Omar Galárraga

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• MA, PhD
• Professor at Brown University

Conditional economic incentives can improve medication-taking behaviors among populations at risk of contracting human immunodeficiency virus (HIV). However, there are no data on the cost-effectiveness of incentive programs for improving pre-exposure prophylaxis (PrEP) adherence among male sex workers (MSWs) who have one of the highest HIV acquisit...

Background As envisioned by the 2010 Constitution, Kenya implemented a devolved system of government in March 2013, setting up 47 counties and a corresponding number of local governments. These counties differed in their levels of development. While counties such as Nairobi and Kiambu led in social and economic indicators, others such as Turkana, M...

Introduction The relationship between food insecurity and access to healthcare in low-resource settings remains unclear. Some studies find that food insecurity is a barrier to accessing care, while others report that food insecurity is associated with a greater need for care, leading to more care utilisation. We use data from the Harambee study in...

Background: Influenza poses a substantial health burden, especially among older adults in China. While vaccination is one of the most effective preventions, influenza vaccine uptake rates among Chinese older adults remain low. This study examines the individual and combined effects of behavioral interventions based on the Information–Motivation–Beh...

Integrating gender-affirming care with biomedical HIV prevention could help address the disproportionate HIV risk experienced by transgender and nonbinary (trans) adults. This discrete choice experiment assesses and identifies the most important programming factors influencing the decisions of trans adults to use injectable long-acting HIV pre-expo...

Introduction During the COVID-19 response, Kenya experienced widespread regional floods, resulting in the displacement of communities and agricultural loss. This study aimed to characterise food insecurity and other social and economic impacts of these emergencies on people living with HIV and to investigate whether and how existing microfinance ac...

Low adherence to preventative medications against life-long health conditions is a major contributor to global morbidity and mortality. We implemented a pilot randomized controlled trial in Mexico to measure the extent to which conditional economic incentives help male sex workers increase their adherence to pre-exposure prophylaxis (PrEP) for HIV...

HIV pre-exposure prophylaxis (PrEP) is a highly effective biomedical prevention for HIV infections. PrEP persistence is critical to achieving optimal protection against HIV infection. However, little is known about PrEP persistence in the United States. This study utilized the Connecticut All-Payer Claims Database (APCD) to identify PrEP persistenc...

Background There is some evidence that differentiated service delivery (DSD) models, which use a client-centered approach to simplify and increase access to care, improve clinical outcomes among people living with HIV (PLHIV) in high HIV prevalence countries. Integrating economic strengthening tools (e.g., microcredit, cash transfers, food assistan...

Introduction This study aimed to understand the sociocultural context of teenage pregnancy in an Ecuadorian city with a large indigenous population, to gauge the acceptability of a multifaceted pregnancy prevention program for adolescents, and to elicit perspectives on the optimal program design from adolescents and adult key informants. Methods W...

Introduction There is an urgent issue to relieve the burdens caused by tobacco use through feasible and effective smoking cessation interventions, particularly in a middle-income country with less accessible smoking cessation services and high demand for quitting smoking. Financial incentives have shown effective in changing health behaviours, thus...

Background The rapidly growing burden of non-communicable diseases (NCDs) among people living with HIV in sub-Saharan Africa (SSA) has expanded the number of multidisease models predicting future care needs and health system priorities. Usefulness of these models depends on their ability to replicate real-life data and be readily understood and app...

In Samoa, adult Type 2 diabetes prevalence has increased within the past 30 years. Patient preferences for care are factors known to influence treatment adherence and are associated with reduced disease progression and severity. However, patient preferences for diabetes care, generally, are understudied, and other patient-centered factors such as w...

Background Street-connected individuals (SCI) in Kenya experience barriers to accessing HIV care. This pilot study provides proof-of-concept for Enabling Adherence to Treatment (EAT), a combination intervention providing modified directly observed therapy (mDOT), daily meals, and peer navigation services to SCI living with HIV or requiring therapy...

Introduction Peer support can help navigate the isolation and psychological strain frequently experienced by youth living with chronic illness. Yet, data are lacking on the impact of providing support for youth living with mixed chronic conditions. We assessed the acceptability, feasibility and preliminary mental health impacts of a clinic‐based pe...

Introduction Daily oral pre-exposure prophylaxis (PrEP) is highly safe and effective for HIV prevention, yet barriers to PrEP access and adherence persist among key populations. In Mexico, incentive-based pilot programs have been effective in improving PrEP adherence among male sex workers. Understanding the experiences of providers and program imp...

