School of Public Health
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Item CD4+ T-cell count at antiretroviral therapy initiation in the "Treat AII" era in South A: an interrupted time series analysis.(2012-11-05) Yapa HM; Kim H-y; Post FA; Jiamsakul A; de Neve J-W; Tanser F; Iwuji C; Baisley K; Shamanesh M; Pillay D; Siedner MJ; Barnighausen T; Bot JItem Human respiratory syncytial virus diversity and epidemiology among patients hospitalized with severe respiratory illness in South Africa, 2012–2015(2015) Ziyaad Valley-Omar; Stefano Tempia; Orienka Hellferscee; Sibongile Walaza; Ebrahim Variava6; Halima Dawood; Kathleen Kahn; Meredith McMorrow; Marthi Pretorius; Senzo Mtshali; Ernest Mamorobela; Nicole Wolter; Marietjie Venter; Anne von Gottberg; Cheryl Cohen; Florette K. TreurnichtBackground: We aimed to describe the prevalence of human respiratory syncytial virus (HRSV) and evaluate associations between HRSV subgroups and/or genotypes and epidemiologic characteristics and clinical outcomes in patients hospitalized with severe respiratory illness (SRI). Methods: Between January 2012 and December 2015, we enrolled patients of all ages admitted to two South African hospitals with SRI in prospective hospital-based syndromic surveillance. We collected respiratory specimens and clinical and epidemiological data. Unconditional random effect multivariable logistic regression was used to assess factors associated with HRSV infection. Results: HRSV was detected in 11.2% (772/6908) of enrolled patients of which 47.0% (363/772) were under the age of 6 months. There were no differences in clinical outcomes of HRSV subgroup A-infected patients compared with HRSV subgroup B-infected patients but among patients aged <5 years, children with HRSV subgroup A were more likely be coinfected with Streptococcus pneumoniae (23/208 11.0% vs. 2/90, 2.0%; adjusted odds ratio 5.7). No significant associations of HRSV A genotypes NA1 and ON1 with specific clinical outcomes were observed. Conclusions: While HRSV subgroup and genotype dominance shifted between seasons, we showed similar genotype diversity as noted worldwide. We found no association between clinical outcomes and HRSV subgroups or genotypes.Item Estimates of HIV incidence among drug users in St. Petersburg, Russia: continued growth of a rapidly expanding epidemic(2010-07-30) Linda M. Niccolai; Sergei V. Verevochkin; Olga V. Toussova; Edward White; Russell Barbour; Andrei P. Kozlov; Robert HeimerBackground: Russia has one of the world’s fastest growing HIV epidemics and it has been largely concentrated among injection drug users (IDU). St Petersburg, Russia’s second largest city, is one of the country’s regions that has been most affected by the HIV epidemic. To monitor the current epidemic situation, we sought to estimate recent HIV incidence among IDU in St Petersburg. Methods: In a cross-sectional study of 691 IDU recruited during 2005–08, HIV incidence was estimated by two methods: a retrospective cohort analysis and BED capture enzyme immunoassay (EIA) results. Socio-demographic and behavioural correlates of incident infections and spatial patterns were examined. Results: In the retrospective cohort analysis, the incidence rate was estimated to be 14.1/100 person-years [95% confidence interval (CI) 10.7–17.6]. Using results of BED EIA and two correction formulas for known misclassification, incidence estimates were 23.9 (95% CI 17.8–30.1) and 25.5 (95% CI 18.9–32.0) per 100 person-years. Independent correlates of being recently infected included current unemployment (P = 0.004) and not having injected drugs in the past 30 days (P = 0.03). HIV incident cases were detected in all but one district in the city, with focal areas of transmission observed to be expanding. Conclusions: High HIV incidence among IDU in St Petersburg attests to continued growth of the epidemic. The need for expansion of HIV prevention interventions targeted to vulnerable populations throughout the city is urgent. These results also suggest that the BED EIA may over-estimate incidence even after correction for low specificity.Item Performance of four computer-coded verbal autopsy methods for cause of death assignment compared with physician coding on 24,000 deaths in low- and middle-income countries(2014) Nikita Desai; Lukasz Aleksandrowicz; Pierre Miasnikof; Ying Lu; Jordana