Stephen M Tollman

Umeå University, Umeå, Västerbotten, Sweden

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Publications (130)490.02 Total impact

  • Development Southern Africa 09/2014; · 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;
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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: 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. · 1.77 Impact Factor
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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.
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    ABSTRACT: Health and Demographic Surveillance Systems (HDSS) have been instrumental in advancing population and health research in low- and middle- income countries where vital registration systems are often weak. However, the utility of HDSS would be enhanced if their databases could be linked with those of local health facilities. We assess the feasibility of record linkage in rural South Africa using data from the Agincourt HDSS and a local health facility.
    BMC Medical Research Methodology 05/2014; 14(1):71. · 2.21 Impact Factor
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    ABSTRACT: South Africa is experiencing a health and social transition including an ageing population and an HIV epidemic. We report mortality experience of an older rural South African population.
    International journal of epidemiology. 05/2014;
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    ABSTRACT: The Study on global AGEing and adult health (SAGE) aims at improving empirical understanding of the health and well-being of older adults in low- and middle-income countries. A total of 321 adults aged 50 years and older were interviewed in rural Pune district, India, in 2007. We used Structural Equation Modelling (SEM) to examine the pathways through which social factors, functional disability, risk behaviours, and chronic disease experience influence self-rated health (SRH) and quality of life (QOL) amongst older adults in India. Both SRH and QOL worsened with increased age (indirect effect) and limitations in functional ability (direct effect). QOL, socio-economic status (SES), and social networking had no significant effect on SRH. Smoking was associated with the presence of at least one chronic illness, but this did not have a statistically significant effect on SRH. Higher social networking was seen amongst the better educated and those with regular income, which in turn positively affected the QOL rating. QOL had a direct, but statistically not significant, effect on SRH. In conclusion, the indirect effects of age on SRH mediated through functional ability, and the effects of SES on QOL mediated through social networking, provide new understanding of how age and socio-economic status affect SRH and QOL. By allowing for measurement errors, solving for collinearity in predictor variables by integrating them into measurement models, and specifying causal dependencies between the underlying latent constructs, SEM provides a strong link between theory and empirics.
    Social Indicators Research 05/2014; · 1.26 Impact Factor
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    ABSTRACT: To determine whether training community health workers (CHWs) about hypertension in order to improve adherence to medications is a cost-effective intervention among community members in South Africa. We used an established Markov model with age-varying probabilities of cardiovascular disease (CVD) events to assess the benefits and costs of using CHW home visits to increase hypertension adherence for individuals with hypertension and aged 25-74 in South Africa. Subjects considered for CHW intervention were those with a previous diagnosis of hypertension and on medications but who had not achieved control of their blood pressure. We report our results in incremental cost-effectiveness ratios (ICERs) in US dollars per disability-adjusted life-year (DALY) averted. The annual cost of the CHW intervention is about $8 per patient. This would lead to over a 2% reduction in CVD events over a life-time and decrease DALY burden. Due to reductions in non-fatal CVD events, lifetime costs are only $6.56 per patient. The CHW intervention leads to an incremental cost-effectiveness ratio of $320/DALY averted. At an annual cost of $6.50 or if the blood pressure reduction is 5 mmHg or greater per patient the intervention is cost-saving. Additional training for CHWs on hypertension management could be a cost-effective strategy for CVD in South Africa and a very good purchase according to World Health Organization (WHO) standards. The intervention could also lead to reduced visits at the health centres freeing up more time for new patients or reducing the burden of an overworked staff at many facilities.
    BMC Public Health 03/2014; 14(1):240. · 2.08 Impact Factor
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    ABSTRACT: To examine the feasibility of providing young adults with mobile phones for the purpose of mobile phone-assisted self-interviewing to improve retention in a long-term birth cohort study, mobile phones with survey software were distributed to 1,000 twenty-year-olds in the Birth to Twenty birth cohort study. Eleven months later, a targeted sampling frame was used to randomly select 435 participants from the subset of 734 phones that were still functional as survey tools. Text message notifications were dispatched at two time points, 2 weeks apart, requesting the completion of a 60-item survey. From the 435 young adults invited to participate in the survey, 105 (36.5%) submitted data in response to the first request and 84 (30.9%) submitted data in response to the second. The overall survey response rate was 33.7%, and item response rate varied from 88.5% to 100%. Contributing to the low response rate were challenges faced by both participant, including device loss and overly complicated survey procedures, and research team such as the deletion of the survey app by participants and the swapping out of study phone subscriber identity module cards making device management difficult. Reducing the effort required by participants to complete a survey, improving participant engagement in the data collection process, and using participants own handset are all suggestions for improving mobile survey data quality and responses rates.
    Social Science Computer Review 02/2014; 32(1):105-112. · 1.30 Impact Factor
