Ryan G Wagner

Ryan G Wagner
University of the Witwatersrand | wits · MRC/Wits Rural Public Health and Health Transitions Research Unit

MBBCh; MSc(Med); PhD

About

151
Publications
16,769
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Introduction
Dr Ryan Wagner is an NRF-rated epidemiologist and medical doctor, with training in neuroscience and health economics. Ryan attained a PhD in Medicine, with a Global Health focus in 2016. He has been based within the MRC/Wits Agincourt Research Unit for the past 14 years, 10 of which he lived and worked at the rural Agincourt research site. In his role as a Research Fellow, Ryan leads and supports population-based research focused on epilepsy, cognition and work engaging with traditional healers.
Additional affiliations
December 2011 - June 2016
Umeå University
Position
  • PostDoc Position
May 2011 - July 2015
University of the Witwatersrand
Position
  • Research Fellow & Trials Manager
Education
December 2011 - June 2016
Umeå University
Field of study
  • Medicine
April 2008 - July 2011
University of the Witwatersrand
Field of study
  • Field-based Epidemiology
August 2003 - May 2007
Vanderbilt University
Field of study
  • Neuroscience (major), History (major), Chemistry (minor)

Publications

Publications (151)
Article
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Introduction: Empirical research on the burden and determinants of common mental disorders (CMDs), especially depression and anxiety, among older adults living with HIV (OALWH) in sub-Saharan Africa is inadequate. To bridge the gap in Kenya we: (1) determined the prevalence of CMDs among OALWH on routine HIV care compared to HIV-negative peers; (2...
Article
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Background : Physical and mental health problems are common among older adults living with HIV (OALWH). Adaptive coping strategies play a vital role in improving these adults' mental health and well-being despite the deleterious effects of HIV and ageing. However, in sub-Saharan Africa, limited evidence exists on the commonly utilized coping strate...
Article
Objective: There is a lack of research on experiences of WASH-related violence. This study aims to quantify the association between experience or worry of violence when using the toilet or collecting water and depressive symptoms among a cohort of young women in South Africa. Methods: Data are from visit 3 of the HPTN 068 cohort of adolescent gi...
Article
Background : Epilepsy affects 70 million people worldwide, 80% of whom are in low-and-middle income countries (LMICs). Parasitic infections contribute considerably to the burden of epilepsy in LMICs, but the nature and presentation of epilepsy following these infections is not fully understood. We examined if epilepsy outcomes are associated with t...
Preprint
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Background: The burden and determinants of frailty in sub-Saharan Africa (SSA) are largely unknown despite a rapidly aging population in the region. To address the gap in Kenya, we: a) determined the prevalence of frailty among older adults living with HIV (OALWH) and compared to their uninfected peers; b) investigated HIV status as an independent...
Preprint
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Background Kenya, like many sub-Saharan African countries (SSA), is experiencing a rise in the number of HIV infected adults aged ≥50 years (recognized as older adults living with HIV [OALWH]). This trend has created a subgroup of vulnerable older adults demanding a prompt response in research, policy, and practice to address their complex and tran...
Article
Objective: Global action for epilepsy requires information on the cost of epilepsy, which is currently unknown for most countries and regions of the world. To address this knowledge gap, the International League Against Epilepsy Commission on Epidemiology formed the Global Cost of Epilepsy Task Force. Methods: We completed a systematic search of...
Article
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Human gut microbiome research focuses on populations living in high-income countries and to a lesser extent, non-urban agriculturalist and hunter-gatherer societies. The scarcity of research between these extremes limits our understanding of how the gut microbiota relates to health and disease in the majority of the world’s population. Here, we eva...
Article
Objective In order to more appropriately apply and understand the “epilepsy treatment gap” (ETG) concept in current health systems, revised conceptual and operational definitions of ETG are timely and necessary. This article therefore systematically reviews worldwide studies of the ETG, distinguishing high-, middle-, and low-income regions, and pro...
Article
Background Sub-Saharan Africa is undergoing an epidemiological transition fueled by the interaction between infectious and cardiovascular diseases. Our cross-sectional study aimed to characterize the spectrum of abnormalities suggesting end-organ damage on ECG and transthoracic echocardiograms (TTE) among older adults with cardiovascular diseases i...
Article
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Introduction Pregnancy-related health services, an important mediator of global health priorities, require robust health infrastructure. We described pregnancy-related healthcare utilisation among rural South African women from 1993 to 2018, a period of social, political and economic transition. Methods We included participants enrolled in the Agi...