Diabetes is a major health issue in middle-income countries like Mexico. Multidisciplinary healthcare (MHC) models aim to improve diabetes care and reduce costs. However, the relationship between management practices, efficiency, and quality of care in MHC and traditional healthcare (THC) models is unclear. This study evaluates the efficiency and q...

Introduction: Transfeminine adults are impacted by the HIV epidemic in the Philippines, and newly approved modalities of pre-exposure prophylaxis (PrEP), including long-acting injectable (LAI-PrEP), could be beneficial for this group. To inform implementation, we analysed PrEP awareness, discussion and interest in taking LAI-PrEP among Filipina tr...

Objectives: To compare the incidence of HIV, death, and abuse among orphaned children to non-orphaned children living in households caring for orphaned children in western Kenya. Study design: A random sample was taken of 300 households caring for at least one orphaned child in Uasin Gishu County, Kenya. All orphaned and non-orphaned children in...

This study determined the efficiency of two different models of diabetes care (traditional units and multidisciplinary units), estimated quality levels, and identified management practices associated with better quality and efficiency of both models in Mexico. A random sample consisting of 40 units (20 for each type of unit), allowed us to estimate...

During public health crises, people living with HIV (PLWH) may become disengaged from care. The goal of this study was to understand the impact of the COVID-19 pandemic and recent flooding disasters on HIV care delivery in western Kenya. We conducted ten individual in-depth interviews with HIV providers across four health facilities. We used an ite...

Background More than two years into the coronavirus disease (COVID-19) pandemic, it remains unclear whether financial incentives can reduce vaccine hesitancy and improve uptake among key unvaccinated populations. This study estimated the willingness of racial/ethnic minority adults in the United States to accept financial incentives for COVID-19 va...

Background The Harambee study is a cluster randomized trial in Western Kenya that tests the effect, mechanisms, and cost-effectiveness of integrating community-based HIV and non-communicable disease care within microfinance groups on chronic disease treatment outcomes. This paper documents the stages of our feasibility study conducted in preparatio...

Purpose. Strengthening family-based care is a key policy response to the more than 15 million orphaned and separated children who have lost 1 or both parents in sub-Saharan Africa. This analysis estimated the cost-effectiveness of family-based care environments for preventing HIV and death in this population. Design. We developed a time-homogeneous...

To slow the spread of COVID-19, most countries implemented stay-at-home orders, social distancing, and other nonpharmaceutical mitigation strategies. To understand individual preferences for mitigation strategies, we piloted a web-based Respondent Driven Sampling (RDS) approach to recruit participants from four universities in three countries to co...

Transfeminine adults are impacted by the HIV epidemic in the Philippines, and newly approved modalities of pre-exposure prophylaxis (PrEP), including long-acting injectable (LAI-PrEP), could be beneficial for this group. We utilized secondary data from the #ParaSaAtin survey that sampled Filipina transfeminine adults (n=139) and conducted a series...

Adolescent-tailored antiretroviral therapy (ART) adherence interventions take place within the context of unique developmental stage. Suboptimal ART adherence among adolescents living with HIV in South Africa underscores that interventions are urgently needed to improve adherence. We conducted semistructured in-depth interviews with 35 adolescents...

We sought to determine the relationship between continuity of care and adherence to clinic appointments among patients receiving HIV care in high vs. low clinician-to-patient (C:P) ratios facilities in western Kenya. This retrospective analysis included 12,751 patients receiving HIV care from the Academic Model Providing Access to Healthcare (AMPAT...

Objectives: A variety of care coordination and delivery models have been used to address the social and medical needs of high-need, high-cost patient populations. However, the evidence on the effectiveness of such models is far from clear. The purpose of this study is to determine whether the Community Health Team (CHT) program, a community-based...

Background With rising cost pressures on health care systems, machine-learning (ML)-based algorithms are increasingly used to predict health care costs. Despite their potential advantages, the successful implementation of these methods could be undermined by biases introduced in the design, conduct, or analysis of studies seeking to develop and/or...

Although antiretroviral therapy (ART) has changed the expected health outcomes for HIV, there are still issues related to stigma, how people living with HIV are perceived, and the availability of social support. The purpose of this study was to explore the associations between family structure and psychosocial wellbeing reflected by perceived HIV s...

Background: Effective patient-centered interventions are needed to promote patient engagement in HIV care. We assessed the impact of a patient-centered intervention referred to as Enhanced Patient Care (EPC) on viral suppression among unsuppressed patients living with HIV in Kenya. Setting: Two rural HIV clinics within the Academic Model Providi...