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    ABSTRACT: Physical inactivity is increasing among children and adolescents and may be contributing to the increasing prevalence of overweight and obesity. This study examines physical activity and sedentary behavior patterns, and explores associations with individual, maternal, household, and community factors amongst rural South African adolescents. In 2009, 381 subjects, stratified by ages 11-12-years and 14-15-years, were randomly selected from 3511 children and adolescents who had participated in a growth survey two years previously. Weight and height were measured and self-reported Tanner pubertal stage was collected. A questionnaire quantifying frequency and duration of physical activity (PA) domains and sedentary time for the previous 12 months was administered. Moderate-vigorous physical activity (MVPA mins/wk) was calculated for time spent in school and club sport. Socio-demographic and other related data were included from the Agincourt health and socio-demographic system (HDSS). The Agincourt HDSS was established in 1992 and collects prospective data on the community living in the Agincourt sub-district of Mpumalanga Province in rural north-east South Africa. Puberty, maternal education and socio-economic status (SES) contributed significantly to the mulitiple linear regression model for sedentary behavior (R2 = 0.199; adjusted R2 = 0.139; p < 0.000), and sex, SES and maternal education contributed to the tobit regression model for school and club sport MVPA (p < 0.000). MVPA, calculated from school and club sport, was higher in boys than girls (p < 0.001), and informal activity was lower (boys: p < 0.05 and girls: p < 0.01) while sedentary time was higher (girls: p < 0.01) in the older than the younger groups. Ninety-two percent (92%) of the sample reported walking for transport. In this study of rural South African adolescent boys and girls, SES at the maternal, household and community level independently predicted time spent in sedentary behaviors, and school and club MVPA. This study provides local data that can be used to develop health promotion strategies specific to this community, and other similar communities in developing countries.
    BMC Public Health 01/2014; 14(1):40. · 2.08 Impact Factor
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    ABSTRACT: Rationale Epilepsy is among the most common neurological disorders worldwide. However, there are no large, population-based studies of the prevalence and risk factors for epilepsy in southern Africa. Methods From August 2008 to February 2009, as part of a multi-site study, we undertook a three-stage, population-based study, embedded within the Agincourt health and socio-demographic surveillance system, to estimate the prevalence and identify risk factors of active convulsive epilepsy (ACE) in a rural South African population. Results The crude prevalence of ACE, after adjusting for non-response and the sensitivity of the screening method, was 7.0/1,000 individuals (95%CI 6.4-7.6) with significant geographic heterogeneity across the study area. Being male (OR = 2.3; 95%CI 1.6- 3.2), family history of seizures (OR= 4.0; 95%CI 2.0-8.1), a sibling with seizures (OR = 7.0; 95%CI 1.6-31.7), problems after delivery (OR= 5.9; 95%CI 1.2-24.6), and history of snoring (OR = 6.5; 95%CI 4.5-9.5) were significantly associated with ACE. For children, their mother's exposure to some formal schooling was protective (OR = 0.30; 95%CI 0.11-0.84) after controlling for age and sex. Human immunodeficiency virus was not found to be associated with ACE. Conclusions ACE is less frequent in this part of rural South Africa than other parts of sub-Saharan Africa. Improving obstetric services could prevent epilepsy. The relationship between snoring and ACE requires further investigation, as does the relative contribution of genetic and environmental factors to examine the increased risk in those with a family history of epilepsy.
    Epilepsy research 01/2014; · 2.48 Impact Factor
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    ABSTRACT: Background: Nearly one in three South Africans will suffer from a mental disorder in his or her lifetime, a higher prevalence than many low- and middle-income countries. Understanding the economic costs and consequences of prevention and packages of care is essential, particularly as South Africa considers scaling-up mental health services and works towards universal health coverage. Economic evaluations can inform how priorities are set in system or spending changes. Objective: To identify and review research from South Africa and sub-Saharan Africa on the direct and indirect costs of mental, neurological, and substance use (MNS) disorders and the cost-effectiveness of treatment interventions. Design: Narrative overview methodology. Results and conclusions: Reviewed studies indicate that integrating mental health care into existing health systems may be the most effective and cost-efficient approach to increase access to mental health services in South Africa. Integration would also direct treatment, prevention, and screening to people with HIV and other chronic health conditions who are at high risk for mental disorders. We identify four major knowledge gaps: 1) accurate and thorough assessment of the health burdens of MNS disorders, 2) design and assessment of interventions that integrate mental health screening and treatment into existing health systems, 3) information on the use and costs of traditional medicines, and 4) cost-effectiveness evaluation of a range of specific interventions or packages of interventions that are tailored to the national context.
    Global Health Action 01/2014; 7:23431. · 2.06 Impact Factor
