Rural South African Population Research Articles

Double malnutrition and associated factors in a middle-aged and older, rural South African population

IntroductionDouble malnutrition (co-existing overnutrition and undernutrition) is increasingly prevalent in sub-Saharan Africa due to rapid epidemiological and nutritional transitions. In this region, studies of double malnutrition have largely been conducted at country and household level, with individual-level studies primarily limited to children and women of reproductive age. We investigated the prevalence and determinants of individual-level double malnutrition in middle-aged and older adults who constitute an increasing proportion of the sub-Saharan African population.Methods250 individuals aged 40–70 years (50% women) and resident in the Agincourt Health and socio-Demographic Surveillance System in rural Mpumalanga province, South Africa, were randomly selected. Double malnutrition was defined as overweight/obesity and anaemia only, overweight/obesity and iodine insufficiency, or overweight/obesity and any micronutrient deficiency (anaemia and/or iodine insufficiency). The Chi-squared goodness of fit test was used to compare the expected and observed numbers of individuals with the type of double malnutrition. Logistic regression was used to investigate determinants of each type of double malnutrition.ResultsDouble malnutrition was present in 22–36% of participants, depending on the definition used. All types of double malnutrition were more common in women than in men (overweight/obesity and anaemia: 34% vs. 10.2%, p < 0.01; overweight/obesity and iodine insufficiency: 32% vs. 12.2%, p < 0.01 and overweight/obesity and any micronutrient deficiency: 50.5% vs. 20.4%, p < 0.01). There were no differences between the overall expected and observed numbers of individuals with combinations of overweight and micronutrient deficiencies [overweight/obesity and anaemia (p = 0.28), overweight/obesity and iodine insufficiency (p = 0.27) or overweight/obesity and any micronutrient deficiency (p = 0.99)]. In models adjusted for socio-demographic factors, HIV and antiretroviral drug status, and food security or dietary diversity, men were 84–85% less likely than women to have overweight/obesity and anaemia, 65% less likely to have overweight/obesity and iodine insufficiency and 74% less likely to have overweight/obesity and any micronutrient deficiency.ConclusionsIndividual-level double malnutrition is prevalent in middle-aged and older adults in a rural sub-Saharan African community. Interventions to improve nutrition in similar settings should target individuals throughout the life course and a focus on women may be warranted.

Community dialogue to enhance understanding of beliefs, behaviours and barriers to care for people living with liver disease and HBV infection in KwaZulu Natal, South Africa

IntroductionThe World Health Organisation (WHO) has set targets for the elimination of Hepatitis B virus (HBV), which include preventing new infections and reducing deaths. We explored beliefs, behaviours and barriers to diagnosis, prevention and treatment for people living with HBV infection (PLWHB) and those with liver disease in a rural South African population in KwaZulu-Natal, to gather information to inform research and support the development of improved clinical and public health services. MethodsUsing an interdisciplinary approach (combining public engagement, social science, clinical and laboratory team members) we conducted a community dialogue with members of the Africa Health Research Institute (AHRI) Community Advisory Board (CAB). Notes from the discussions were used to write up an account from which themes were identified during a team debrief session for data analysis. ResultsThere was a lack of knowledge and awareness of HBV infection and transmission and prevention amongst CAB members, also reported among community members and healthcare workers. The participants recognised liver disease symptoms. Perceived causes of liver disease reported by the CAB were alcohol and non-adherence to HIV treatment. Barriers to care included stigma, poverty, and delays in referrals for HBV diagnosis and management. ConclusionUnderstanding barriers to care is important to shape future services for diagnosis, treatment and prevention of HBV and liver disease which are accessible, affordable and acceptable to the local population. Education, awareness and advocacy for improved liver health care pathways are required to make them effective for local communities.

Prevalence of and Risk Factors for Peripheral Artery Disease in Rural South Africa: A Cross-Sectional Analysis of the HAALSI Cohort.

