Stephen M Tollman

Umeå University, Umeå, Västerbotten, Sweden

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Publications (148)601.41 Total impact

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    ABSTRACT: To inform health care and training, resource and research priorities, it is essential to establish how non-communicable disease risk factors vary by HIV-status in high HIV burden areas; and whether long-term anti-retroviral therapy (ART) plays a modifying role. As part of a cohort initiation, we conducted a baseline HIV/cardiometabolic risk factor survey in 2010-2011 using an age-sex stratified random sample of ages 15+ in rural South Africa. We modelled cardiometabolic risk factors and their associations by HIV-status and self-reported ART status for ages 18+ using sex-stratified logistic regression models. Age-standardised HIV prevalence in women was 26% (95% CI 24-28%) and 19% (95% CI 17-21) in men. People with untreated HIV were less likely to have a high waist circumference in both women (OR 0.67; 95% CI 0.52-0.86) and men (OR 0.42; 95% CI 0.22-0.82). Untreated women were more likely to have low HDL and LDL, and treated women high triglycerides. Cardiometabolic risk factors increased with age except low HDL. The prevalence of hypertension was high (40% in women; 30% in men). Sub-Saharan Africa is facing intersecting epidemics of HIV and hypertension. In this setting, around half the adult population require long-term care for at least one of HIV, hypertension or diabetes. Together with the adverse effects that HIV and its treatment have on lipids, this may have serious implications for the South African health care system. Monitoring of the interaction of HIV, ART use, and cardiometabolic disease is needed at both individual and population levels.
    BMC Public Health 12/2015; 15(1). DOI:10.1186/s12889-015-1467-1 · 2.32 Impact Factor
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    ABSTRACT: Coverage of civil registration and vital statistics varies globally, with most deaths in Africa and Asia remaining either unregistered or registered without cause of death. One important constraint has been a lack of fit-for-purpose tools for registering deaths and assigning causes in situations where no doctor is involved. Verbal autopsy (interviewing care-givers and witnesses to deaths and interpreting their information into causes of death) is the only available solution. Automated interpretation of verbal autopsy data into cause of death information is essential for rapid, consistent and affordable processing. Verbal autopsy archives covering 54 182 deaths from five African and Asian countries were sourced on the basis of their geographical, epidemiological and methodological diversity, with existing physician-coded causes of death attributed. These data were unified into the WHO 2012 verbal autopsy standard format, and processed using the InterVA-4 model. Cause-specific mortality fractions from InterVA-4 and physician codes were calculated for each of 60 WHO 2012 cause categories, by age group, sex and source. Results from the two approaches were assessed for concordance and ratios of fractions by cause category. As an alternative metric, the Wilcoxon matched-pairs signed ranks test with two one-sided tests for stochastic equivalence was used. The overall concordance correlation coefficient between InterVA-4 and physician codes was 0.83 (95% CI 0.75 to 0.91) and this increased to 0.97 (95% CI 0.96 to 0.99) when HIV/AIDS and pulmonary TB deaths were combined into a single category. Over half (53%) of the cause category ratios between InterVA-4 and physician codes by source were not significantly different from unity at the 99% level, increasing to 62% by age group. Wilcoxon tests for stochastic equivalence also demonstrated equivalence. These findings show strong concordance between InterVA-4 and physician-coded findings over this large and diverse data set. Although these analyses cannot prove that either approach constitutes absolute truth, there was high public health equivalence between the findings. Given the urgent need for adequate cause of death data from settings where deaths currently pass unregistered, and since the WHO 2012 verbal autopsy standard and InterVA-4 tools represent relatively simple, cheap and available methods for determining cause of death on a large scale, they should be used as current tools of choice to fill gaps in cause of death data.
    Global journal of health science 06/2015; 5(1):010402. DOI:10.7189/jogh.05.010402
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    ABSTRACT: Sexual activity may be less likely to occur during periods of school enrolment because of the structured and supervised environment provided, the education obtained and the safer peer networks encountered while enrolled. We examined whether school enrolment was associated with teen pregnancy in South Africa. Using longitudinal demographic surveillance data from the rural Agincourt sub-district, we reconstructed the school enrolment status from 2000 through 2011 for 15 457 young women aged 12-18 years and linked them to the estimated conception date for each pregnancy during this time. We examined the effect of time-varying school enrolment on teen pregnancy using a Cox proportional hazard model, adjusting for: age; calendar year; household socioeconomic status; household size; and gender, educational attainment and employment of household head. A secondary analysis compared the incidence of pregnancy among school enrolees by calendar time: school term vs school holiday. School enrolment was associated with lower teen pregnancy rates [adjusted hazard ratio (95% confidence interval): 0.57 (0.50, 0.65)].This association was robust to potential misclassification of school enrolment. For those enrolled in school, pregnancy occurred less commonly during school term than during school holidays [incidence rate ratio (95% confidence interval): 0.90 (0.78, 1.04)]. Young women who drop out of school may be at higher risk for teen pregnancy and could likely benefit from receipt of accessible and high quality sexual health services. Preventive interventions designed to keep young women in school or addressing the underlying causes of dropout may also help reduce the incidence of teen pregnancy. © The Author 2015; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.
