About

Sydney Rosen, M.P.A., is a Research Professor in the Department of Global Health at the Boston University School of Public Health. She is also a Co-Director of the Health Economics and Epidemiology Research Office (HE2RO) of the University of the Witwatersrand in Johannesburg, South Africa. Her research addresses the economic consequences of the HIV/AIDS epidemic, focusing on the outcomes, costs, cost-effectiveness, and benefits of HIV and TB care and treatment interventions and models of service delivery. She is the principal investigator of multiple studies supported by USAID, NIH, and foundations, and has extensive work experience in South Africa, Zambia, Malawi, and Kenya. Her technical training is in policy analysis and applied economics, and she holds a BA magna cum laude from Harvard University and an MPA from the Kennedy School of Government at Harvard.

Research topics

• Medicine
• Family medicine
• Internal medicine
• Pediatrics
• Physical therapy
• Virology
• Environmental health
• Nursing
• Marketing
• Medical physics
• Business
• Geography
• Psychology
• Surgery

Selected publications

• BRIDGE: Behavioral Risk Identification and Decision Guidance for Engagement

  Open MIND · 2026-01-01 · 1 citations

  articleOpen access1st authorCorresponding

  Protocol and SPIRIT checklist for the BRIDGE study; preprint of protocol paper can be found at https://verixiv.org/articles/3-133/v1.

  PublisherDOI

• Triaging Clients at Risk of Disengagement from HIV Care: Application of a Predictive Model to Clinical Trial Data in South Africa

  Risk Management and Healthcare Policy · 2025-05-01 · 5 citations

  articleOpen accessSenior author

  Purpose: To reach South Africa's targets for HIV treatment and viral suppression, retention on antiretroviral therapy (ART) must increase. Here, we aim to successfully identify ART clients at risk of loss from care prior to disengagement. Patients and Methods: We applied a previously developed machine learning and predictive modelling algorithm (PREDICT) to ART client data from SLATE I and II trials. The primary outcome was interruption in treatment (IIT), defined as missing the next scheduled clinic visit by >28 days. We tested two risk triaging approaches: 1) threshold approach classifying individuals into low, moderate, or high risk of IIT; and 2) archetype approach identifying subgroups with characteristics associated with risk of ITT. We report associations between risk category groups and subsequent IIT at the next scheduled visit using crude risk differences and relative risks with 95% confidence intervals. Results: SLATE datasets included 7199 client visits for 1193 clients over ≤14 months of follow-up. The threshold approach consistently and accurately assigned levels of IIT risk for multiple stages of the care cascade. The archetype approach identified several subgroups at increased risk of IIT, including those late to previous appointments, returning after a period of disengagement, living alone or without a treatment supporter. Behavioural elements of the archetypes tended to drive the risk of treatment interruption more consistently than demographics; eg adolescent boys/young men who attended visits on time experienced the lowest rates of treatment interruption (10% PREDICT datasets; 7% SLATE datasets), while adolescent boys/young men returning after previously disengaging had the highest rates of subsequent treatment interruption (31% PREDICT datasets; 40% SLATE datasets). Conclusion: Routinely collected medical record data can be combined with basic demographic and socioeconomic data to assess individual risk of future treatment disengagement. This approach offers an opportunity to prevent disengagement from HIV care, rather than responding only after it has occurred. Trial Registration: SLATE I trial: Clinicaltrials.gov NCT02891135, registered September 1, 2016. First participant enrolled March 6, 2017, in South Africa and July 13, 2017, in Kenya. SLATE II trial: Clinicaltrials.gov NCT03315013, registered 19 October 2017. First participant enrolled 14 March 2018.

  PublisherOA PDFDOI

• Gaps in the Type 1 Diabetes Mellitus care cascade: a national perspective using South Africa’s National Health Laboratory Service (NHLS) database

