day) and higher potassium excretion (21.9% of cohort). Compared with this reference group, the combinations of low potassium with low sodium excretion (hazard ratio 1.23, 1.11 to 1.37; 7.4% of cohort) and low potassium with high sodium excretion (1.21, 1.11 to 1.32; 13.8% of cohort) were associated with the highest risk, followed by low sodium excretion (1.19, 1.02 to 1.38; 3.3% of cohort) and high sodium excretion (1.10, 1.02 to 1.18; 29.6% of cohort) among those with potassium excretion greater than the median. Higher potassium excretion attenuated the increased cardiovascular risk associated with high sodium excretion (P for interaction=0.007).

CONCLUSIONS

These findings suggest that the simultaneous target of low sodium intake (<2 g/day) with high potassium intake (>3.5 g/day) is extremely uncommon. Combined moderate sodium intake (3-5 g/day) with high potassium intake is associated with the lowest risk of mortality and cardiovascular events.

Evaluation of waist-to-height ratio to predict 5 year cardiometabolic risk in sub-Saharan African adults

BACKGROUND AND AIMS

Simple, low-cost central obesity measures may help identify individuals with increased cardiometabolic disease risk, although it is unclear which measures perform best in African adults. We aimed to: 1) cross-sectionally compare the accuracy of existing waist-to-height ratio (WHtR) and waist circumference (WC) thresholds to identify individuals with hypertension, pre-diabetes, or dyslipidaemia; 2) identify optimal WC and WHtR thresholds to detect CVD risk in this African population; and 3) assess which measure best predicts 5-year CVD risk.

METHODS AND RESULTS

Black South Africans (577 men, 942 women, aged >30years) were recruited by random household selection from four North West Province communities. Demographic and anthropometric measures were taken. Recommended diagnostic thresholds (WC > 80 cm for women, >94 cm for men; WHtR > 0.5) were evaluated to predict blood pressure, fasting blood glucose, lipids, and glycated haemoglobin measured at baseline and 5 year follow up. Women were significantly more overweight than men at baseline (mean body mass index (BMI) women 27.3 ± 7.4 kg/m(2), men 20.9 ± 4.3 kg/m(2)); median WC women 81.9 cm (interquartile range 61-103), men 74.7 cm (63-87 cm), all P < 0.001). In women, both WC and WHtR significantly predicted all cardiometabolic risk factors after 5 years. In men, even after adjusting WC threshold based on ROC analysis, WHtR better predicted overall 5-year risk. Neither measure predicted hypertension in men.

CONCLUSIONS

The WHtR threshold of >0.5 appears to be more consistently supported and may provide a better predictor of future cardiometabolic risk in sub-Saharan Africa.

Contrasting Associations Between Diabetes and Cardiovascular Mortality Rates in Low-, Middle-, and High-Income Countries: Cohort Study Data From 143,567 Individuals in 21 Countries in the PURE Study

OBJECTIVE

We aimed to compare cardiovascular (CV) events, all-cause mortality, and CV mortality rates among adults with and without diabetes in countries with differing levels of income.

RESEARCH DESIGN AND METHODS

The Prospective Urban Rural Epidemiology (PURE) study enrolled 143,567 adults aged 35-70 years from 4 high-income countries (HIC), 12 middle-income countries (MIC), and 5 low-income countries (LIC). The mean follow-up was 9.0 ± 3.0 years.

RESULTS

Among those with diabetes, CVD rates (LIC 10.3, MIC 9.2, HIC 8.3 per 1,000 person-years, P < 0.001), all-cause mortality (LIC 13.8, MIC 7.2, HIC 4.2 per 1,000 person-years, P < 0.001), and CV mortality (LIC 5.7, MIC 2.2, HIC 1.0 per 1,000 person-years, P < 0.001) were considerably higher in LIC compared with MIC and HIC. Within LIC, mortality was higher in those in the lowest tertile of wealth index (low 14.7%, middle 10.8%, and high 6.5%). In contrast to HIC and MIC, the increased CV mortality in those with diabetes in LIC remained unchanged even after adjustment for behavioral risk factors and treatments (hazard ratio [95% CI] 1.89 [1.58-2.27] to 1.78 [1.36-2.34]).

CONCLUSIONS

CVD rates, all-cause mortality, and CV mortality were markedly higher among those with diabetes in LIC compared with MIC and HIC with mortality risk remaining unchanged even after adjustment for risk factors and treatments. There is an urgent need to improve access to care to those with diabetes in LIC to reduce the excess mortality rates, particularly among those in the poorer strata of society.