Article
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Background The relationship between subjective social position (SSP) and cognitive ageing unclear, especially in low-income settings. We aimed to investigate the relationship between SSP and cognitive function over time among older adults in rural South Africa. Methods Data were from 3771 adults aged ≥40 in the population-representative ‘Health an...
Article
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Background Levels of obesity are rising in South Africa, notably among adolescent females. Excessive energy-dense diets and physical inactivity are among the factors contributing to this increase. Given that these factors are largely behavioural, understanding young people’s views of obesity can contribute to more targeted behavioural interventions...
Article
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Objective In this systematic review, we aimed to summarise the empirical evidence on common mental disorders (CMDs), cognitive impairment, frailty and health-related quality of life (HRQoL) among people living with HIV aged ≥50 years (PLWH50 +) residing in sub-Saharan Africa (SSA). Specifically, we document the prevalence and correlates of these ou...
Article
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Background : Epilepsy affects 70 million people worldwide, 80% of whom are in low-and-middle income countries (LMICs). Infections of the central nervous system (CNS) contribute considerably to the burden of epilepsy in LMICs, but the nature and presentation of epilepsy following these infections is not fully understood. We examined if epilepsy fout...
Article
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This study, a secondary analysis of the HPTN 068 randomized control trial, aimed to quantify the association of father and male presence with HIV incidence and first pregnancy among 2533 school-going adolescent girls and young women (AGYW) in rural South Africa participating in the trial between March 2011 and April 2017. Participants’ ages ranged...
Article
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Purpose The PHIRST study (Prospective Household cohort study of Influenza, Respiratory Syncytial virus, and other respiratory pathogens community burden and Transmission dynamics in South Africa) aimed to estimate the community burden of influenza and respiratory syncytial virus (RSV) including the incidence of infection, symptomatic fraction, and...
Article
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Background: Describing contact patterns is crucial to understanding infectious disease transmission dynamics and guiding targeted transmission mitigation interventions. Data on contact patterns in Africa, especially South Africa, are limited. We measured and compared contact patterns in a rural and urban community, South Africa. We assessed partic...
Article
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Background Data on influenza community burden and transmission are important to plan interventions especially in resource-limited settings. However, data are limited, particularly from low-income and middle-income countries. We aimed to evaluate the community burden and transmission of influenza in a rural and an urban setting in South Africa. Met...
Article
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Objectives We investigated concordance between haemoglobin A1c (HbA 1 c)-defined diabetes and fasting plasma glucose (FPG)-defined diabetes in a black South African population with a high prevalence of obesity. Design Cross-sectional study. Setting Rural South African population-based cohort. Participants 765 black individuals aged 40–70 years a...
Article
Objectives: Our study investigates measurement, correlates, and functional associations of vision impairment (VI) in an aging population in rural South Africa. Methods: 1582 participants aged 40–69 reported on near (NVI) and distance vision impairment (DVI) and completed objective vision tests. Logistic and linear regression were used to evaluate s...
Article
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Short, reliable, easily administered executive function (EF) assessment tools are needed to measure EF in low-and middle-income countries, particularly in sub-Saharan Africa given the prevalence of human immunodeficiency virus (HIV)-associated neurocognitive disorder. We administered Oxford Cognitive Screen-Executive Function (OCS-EF) to 932 rural...
Article
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There are estimated two million traditional healers in sub-Saharan Africa (SSA), with more than 10% (200,000) working in South Africa. Traditional healers in SSA are frequently exposed to bloodborne pathogens through the widespread practice of traditional ‘injections’, in which the healers perform dozens of subcutaneous incisions to rub herbs direc...
Article
Introduction: Despite rapid population aging, there are currently limited data on the incidence of aging-related cognitive impairment in sub-Saharan Africa. We aimed to determine the incidence of cognitive impairment and its distribution across key demographic, social, and health-related factors among older adults in rural South Africa. Methods:...
Article
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Background: Improving hypertension control is an important global health priority yet, to our knowledge, there is no direct evidence on the blood pressure (BP)-mortality relationship in sub-Saharan Africa. We investigate the BP-mortality relationship in South Africa and assess the comparative effectiveness of different care targets for clinical ca...
Preprint
Full-text available
Purpose The PHIRST study (Prospective Household cohort study of Influenza, Respiratory Syncytial virus, and other respiratory pathogens community burden and Transmission dynamics in South Africa) aimed to estimate the community burden of influenza and respiratory syncytial virus (RSV) including the incidence of infection, symptomatic fraction, and...