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    ABSTRACT: In 2011 there were 5.5 million HIV infected people in South Africa and 71% of those requiring antiretroviral therapy (ART) received it. The effective integration of traditional medical practitioners and biomedical providers in HIV prevention and care has been demonstrated. However concerns remain that the use of traditional treatments for HIV-related disease may lead to pharmacokinetic interactions between herbal remedies and ART drugs and delay ART initiation. Here we analyse the changing prevalence and determinants of traditional healthcare use amongst those dying of HIV-related disease, pulmonary tuberculosis and other causes in a rural South African community between 2003 and 2011. ART was made available in this area in the latter part of this period. Data was collected during household visits and verbal autopsy interviews. InterVA-4 was used to assign causes of death. Spatial analyses of the distribution of traditional healthcare use were performed. Logistic regression models were developed to test associations of determinants with traditional healthcare use. There were 5929 deaths in the study population of which 47.7% were caused by HIV-related disease or pulmonary tuberculosis (HIV/AIDS and TB). Traditional healthcare use declined for all deaths, with higher levels throughout for those dying of HIV/AIDS and TB than for those dying of other causes. In 2003-2005, sole use of biomedical treatment was reported for 18.2% of HIV/AIDS and TB deaths and 27.2% of other deaths, by 2008-2011 the figures were 49.9% and 45.3% respectively. In bivariate analyses, higher traditional healthcare use was associated with Mozambican origin, lower education levels, death in 2003-2005 compared to the later time periods, longer illness duration and moderate increases in prior household mortality. In the multivariate model only country of origin, time period and illness duration remained associated. There were large decreases in reported traditional healthcare use and increases in the sole use of biomedical treatment amongst those dying of HIV/AIDS and TB. No associations between socio-economic position, age or gender and the likelihood of traditional healthcare use were seen. Further qualitative and quantitative studies are needed to assess whether these figures reflect trends in healthcare use amongst the entire population and the reasons for the temporal changes identified.
    BMC Complementary and Alternative Medicine 12/2014; 14(1):504. DOI:10.1186/1472-6882-14-504 · 1.88 Impact Factor
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    ABSTRACT: Given the importance of Africa to studies of human origins and disease susceptibility, detailed characterization of African genetic diversity is needed. The African Genome Variation Project provides a resource with which to design, implement and interpret genomic studies in sub-Saharan Africa and worldwide. The African Genome Variation Project represents dense genotypes from 1,481 individuals and whole-genome sequences from 320 individuals across sub-Saharan Africa. Using this resource, we find novel evidence of complex, regionally distinct hunter-gatherer and Eurasian admixture across sub-Saharan Africa. We identify new loci under selection, including loci related to malaria susceptibility and hypertension. We show that modern imputation panels (sets of reference genotypes from which unobserved or missing genotypes in study sets can be inferred) can identify association signals at highly differentiated loci across populations in sub-Saharan Africa. Using whole-genome sequencing, we demonstrate further improvements in imputation accuracy, strengthening the case for large-scale sequencing efforts of diverse African haplotypes. Finally, we present an efficient genotype array design capturing common genetic variation in Africa.