Lean Mass Appears to Be More Strongly Associated with Bone Health than Fat Mass in Urban Black South African Women

OBJECTIVES

To examine the association between body composition (fat mass, lean mass and body mass index, BMI) and bone health (bone mineral density, BMD and fracture risk) in urban black South African women.

DESIGN

A cross sectional study examining associations between body composition, dietary intake (food frequency questionnaire), habitual physical activity (Activity energy expenditure (AEE) measured using an accelerometer with combined heart rate monitor and physical activity questionnaire) and bone health (BMD using dual-energy X ray absorptiometry, DXA and fracture risk).

SETTING

Urban community dwellers from Ikageng in the North-West Province of South Africa.

PARTICIPANTS

One hundred and eighty nine (189) healthy postmenopausal women aged ≥43 years.

RESULTS

Fat mass and lean mass were significantly associated with BMD and fracture risk when adjusted for potential confounders. However, lean mass and not fat mass remained significantly associated with femoral neck BMD (β = 0.49, p <0.001), spine BMD (β = 0.48, p< 0.0001) and hip BMD (β = 0.59, p< 0.0001). Lean mass was also negatively associated with fracture risk (β = -0.19 p =0.04) when both lean and fat mass were in the same model.

CONCLUSION

Lean mass and fat mass were positively associated with femoral neck, spine and hip BMDs and negatively associated with fracture risk in urban black South African women. Our finding suggests that increasing lean mass rather than fat mass is beneficial to bone health. Our study emphasises the importance of positive lifestyle changes, intake of calcium from dairy and adequate weight to maintain and improve bone health of postmenopausal women.

Does greater individual social capital improve the management of hypertension? Cross-national analysis of 61 229 individuals in 21 countries

Introduction

Social capital, characterised by trust, reciprocity and cooperation, is positively associated with a number of health outcomes. We test the hypothesis that among hypertensive individuals, those with greater social capital are more likely to have their hypertension detected, treated and controlled.

Methods

Cross-sectional data from 21 countries in the Prospective Urban and Rural Epidemiology study were collected covering 61 229 hypertensive individuals aged 35–70 years, their households and the 656 communities in which they live. Outcomes include whether hypertensive participants have their condition detected, treated and/or controlled. Multivariate statistical models adjusting for community fixed effects were used to assess the associations of three social capital measures: (1) membership of any social organisation, (2) trust in other people and (3) trust in organisations, stratified into high-income and low-income country samples.

Results

In low-income countries, membership of any social organisation was associated with a 3% greater likelihood of having one’s hypertension detected and controlled, while greater trust in organisations significantly increased the likelihood of detection by 4%. These associations were not observed among participants in high-income countries.

Conclusion

Although the observed associations are modest, some aspects of social capital are associated with better management of hypertension in low-income countries where health systems are often weak. Given that hypertension affects millions in these countries, even modest gains at all points along the treatment pathway could improve management for many, and translate into the prevention of thousands of cardiovascular events each year.

Magnesium Intake Predicts Bone Turnover in Postmenopausal Black South African Women

This prospective study investigated the association between nutrient intake, dietary patterns, and changes in bone turnover and bone mineral density (BMD) in postmenopausal urban black South African women over two years. These women (n = 144) underwent BMD measurements at the distal radius, lumbar spine, femoral neck (FN), as well as a biochemical analysis which included the parathyroid hormone (PTH), 25-hydroxyvitamin D, C-Telopeptide of type I collagen (CTX-1) in 2010 and 2012. Their dietary intake was assessed in 2010 using a food frequency questionnaire, and sociodemographic and health information was collected. Four dietary patterns explained 54.4% of the variance of dietary intake, namely staple foods and processed meats, home cooking, snacking, and high sugar. Dietary magnesium negatively correlated with CTx-1 in 2012 (r = −0.21, p = 0.02), calcium correlated with distal radius BMD in 2010 (r = 0.22, p = 0.01) and 2012 (r = 0.24, p = 0.005), and the snacking dietary pattern score correlated with FN BMD in 2010 (r = 0.18, p = 0.03) and 2012 (r = 0.21, p = 0.02). The baseline CTx-1 and dietary magnesium intake predicted 22% of the variance in percentage change of CTx-1 over two years (p < 0.001).The magnesium intake predicted short-term bone resorption over two years.

Lifestyle factors associated with the transition from healthy to unhealthy adiposity among black South African adults over 10 years

BACKGROUND AND AIMS

Obesity is associated with an increasing prevalence of cardiovascular diseases in Africa, but some obese individuals maintain cardiometabolic health. The aims were to track metabolically healthy overweight or obesity (MHO) over 10 years in African adults and to identify factors associated with a transition to metabolically unhealthy overweight or obesity (MUO).