Article
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Introduction Cardiovascular disease (CVD) risk factors are increasing in sub-Saharan Africa. The impact of these risk factors on future CVD outcomes and burden is poorly understood. We examined the magnitude of modifiable risk factors, estimated future CVD risk and compared results between three commonly used 10-year CVD risk factor algorithms and...
Article
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Background: NCDs are non-infectious, long-term conditions that account for 40 million deaths per annum. 87% of premature NCD mortality occurs in low- and middle-income countries. Objective: The aims were:develop methods to provide integrated biosocial accounts of NCD mortality; and explore the practical utility of extended mortality data for the pr...
Article
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We estimated the incidence of cognitive impairment and its key sociodemographic, social, and health-related predictors at the first longitudinal follow-up of the population-representative “Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI) cohort of adults aged ≥40 in rural Agincourt, South Africa. Co...
Article
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Executive function (EF) may predict sexual risk-taking and HIV risk in young women in rural South Africa. We tested associations between EF and seven risky behavioural outcomes: binge drinking, illicit substance use, unprotected vaginal sex, concurrent sexual relationships, transactional sex, herpes simplex virus type 2 (HSV-2) infection, and HIV i...
Article
We aimed to determine the incidence of cognitive impairment and its key sociodemographic, social, and health‐related predictors at the first longitudinal follow‐up of the population‐representative “Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI) cohort in South Africa. Data were from 3,861 adults a...
Article
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Objective Epilepsy is a common, chronic neurological disorder that disproportionately affects individuals living in low‐ and middle‐income countries (LMICs), where the treatment gap remains high and adherence to medication remains low. Community health workers (CHWs) have been shown to be effective at improving adherence to chronic medications, yet...
Article
Background The African continent is undergoing an epidemiologic transition from infectious to cardiovascular (CV) diseases. National health systems face a critical shortage of population-level data to target the growing burden of hypertension (HTN). Very little is known on the impact of HTN on the rural population in many African countries, where o...
Article
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Background Comparisons of traditional hunter-gatherers and pre-agricultural communities in Africa with urban and suburban Western North American and European cohorts have clearly shown that diet, lifestyle and environment are associated with gut microbiome composition. Yet, little is known about the gut microbiome composition of most communities in...
Article
Objective: To understand the risk of HIV acquisition through occupational exposure among rural South African traditional healers, notably via the practice of traditional skin incisions with razors. Design: A random sample of traditional healers living in South Africa participated in a cross-sectional survey that included a rapid HIV test. Setti...
Article
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Previous clinical studies have reported adverse cognitive outcomes for people living with HIV (PLWH), but there are no population-based studies comparing cognitive function between older PLWH and comparators without HIV in sub-Saharan Africa. We analyzed baseline data of 40 + years-old participants in "Health and Aging in Africa: A Longitudinal Stu...
Article
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Despite the growing popularity of multidimensional poverty measurement and analysis, its use to measure the impact of social protection programs remains scarce. Using primary data collected for the evaluation of HIV Prevention Trials Network (HPTN) 068, a randomized, conditional cash transfer intervention for young girls in South Africa that ran fr...
Article
In 2018, nearly 800,000 HIV positive individuals in South Africa were unaware of their status. Traditional healers see patients who avoid health clinics, including those who refuse HIV testing. This manuscript details the results of a qualitative study to understand traditional healer perspectives on performing healer-initiated HIV counseling and t...
Article
Research on early life adversity and later-life cognitive function is conflicting, with little evidence from low-income settings. We investigated associations between adverse childhood experiences and cognitive function in an older population who grew up under racial segregation during South African apartheid. Data were from 1,871 adults aged 40-79...
Article
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Background: Traditional healers are frequently exposed to hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) through the widespread practice of traditional "injections", in which the healer performs dozens of subcutaneous incisions using a razor blade to rub herbs directly into bloodied tissue. An average heal...
Article
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Background Several theories seek to explain how social connections and cognitive function are interconnected in older age. These include that social interaction protects against cognitive decline, that cognitive decline leads to shedding of social connections and that cognitive decline leads to increased instrumental support. We investigated how pa...
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Purpose The percentage of people who are diagnosed with epilepsy (diagnostic gap), access, receive and adhere (treatment gap) to anti-seizure medication (ASM) in low- and middle- income countries remains low. We explored the epilepsy care cascade, measured the diagnostic and treatment gap, and examined socio-demographic factors associated with adhe...
Preprint
Full-text available
While human gut microbiome research often focuses on western populations or nonwestern agriculturalist and hunter-gatherer societies, most of the world’s population resides between these extremes. We present the first study evaluating gut microbiome composition in transitioning South African populations using short- and long-read sequencing. We ana...