    Nature 12/2014; DOI:10.1038/nature13997 · 42.35 Impact Factor
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    ABSTRACT: Antiretroviral treatment (ART) has significantly reduced HIV mortality in South Africa. The benefits have not been experienced by all groups. Here we investigate the factors associated with these inequities. This study was located in a rural South African setting and used data collected from 2007 to 2010, the period when decentralised ART became available. Approximately one-third of the population were of Mozambican origin. There was a pattern of repeated circular migration between urban areas and this community. Survival analysis models were developed to identify demographic, socioeconomic, and spatial risk factors for HIV mortality. Among the study population of 105,149 individuals, there were 2,890 deaths. The HIV/TB mortality rate decreased by 27% between 2007-2008 and 2009-2010. For other causes of death, the reduction was 10%. Bivariate analysis found that the HIV/TB mortality risk was lower for: those living within 5 km of the Bhubezi Community Health Centre; women; young adults; in-migrants with a longer period of residence; permanent residents; and members of households owning motorised transport, holding higher socioeconomic positions, and with higher levels of education. Multivariate modelling showed, in addition, that those with South Africa as their country of origin had an increased risk of HIV/TB mortality compared to those with Mozambican origins. For males, those of South African origin, and recent in-migrants, the risk of death associated with HIV/TB was significantly greater than that due to other causes. In this community, a combination of factors was associated with an increased risk of dying of HIV/TB over the period of the roll-out of ART. There is evidence for the presence of barriers to successful treatment for particular sub-groups in the population, which must be addressed if the recent improvements in population-level mortality are to be maintained.
    11/2014; 7. DOI:10.3402/gha.v7.24826
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    ABSTRACT: South Africa has a high and rising prevalence of hypertension. Many affected individuals are not using medication, and few have controlled blood pressure. Until recently, primary care clinics focused on maternal and child health and management of acute conditions, but new government initiatives have shifted the focus to chronic diseases, including HIV/AIDS and hypertension.
    Trials 11/2014; 15(1):435. DOI:10.1186/1745-6215-15-435 · 2.12 Impact Factor
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    ABSTRACT: This paper investigates household dissolution and changes in asset wealth (socio-economic position) in a rural South African community containing settled refugees. Survival analysis applied to a longitudinal dataset indicated that the covariates increasing the risk of forced household dissolution were a reduction in socio-economic position (asset wealth), adult deaths and the permanent outmigration of more than 40% of the household. Conversely, the risk of dissolution was reduced by bigger households, state grants and older household heads. Significant spatial clusters of former refugee villages also showed a higher risk of dissolution after 20 years of permanent residence. A discussion of the dynamics of dissolution showed how an outflow/inflow of household assets (socio-economic position) was precipitated by each of the selected covariates. The paper shows how an understanding of the dynamics of forced household dissolution, combined with the use of geo-spatial mapping, can inform inter-disciplinary policy in a rural community.
    Development Southern Africa 11/2014; 31(6). DOI:10.1080/0376835X.2014.951991 · 0.43 Impact Factor
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    ABSTRACT: 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.
    Global Health Action 10/2014; 7:25362. DOI:10.3402/gha.v7.25362 · 1.65 Impact Factor
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    ABSTRACT: The MRC/Wits University Agincourt research centre, part of the INDEPTH Network, has documented mortality in a defined population in the rural northeast of South Africa for 20 years (1992-2011) using long-term health and socio-demographic surveillance. Detail on the unfolding, at times unpredicted, mortality pattern has been published. This experience is reviewed here and updated using more recent data.
    Global Health Action 10/2014; 7:25596. DOI:10.3402/gha.v7.25596 · 1.65 Impact Factor
  • Development Southern Africa 09/2014; DOI:10.1080/0376835X.2014. · 0.43 Impact Factor
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    ABSTRACT: South African civil registration (CR) provides a key data source for local health decision making, and informs the levels and causes of mortality in data-lacking sub-Saharan African countries. We linked mortality data from CR and the Agincourt Health and Socio-demographic Surveillance System (Agincourt HDSS) to examine the quality of rural CR data.
    International Journal of Epidemiology 08/2014; 43(6). DOI:10.1093/ije/dyu156 · 9.20 Impact Factor
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    ABSTRACT: South Africa's epidemiological transition is characterised by an increasing burden of chronic communicable and non-communicable diseases. However, little is known about predictors of health care use (HCU) for the prevention and control of chronic diseases among older adults.