Leitao; Peter Byass; Stephen Tollman; Paul Mee; Dewan Alam; Suresh Kumar Rathi; Abhishek Singh; Rajesh Kumar; Faujdar Ram; Prabhat JhaBackground: Physician-coded verbal autopsy (PCVA) is the most widely used method to determine causes of death (CODs) in countries where medical certification of death is uncommon. Computer-coded verbal autopsy (CCVA) methods have been proposed as a faster and cheaper alternative to PCVA, though they have not been widely compared to PCVA or to each other. Methods: We compared the performance of open-source random forest, open-source tariff method, InterVA-4, and the King-Lu method to PCVA on five datasets comprising over 24,000 verbal autopsies from low- and middle-income countries. Metrics to assess performance were positive predictive value and partial chance-corrected concordance at the individual level, and cause-specific mortality fraction accuracy and cause-specific mortality fraction error at the population level. Results: The positive predictive value for the most probable COD predicted by the four CCVA methods averaged about 43% to 44% across the datasets. The average positive predictive value improved for the top three most probable CODs, with greater improvements for open-source random forest (69%) and open-source tariff method (68%) than for InterVA-4 (62%). The average partial chance-corrected concordance for the most probable COD predicted by the open-source random forest, open-source tariff method and InterVA-4 were 41%, 40% and 41%, respectively, with better results for the top three most probable CODs. Performance generally improved with larger datasets. At the population level, the King-Lu method had the highest average cause-specific mortality fraction accuracy across all five datasets (91%), followed by InterVA-4 (72% across three datasets), open-source random forest (71%) and open-source tariff method (54%). Conclusions: On an individual level, no single method was able to replicate the physician assignment of COD more than about half the time. At the population level, the King-Lu method was the best method to estimate cause-specific mortality fractions, though it does not assign individual CODs. Future testing should focus on combining different computer-coded verbal autopsy tools, paired with PCVA strengths. This includes using open-source tools applied to larger and varied datasets (especially those including a random sample of deaths drawn from the population), so as to establish the performance for age- and sex-specific CODsItem Dimensions of internal migration and their relationship to blood pressure in South Africa(2019-11) Chantel F. Pheiffer; Stephen T. McGarvey; Carren Ginsburg; Mark Collinson; F. Xavier Gómez-Olivé; Stephen Tollman; Michael J. WhiteHypertension prevalence is on the rise in low and middle income countries like South Africa, and migration and concomitant urbanization are often considered to be associated with this rise. However, relatively little is known about the relationship between blood pressure (BP) and internal migration - a highly prevalent population process in LMICs. This study employs data for a group of 194 adult men and women from an original pilot dataset drawn from the Agincourt Health and Demographic Surveillance System in northeast South Africa. Migrants in the sample are identified, tracked, and interviewed. The relationship between BP and migration distance and the number of months an individual spends away from his/her home village is estimated using robust OLS regression, controlling for a series of socioeconomic, health, and behavioral characteristics. This study finds migrants who move further distances and for longer durations to have significantly higher systolic and diastolic BP compared with shorter-term migrants and those who remain nearby or in their home village. These associations remain robust and statistically significant when adjusting for measures of socioeconomic conditions, as well as body mass index (BMI), and the number of meals consumed per day. Migration, both in terms of distance and time away, explains significant variation in BP among migrants in a typical South African context. This finding suggests the need for further studies of nutritional and psychosocial factors associated with geographic mobility that may be important factors for understanding rising hypertension in LMICs.Item Cohort Profile: Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI).(2018) F Xavier Go´ mez-Olive´; Livia Montana; Ryan G Wagner; Chodziwadziwa W Kabudula; Julia K Rohr; Kathleen Kahn; Till Ba¨rnighausen; Mark Collinson; David Canning; Thomas Gaziano; Joshua A Salomon; Collin F Payne; Alisha Wad; Stephen M Tollman; Lisa BerkmanItem Genomic and environmental risk factors for cardiometabolic diseases in Africa: methods used for Phase 1 of the AWI-Gen population cross-sectional study(2018-07-12) Stuart A. Al; Cassandra Soo; Godfred Agongo; Marianne Alberts; Lucas Amenga-Etego; Romuald P. Boua; Ananyo Choudhury; Nigel J. Crowther; Cornelius Depuur; F. Xavier GómezOlivé; Issa Guiraud; Tilahun N. Haregu; Scott Hazelhurst; Kathleen Kahn; Christopher Khayeka-Wandabwa; Catherine Kyobutung; Zané Lombard; Felistas Mashinya; Lisa Micklesfield; Shukri F. Mohamed; Freedom Mukomana; Seydou Nakanabo-Diallo; Hamtandi M. Natama; Nicholas Ngomi; Engelbert A. Nonterah; Shane A. Norris; Abraham R. Oduro; Athanase M. Somé; Hermann Sorgho; Paulina Tindana; Halidou Tinto; Stephen Tollman; Rhian Twine; Alisha Wade; Osman Sankoh; Michèle RamsayThere is an alarming tide of cardiovascular and metabolic disease (CMD) sweeping across Africa. This may be a result of an increasingly urbanized lifestyle characterized by the growing consumption of processed and calorie-dense food, combined with physical inactivity and more sedentary behaviour. While the link between lifestyle and public health has been extensively studied in Caucasian and African American populations, few studies have been conducted in Africa. This paper describes the detailed methods for Phase 1 of the AWI-Gen study that were used to capture phenotype data and assess the associated risk factors and end points for CMD in persons over the age of 40 years in sub-Saharan Africa (SSA). We developed a population-based cross-sectional study of disease burden and phenotype in Africans, across six centres in SSA. These centres are in West Africa (Nanoro, Burkina Faso, and Navrongo, Ghana), in East Africa (Nairobi, Kenya) and in South Africa (Agincourt, Dikgale and Soweto). A total of 10,702 individuals between the ages of 40 and 60 years were recruited into the study across the six centres, plus an additional 1021 participants over the age of 60 years from the Agincourt centre. We collected socio-demographic, anthropometric, medical history, diet, physical activity, fat distribution and alcohol/tobacco consumption data from participants. Blood samples were collected for disease-related biomarker assays, and genomic DNA extraction for genome-wide association studies. Urine samples were collected to assess kidney function. The study provides base-line data for the development of a series of cohorts with a second wave of data collection in Phase 2 of the study. These data will provide valuable insights into the genetic and environmental influences on CMD on the African continentItem Hope, the Household Environment, and Sexual Risk Behaviors Among Young Women in Rural South Africa (HPTN 068)(2018-06) Lauren M Hill; Laurie Abler; Suzanne Maman; Rhian Twine; Kathleen Kahn; Catherine MacPhail; Audrey PettiforWe assessed the psychological trait of hope as an explanatory mediator in the relationship between the home environment and sexual risk behaviors among 2533 young women in rural South Africa. Hope mediated the relationship between average household age and sexual debut (mediated effect = −0.003, p<.05), and between household consumption and sexual debut (mediated effect = −0.019, p<.05). Both higher average household age (β = 0.01; 95%CI: 0.00, 0.01) and greater household consumption (β = 0.05; 95%CI: 0.02, 0.08) were marginally associated with higher hope. In turn, greater hope was associated with lower odds of sexual debut (aOR= 0.62; 95%CI: 0.52, 0.74). These results provide important preliminary evidence of the role of the home environment in shaping protective psychological assets and healthy sexual behaviors. Continued exploration of the relationship between hope and the home environment may help to explain why young women in this context have a disproportionate risk for HIV.Item Men’s perspectives on the impact of femaledirected cash transfers on gender relations: Findings from the HPTN 068 qualitative study(2018) Makhosazane Nomhle Khoza; Sinead