Article
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Background: While elevations in fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) are both recognized by the American Diabetes Association (ADA) as diagnostic of hyperglycemia, previous comparisons of these tests have demonstrated discordant individual classifications and population estimates. This may be due to additional postprandi...
Article
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Background HIV testing rates in many hyper-endemic areas are lower than needed to curtail the HIV epidemic. New HIV testing strategies are needed to overcome barriers to traditional clinic based testing; HIV self-testing is one modality that offers promise in reaching individuals who experience barriers to clinic-based testing. Methods We conducte...
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Objectives: Direction and magnitude of gender differences in late-life cognitive function are inextricably tied to sociocultural context. Our study evaluates education and literacy in rural South Africa as primary drivers of gender inequality in late-life cognitive function. Method: Data were collected on 1,938 participants aged 40-79 from Aginc...
Article
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Transactional sex (TS) has been shown to contribute to the HIV epidemic in sub-Saharan Africa. Previous research has yet to identify psychosocial factors that make young women vulnerable to engaging in TS. This analysis examined the association between self-esteem and TS among young women in rural South Africa. A post hoc analysis of post-intervent...
Article
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Introduction Although HIV prevalence is exceptionally high in South Africa, HIV testing rates remain below targeted guidelines. Older adults living with HIV are substantially more likely to remain undiagnosed than younger people. Cognitive function and literacy could play key roles in HIV status knowledge due to the decision‐making processes requir...
Preprint
Full-text available
Background Comparisons of traditional hunter-gatherers and pre-agricultural communities in Africa with urban and suburban Western North American and European cohorts have clearly shown that diet, lifestyle and environment are associated with gut microbiome composition. Yet, little is known about the gut microbiome composition of most African adults...
Article
Full-text available
Objective: In sub-Saharan Africa, transactional sex is associated with an increased risk of HIV infection in adolescent girls and young women, but the mechanisms for this relationship remain unclear. We hypothesise that young women who report transactional sex may have multiple partners and older partners, thereby increasing their HIV risk. Setti...
Article
Purpose: Little is known about temporal patterns of physical intimate partner violence (PIPV) among South African adolescent girls. We sought to identify and describe PIPV risk trajectories and related correlates in this population. Methods: Our analytical cohort came from the HPTN 068 Cash Transfer Trial in Mpumalanga Province, South Africa. Co...
Preprint
Full-text available
Background: Traditional healers are frequently exposed to hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) through the widespread practice of traditional “injections”, in which the healer performs dozens of subcutaneous incisions using a razor blade to rub herbs directly into bloodied tissue. An average heale...
Article
Full-text available
Background: Evidence 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. Methods: We use baseline data from "Health and Aging in Africa: A Longitudinal Study of an INDEPTH...
Article
Full-text available
Rapid population aging in high absolute poverty settings, such as much of South Africa, demands new research on the social context factors that affect cognitive aging in these settings. We investigated the relationships between subjective social position within one’s village and cognitive function and impairment, with the rationale that psychosocia...
Article
The human immunodeficiency virus (HIV) epidemic among adolescent girls and young women (AGYW) in sub-Saharan Africa is a critical public health problem. We assessed whether depressive symptoms in AGYW were longitudinally associated with incident HIV, and identified potential social and behavioral mediators. Data came from a randomized trial of a ca...
Article
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There is increasing interest in home based testing and treatment of HIV to expand access to treatment in sub-Saharan Africa. Such programs rely on self-reported HIV history and use of antiretroviral therapy (ART). However, the accuracy of self-reported ART use in community settings is not well described. In this study, we compared self-reported ART...
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Introduction The rapid ageing of populations around the world is accompanied by increasing prevalence of multimorbidity. This study is one of the first to present the prevalence of multimorbidity that includes HIV in the complex epidemiological setting of South Africa, thus filling a gap in the multimorbidity literature that is dominated by studies...
Article
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Introduction: To maximize impact and minimize costs, antiretroviral pre-exposure prophylaxis (PrEP) interventions should be offered to those at highest risk for HIV infection. The risk score derived from the VOICE trial is one tool currently being utilized to determine eligibility in adolescent PrEP trials in sub-Saharan Africa. This study is aime...
Article
Objectives The HIV treatment cascade is a powerful framework for understanding progress from initial diagnosis to successful treatment. Data sources for cascades vary and often are based on clinical cohorts, population cohorts linked to clinics, or self-reported information. We use both biomarkers and self-reported data from a large population-base...