  medRxiv · 2025-09-28

  preprintOpen access

  Objective: Type 1 diabetes mellitus (T1DM) requires lifelong management, yet access to insulin, specialized care, and education is limited in low- and middle-income countries (LMICs). While cascade-of-care analyses are well documented for type 2 diabetes (T2DM), to our knowledge no population-level estimates of the T1DM care cascade exist from LMICs. We therefore evaluated the T1DM care cascade nationally in South Africa and compared outcomes between youth living with HIV (YLWH) and youth living without HIV (YLWOH). Research Design and Methods: We analyzed South Africa's National Health Laboratory Service (NHLS) data for patients <20 years with a first glycated hemoglobin A1c (HbA1c) or plasma glucose [fasting (FPG), random (RPG)] between April 2004 and March 2015. Laboratory-diagnosed T1DM was defined as HbA1c ≥6.5%, FPG ≥7.0 mmol/L, or RPG ≥11.1 mmol/L. Cascade stages over 24 months were remaining in care and achieving glycemic control (HbA1c <7.0%, FPG <8.0 mmol/L, or RPG <10.0 mmol/L). Results: Of 256,449 youth tested for diabetes, 12.1% met criteria for laboratory-diagnosed T1DM. Among these, 15.9% remained in care and 7.2% achieved glycemic control by 24 months. Retention was similar between YLWH and YLWOH (16.8% vs. 15.8%), but glycemic control was higher among YLWH (72.5% vs. 43.4%). Conclusions: Four of five South African youth with T1DM lacked consistent care, and fewer than 10% achieved glycemic control within two years. Higher control rates among YLWH suggest lessons from HIV care models may strengthen T1DM services. These findings provide the first national estimates of the T1DM care cascade from sub-Saharan Africa and highlight the urgent need for targeted strategies to improve outcomes.

  PublisherOA PDFDOI

• Client preferences for service delivery during the early treatment period in South Africa and Zambia: Mixed-method findings from a discrete choice experiment and concurrent focus group discussions

  medRxiv · 2025-07-29

  preprintOpen access

  Background: Disengagement from antiretroviral therapy (ART) is common in the first 6 months of HIV treatment in sub-Saharan Africa. Using mixed-methods we aimed to understand preferences during this early treatment period. Methods: Between 8/2023-11/2023, adults who had initiated/re-initiated ART a median of 8 months prior were enrolled at 18 healthcare facilities across South Africa (SA) and Zambia to participate in a discrete choice experiment (DCE) and focus group discussion (FGD). In the DCE, participants made 9 choices between unique service delivery scenarios (each comprised of 8 attributes). Analyzed using a conditional logit model, we report findings using odds ratios (95% confidence intervals). Following the DCE, FGDs explored barriers to care seeking and care preferences. Thematic analysis was used to interpret FGDs. DCE and FGD findings were triangulated to understand preferences. Results: We enrolled 250 respondents: 128 in Zambia (55% female, median age 35); 122 in SA (83% female, median age 33). Community-based services were less favorable to respondents than clinic-based care (SA: 0.62 (95% CI 0.52, 0.75); Zambia: 0.44 (0.36, 0.53)). Respondents preferred 6-month dispensing (SA: 1.3 (1.1, 1.6); Zambia: 2.1 (1.8, 2.6)) to 1-month intervals. Respondents also preferred accessing services from friendly providers. Qualitative insights corroborated DCE findings. They also revealed frustrations with long wait times at clinics. Conclusion: Utilizing a decision experiment with qualitative methods allowed us to uniquely capture drivers of client decision-making and the nuanced factors that shape experiences. Results suggest that enrollment in lower-intensity models may improve client experiences during the early treatment period.

  PublisherOA PDFDOI

• Self-reported stigma and other challenges to HIV treatment adherence for clients in their first 6 months after treatment initiation in Zambia

  medRxiv · 2025-08-21

  preprintOpen accessSenior author

  Abstract Background The first six months after initiating or re-initiating antiretroviral therapy (ART) for HIV is the highest risk period for disengagement from care. Little qualitative research has explored ART clients’ experiences in this period in the era of universal ART eligibility. We aimed to understand clients’ challenges in the early treatment period in order to identify potential interventions that could both meet ART clients’ needs and optimize efficiency in this time of declining resources. Methods We surveyed adults who were initiating or had recently initiated (&lt;6 months) ART at 12 healthcare facilities in two provinces of Zambia. A subset of survey respondents who had experienced or anticipated experiencing adherence challenges were recruited to participate in focus group discussions (FGDs) up to 12 months after the survey. FGDs included up to 10 participants each and were led by facilitators trained in qualitative methods. Results Fifteen FGDs were conducted (n=126 participants, median age 35). Themes emerged at the individual, interpersonal, facility, and community levels. Stigma related to HIV was the most common theme at all levels. Participants expressed self-stigma, fear of disclosure to family and acquaintances, concerns about what would happen to romantic relationships if their partner learned of their status, and fear of community gossip. Food insecurity was common. Clinic congestion, lack of privacy, and unsympathetic providers emerged as facility-level barriers. Participants mentioned lack of transport money and work conflicts as other impediments. Religious leaders and reliance on traditional healers discouraged ongoing engagement in care. Discussion Zambian ART clients faced multifaceted barriers to remaining in care during the critical first few months, with particular concern about the insidious roles of stigma influencing their behavior. While societal stigma remains stubbornly difficult to offset, clients’ early clinic experiences—often marked by unwelcome disclosure, facility inefficiency that is perceived as disrespect, and negative provider interactions—and financial and logistical challenges may be amenable to improvement by adapting existing evidence-based interventions.