The burden of peripheral artery disease (PAD) is increasing in low- and middle-income countries. Existing literature from sub-Saharan Africa is limited and lacks population-representative estimates. We estimated the burden and risk factor profile of PAD for a rural South African population. We used data from 1883 participants from a rural, low-incomecohort of South African adults aged 40 to 69 years with available ankle-brachial index measurements. We defined clinical PAD as ankle-brachial index ≤0.90 or >1.40, and borderline PAD as ankle-brachial index >0.90 and ≤1.00. We compared the distribution of sociodemographic variables, biomarkers, and comorbidities across PAD classifications. To identify associated factors, we calculated unadjusted and age-sex-adjusted prevalence ratios (PRs) with log-binomial models. Overall, 6.6% (95% CI, 5.6-7.7) of the sample met the diagnostic criteria for clinical PAD, while 44.7% (95% CI, 42.4-47.0) met the diagnostic criteria for borderline PAD. Age (PR: 1.9 [95% CI, 1.2-3.1] for ages 50-59 years compared with 40-49 years; PR: 2.5 [95% CI, 1.5-4.0] for ages 60-69 years compared with 40-49 years); diagnosed hypertension (PR: 1.53 [95% CI, 1.08-2.17]); and C-reactive protein (PR: 1.08 [95% CI, 1.03-1.12]) were associated with increased prevalence of clinical PAD. All other examined factors were not significantly associated with clinical PAD. We found high PAD prevalence for younger age groups compared with previous research and a lack of statistical evidence for the influence of traditional risk factors for this rural, low-income population. Future research should focus on identifying the underlying risk factors for PAD in this setting. South African policymakers and clinicians should consider expanded screening for early PAD detection in rural areas.

Cerebrovascular disease is associated with memory function in the Health and Aging in Africa Longitudinal Study of an INDEPTH community in rural South Africa

AbstractBackgroundHealth and Aging in Africa Longitudinal Study of an INDEPTH community in South Africa (HAALSI) is a sister study to the US‐based Health and Retirement Study. The purpose of HAALSI is to characterize the social, economic, biological, physical, and mental health factors in a population‐representative cohort of older adults in a rural community in Agincourt, South Africa. Beginning in 2020, as part of an Alzheimer’s disease and related disorders (ADRD) substudy, we conducted neuropsychological evaluations and structural magnetic resonance imaging (MRI) in a subset of HAALSI participants. Here, we report preliminary observations on the relationship of white matter hyperintensity (WMH) volume, a marker of small vessel cerebrovascular disease, and hippocampal volume, a marker of neurodegeneration, on memory function in a group of substudy participants.MethodNinety‐nine HAALSI ADRD participants with available MRI scans and neuropsychological outcomes at time of analysis (mean ± SD; age = 70.3 ± 10.9, 87% with no formal education or some primary education) were included in these analyses. Participants received research‐grade, harmonized 1.5T MRI scanning at a private hospital and were evaluated with a battery of neuropsychological tests. Using in‐house developed software and FreeSurfer, respectively, we derived total WMH volume and total hippocampal volume. We examined the association of these variables with memory function, operationalized as the delayed recall score of the Logical Memory Test, adapted for context.ResultAdjusting for education level, increased WMH volume was associated with poorer performance on the Logical Memory Test (standardized β = ‐0.21, p&lt;0.05) but hippocampal volume was not (standardized β = 0.09, p = 0.41). Associations of these MRI markers with memory function did not interact with education level.ConclusionIn these preliminary analyses of older adults in a rural South African community, markers of small vessel cerebrovascular disease but not neurodegeneration are associated with poorer cognitive outcomes. Future work will examine the pathways that give rise to cognitive impairment and dementia in this rural South African population and track cognitive trajectories over time.

Identifying sex-specific anthropometric measures and thresholds for dysglycemia screening in an HIV-endemic rural South African population.

Valid screening and diagnostic algorithms are needed to achieve 2030 targets proposed by the WHO's Global Diabetes Compact. We explored anthropometric thresholds to optimally screen and refer individuals for diabetes testing in rural South Africa. We evaluated screening thresholds for waist circumference (WC), body mass index (BMI), and waist-hip ratio (WHR) to detect dysglycemia based on a glycated hemoglobin (HbA1C) ≥6.5% among adults in a population-based study in South Africa using weighted, non-parametric ROC regression analyses. We then assessed the diagnostic validity of traditional obesity thresholds, explored optimal thresholds for this population, and fit models stratified by sex, age, and HIV status. The prevalence of dysglycemia in the total study population (n = 17,846) was 7.7%. WC had greater discriminatory capacity than WHR to detect dysglycemia in men (p-value<0.001) and women (p<0.001). WC had greater discriminatory capacity than BMI to detect dysglycemia in women (p<0.001). However, BMI and WC performed similarly for men (p = 0.589). Whereas traditional WC thresholds for women (>81cm) performed well (sensitivity 91%, positive predictive value [PPV] 14.9%), substantially lower thresholds were needed to achieve acceptable sensitivity and PPV among men (traditional >94cm, derived >79.5cm). WC outperforms BMI as an anthropometric screening measure for dysglycemia in rural South Africa. Whereas WC guideline thresholds are appropriate for women, male-derived WC cutoffs performed better at lower thresholds. In this rural South African population, thresholds that maximize specificity and PPV for efficient resource allocation may be preferred.