METHODS AND RESULTS

The participants were the South African cohort of the international Prospective Urban and Rural Epidemiological study. From the baseline data of 1937 adults, 649 women and 274 men were followed for 10 years. The combined overweight and obesity prevalence of men (19.2%-23.8%, p = .02) and women (58%-64.7%, p < .001), and the prevalence of the metabolic syndrome in all participants (25.4%-40.2%, p < .001) increased significantly. More than a quarter (26.2%) of the women and 10.9% of men were MHO at baseline, 11.4% of women and 5.1% of men maintained MHO over 10 years, while similar proportions (12.3% of women, 4.7% of men) transitioned to MUO. Female sex, age, and total fat intake were positively associated with a transition to MUO over 10 years, while physical activity was negatively associated with the transition. HIV positive participants were more likely to be MHO at follow-up than their HIV negative counterparts.

CONCLUSIONS

One in two black adults with BMI ≥25 kg/m² maintained MHO over 10 years, while a similar proportion transitioned into MUO. Interventions should focus on lower fat intakes and higher physical activity to prevent the transition to MUO.

Bone turnover markers in HIV-infected women on tenofovir-based antiretroviral therapy

Background

Tenofovir disoproxil fumarate (TDF) antiretroviral therapy is associated with disruption of the bone turnover process.

Objectives

The objective of this study was to determine the association between tenofovir (TFV) plasma concentration and various bone turnover markers and compare these markers in HIV-infected women and HIV-uninfected controls.

Method

A cross-sectional sub-study included 30 HIV-infected women on TDF and 30 HIV-uninfected matched participants. Serum calcium (SrCa), serum phosphate (SrP), C-terminal telopeptide (CTx), parathyroid hormone (PTH), alkaline phosphatase (ALP), C-reactive protein (CRP), vitamin D (VitD) and bone mineral density (BMD) were measured. Plasma TFV was assayed on HPLC-MS/MS. The statistical tests applied were Mann-Whitney test, unpaired t-test, analysis of covariance, regression and correlation analysis.

Results

In HIV-infected women, no correlation existed between plasma TFV concentration and CTx, PTH, ALP, SrCa, SrP, VitD or BMD (p > 0.05). After adjusting for smoking and alcohol use, ALP (p < 0.001), CTx (p = 0.027) and PTH (p = 0.050) were significantly higher in HIV-infected compared to HIV-uninfected women. Women with TFV concentration ≥ 120 ng/mL had higher PTH concentrations (p = 0.037) compared to those with ≤ 100 ng/mL. Significant correlations between SrCa and PTH and SrCa and SrP including CTx and PTH (p < 0.05) were present in HIV-uninfected women while absent in HIV-infected counterparts (p > 0.05).

Conclusion

The results indicate possible increased bone turnover at higher TFV concentrations. The normal regular bone turnover processes in HIV-infected women on TDF therapy are altered. Larger studies are warranted to confirm these results.

Comparison of dietary and plasma phospholipid fatty acids between normal weight and overweight black South Africans according to metabolic health: The PURE study

BACKGROUND

Information regarding circulating fatty acids (FA) in association with metabolic health in black Africans is scarce, while the usefulness of circulating FAs as biomarkers of dietary fat intake and predictors for medical conditions is increasing.

OBJECTIVE

We compared eleven dietary and the levels of 26 plasma phospholipid FAs in metabolically healthy and unhealthy phenotypes in black South African adults.

METHODS

Adults from the South African arm of the Prospective Urban and Rural Epidemiology study baseline (n = 711) were categorised into four groups, namely normal weight without metabolic syndrome (MetS) (MHNW), normal weight with MetS (MUNW), metabolically healthy overweight/obese (MHO) and metabolically unhealthy overweight/obese (MUO). Dietary and plasma phospholipid FAs were measured by a quantitative food frequency questionnaire and gas chromatography-tandem mass spectrometry, respectively. We compared dietary FAs, plasma phospholipid FAs, and estimated desaturase activity between the metabolic status groups using ANCOVA adjusted for age and energy intake.

RESULTS

MetS was diagnosed in 35% of the participants. After adjustment for age and total energy intake, in comparison to the MHNW reference group, saturated dietary FAs (C14:0 to C18:0) and alpha-linolenic acid intakes were higher in both overweight/obese groups (MHO and MUO), while linoleic acid intakes were higher in the MUO group only. Plasma levels of most saturated FAs (C18:0 to C22:0) and PUFAs were higher, whereas selected MUFAs, palmitic acid, and estimated desaturase activities were lower in the overweight/obese groups.