  PublisherOA PDFDOI

• Evaluating the impact of differentiated service delivery (DSD) on retention in care and HIV viral suppression in South Africa: A target trial emulation using routine healthcare data

  PLoS Medicine · 2025-08-26 · 2 citations

  articleOpen accessCorresponding

  BACKGROUND: Replacing conventional, facility-based HIV treatment with less intensive differentiated service delivery (DSD) models could benefit DSD clients and the health system, but its value depends on maintaining or improving clinical outcomes. We compared retention and viral suppression between antiretroviral therapy (ART) clients enrolled in DSD models to those eligible for but not enrolled in DSD models in South Africa. METHODS AND FINDINGS: We applied a target trial emulation (TTE) methodology to data from South Africa's electronic medical record system (TIER.Net) for 24 public-sector health facilities across three provinces and estimated retention in care (attended facility visit within 12 months) and viral suppression (<400 copies/ml3) at 12, 24, and 36 months after follow-up start date, defined as DSD enrollment date for the intervention arm and the first trial enrollment period facility visit for the comparison arm. Clients were eligible for DSD models if they were ≥18 years old, on ART ≥12 months, and had two suppressed viral load (VL) measurements, per prevailing national guidelines. For the TTE, we designated eight 6-month target trial enrollment periods between 1 July 2017 and 1 July 2021. For each period, we estimated the risk differences for retention in care and viral suppression by comparing those enrolled in DSD models to those not enrolled, using a Poisson distribution with an identity link function. We report adjusted and unadjusted risk differences for clients enrolled in DSD models and for DSD-eligible clients not enrolled in a DSD model. Estimates were adjusted for age, sex, urban/rural facility setting, province, WHO stage at ART initiation, and years on ART at trial enrollment. 49,595 unique individuals were eligible for DSD enrollment over eight target trials, contributing to a total of 148,943 trial-clients, of whom 17% (25,775) were enrolled in DSD models. The pooled adjusted risk difference for retention in care between clients enrolled in DSD and those not enrolled in DSD was 3.2% (95% confidence interval (CI) [1.6%,4.7%]) at 12 months, 4.2% (95% CI [2.4%,6.0%]) at 24 months, and 4.4% (95% CI [2.0%,6.8%]) at 36 months. For viral suppression, the adjusted risk difference comparing DSD to non-DSD was estimated to be 1.4% (95% CI [-0.5%,3.2%]) at 12 months, 1.7% (95% CI [-0.5%,4.0%]) at 24 months, and 1.4% (95% CI [-0.6%,4.4%]) at 36 months. Results remained consistent across target trials. Clients who were younger, received care from a facility in an urban settings, or had less ART experience at trial enrollment had lower retention. Study limitations include reliance on routinely collected medical records and the likely presence of residual confounding. CONCLUSIONS: Clients enrolled in DSD models in South Africa had slightly better retention in care and similar viral suppression to those who were eligible for but not enrolled in DSD. With better or equivalent outcomes, DSD models can be assessed on the basis of non-clinic costs and benefits, such as changes in quality of care and resource utilization. TRIAL REGISTRATION: Clinicaltrials.gov NCT04149782.

  PublisherOA PDFDOI

• Prior antiretroviral therapy exposure among clients presenting for HIV treatment initiation in South Africa: an exploratory mixed-methods study using multiple indicators of exposure