Delany-Moretlwe; Fiona Scorgie; Jennifer Hove; Amanda Selin; John Imrie; Rhian Twine; Kathleen Kahn; Audrey Pettifor; Catherine MacPhailBackground HIV is an inherently gendered disease in eastern and southern Africa, not only because more women than men are infected, but also because socially constructed gender norms work to increase women’s HIV-infection risk. The provision of cash transfers to young women alone in such a context adds another dimension to already existing complex social relations where patriarchal values are entrenched, gender inequality is the norm, and violence against women and girls is pervasive. It raises concerns about complicating young women’s relationships with their male partners or possibly even setting them up for more violence. In our attempt to understand how cash transfers influence social relations in the context of a trial among young women in South Africa, we used qualitative data collected during the trial to explore men’s perceptions of the impact of cash transfers on male-female relationships, both intimate and platonic, peer relationships. Method Between April 2012 and August 2015, we conducted focus group discussions (n = 12) and interviews (n = 20) with the male peers and intimate partners of young women aged 13–20 years, who were participating in a phase III randomised controlled trial of CTs for HIV prevention in Mpumalanga, South Africa. A thematic content analysis approach was used to analyse the data. The codebook was developed on the basis of the topic guides, with additional codes added inductively as they emerged from the data. Results Intimate partners were older (range 20–32 years) and more likely to be working than the male peers. Both intimate partners and male peers were supportive of the CT trial targeting young women; younger peers however expressed some concerns that the money might diminish their power and status in relationships. HIV testing requirements associated with the trial appeared to have improved communication about sex and HIV in intimate relationships, with some women even encouraging their partners to go for an HIV test. Conclusion CTs provide AGYW with a measure of autonomy and power to contribute in their gendered relationships, albeit in limited ways. However, there is potential for CTs to have a negative impact on male-female relationships if the cash received by AGYW is equal to or greater than the income earned by their male counterparts or sexual partners.Item Transactional sex and incident HIV infection in a cohort of young women from rural South Africa(2018) Kelly Kilburn; Meghna Ranganathan; Marie C.D. Stoner; James P. Hughes; Catherine MacPhail; Yaw Agyei; F. Xavier Gomez-Oliv; Kathleen Kahn; Audrey PettiforObjective: In sub-Saharan Africa, young women who engage in transactional sex (the exchange of sex for money or gifts) with a male partner show an elevated risk of prevalent HIV infection. We analyse longitudinal data to estimate the association between transactional sex and HIV incidence. Design: We used longitudinal data from a cohort of 2362 HIV-negative young women (aged 13–20 years) enrolled in a randomized controlled trial in rural, South Africa who were followed for up to four visits over 6 years. Methods: The effect of transactional sex on incident HIV was analysed using stratified Cox proportional hazards models and cumulative incidence curves. Risk ratios were estimated using log-binomial models to compare the effects across visits. Results: HIV incidence was higher for young women that reported transactional sex (hazard ratio 1.59, 95% confidence interval 1.02–2.19), particularly when money and/ or gifts were received frequently (at least weekly) (hazard ratio 2.71, 95% confidence interval 1.44–5.12). We also find that effects were much stronger during the main trial and dissipate at the postintervention visit, despite an increase in both transactional sex and HIV. Conclusion: Transactional sex elevates the risk of HIV acquisition among young women, especially when it involves frequent exchanges of money and/or gifts. However, the effect was attenuatedafterthe main trial, possibly due to the changing nature oftransactionalsex and sexual partners as women age. These findings suggest that reducing transactional sex among young women, especially during adolescence, is important for HIV prevention.