Kobus Herbst

Cohort Profile: Africa Centre Demographic Information System (ACDIS) and population-based HIV survey

The health and demography of the South African population has been undergoing substantial changes as a result of the rapidly progressing HIV epidemic. Researchers at the University of KwaZulu-Natal and the South African Medical Research Council established The Africa Centre for Health and Population Studies in 1997 funded by a large core grant from The Wellcome Trust, UK. Given the urgent need for high quality longitudinal data with which to monitor these changes, and with which to evaluate interventions to mitigate impact, a demographic surveillance system (DSS) was established in a rural South African population facing a rapid and severe HIV epidemic. 1 The DSS, referred to as the Africa Centre Demographic Information System (ACDIS), started in 2000. In 2003, population-based HIV testing (also funded by the Wellcome Trust, UK) was started in ACDIS through annual surveys. In this article, we seek to describe the most salient features of ACDIS and the population-based HIV cohort and briefly present some of the most important results to date.

Continued very high prevalence of HIV infection in rural KwaZulu-Natal, South Africa: a population-based longitudinal study.

Objective:To estimate the prevalence of HIV and associated sociodemographic factors including mobility and migration in a rural population in KwaZulu-Natal, South Africa. Methods:A household-based HIV serosurvey of a population that has been under longitudinal demographic surveillance since 2000. All residents (women aged 15–49 years; men aged 15–54 years) and a sample of non-residents (‘migrants’) who return periodically to their households in the area were identified and approached for finger-prick HIV testing. Results:A total of 8325/11 505 male and 11 542/14 396 female residents were traced. Of these, 4692 men and 6859 women consented to HIV testing. Overall, 27% of female and 13.5% of male residents were HIV infected. HIV prevalence peaked at 51% among resident women aged 25–29 years and 44% among resident men aged 30–34 years, with the highest infection rates of 57.5% among 26-year-old women. The female: male infection ratio for residents aged 15–19 years was 13.0. Many factors, including increased mobility, associated with an increased risk of HIV infection among residents, were also associated with non-participation. Among non-residents, 34% of men aged 15–54 years and 41% of women aged 15–49 years were HIV infected. Conclusion:The extremely high prevalence of HIV suggests an urgent need to allocate adequate resources for HIV prevention and treatment in rural areas. Effective monitoring of the epidemic in Africa needs to include efforts to strengthen sentinel surveillance in rural areas and strategies for the surveillance of migrants and mobile individuals.

Data cleaning: detecting, diagnosing, and editing data abnormalities.

In this policy forum the authors argue that data cleaning is an essential part of the research process, and should be incorporated into study design.

An evaluation of the District Health Information System in rural South Africa

BACKGROUND Since reliable health information is essential for the planning and management of health services, we investigated the functioning of the District Health Information System (DHIS) in 10 rural clinics. DESIGN AND SUBJECTS Semi-structured key informant interviews were conducted with clinic managers, supervisors and district information staff. Data collected over a 12-month period for each clinic were assessed for missing data, data out of minimum and maximum ranges, and validation rule violations. SETTING Our investigation was part of a larger study on improving information systems for primary care in rural KwaZulu-Natal. OUTCOMES We assessed data quality, the utilisation for facility management, perceptions of work burden, and usefulness of the system to clinic staff. RESULTS A high perceived work burden associated with data collection and collation was found. Some data collation tools were not used as intended. There was good understanding of the data collection and collation process but little analysis, interpretation or utilisation of data. Feedback to clinics occurred rarely. In the 10 clinics, 2.5% of data values were missing, and 25% of data were outside expected ranges without an explanation provided. CONCLUSIONS The culture of information use essential to an information system having an impact at the local level is weak in these clinics or at the sub-district level. Further training and support is required for the DHIS to function as intended.

High HIV incidence in a community with high HIV prevalence in rural South Africa: Findings from a prospective population-based study.

Objectives: To measure HIV incidence in a rural area of South Africa with high HIV prevalence and to analyze risk factors for acquisition of HIV using a prospective population-based cohort study. Methods: Data from two rounds (2003–2005) of a large prospective population-based HIV survey in rural KwaZulu-Natal were used to calculate HIV incidence by sex and 5-year age group. Multiple imputations (MI) were used to adjust for selection effects and risk factors for acquiring HIV were examined in Weibull multiple regression. Results: During 5253 person-years at risk, 170 individuals became seropositive. The crude HIV incidence rate per 100 person-years was 3.8 [95% confidence interval (CI), 3.2–4.6] in women aged 15–49 years and 2.3 (95% CI, 1.8–3.1) in men aged 15–54 years. MI significantly increased the HIV incidence rates both in women and men [7.9/100 person-years (95% CI, 7.4–8.4) and 5.1/100 person-years (95% CI 4.1–6.2), respectively]. When holding other factors constant in Weibull multiple regression, the hazard of HIV seroconversion was approximately twice as high in people who were currently unmarried but had a partner than among people who were currently married (P < 0.001) and increased with increasing distance from a government health clinic (P = 0.051) and decreasing distance from a primary road (P = 0.002). Conclusion: In this high HIV prevalence community in rural South Africa HIV incidence is very high. The present focus on antiretroviral treatment needs to be balanced with a renewed emphasis on HIV prevention for both sexes.