    Global Health Action 08/2014; 7:24771. DOI:10.3402/gha.v7.24771 · 1.65 Impact Factor
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    ABSTRACT: Purpose: Epilepsy, one of the most common neurological disorders globally, affects roughly 70 million individuals. There are few studies that estimate the burden of epilepsy in low income countries, in terms of Disability Adjusted Life Years (DALYs), a summary measure of both morbidity and mortality, used most recently in the 2010 global burden of disease study. Method: Using prevalence, incidence and mortality data on convulsive epilepsy collected within the Agincourt Health and Socio-demographic surveillance site in rural northeastern South Africa between 2008 and 2012, we estimated the DALYs due to convulsive epilepsy, using both prevalence and incidence-based methods for calculating years of life lived with disability (YLD). Results: Using the prevalence-based method, we found that convulsive epilepsy was responsible for 332.1 (95% CI: 215.9–454.8) DALYs in the Agincourt HDSS. This equated to 4.1 DALYs per 1,000 individuals (95% CI: 2.7–5.7). Seventy-four percent of this was due to morbidity while 26% was due to excess mortality. The overall number of DALYs increased by 10% when using the incidence-based method to calculate YLDs. Sensitivity analysis concluded that using Agincourt life expec- tancy values resulted in a 24% reduction in DALYs. Conclusion: This is the first study to report the DALY burden of convul- sive epilepsy in South Africa and the findings are similar to figures reported from rural Kenya and those from the 2010 global burden of dis- ease study. Excess mortality is associated with a significant portion of the burden. Using context-specific life expectancy values (rather than those used in the 2010 global burden of disease study) reduced the burden of epilepsy suggesting that a substantial portion of the burden may be due to context rather than epilepsy. Interventions aimed at increasing treatment coverage and improving the quality of life in people with epilepsy would likely lower the burden of convulsive epilepsy in rural South Africa.
    11th European Congress on Epileptology, Stockholm, Sweden; 06/2014
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    ABSTRACT: The HIV pandemic has led to dramatic increases and inequalities in adult mortality, and the diffusion of antiretroviral treatment, together with demographic and socioeconomic shifts in sub-Saharan Africa, has further changed mortality patterns. We describe all-cause and cause-specific mortality patterns in rural South Africa, analyzing data from the Agincourt health and socio-demographic surveillance system from 1994 to 2009 for those aged 5 years and older. Mortality increased during that period, particularly after 2002 for ages 30-69. HIV/AIDS and TB deaths increased and recently plateaued at high levels in people under age 60. Noncommunicable disease deaths increased among those under 60, and recently also increased among those over 60. There was an inverse gradient between mortality and household SES, particularly for deaths due to HIV/AIDS and TB and noncommunicable diseases. A smaller and less consistent gradient emerged for deaths due to other communicable diseases. Deaths due to injuries remained an important mortality risk for males but did not vary by SES. Rural South Africa continues to have a high burden of HIV/AIDS and TB mortality while deaths from noncommunicable diseases have increased, and both of these cause-categories show social inequalities in mortality.
    PLoS ONE 06/2014; 9(6):e100420. DOI:10.1371/journal.pone.0100420 · 3.53 Impact Factor
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    ABSTRACT: South Africa (SA) is undergoing multiple transitions with an increasing burden of non-communicable diseases and high levels of overweight and obesity in adolescent girls and women. Adolescence is key to addressing trans-generational risk and a window of opportunity to intervene and positively impact on individuals' health trajectories into adulthood. Using Intervention Mapping (IM), this paper describes the development of the Ntshembo intervention, which is intended to improve the health and well-being of adolescent girls in order to limit the inter-generational transfer of risk of metabolic disease, in particular diabetes risk.
    BMC Public Health 06/2014; 14 Suppl 2(Suppl 2). DOI:10.1186/1471-2458-14-S2-S5 · 2.32 Impact Factor
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    ABSTRACT: Our understanding of genome biology, genomics, and disease, and even hu-man history, has advanced tremen-dously with the completion of the Human Genome Project. Technologi-cal advances coupled with significant cost reductions in genomic research have yielded novel insights into disease etiol-ogy, diagnosis, and therapy for some of the world's most intractable and devastat-ing diseases—including ma-laria, HIV/AIDS, tuberculosis, cancer, and diabetes. Yet, de-spite the burden of infectious diseases and, more recently, noncommunicable diseases (NCDs) in Africa, Africans have only par-ticipated minimally in genomics research. Of the thousands of genome-wide association studies (GWASs) that have been conducted globally, only seven (for HIV susceptibility, malaria, tuberculosis, and podoconiosis) have been conducted exclusively on Afri-can participants; four others (for prostate cancer, obsessive compulsive disorder, and anthropometry) included some African participants (www.genome.gov/gwastudies/). As discussed in 2011 (www.h3africa.org), if the dearth of genomics research involving Africans persists, the potential health and economic benefits emanating from genomic