Association between prior tuberculosis disease and dysglycemia within an HIV-endemic, rural South African population.

Tuberculosis (TB) may predispose individuals to the development of diabetes. Such a relationship could have an outsized impact in high-prevalence TB settings. However, few studies have explored this relationship in populations heavily burdened by diabetes and TB. We analyzed data from a community-based population cohort that enrolled adults in rural South Africa. Individuals were considered to have prior TB if they self-reported a history of TB treatment. We fitted sex-specific logistic regression models, adjusted for potential clinical and demographic confounders, to estimate relationships between dysglycemia (HBA1c ≥6.5%) and prior TB. Propensity score-matched cohorts accounted for the differential age distributions between comparator groups. We examined the interactions between sex, prior TB, and HIV status. In the analytic cohort (n = 17,593), the prevalence of prior TB was 13.8% among men and 10.7% among women. Dysglycemia was found in 9.1% of the population, and HIV prevalence was 34.0%. We found no difference in dysglycemia prevalence by prior TB (men OR 0.96, 95% CI 0.60-1.56: women OR 1.05, 95% CI 0.79-1.39). However, there was a qualitative interaction by HIV serostatus, such that among men without HIV, those with a history of TB had a greater prevalence of dysglycemia than those without prior TB (10.1% vs. 4.6%, p = 0.0077). An inverse relationship was observed among men living with HIV (prior TB 3.3% vs. no TB 7.3%, p = 0.0073). Treated TB disease was not associated with dysglycemia in an HIV-endemic, rural South African population. However, we found a significant interaction between prior TB and HIV status among men, suggesting distinct pathophysiological mechanisms between the two infections that may impact glucose metabolism. Longitudinal studies are needed to better establish a causal effect and underlying mechanisms related to resolved TB, HIV, and diabetes.

1165. Ascertainment of anthropometric thresholds to identify glucose intolerance in HIV-endemic African populations: results from a population-based survey in rural KwaZulu-Natal, South Africa

Abstract Background Improved screening and diagnostic algorithms are needed to achieve 2030 targets proposed by the Global Diabetes Compact. We sought to explore anthropometric thresholds to optimally screen and refer individuals for glucose intolerance testing in an HIV-endemic rural South African population. Methods We analyzed data from the cross-sectional Vukuzazi study that enrolled adults living in rural KwaZulu-Natal, South Africa. We assessed screening thresholds for waist circumference (WC), body mass index (BMI), and waist hip ratio (WHR) to detect glucose intolerance (hemoglobin A1c &amp;gt;6.5%) using weighted, non-parametric ROC regression analyses. We then assessed the diagnostic validity of traditional obesity thresholds, explored optimal thresholds for the South African population, and fit models stratified by sex, age, and HIV. Results In the total cohort (n=17,868), the prevalence of glucose intolerance was 7.8% (95% CI 7.4–8.2) and HIV prevalence was 33.8% (95% CI 33.1-34.5). WC outperformed BMI and WHR in detecting glucose intolerance (males p&amp;lt; 0.001; females p&amp;lt; 0.001). Whereas guideline WC thresholds for females performed well for glucose intolerance (Sensitivity 91% [95% CI 89.5-92.5], positive predictive value [PPV] 14.9%), substantially lower thresholds were needed to achieve acceptable sensitivity and positive predictive values among men. We found significant sub-groups effects by sex and age, but HIV status did not affect WC thresholds for identifying glucose intolerance. Conclusion Waist circumference improves anthropometric screening for glucose intolerance in South Africa. Guideline-based WC thresholds are appropriate for females, but male-derived WC cutoffs were optimized at lower thresholds. HIV did not affect the performance of WC thresholds in either sex. In rural African populations, thresholds that maximize specificity and PPV for efficient resource allocation may be preferred. Disclosures All Authors: No reported disclosures.

The geography and inter-community configuration of new sexual partnership formation in a rural South African population over fourteen years (2003-2016).