Effect of HIV infection on pregnancy-related mortality in sub-Saharan Africa: secondary analyses of pooled community-based data from the network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA)

Summary Background Model-based estimates of the global proportions of maternal deaths that are in HIV-infected women range from 7% to 21%, and the effects of HIV on the risk of maternal death is highly uncertain. We used longitudinal data from the Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA) network to estimate the excess mortality associated with HIV during pregnancy and the post-partum period in sub-Saharan Africa. Methods The ALPHA network pooled data gathered between June, 1989 and April, 2012 in six community-based studies in eastern and southern Africa with HIV serological surveillance and verbal-autopsy reporting. Deaths occurring during pregnancy and up to 42 days post partum were defined as pregnancy related. Pregnant or post-partum person-years were calculated for HIV-infected and HIV-uninfected women, and HIV-infected to HIV-uninfected mortality rate ratios and HIV-attributable rates were compared between pregnant or post-partum women and women who were not pregnant or post partum. Findings 138 074 women aged 15–49 years contributed 636 213 person-years of observation. 49 568 women had 86 963 pregnancies. 6760 of these women died, 235 of them during pregnancy or the post-partum period. Mean prevalence of HIV infection across all person-years in the pooled data was 17·2% (95% CI 17·0–17·3), but 60 of 118 (50·8%) of the women of known HIV status who died during pregnancy or post partum were HIV infected. The mortality rate ratio of HIV-infected to HIV-uninfected women was 20·5 (18·9–22·4) in women who were not pregnant or post partum and 8·2 (5·7–11·8) in pregnant or post-partum women. Excess mortality attributable to HIV was 51·8 (47·8–53·8) per 1000 person-years in women who were not pregnant or post partum and 11·8 (8·4–15·3) per 1000 person-years in pregnant or post-partum women. Interpretation HIV-infected pregnant or post-partum women had around eight times higher mortality than did their HIV-uninfected counterparts. On the basis of this estimate, we predict that roughly 24% of deaths in pregnant or post-partum women are attributable to HIV in sub-Saharan Africa, suggesting that safe motherhood programmes should pay special attention to the needs of HIV-infected pregnant or post-partum women. Funding Wellcome Trust, Health Metrics Network (WHO).

Hiding in the shadows of the HIV epidemic: obesity and hypertension in a rural population with very high HIV prevalence in South Africa

Hiding in the shadows of the HIV epidemic: obesity and hypertension in a rural population with very high HIV prevalence in South Africa

Population and antenatal-based HIV prevalence estimates in a high contracepting female population in rural South Africa

BackgroundTo present and compare population-based and antenatal-care (ANC) sentinel surveillance HIV prevalence estimates among women in a rural South African population where both provision of ANC services and family planning is prevalent and fertility is declining. With a need, in such settings, to understand how to appropriately adjust ANC sentinel surveillance estimates to represent HIV prevalence in general populations, and with evidence of possible biases inherent to both surveillance systems, we explore differences between the two systems. There is particular emphasis on unrepresentative selection of ANC clinics and unrepresentative testing in the population.MethodsHIV sero-prevalence amongst blood samples collected from women consenting to test during the 2005 annual longitudinal population-based serological survey was compared to anonymous unlinked HIV sero-prevalence amongst women attending antenatal care (ANC) first visits in six clinics (January to May 2005). Both surveillance systems were conducted as part of the Africa Centre Demographic Information System.ResultsPopulation-based HIV prevalence estimates for all women (25.2%) and pregnant women (23.7%) were significantly lower than that for ANC attendees (37.7%). A large proportion of women attending urban or peri-urban clinics would be predicted to be resident within rural areas. Although overall estimates remained significantly different, presenting and standardising estimates by age and location (clinic for ANC-based estimates and individual-residence for population-based estimates) made some group-specific estimates from the two surveillance systems more predictive of one another.ConclusionIt is likely that where ANC coverage and contraceptive use is widespread and fertility is low, population-based surveillance under-estimates HIV prevalence due to unrepresentative testing by age, residence and also probably by HIV status, and that ANC sentinel surveillance over-estimates prevalence due to selection bias in terms of age of sexual debut and contraceptive use. The results presented highlight the importance of accounting for unrepresentative testing, particularly by individual residence and age, through system design and statistical analyses.