Pre-exposure prophylaxis (PrEP) is highly effective in preventing HIV but requires sustained adherence. Conditional economic incentives (CEIs) can improve medication-taking behaviors, yet preferences for programs that employ CEIs to increase PrEP use among male sex workers (MSWs) have not been investigated. We conducted a discrete choice experiment...

Background: The Harambee Study is a cluster randomized trial in western Kenya that tests the effect, mechanisms, and cost-effectiveness of integrating community-based HIV and non-communicable disease (NCD) care with group microfinance (MF) on HIV treatment outcomes. This paper documents the formative work to: (1) identify, enumerate, and characteri...

The novel coronavirus is part of a series of infectious disease outbreaks that include: Ebola, Avian influenza, Middle East respiratory syndrome coronavirus, and Influenza A. This paper addresses the question of how do these epidemics and pandemics affect income inequality in countries around the world during the first two decades of this century....

Background There are approximately 140 million orphaned and separated children (OSCA) around the world. In Kenya, many of these children live with extended family while others live in institutions. Despite evidence that orphans are less likely to be enrolled in school than non-orphans, there is little evidence regarding the role of care environment...

Incentive-based interventions are used to encourage HIV testing, linkage to HIV care, and antiretroviral therapy (ART) adherence. Studies assessing efficacy of cash incentives have raised questions about the perceived ethicality of and attitudes towards incentives. Here we explore patients’ and health providers’ perspectives of the acceptability of...

Background Male sex workers are at high-risk for acquisition of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). We quantified incidence rates of STIs and identified their time-varying predictors among male sex workers in Mexico City. Methods From January 2012 to May 2014, male sex workers recruited from the la...

Background The ImPrEP México demonstration project is the first to distribute free HIV pre-exposure prophylaxis (PrEP) to men who have sex with men (MSM) and transgender women living in Mexico. In Mexico City, MSM who are also male sex workers (MSWs) face a disproportionately high risk of HIV infection. PrEP is highly effective for HIV prevention,...

Background With rising cost pressures on health care systems, machine-learning (ML) based algorithms are increasingly used to predict health care costs. Despite their potential advantages, the successful implementation of these methods could be undermined by biases introduced in the design, conduct, or analysis of studies seeking to develop and/or...

Most Ugandans live in rural, medically underserved communities where geography and poverty lead to reduced access to healthcare. We present a novel low-cost approach for supplemental primary care financing through 1) pooling community wealth to cover overhead costs for outreach clinic activities and 2) issuing microfinance loans to motorcycle taxi...

Importance In 2015, there were nearly 140 million orphaned children globally, particularly in low- and middle-income regions, and millions more for whom the street is central to their everyday lives. A total of 16.6 million children were orphaned because of deaths associated with HIV/AIDS, of whom 90% live in sub-Saharan Africa. Although most orpha...

Research Objective The trajectory of COVID-19 pandemic has been different across different countries and regions, with varying number of per-population cases and deaths. Such variation may be a function of a number of country-specific factors such as population distribution, disease profile, non-pharmaceutical interventions (e.g., lockdowns) undert...

There has been a historic separation between systems that address behavioral health problems and the medical care system that addresses other health issues. Integration of the 2 has the potential to improve care. The aim of this study was to evaluate the impact of Integrated Behavioral Health program on health care utilization and costs. Claims dat...

Objective: To measure associations between participation in community-based microfinance groups, retention in HIV care, and death among people living with HIV (PLHIV) in low-resource settings. Design and methods: We prospectively analyzed data from 3,609 patients enrolled in an HIV care program in western Kenya. HIV patients who were eligible an...

Background: Institutionalization has shown contradictory effects on the mental health of orphaned and separated children and adolescents (OSCA) in sub-Saharan Africa. There is a paucity of data surrounding the cost-effectiveness of different care environments for improving OSCA's mental health. Aims of the study: The goal of this analysis was to...

Background: Patient engagement is effective in promoting adherence to HIV care. In an effort to promote patient-centered care, we implemented an enhanced patient care (EPC) intervention that addresses a combination of system-level barriers including provider training, continuity of clinician-patient relationship, enhanced treatment dialogue and be...

Introduction In Kenya, distance to health facilities, inefficient vertical care delivery and limited financial means are barriers to retention in HIV care. Furthermore, the increasing burden of non-communicable diseases (NCDs) among people living with HIV complicates chronic disease treatment and strains traditional care delivery models. Potential...

Adherence to antiretroviral therapy (ART) and psychosocial support to manage stigma and disclosure is essential for adolescents living with HIV (ALHIV). Peer support groups can help ALHIV and their families live successfully with HIV. This qualitative study aimed to examine adolescent and caregiver perspectives on peer support groups. Three themes...