Understanding spatial configuration of sexual network structure is critical for effective use of HIV preventative interventions in a community. However, this has never been described at the population level for any setting in sub-Saharan Africa. We constructed the comprehensive geospatial sexual network among new heterosexual partnerships in rural KwaZulu-Natal, South Africa. In the Africa Health Research Institute (AHRI)'s population-based surveillance, we identified stable sexual partnerships among individuals (≥15 years) from 2003 to 2016. Sexual partnerships and residency were recorded via household surveys (every 4-6 months). We geolocated residents and migration events and mapped the geospatial linkages of sexual partners at the start of sexual partnerships. In a grid composed by 108 cells (nodes; 3kmx3km per cell) covering the surveillance area (438km2), we calculated the degree of connectivity and centrality of the nodes and examined their association with HIV prevalence and incidence per cell. Of 2401 new sexual partnerships, 21% (n = 495) had both partners living within the surveillance area at the start of sexual partnerships, and 76% (376/495) were linked to the geographic HIV cluster with high HIV prevalence identified in a peri-urban community. Overall, 57 nodes had at least one connection to another node. The nodes in the peri-urban cluster had higher connectivity (mean = 19, range: 9-32), compared to outside the cluster (6, range: 1-16). The node's degree of connectivity was positively associated with HIV prevalence of the cell (Pearson correlation coefficient = 0.67; p <0.005). The peri-urban cluster contained nine of the 10 nodes that composed of a single large central module in the community. About 17% of sexual partnerships (n = 421) were formed between a resident and a non-resident partner who out-migrated. Most of these non-resident partners lived in KwaZulu-Natal (86.7%), followed by Gauteng (9.7%), and the median distance between a resident and a non-resident partner was 50.1km (IQR: 23.2-177.2). We found that the peri-urban HIV cluster served as the highly connected central node of the network for sexual partnership formation. The network was also connected beyond the surveillance area across South Africa. Understanding spatial sexual network can improve the provision of spatially targeted and effective interventions.

Mortality transition over a quarter century in rural South Africa: findings from population surveillance in Agincourt 1993-2018

ABSTRACT Background Mortality burden in South Africa since the mid-1990s has been characterized by a quadruple disease burden: HIV/AIDS and tuberculosis (TB); other communicable diseases (excluding HIV/AIDS and TB), maternal causes, perinatal conditions and nutritional deficiencies; non-communicable diseases (NCDs); and injuries. Causes from these broad groupings have persistently constituted the top 10 causes of death. However, proportions and rankings have varied over time, alongside overall mortality levels. Objective To provide evidence on the contributions of age and cause-of-death to changes in mortality levels in a rural South African population over a quarter century (1993–2018). Methods Using mortality and cause-of-death data from the Agincourt Health and Socio-Demographic Surveillance System (HDSS), we derive estimates of the distribution of deaths by cause, and hazards of death by age, sex, and time period, 1993–2018. We derive estimates of life expectancies at birth and years of life expectancy gained at age 15 if most common causes of death were deleted. We compare mortality indicators and cause-of-death trends from the Agincourt HDSS with South African national indicators generated from publicly available datasets. Results Mortality and cause-of-death transition reveals that overall mortality levels have returned to pre-HIV epidemic levels. In recent years, the concentration of mortality has shifted towards older ages, and the mortality burden from cardiovascular diseases and other chronic NCDs are more prominent as people living with HIV/AIDS access ART and live longer. Changes in life expectancy at birth, distribution of deaths by age, and major cause-of-death categories in the Agincourt population follow a similar pattern to the South African population. Conclusion The Agincourt HDSS provides critical information about general mortality, cause-of-death, and age patterns in rural South Africa. Realigning and strengthening the South African public health and healthcare systems is needed to concurrently cater for the prevention, control, and treatment of multiple disease conditions.

Multimorbidity and mortality in an older, rural black South African population cohort with high prevalence of HIV findings from the HAALSI Study

ObjectivesMultimorbidity is associated with mortality in high-income countries. Our objective was to investigate the relationship between multimorbidity (≥2 of the following chronic medical conditions: hypertension, diabetes, dyslipidaemia, anaemia, HIV, angina,...