CONCLUSIONS

The overweight groups generally had higher fat intakes than normal-weight groups, but lower plasma levels of palmitic, palmitoleic, oleic, cis-vaccenic and estimated desaturase activities. Therefore, in this population, lower plasma levels of palmitic, palmitoleic, oleic, and cis-vaccenic acids and decreased estimated desaturase activities may be biomarkers of abnormal metabolic health in overweight/obese study participants.

Arterial structure and function in Africans with HIV for > 5 years: longitudinal relationship with endothelial activation and cardiovascular risk markers

OBJECTIVES

We aimed to determine whether people with human immunodeficiency virus (PWHIV) have increased measures of arterial injury [carotid intima-media thickness (cIMT)] and large artery stiffness [carotid-femoral pulse wave velocity (cfPWV)] when compared with their counterparts without HIV, and whether baseline markers of endothelial activation and cardiovascular risk are associated with cIMT and cfPWV after 5 years.

METHODS

We matched 126 PWHIV from North West Province, South Africa, to 126 without HIV according to age, sex and locality. Cardiovascular risk and endothelial function markers [soluble intracellular adhesion molecule (ICAM-1) and soluble vascular cell adhesion molecule (VCAM-1)] were measured at baseline and cIMT and cfPWV at follow-up.

RESULTS

This study included 21.4% men. The use of antiretroviral therapy (ART) increased from 44.1% at baseline to 81.4% at follow-up. At follow-up, cIMT (P = 0.90) and cfPWV (P = 0.35) were similar in the groups. Despite elevated ICAM-1 and VCAM-1 in the PWHIV (all P < 0.001) at baseline, these markers did not associate with cIMT and cfPWV after 5 years. In multivariable-adjusted regression analysis, cIMT associated positively with age (β = 0.31, P = 0.002) and triglyceride: high-density lipoprotein-cholesterol (β = 0.23, P = 0.016) in PWHIV. Mean arterial pressure (MAP) (β = 0.28, P = 0.010) associated positively with cfPWV in the PWHIV. In the people without HIV, sex (β = 0.31, P = 0.004) and glycated haemoglobin (HbA1c) (β = 0.24, P = 0.026) associated with cIMT while age (β = 0.17, P = 0.049), sex (β = 0.29, P = 0.003), MAP (β = 0.31, P = 0.001) and HbA1c (β = 0.21, P = 0.041) associated positively with cfPWV.

CONCLUSIONS

Measures of arterial structure and function were similar in Africans with HIV and their age, sex and locality matched controls. Traditional cardiovascular risk markers rather than elevated endothelial activation at baseline were independently associated with cIMT and cfPWV over 5 years.

Cardiac Troponin T as Early Marker of Subclinical Cardiovascular Deterioration in Black Hypertensive Women

BACKGROUND

Hypertensive heart disease is a rising concern, especially among black South African women. As high sensitivity cardiac troponin T (cTnT) is a marker of cardiomyocyte damage, we determined the potential link of (i) systemic endothelial dysfunction (reflected by urinary albumin-to-creatinine ratio), (ii) large artery stiffness, (iii) cardiac volume load (estimated by the N-terminal prohormone B-type natriuretic peptide (Nt-proBNP)), and (iv) ECG left ventricular hypertrophy in post-menopausal black women.

METHODS

In 121 (50 normotensive and 71 hypertensive) black women (mean age: 60.6 years), basic cardiovascular assessments including blood pressure and ECG were performed, along with plasma and urinary biomarkers including cTnT.

RESULTS

The cTnT levels (p=0.049) along with Nt-proBNP (p=0.003), pulse pressure (p<0.0001) and the Cornell product (p=0.030) were higher in hypertensive than normotensive women. Only in hypertensive women, was cTnT independently associated with urinary albumin-to-creatinine ratio (β=0.25; p=0.019), pulse pressure (β=0.31; p=0.019), Nt-proBNP (β=0.47; p<0.0001) and Cornell product (β=0.31; p=0.018). An independent association between albumin-to-creatinine ratio and cTnT was also evident in normotensive women (β=0.34; p=0.037).

CONCLUSION

We found cTnT to be a useful marker in an elderly black population relating to several measures of cardiovascular deterioration - from subclinical endothelial dysfunction to left ventricular hypertrophy.

Noncommunicable Disease Conditions and HIV in Rural and Urban South Africa: 2005-2015

Purpose

Hypertension, obesity, hyperlipidemia, and type 2 diabetes contribute primarily to noncommunicable disease deaths and together with human immunodeficiency virus contribute largely to mortality in South Africa. Our longitudinal study provides the necessary data and insights over a 10-year period to highlight the areas where improved management is required in urban and rural localities.