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    ABSTRACT: Background: Migration and urbanization are central to sustainable development and health, but data on temporal trends in defined populations are scarce. Healthy men and women migrate because opportunities for employment and betterment are not equally distributed geographically. The disruption can result in unhealthy exposures and environments and income returns for the origin household. Objectives: The objectives of the paper are to describe the patterns, levels, and trends of temporary migration in rural northeast South Africa; the mortality trends by cause category over the period 2000-2011; and the associations between temporary migration and mortality by broad cause of death categories. Method: Longitudinal, Agincourt Health and Demographic Surveillance System data are used in a continuous, survival time, competing-risk model. Findings: In rural, northeast South Africa, temporary migration, which involves migrants relocating mainly for work purposes and remaining linked to the rural household, is more important than age and sex in explaining variations in mortality, whatever the cause. In this setting, the changing relationship between temporary migration and communicable disease mortality is primarily affected by reduced exposure of the migrant to unhealthy conditions. The study suggests that the changing relationship between temporary migration and non-communicable disease mortality is mainly affected by increased livelihood benefits of longer duration migration. Conclusion: Since temporary migration is not associated with communicable diseases only, public health policies should account for population mobility whatever the targeted health risk. There is a need to strengthen the rural health care system, because migrants tend to return to the rural households when they need health care.
    Global Health Action 01/2014; 7:23514. · 2.06 Impact Factor
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    ABSTRACT: Computer-coded verbal autopsy (CCVA) methods to assign causes of death (CODs) for medically unattended deaths have been proposed as an alternative to physician-certified verbal autopsy (PCVA). We conducted a systematic review of 19 published comparison studies (from 684 evaluated), most of which used hospital-based deaths as the reference standard. We assessed the performance of PCVA and five CCVA methods: Random Forest, Tariff, InterVA, King-Lu, and Simplified Symptom Pattern. The reviewed studies assessed methods' performance through various metrics: sensitivity, specificity, and chance-corrected concordance for coding individual deaths, and cause-specific mortality fraction (CSMF) error and CSMF accuracy at the population level. These results were summarized into means, medians, and ranges. The 19 studies ranged from 200 to 50,000 deaths per study (total over 116,000 deaths). Sensitivity of PCVA versus hospital-assigned COD varied widely by cause, but showed consistently high specificity. PCVA and CCVA methods had an overall chance-corrected concordance of about 50% or lower, across all ages and CODs. At the population level, the relative CSMF error between PCVA and hospital-based deaths indicated good performance for most CODs. Random Forest had the best CSMF accuracy performance, followed closely by PCVA and the other CCVA methods, but with lower values for InterVA-3. There is no single best-performing coding method for verbal autopsies across various studies and metrics. There is little current justification for CCVA to replace PCVA, particularly as physician diagnosis remains the worldwide standard for clinical diagnosis on live patients. Further assessments and large accessible datasets on which to train and test combinations of methods are required, particularly for rural deaths without medical attention.
    BMC Medicine 01/2014; 12(1):22. · 6.68 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 01/2014; 14 Suppl 2. · 2.08 Impact Factor
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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 01/2014; 9(6):e100420. · 3.73 Impact Factor
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    ABSTRACT: 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. 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. 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%). 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 CODs.
    BMC Medicine 01/2014; 12(1):20. · 6.68 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 01/2014; 7:24771. · 2.06 Impact Factor
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    ABSTRACT: We investigate the sex-age-specific changes in the mortality of a prospectively monitored rural population in South Africa. We quantify changes in the age pattern of mortality in a parsimonious way by estimating the eight parameters of the Heligman-Pollard (HP) model of age-specific mortality. In its traditional form this model is difficult to fit and does not account for uncertainty. 1. To quantify changes in the sex-age pattern of mortality experienced by a population with endemic HIV. 2. To develop and demonstrate a robust Bayesian estimation method for the HP model that accounts for uncertainty. Bayesian estimation methods are adapted to work with the HP model. Temporal changes in parameter values are related to changes in HIV prevalence. Over the period when the HIV epidemic in South Africa was growing, mortality in the population described by our data increased profoundly with losses of life expectancy of ~15 years for both males and females. The temporal changes in the HP parameters reflect in a parsimonious way the changes in the age pattern of mortality. We develop a robust Bayesian method to estimate the eight parameters of the HP model and thoroughly demonstrate it. Changes in mortality in South Africa over the past fifteen years have been profound. The HP model can be fit well using Bayesian methods, and the results can be useful in developing a parsimonious description of changes in the age pattern of mortality. The motivating aim of this work is to develop new methods that can be useful in applying the HP eight-parameter model of age-specific mortality. We have done this and chosen an interesting application to demonstrate the new methods.
    Demographic Research 12/2013; 29:1039-1096. · 1.20 Impact Factor

Publication Stats

2k Citations
490.02 Total Impact Points

Institutions

  • 2010–2014
    • Umeå University
      • Department of Public Health and Clinical Medicine
      Umeå, Västerbotten, Sweden
    • University of Colorado at Boulder
      • Institute of Behavioral Science (IBS)
      Boulder, CO, United States
  • 1999–2014
    • University of the Witwatersrand
      • School of Public Health
      Johannesburg, Gauteng, South Africa
  • 2007–2013
    • University of Washington Seattle
      • • Department of Global Health
      • • Department of Sociology
      Seattle, WA, United States
    • Makerere University
      Kampala, Central Region, Uganda
    • 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
    • University of St Andrews
      • School of Geography and Geosciences
      Saint Andrews, SCT, United Kingdom
  • 1995
    • Johannesburg Hospital
      Johannesburg, Gauteng, South Africa