Conditional cash transfers (CCTs) have become important components of social protection policies in Latin America. By establishing coresponsibilities tied to health and education, CCTs may reduce poverty and encourage human capital investment. While CCT programs can have unintended effects on sexual and reproductive health outcomes, such effects ha...

Several countries have implemented “family-centered” abstinence-only policies for teenagers, as opposed to encouraging utilization and expansion of reproductive health services and education. Little is known, however, about the effects of these more restrictive policies on adolescent birth rates at the national level or their differential effects b...

Background The adherence biomarker tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is associated with viral suppression and predicts future viremia. However, its association with social determinants of health (SDoH) in people with HIV (PWH) remains unknown. Methods DBS for TFV-DP were longitudinally collected from a clinical cohort of PW...

Introduction: Male sex workers (MSWs) are at high-risk for HIV/STI acquisition. We quantified HIV/STI incidence rates and identified their time-varying predictors among MSWs in Mexico City. Methods: MSWs recruited from the largest HIV clinic and community sites in Mexico City were tested for chlamydia, gonorrhea, syphilis, hepatitis, and HIV at bas...

Introduction: Male sex workers are at high-risk for acquisition of sexually transmitted infections, including human immunodeficiency virus. We quantified incidence rates of sexually transmitted infections and identified their time-varying predictors among male sex workers in Mexico City. Methods: Male sex workers recruited from the largest human i...

Background: Male sex workers are at high-risk for acquisition of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). We quantified incidence rates of STIs and identified their time-varying predictors among male sex workers in Mexico City. Methods: From January 2012 to May 2014, Male sex workers recruited from the l...

High adherence to antiretroviral therapy (ART) is essential for achieving viral suppression and preventing HIV transmission. Yet adherence is suboptimal among adolescents who face unique adherence challenges. Little is known about the role of conditional economic incentives (CEIs) for increasing ART adherence in this population. During 2017-2019, w...

Introduction: Male sex workers (MSWs) are at high-risk for HIV/STI acquisition. We quantified HIV/STI incidence rates and identified their time-varying predictors among MSWs in Mexico City. Methods: MSWs recruited from the largest HIV clinic and community sites in Mexico City were tested for chlamydia, gonorrhea, syphilis, hepatitis, and HIV at bas...

: As Covid-19 restrictions upend the community bonds that have enabled African communities to thrive in the face of numerous challenges, it is vital that the gains made in community-based health care are preserved by adapting our approaches. Instead of reversing the many gains made through locally driven development partnerships with international...

Introduction Like many countries in sub‐Saharan Africa, Kenya is experiencing a rapid rise in the burden of non‐communicable diseases (NCDs): NCDs now contribute to over 50% of inpatient admissions and 40% of hospital deaths in the country. The Academic Model Providing Access to Healthcare (AMPATH) Chronic Disease Management (CDM) programme builds...

Background: The global push to achieve the 90-90-90 targets designed to end the HIV epidemic has called for the removing of policy barriers to prevention and treatment, and ensuring financial sustainability of HIV programs. Universal health insurance is one tool that can be used to this end. In sub-Saharan Africa, where HIV prevalence and incidence...

Background This paper investigates the impact of Kenyan unconditional cash transfer programs on a range of HIV risk indicators, including transactional sex, sexual concurrency, knowledge of HIV, and HIV testing. Previous research on cash transfers in similar contexts suggests that the provision of cash transfers can be a potent method to bolster HI...

Introduction Pre-exposure prophylaxis (PrEP) in the form of daily emtricitabine and tenofovir disoproxil fumarate (FTC/TDF) is effective for preventing HIV infection. Implementation has been limited by an inability to systematically evaluate uptake and use. All payer claims databases (APCDs) provide an opportunity to evaluate population-level PrEP...

Background: Reducing maternal morbidity and mortality remains a top global health agenda especially in high HIV/AIDS endemic locations where there is increased likelihood of mother to child transmission (MTCT) of HIV. Social health insurance (SHI) has emerged as a viable option to improve population access to health services, while improving outco...

In Mexico City, male sex workers (MSWs) are up to 126 times more likely to be living with HIV than the general public. We conducted interviews with 23 MSWs in Mexico City to examine their subjective understandings about their sexual risk behaviors and explore opportunities about HIV pre-exposure prophylaxis (PrEP) as a prevention approach in this g...

This study evaluated the safety and preliminary efficacy of a group-based conditional economic incentives (CEI) program for ART adherence improvement among a sample of adolescents living in Ghana. A total of 35 adolescents (mean age: 14.7 years) on ART, though still with detectable viral load, were recruited from an HIV clinic and divided into 5 ba...