Convergence of infectious and non-communicable disease epidemics in rural South Africa: a cross-sectional, population-based multimorbidity study

SummaryBackgroundThere has been remarkable progress in the treatment of HIV throughout sub-Saharan Africa, but there are few data on the prevalence and overlap of other significant causes of disease in HIV endemic populations. Our aim was to identify the prevalence and overlap of infectious and non-communicable diseases in such a population in rural South Africa.MethodsWe did a cross-sectional study of eligible adolescents and adults from the Africa Health Research Institute demographic surveillance area in the uMkhanyakude district of KwaZulu-Natal, South Africa. The participants, who were 15 years or older, were invited to participate at a mobile health camp. Medical history for HIV, tuberculosis, hypertension, and diabetes was established through a questionnaire. Blood pressure measurements, chest x-rays, and tests of blood and sputum were taken to estimate the population prevalence and geospatial distribution of HIV, active and lifetime tuberculosis, elevated blood glucose, elevated blood pressure, and combinations of these.Findings17 118 adolescents and adults were recruited from May 25, 2018, to Nov 28, 2019, and assessed. Overall, 52·1% (95% CI 51·3–52·9) had at least one active disease. 34·2% (33·5–34·9) had HIV, 1·4% (1·2–1·6) had active tuberculosis, 21·8% (21·2–22·4) had lifetime tuberculosis, 8·5% (8·1–8·9) had elevated blood glucose, and 23·0% (22·4–23·6) had elevated blood pressure. Appropriate treatment and optimal disease control was highest for HIV (78·1%), and lower for elevated blood pressure (42·5%), active tuberculosis (29·6%), and elevated blood glucose (7·1%). Disease prevalence differed notably by sex, across age groups, and geospatially: men had a higher prevalence of active and lifetime tuberculosis, whereas women had a substantially high prevalence of HIV at 30–49 years and an increasing prevalence of multiple and poorly controlled non-communicable diseases when older than 50 years.InterpretationWe found a convergence of infectious and non-communicable disease epidemics in a rural South African population, with HIV well treated relative to all other diseases, but tuberculosis, elevated blood glucose, and elevated blood pressure poorly diagnosed and treated. A public health response that expands the successes of the HIV testing and treatment programme to provide multidisease care targeted to specific populations is required to optimise health in such settings in sub-Saharan Africa.FundingWellcome Trust, Bill & Melinda Gates Foundation, the South African Department of Science and Innovation, South African Medical Research Council, and South African Population Research Infrastructure Network.TranslationFor the isiZulu translation of the abstract see Supplementary Materials section.

Body Roundness Index, A Body Shape Index, Conicity Index, and Their Association with Nutritional Status and Cardiovascular Risk Factors in South African Rural Young Adults.

Background: The study aimed to investigate the association of Body Roundness Index (BRI), A Body Shape Index (ABSI), and Conicity Index with nutritional status and cardiovascular risk factors in South African rural young adults. Methods: The study included a total of 624 young adults aged 21–30 years from the Ellisras rural area. Anthropometric indices, blood pressure (BP), and biochemical measurements were measured. Results: BRI was significantly correlated with insulin (0.252 males, females 0.255), homeostatic model assessment (HOMA)-β (0.250 males, females 0.245), and TG (0.310 males, females 0.216). Conicity Index was significantly associated with pulse rate (PR) (β 0.099, 95% confidence interval (CI) 0.017, 0.143, p < 0.013; β 0.081, 95% CI 0.000 0.130, p < 0.048), insulin (β 0.149, 95% CI 0.286 0.908, p < 0.001; β 0.110, 95% CI 0.123 0.757, p < 0.007). Conicity Index is associated with insulin resistance (IR) (odds ratio (OR) 7.761, 95% CI 5.783 96.442, p < 0.001; OR 4.646, 95% CI 2.792 74.331, p < 0.007), underweight (OR 0.023, 95% CI 0.251 0.433, p < 0.001; OR 0.031, 95% CI 0.411 0.612, p < 0.001), and obesity (OR 1.058, 95% CI 271.5 4.119, p < 0.001; OR 1.271, 95% CI 0.672 1.099, p < 0.001). Conclusion: Conicity Index was positively associated with insulin resistance, hypertension and dyslipidaemia. Further investigation of these indices and their association with nutritional status and cardiovascular diseases (CVDs) could assist in efforts to prevent CVD in the rural South African population.

Ideal Cardiovascular Health Index and Its Determinants in a Rural South African Population.