science may elude an entire continent. The lack of large-scale genomics studies in Africa is the result of many deep-seated issues, including a shortage of African scien-tists with genomic research expertise, lack of biomedical research infrastructure, lim-ited computational expertise and resources, lack of adequate support for biomedical research by African governments, and the participation of many African scientists in collaborative research at no more than the level of sample collection. Overcoming these limitations will, in part, depend on African Enabling the genomic revolution in Africa By The H3Africa Consortium * H3Africa is developing capacity for health-related genomics research in Africa Yet, roughly a decade ago, newly pro-posed DNA-based taxonomy (11) promised to solve the species debate. A Barcode of Life Data Systems (BOLD) (12) quickly emerged, seeking to provide a reliable, cost-effective solution to the problem of species identification (12) and a standard screening threshold of sequence differ-ence (10× average intraspecific difference) to speed the discovery of new animal spe-cies (13). Sometimes considered a "carica-ture of real taxonomy" (14), this approach failed to identify, perhaps not surprisingly, two American crow species and a number of members of the herring gull Larus ar-gentatus species assemblage above the set threshold (13). Furthermore, despite past (3) and present (6) sequencing projects, carrion crows and hooded crows can also not be differentiated from one another by means of DNA-barcode approaches. By contrast, Poelstra et al. show that much more DNA sequencing data are needed, combined with RNA expression data, to reconstruct the evolution of a reproductive barrier that culminated in the speciation of these two crow taxa. Armed with this new very detailed genetic informa-tion, it is clear that none of the currently formulated species concepts fully apply to these two crow taxa (unless one is willing relax some stringency in the various definitions). In-deed, the genomes of German carrion crows are much more similar to those of hooded crows than to Spanish car-rion crows. Put simply, apart from the few carrion crow type "speciation islands," German carrion crows could be con-sidered to represent hooded crows with a black (carrion crow) phenotype. There is a clear need for ad-ditional population genomic studies using a more dense sampling, especially among the fully black carrion crows, before the complexity of repro-ductive isolation and speciation among these two taxa can be fully understood. The specia-tion genomics strategy already proved itself in unraveling the complexities of mimicry among many Heliconius butterfly taxa (7) and, as in the study of Poelstra et al., stresses the im-portance of using RNA-based information in addition to DNA. Only time will tell if, and when, German carrion crows will adopt the "hooded phenotype," a fate that seems un-avoidable. Until then, we can only applaud these crows for defeating Linnaeus's curse.
    Science 06/2014; 344(6190):1346-1348. · 31.48 Impact Factor
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    ABSTRACT: Youth-friendly health services are a key strategy for improving young people's health. This is the first study investigating provision of the Youth Friendly Services programme in South Africa since the national Department of Health took over its management in 2006. In a rural area of South Africa, we aimed to describe the characteristics of the publicly-funded primary healthcare facilities, investigate the proportion of facilities that provided the Youth Friendly Services programme and examine healthcare workers' perceived barriers to and facilitators of the provision of youth-friendly health services.
    BMC Health Services Research 06/2014; 14(1):259. DOI:10.1186/1472-6963-14-259 · 1.66 Impact Factor
  • African Population Studies 06/2014; 28:590. DOI:10.11564/28-0-517
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    ABSTRACT: In this study we analysed the spatial and temporal changes in patterns of mortality over a period when antiretroviral therapy (ART) was rolled out in a rural region of north-eastern South Africa. Previous studies have identified localised concentrated HIV related sub-epidemics and recommended that micro-level analyses be carried out in order to direct focused interventions.
    Global journal of health science 06/2014; 4(1):010403. DOI:10.7189/jogh.04.010403

Publication Stats

3k Citations
601.41 Total Impact Points

Institutions

  • 2008–2015
    • Umeå University
      • Department of Public Health and Clinical Medicine
      Umeå, Västerbotten, Sweden
  • 2014
    • Ecole des hautes études en santé publique
      Roazhon, Brittany, France
    • University of Toronto
      Toronto, Ontario, Canada
  • 1999–2014
    • University of the Witwatersrand
      • • School of Public Health
      • • Centre for Health Policy (CHP)
      Johannesburg, Gauteng, South Africa
  • 2013
    • INDEPTH
      Madina, Greater Accra, Ghana
    • University of Washington Seattle
      • Department of Sociology
      Seattle, Washington, United States
  • 2004–2012
    • University of Colorado at Boulder
      • Institute of Behavioral Science (IBS)
      Boulder, Colorado, United States
  • 2007
    • Max Planck Institute for Demographic Research
      Rostock, Mecklenburg-Vorpommern, Germany
    • Institut Pasteur
      Lutetia Parisorum, Île-de-France, France
    • The University of Edinburgh
      Edinburgh, Scotland, United Kingdom
  • 2006
    • American University Washington D.C.
      Washington, Washington, D.C., United States
  • 1995
    • Johannesburg Hospital
      Johannesburg, Gauteng, South Africa