  BMC Infectious Diseases · 2025-07-26 · 1 citations

  articleOpen accessSenior author

  BACKGROUND: The era of universal treatment for HIV has seen high rates of disengagement from antiretroviral therapy (ART) programs and re-engagement after interruptions, with modeled estimates of non-naïve initiators > 50% in many places. Most re-engagers are reluctant to admit prior antiretroviral exposure, and non-self-reported data on proportions reinitiating are scarce. We conducted a sequential, mixed-methods study to explore the proportion of people who present for initiation with evidence of prior ART use and understand why many are reluctant to admit prior exposure in South Africa. METHODS: We enrolled a sequential sample of adults presenting to initiate ART or re-initiate ART after an interruption > 3 months and collected (1) self-reported previous treatment experience; (2) electronic medical record (EMR) evidence of prior ART clinic visits; (3) baseline blood tests for metabolites of tenofovir diphosphate; and (4) laboratory records indicating prior ART-related tests. Interviews were conducted with clients who self-reported no prior ART use but had evidence of metabolites. RESULTS: Among 89 enrolled participants (median age 32.5, 62% female), 21 (24%) self-reported previously taking ART > 3 months prior to enrolment. An additional 19 (21%) who did not self-report prior exposure had EMR or laboratory evidence of prior ART use, for a total of 40 (45%) clients with known prior treatment exposure at initiation. Sensitivity of self-report was 40% (95% CI: 25-57%), EMR 43% (27-59%), metabolite testing 45% (29-62%), and laboratory records 73% (56-87%). Interviewees (n = 11) reported opting to present as naïve because they perceived that disclosure of prior disengagement would cause delays accessing treatment, require additional documentation, and elicit negative responses from healthcare workers. Study limitations included short duration of metabolite detectability, inability to link individuals within the EMR to discern ART experience at other facilities, and lack of baseline viral load testing. CONCLUSIONS: At least 45% of clients initiating ART in South Africa have prior treatment experience, but only a third of re-initiators voluntarily reveal this. Laboratory records yielded the most accurate results for ascertaining prior treatment exposure. As numbers re-engaging in HIV care after a treatment interruption increase, understanding reluctance to self-report ART experience and exploring opportunities to overcome barriers are critical for preventing repeated interruptions. REGISTRATION: The protocol was registered on July 12, 2022 on clinicaltrials.gov (NCT05454839).

  PublisherOA PDFDOI

• Advanced HIV disease during the first six months on antiretroviral therapy in Zambia: research protocol for a prospective, observational, multi-cohort study

  Gates Open Research · 2025-08-27

  preprintOpen accessSenior authorCorresponding

  Background: The proportion of HIV-positive individuals who present for initiation or re-initiation of antiretroviral therapy (ART) with advanced HIV disease (AHD) and are at risk for morbidity and mortality remains high throughout sub-Saharan Africa. In Zambia, where 20% of ART initiators are diagnosed with AHD, little is known about the characteristics of those starting ART with AHD, why treatment initiation is delayed, how AHD clinical management influences clinical and non-clinical outcomes, or implementation of national AHD guidelines at facility level. Protocol: AHD-Zambia is a mixed-methods observational study to describe AHD clients and care during the first six months after starting or re-starting ART in Zambia. The study will be conducted at 24 public sector primary health facilities in four provinces. It will enroll ART clients screened for AHD during a three-month data collection period (Cohort 1), clients screened for AHD in the 12 months prior to the data collection period (Cohort 2), patients hospitalized for AHD-related conditions (Cohort 3); and clinical providers at the study sites who manage clients with AHD (Cohort 4). Data collection will include quantitative surveys, medical record review during the 12 months before and after enrollment, qualitative interviews, and focus group discussions. Facility-level indicators will also be collected. Outcomes will include detailed profiles of AHD clients and their 6 and 12-month retention in care and viral suppression, provider and client views on barriers to and preferences for AHD care, and assessment of facility fidelity to AHD guidelines. Discussion: This study will generate a comprehensive profile of clients presenting with AHD in Zambia, including clinical, demographic, social, and behavioral characteristics, treatment outcomes, and barriers to providing guideline-compliant care. Findings will provide insight into the delivery of AHD services, identify gaps in implementation, and support improvements to retention and care during the early treatment period. Registration: Clinicaltrials.gov NCT06904456.

  PublisherOA PDFDOI

• Integrated multi‐month dispensing for HIV and hypertension in South Africa: A model of epidemiological impact and cost‐effectiveness