Background:The ideal cardiovascular health index (CVHI) is a measure to summarize cardiovascular (CV) health, and includes smoking, body-mass index, physical activity, blood pressure, glucose, total cholesterol, and diet.Objective:This study aimed to assess CV health using the CVHI and determinants on CV health in a rural African population, and correlate carotid intima-media thickness (CIMT), a surrogate marker for atherosclerosis, with CVHI.Methods:A cross-sectional analysis was performed on baseline data of the Ndlovu Cohort Study, located in rural South Africa. CVHI score (CVHIs) was calculated by the sum of favourable CVHI factors (range 0 to 7). Logistic regression was performed to examine the association of age, sex, HIV-status, education level, employment status, and income with good CV health (5–7 favourable health factors). Mean CIMT was displayed by poor, intermediate and good CV health.Results:The study included 1927 participants with a mean age of 38.7 years (SD ± 12.8). Of the factors contributing to the CVHI, glucose and total cholesterol scored best; diet least good. Average CVHIs for the population was 4.4 (SD ± 1.2) and 53% of the population had a good CV health. Determinants associated with good CV health were younger age, higher educational attainment, and HIV positivity. CVHIs showed good agreement with CIMT.Conclusion:CVHIs showed that more than half of the participants had a good CV health. Agreement between CVHIs and CIMT indicates potential use of CVHIs as a surrogate marker for CV risk. The study highlights the importance of education for health promotion; good CV health in HIV-positive participants may in part be attributed to more frequent health care contact and provision of chronic disease care.HighlightsGood cardiovascular health (CVH) was observed in 53% of the study population.In global comparison, rural African study participants showed a good CVH score.HIV positivity was associated with a good CVH score.CVH score showed good agreement with carotid intima-media thickness.

The Relationship between Binge Drinking and Metabolic Syndrome Components amongst Young Adults Aged 21 to 31 Years: Ellisras Longitudinal Study.

Background: Evidence is lacking on the effects of binge alcohol consumption on metabolic syndrome in the rural South African population. The purpose of this study was to investigate the association between binge drinking and components of metabolic syndrome (MetS) amongst Ellisras rural young adults aged 21 to 31 years who are part of the Ellisras Longitudinal Study. Methods: Logistic regression analysis was applied to a total of 624 participants (306 males and 318 females) aged 21 to 31 years who took part in the Ellisras Longitudinal Study (ELS). The model was adjusted for covariates, including smoking, age, and gender. Binge alcohol consumption was assessed using a standardised questionnaire that was validated for the Ellisras rural community. A standardised method of determining the components MetS was used after fasting blood samples were collected from all the participants. Results: Binge drinking remained significantly associated with low levels of high-density lipoprotein cholesterol (HDL-C) (OR = 2.64, 95% CI = 1.23–5.65), after being adjusted for smoking, age, and gender. Other MetS components were not predicted. Instead, gender remained significantly associated with all MetS components, except triglycerides, at multivariate analysis. Age retained significance at multivariate analysis with waist girth (OR = 2.13, 95% CI = 1.37–3.34), triglycerides (OR = 2.30, 95% CI = 1.05–5.02), and the MetS composite (OR = 1.65, 95% CI = 1.12–2.41). Conclusion: Binge drinking was significantly associated with lower levels of HDL-C. Future studies should investigate the relationship between alcohol abuse and the components of incident MetS in this population.

HIV incidence declines in a rural South African population: a G-imputation approach for inference

BackgroundAd hoc assumptions about the unobserved infection event, which is known only to occur between the latest-negative and earliest-positive test dates, can lead to biased HIV incidence rate estimates. Using a G-imputation approach, we infer the infection dates from covariate data to estimate the HIV incidence rate in a hyper-endemic South African setting.MethodsA large demographic surveillance system has annually tested a cohort of HIV-uninfected participants living in the KwaZulu-Natal province. Using this data, we estimated a cumulative baseline hazard function and the effects of time-dependent covariates on the interval censored infection dates. For each HIV-positive participant in the cohort, we derived a cumulative distribution function and sampled multiple infection dates conditional on the unique covariate values. We right censored the data at the imputed dates, calculated the annual HIV incidence rate per 100 person-years, and used Rubin’s rules to obtain the 95% confidence intervals.ResultsA total of 20,011 uninfected individuals with a repeat HIV test participated in the incidence cohort between 2005 and 2018. We observed 2,603 infections per 58,769 person-years of follow-up among women and 845 infections per 41,178 person-years of follow-up among men. Conditional on age and circumcision status (men only), the female HIV incidence rate declined by 25%, from 5.0 to 3.7 infections per 100 person-years between 2014 and 2018. During this period, the HIV incidence rate among men declined from 2.1 to 1.1 infections per 100 person-years—a reduction of 49%. We observed similar reductions in male and female HIV incidence conditional on condom-use, marital status, urban residential status, migration history, and the HIV prevalence in the surrounding community.ConclusionWe have followed participants in one of the world’s largest and longest running HIV cohorts to estimate long-term trends in the population-wide incidence of infection. Using a G-imputation approach, we present further evidence for HIV incidence rate declines in this hyper-endemic South African setting.