Methods

This study included 536 rural and 387 urban Black participants aged 32 to 93 years from the North-West province, South Africa. Disease prevalence, treatment, and control were determined in 2005 and were re-evaluated in 2015. Multiple measures analyses were used to determine the trends of blood pressure and waist circumference.

Results

The initial prevalence of hypertension was 53.2%, obesity was 23.6%, hyperlipidemia was 5.1%, diabetes was 2.9%, and human immunodeficiency virus was 10.7% in 2005. By 2015, the rural population had higher rates of hypertension (63.7% versus 58.5%) and lower rates diabetes (4.3% versus 7.9%) and hyperlipidemia (6.6% versus 18.0%) with similar obesity rates (41.7% versus 42.4%). The average blood pressure levels of urban hypertensives decreased (Ptrend<.001), whereas levels were maintained in the rural group (Ptrend=.52). In both locations, treatment and control rates increased from 2005 to 2015 for all conditions (all ≥6.7%), except for diabetes in which a decrease in control was observed. Waist circumference increased (Ptrend>.001) in both sex and locality groups over the 10-year period.

Conclusion

Although average blood pressure of urban hypertensive individuals decreased, urgent measures focused on early identification, treatment, and control of the respective conditions should be implemented to decrease the burden of noncommunicable diseases.

Strategies of Modelling Incident Outcomes Using Cox Regression to Estimate the Population Attributable Risk

When the Cox model is applied, some recommendations about the choice of the time metric and the model's structure are often disregarded along with the proportionality of risk assumption. Moreover, most of the published studies fail to frame the real impact of a risk factor in the target population. Our aim was to show how modelling strategies affected Cox model assumptions. Furthermore, we showed how the Cox modelling strategies affected the population attributable risk (PAR). Our work is based on data collected in the North-West Province, one of the two PURE study centres in South Africa. The Cox model was used to estimate the hazard ratio (HR) of mortality for all causes in relation to smoking, alcohol use, physical inactivity, and hypertension. Firstly, we used a Cox model with time to event as the underlying time variable. Secondly, we used a Cox model with age to event as the underlying time variable. Finally, the second model was implemented with age classes and sex as strata variables. Mutually adjusted models were also investigated. A statistical test to the multiplicative interaction term the exposures and the log transformed time to event metric was used to assess the proportionality of risk assumption. The model's fitting was investigated by means of the Akaike Information Criteria (AIC). Models with age as the underlying time variable with age and sex as strata variables had enhanced validity of the risk proportionality assumption and better fitting. The PAR for a specific modifiable risk factor can be defined more accurately in mutually adjusted models allowing better public health decisions. This is not necessarily true when correlated modifiable risk factors are considered.

Determinants of mortality status and population attributable risk fractions of the North West Province, South African site of the international PURE study

BACKGROUND

Mortality data and comparative risk assessments from sub-Saharan Africa are limited. There is an urgent need for high quality population health surveys to be conducted, to improve the national health surveillance system. Our aim was to perform a comparative risk assesment and report on the mortality status and cause of death data of participants from a South African site of the international Prospective Urban Rural Epidemiology study.

METHODS

1 921 Black participants were included, with a median observational time of 13 years resulting in 21 525 person-years. We performed a comparative risk assessment considering four health status domains: locality (rural vs. urban), socio-economic status (SES) (education and employment), lifestyle factors (physical activity, smoking and alcohol consumption) and prevalent diseases (human immunodeficiency virus (HIV), type 2 diabetes mellitus and hypertension). Next, population-attributable fractions (PAFs) were calculated to determine the mortality risk attributable to modifiable determinants.

RESULTS

577 all-cause deaths occurred. Infectious diseases (28.1% of all deaths) were the most frequent cause of death, followed by cardiovascular disease (CVD) (22.4%), respiratory diseases (11.6%) and cancer (11.1%). The three main contributors to all-cause mortality were HIV infection, high SES and being underweight. HIV infection and underweight were the main contributors to infectious disease mortality and hypertension, the urban environment, and physical inactivity to CVD mortality. HIV had the highest PAF, followed by physical inactivity, alcohol and tobacco use and hypertension (for CVD mortality).

CONCLUSION

This African population suffers from a quadruple burden of disease. Urban locality, high SES, prevalent disease (HIV and hypertension) and lifestyle factors (physical inactivity, tobacco and alcohol use) all contributed in varying degrees to all-cause and cause-specific mortalities. Our data confirm the public health importance of addressing HIV and hypertension, but also highlights the importance of physical inactivity, tobacco use and alcohol consumption as focal points for public health strategies to produce the most efficient mortality reduction outcomes.