[This corrects the article DOI: 10.1371/journal.pone.0199915.].

Background: As the noncommunicable disease (NCD) burden is rising in regions with high HIV prevalence, patients with comorbid HIV and chronic NCDs may benefit from integrated chronic disease care. There are few evaluations of the effectiveness of such strategies, especially those that directly leverage and extend the existing HIV care system to pr...

Objective: To pilot test two low-cost and thus financially sustainable incentive programs to promote physical activity (PA) among low-active adults in a community setting. Method: In a three-arm randomized controlled trial the effects of small monetary incentives (cash incentives $1/day; n = 25) were compared to charitable donations (donation $1...

Pre-exposure prophylaxis (PrEP) is an effective tool for preventing HIV infection among men who have sex with men (MSM), but its cost-effectiveness has varied across settings. Using an agent-based model, we projected the cost-effectiveness of a statewide PrEP program for MSM in Rhode Island over the next decade. In the absence of PrEP, the model pr...

Background Pre-exposure prophylaxis (PrEP) in the form of daily tenofovir disoproxil fumarate (TDF/FTC) is a potentially transformative tool to prevent HIV infection. However, PrEP scale-up in the United States has been slow and difficult to evaluate comprehensively. All payer claims databases (APCDs) are large datasets that contain information on...

Linkage to care from mobile clinics is often poor and inadequately understood. This multimethod study assessed linkage to care and antiretroviral therapy (ART) uptake following ART-referral by a mobile clinic in Cape Town (2015/2016). Clinic record data (N = 86) indicated that 67% linked to care (i.e., attended a clinic) and 42% initiated ART withi...

and Keywords Conditional economic incentives are a theoretically grounded approach for eliciting be­ havior change. The rationale stems from present-biased preferences, by which individuals attach greater value to benefits in the present and heavily discount long-term health. A growing literature documents the use of economic incentives in the HIV...

New and innovative approaches are needed to improve the prevention, diagnosis, and treatment of HIV in low-income and middle-income countries. Several trials use conditional economic incentives (CEIs) to improve HIV outcomes. Most CEI interventions use a traditional economic theory approach, although some interventions incorporate behavioural econo...

Pre-exposure prophylaxis (PrEP) has the potential to significantly reduce HIV incidence among men who have sex with men (MSM) in the United States. However, the extent to which suboptimal PrEP adherence and retention in care may limit successful implementation is unknown. An agent-based model was used to represent the entire population of MSM in Rh...

Background Microfinance interventions have the potential to improve HIV treatment outcomes, but the mechanisms through which they operate are not entirely clear. Objectives To construct a synthesizing conceptual framework for the impact of microfinance interventions on HIV treatment outcomes using evidence from our systematic review. Methods We c...

Introduction: Adherence to antiretroviral therapy (ART) is essential to reduce HIV-related morbidity and mortality as well as the risk of virological failure and HIV transmission. We determined the trends in ART adherence during the periods of therapeutic advances, wider use of ART and greater attention to ART adherence. To understand the general...

Objective: To estimate the effect of patient-centered medical home (PCMH) participation on cost and utilization of care for patients in Rhode Island's statewide, multipayer PCMH program, which serves over one-third of the state population. Data sources/study setting: 2009-2014 claims data from all payers in Rhode Island, representing >743,000 un...

Health systems in sub-Saharan Africa are facing an ongoing HIV epidemic and increasing burden of noncommunicable disease. With the focus shifting to the development of comprehensive primary health care and chronic disease treatment, multidisease modeling is integral to estimating future health care needs. We extended an established agent-based mode...

Background Discontinuous Medicaid insurance erodes access to care, increases administrative costs, and exposes enrollees to substantial out-of-pocket spending. Objective To assess the impact of Medicaid expansion under the Affordable Care Act on continuity of Medicaid coverage among those enrolled prior to expansion. Design Using a difference-in-...

Holding support groups with the same cohort of adolescents during clinic visits promises to increase engagement in care. Participants (N ¼ 35 patients, aged 12-18, 50% female, from an adolescent HIV clinic in Kumasi, Ghana, were divided into 5 teams. Clinic visits were coordinated for members of each team. Team members participated in group discuss...

Background As antiretroviral therapy has become more effective, persons with HIV live longer and develop conditions that are characteristic of older populations. Understanding changes in comorbid conditions has important implications for the complexity and cost of care, particularly for Medicaid programs and their enrollees, which comprise about 40...