Time-critical conditions: assessment of burden and access to care using verbal autopsy in Agincourt, South Africa

BackgroundTime-critical conditions (TCC) are estimated to cause substantial mortality in low and middle-income countries. However, quantification of deaths and identification of contributing factors to those deaths are challenging in settings...

Cognitive function and cardiometabolic disease risk factors in rural South Africa: baseline evidence from the HAALSI study

BackgroundEvidence on cognitive function in older South Africans is limited, with few population-based studies. We aimed to estimate baseline associations between cognitive function and cardiometabolic disease risk factors in rural South Africa.MethodsWe use baseline data from “Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI), a population-based study of adults aged 40 and above in rural South Africa in 2015. Cognitive function was measured using measures of time orientation, immediate and delayed recall, and numeracy adapted from the Health and Retirement Study cognitive battery (overall total cognitive score range 0–26). We used multiple linear regression to estimate associations between cardiometabolic risk factors (including BMI, hypertension, dyslipidemia, diabetes, history of stroke, alcohol frequency, and smoking status) and the overall cognitive function score, adjusted for potential confounders.ResultsIn multivariable-adjusted analyses (n = 3018; male = 1520; female = 1498; median age 59 (interquartile range 50–67)), cardiometabolic risk factors associated with lower cognitive function scores included: diabetes (b = − 1.11 [95% confidence interval: − 2.01, − 0.20] for controlled diabetes vs. no diabetes); underweight BMI (b = − 0.87 [CI: − 1.48, − 0.26] vs. normal BMI); and current and past smoking history compared to never smokers. Factors associated with higher cognitive function scores included: obese BMI (b = 0.74 [CI: 0.39, 1.10] vs. normal BMI); and controlled hypertension (b = 0.53 [CI: 0.11, 0.96] vs. normotensive).ConclusionsWe provide an important baseline from rural South Africa on the associations between cardiometabolic disease risk factors and cognitive function in an older, rural South African population using standardized clinical measurements and cut-offs and widely used cognitive assessments. Future studies are needed to clarify temporal associations as well as patterns between the onset and duration of cardiometabolic conditions and cognitive function. As the South African population ages, effective management of cardiometabolic risk factors may be key to lasting cognitive health.

Prevalence and health effects of communicable and non-communicable disease comorbidity in rural KwaZulu-Natal, South Africa.

To describe changes in prevalence of hypertension, diabetes, HIV and tuberculosis, and prevalence of comorbidity, and to investigate associations between each condition, and combinations of conditions, with self-reported general health and hospital admission. This study used data from a longitudinal population-based HIV and health surveillance cohort, conducted by the Africa Health Research Institute in Umkhanyakude district of rural KwaZulu-Natal, South Africa. Prevalence of hypertension, HIV and diabetes increased from 2009 to 2015, and prevalence of tuberculosis decreased. 81% of the 47334 participants were female; hypertension and diabetes were the commonest conditions in people over age 50, whereas HIV was most common in those younger than 50years. Comorbidity of communicable and non-communicable conditions was commonest in 40- to 60-year-olds. The adjusted odd ratios (OR) for better self-reported general health with multimorbidity were 0.53 (95% CI 0.51-0.56), 0.29 (95% CI 0.27-0.29), 0.25 (95% CI 0.21-0.37) and 0.21 (95% CI 0.12-0.37) for one, two, three and four conditions, respectively, vs. no conditions. Tuberculosis was most strongly and inversely associated with better general health (OR 0.34 (0.31-0.37) and most strongly associated with hospital admission (OR 3.26 (2.32-2.99)). The high prevalence of communicable and non-communicable conditions in this rural South African population is giving rise to a burden of multimorbidity, as increased access to antiretroviral treatment has reduced mortality in people with HIV. Healthcare systems must adapt by working towards integrated primary care for HIV/AIDS and non-communicable diseases.