Mortality trends in the era of antiretroviral therapy: evidence from the Network for Analysing Longitudinal Population based HIV/AIDS data on Africa (ALPHA)

Background:The rollout of antiretroviral therapy (ART) is one of the largest public health interventions in Eastern and Southern Africa of recent years. Its impact is well described in clinical cohort studies, but population-based evidence is rare. Methods:We use data from seven demographic surveillance sites that also conduct community-based HIV testing and collect information on the uptake of HIV services. We present crude death rates of adults (aged 15–64) for the period 2000–2011 by sex, HIV status, and treatment status. Parametric survival models are used to estimate age-adjusted trends in the mortality rates of people living with HIV (PLHIV) before and after the introduction of ART. Results:The pooled ALPHA Network dataset contains 2.4 million person-years of follow-up time, and 39114 deaths (6893 to PLHIV). The mortality rates of PLHIV have been relatively static before the availability of ART. Mortality declined rapidly thereafter, with typical declines between 10 and 20% per annum. Compared with the pre-ART era, the total decline in mortality rates of PLHIV exceeds 58% in all study sites with available data, and amounts to 84% for women in Masaka (Uganda). Mortality declines have been larger for women than for men; a result that is statistically significant in five sites. Apart from the early phase of treatment scale up, when the mortality of PLHIV on ART was often very high, mortality declines have been observed in PLHIV both on and off ART. Conclusion:The expansion of treatment has had a large and pervasive effect on adult mortality. Mortality declines have been more pronounced for women, a factor that is often attributed to womens greater engagement with HIV services. Improvements in the timing of ART initiation have contributed to mortality reductions in PLHIV on ART, but also among those who have not (yet) started treatment because they are increasingly selected for early stage disease.

Cause-specific childhood mortality in Africa and Asia: evidence from INDEPTH health and demographic surveillance system sites

Background Because most deaths in Africa and Asia are not well documented, estimates of mortality are often made using scanty data. The INDEPTH Network works to alleviate this problem by collating detailed individual data from defined Health and Demographic Surveillance sites. By registering all deaths over time and carrying out verbal autopsies to determine cause of death across many such sites, using standardised methods, the Network seeks to generate population-based mortality statistics that are not otherwise available. Objective To build a large standardised mortality database from African and Asian sites, detailing the relevant methods, and use it to describe cause-specific mortality patterns. Design Individual demographic and verbal autopsy (VA) data from 22 INDEPTH sites were collated into a standardised database. The INDEPTH 2013 population was used for standardisation. The WHO 2012 VA standard and the InterVA-4 model were used for assigning cause of death. Results A total of 111,910 deaths occurring over 12,204,043 person-years (accumulated between 1992 and 2012) were registered across the 22 sites, and for 98,429 of these deaths (88.0%) verbal autopsies were successfully completed. There was considerable variation in all-cause mortality between sites, with most of the differences being accounted for by variations in infectious causes as a proportion of all deaths. Conclusions This dataset documents individual deaths across Africa and Asia in a standardised way, and on an unprecedented scale. While INDEPTH sites are not constructed to constitute a representative sample, and VA may not be the ideal method of determining cause of death, nevertheless these findings represent detailed mortality patterns for parts of the world that are severely under-served in terms of measuring mortality. Further papers explore details of mortality patterns among children and specifically for NCDs, external causes, pregnancy-related mortality, malaria, and HIV/AIDS. Comparisons will also be made where possible with other findings on mortality in the same regions. Findings presented here and in accompanying papers support the need for continued work towards much wider implementation of universal civil registration of deaths by cause on a worldwide basis.Background Because most deaths in Africa and Asia are not well documented, estimates of mortality are often made using scanty data. The INDEPTH Network works to alleviate this problem by collating detailed individual data from defined Health and Demographic Surveillance sites. By registering all deaths over time and carrying out verbal autopsies to determine cause of death across many such sites, using standardised methods, the Network seeks to generate population-based mortality statistics that are not otherwise available. Objective To build a large standardised mortality database from African and Asian sites, detailing the relevant methods, and use it to describe cause-specific mortality patterns. Design Individual demographic and verbal autopsy (VA) data from 22 INDEPTH sites were collated into a standardised database. The INDEPTH 2013 population was used for standardisation. The WHO 2012 VA standard and the InterVA-4 model were used for assigning cause of death. Results A total of 111,910 deaths occurring over 12,204,043 person-years (accumulated between 1992 and 2012) were registered across the 22 sites, and for 98,429 of these deaths (88.0%) verbal autopsies were successfully completed. There was considerable variation in all-cause mortality between sites, with most of the differences being accounted for by variations in infectious causes as a proportion of all deaths. Conclusions This dataset documents individual deaths across Africa and Asia in a standardised way, and on an unprecedented scale. While INDEPTH sites are not constructed to constitute a representative sample, and VA may not be the ideal method of determining cause of death, nevertheless these findings represent detailed mortality patterns for parts of the world that are severely under-served in terms of measuring mortality. Further papers explore details of mortality patterns among children and specifically for NCDs, external causes, pregnancy-related mortality, malaria, and HIV/AIDS. Comparisons will also be made where possible with other findings on mortality in the same regions. Findings presented here and in accompanying papers support the need for continued work towards much wider implementation of universal civil registration of deaths by cause on a worldwide basis.