  Journal of the International AIDS Society · 2025-02-01 · 5 citations

  articleOpen access

  INTRODUCTION: In the current era of universal antiretroviral treatment (ART), health systems have the dual challenge of a growing number of people living with HIV and on ART who are also receiving chronic, life-long treatment for non-communicable diseases. Current evidence suggests that 6-month multi-month dispensing (6MMD) can maintain at least equivalent clinical outcomes to conventional care and reduce costs, but little is known when integrating 6MMD for multiple conditions. We examined the cost-effectiveness of integrated multi-month drug dispensing for people living with HIV and hypertension. METHODS: Using an age- and sex-specific hybrid decision tree and Markov state-transition model, we constructed a 100,000-person simulated population cohort who may develop HIV and hypertension and initiate treatment at clinics in South Africa over a 10-year time horizon. We assessed the incremental costs and effectiveness of 6MMD versus conventional care from a health system perspective under different conditions of care-seeking, eligibility and uptake of 6MMD for clinically stable patients. Model inputs were sourced from previously published literature. 6MMD was defined as reducing the frequency of clinic visits by increasing the number of medications dispensed to stable patients at each visit from 3 to 6 months. For the integrated 6MMD, we assumed that comorbid patients receive both HIV and hypertension drugs at the same facility on the same day. RESULTS: Our study demonstrates that integrated 6MMD for HIV and hypertension in South Africa can avert between 0.8 and 1 DALYs and increase health systems costs between $24 and $49 per patient per year, compared to the status quo. One-way sensitivity analysis showed that HTN drug cost and prevalence of HIVHTN and HIV were key drivers in the cost per DALYs averted. Overall, integrated 6MMD with a greater proportion of well-controlled patients and lower mortality rates led to greater cost savings or better cost-effectiveness (less than $50 per DALY averted) across a wide range of loss-to-follow-up (LTFU) factor variation. CONCLUSIONS: By better controlling disease among patients already in care, integrated 6MMD can be more beneficial than the status quo treatment by resulting in fewer cases of LTFU and fewer deaths through high-quality care.

  PublisherOA PDFDOI

• Patterns of engagement in care during clients’ first 12 months after HIV treatment initiation in Zambia: a retrospective cohort analysis using routinely collected data

  BMJ Global Health · 2025-08-01 · 3 citations

  articleOpen accessSenior author

  BACKGROUND: The first year after HIV treatment initiation or re-initiation is the period of highest risk of a treatment interruption or disengagement, yet little is known about the timing, patterns and effects of interruptions in the early treatment period. METHODS: Using routinely collected electronic medical record data from 543 Zambian facilities from 2018 to 2023, we described patterns of engagement during the first year of HIV treatment. We defined engagement patterns for months 0-6 and months 7-12 after initiation or reinitiation as (1) continuous (attended all scheduled clinic and medication pickup visits as planned; (2) cyclical (attended ≥1 visits late >28 days but returned to and remained in care) or (3) disengaged (missed a scheduled visit by >28 days and had no evidence of return). RESULTS: Our sample population comprised 159 429 adult participants (61% female, median age 33). Of the 513 322 interactions observed ≤12 months after initiation, 53% occurred as planned, 22% were late ≤28 days late, 9% were >28 days late, and 17% were scheduled but never attended. In 0-6 months after initiation, 51% clients were continuously engaged, 12% cyclically engaged and 33% disengaged. Two-thirds of disengagers (21% of cohort) did not return after the initiation visit. During months 7-12, most clients who had been continuously engaged in months 0-6 (54%) remained continuous, while 18% moved to cyclical engagement. Among cyclical engagers in months 0-6, nearly half (47%) moved to being continuously engaged by month 12. Only 34% of the study population remained engaged continuously by the end of the 12-month period. CONCLUSIONS: Fewer than 60% of clients initiating antiretroviral therapy care between 2018 and 2022 at Zambian facilities remained continuously engaged at month 6 and 34% at month 12. Cyclical engagement and frequent interruptions should be accepted as the norm and models of service delivery designed to accommodate them.

  PublisherOA PDFDOI

Recent grants

• NIH Grant U01AI100015

  NIH · $1.2M · 2017

Frequent coauthors

• Matthew P. Fox

  University of the Witwatersrand

  367 shared

• Lawrence Long

  Boston University

  208 shared

• Alana T. Brennan

  Africa Health Research Institute

  192 shared

• Ian Sanne

  Advanced Biological Laboratories (Luxembourg)

  173 shared

• Brooke E. Nichols

  Foundation for Innovative New Diagnostics

  127 shared

• Bruce A. Larson

  Boston University

  106 shared

• Gesine Meyer‐Rath

  Boston University

  98 shared

• Mariet Benade

  Amsterdam University Medical Centers

  75 shared

Labs

• Admissions TeamPI

Education

• Master of Public Administration (MPA), Kennedy School of Government

  Harvard University

  1995

• BA Magna Cum Laude

  Harvard University

  1987