Space-time clustering of recently-diagnosed tuberculosis and impact of ART scale-up: Evidence from an HIV hyper-endemic rural South African population

In HIV hyperendemic sub-Saharan African communities, particularly in southern Africa, the likelihood of achieving the Sustainable Development Goal of ending the tuberculosis (TB) epidemic by 2030 is low, due to lack of cost-effective and practical interventions in population settings. We used one of Africa’s largest population-based prospective cohorts from rural KwaZulu-Natal Province, South Africa, to measure the spatial variations in the prevalence of recently-diagnosed TB disease, and to quantify the impact of community coverage of antiretroviral therapy (ART) on recently-diagnosed TB disease. We collected data on TB disease episodes from a population-based sample of 41,812 adult individuals between 2009 and 2015. Spatial clusters (‘hotspots’) of recently-diagnosed TB were identified using a space-time scan statistic. Multilevel logistic regression models were fitted to investigate the relationship between community ART coverage and recently-diagnosed TB. Spatial clusters of recently-diagnosed TB were identified in a region characterized by a high prevalence of HIV and population movement. Every percentage increase in ART coverage was associated with a 2% decrease in the odds of recently-diagnosed TB (aOR = 0.98, 95% CI:0.97–0.99). We identified for the first time the clear occurrence of recently-diagnosed TB hotspots, and quantified potential benefit of increased community ART coverage in lowering tuberculosis, highlighting the need to prioritize the expansion of such effective population interventions targeting high-risk areas.

MON-604 Reference Ranges for Thyroid Stimulating Hormone and Free Thyroxine in an Older Rural South African Population

Background: Despite recognition that TSH and free T4 (fT4) ranges are population-specific, little data exist on these ranges in sub-Saharan African (SSA) populations. Evaluation of thyroid function is therefore based on reference ranges that may not be representative, potentially resulting in misdiagnosis. We hypothesized that population-specific reference ranges for TSH and fT4 in an older, rural South African population would differ from those cited by the assay manufacturer. Methods: 1498 people, 40-80 years, were randomly selected from the population-based Health and Ageing in Africa: a Longitudinal Study of an INDEPTH Community in South Africa (HAALSI) cohort in Mpumalanga province in rural South Africa, an iodine-sufficient country. 3rd generation TSH, fT4 and antithyroperoxidase antibodies (antiTPO Ab) were measured using chemiluminescent immunoassays. A disease-free population without self-reported thyroid disease was identified (n=1466). Non-pregnant, HIV-negative individuals with antiTPO Ab <35 IU/ml were then selected, with further exclusion of those with overt hypo/hyperthyroidism (TSH>4μIU/ml & fT4<0.89 ng/dl or TSH<0.4 μIU/ml & fT4>1.76 ng/dl) and with potential subclinical dysfunction (normal fT4 with TSH<0.1 μIU/ml or >10 μIU/ml) to form a reference population (n=681). Median, 2.5th and 97.5th percentile values of TSH and fT4 were determined for the overall reference population and for subgroups defined by age and sex. Population-specific ranges were used to classify the disease-free population. Results: Median age of the reference population was 61 years, with 51.5% males. Median TSH was 1.27 μIU/ml and median fT4 was 1.04 ng/dl. Population-specific TSH range was 0.43-3.86 μIU/ml (manufacturer 0.4-4.0 μIU/ml). There were no significant differences in age (p=0.061) or gender distribution (p=0.696), but those aged 70-80 had an upper reference limit of 5.03 μIU/ml. fT4 range was 0.70-1.47 ng/dl (manufacturer 0.89-1.76 ng/dl), with distribution of fT4 differing by sex (p=0.025) and age (p<0.001). 3.3% of the disease-free population had overt or subclinical hypothyroidism and 3.1 % had overt or subclinical hyperthyroidism. Conclusion: In one of the first population-based studies of TSH and fT4 reference ranges in SSA, we demonstrate that, in those <70, the upper limit of TSH and ranges for fT4 in a rural South African population are lower than manufacturer-specified values, mimicking findings in African-American (AA) populations, though in contrast to AAs, the lower limit of TSH in our population was higher than the manufacturer value. Hypothyroidism may therefore be underdiagnosed when TSH alone is used to screen for thyroid dysfunction. Further work is needed to define normal ranges in specific South African populations, such as pregnant women, who may be more vulnerable to the effects of thyroid dysfunction. Funding: FIC/NIH; NIA/NIH, NHGRI/NIH, OD/NIH