H2R Newsletter

New Approaches in H2R Research Methods

Three-source Capture-Recapture (3S-CRC)

Innovative methods like Capture-Recapture can estimate the size of hard-to-reach populations.

Tuyishime et al. applied a three-source Capture-Recapture (3S-CRC) method to estimate the population of Men Who Have Sex with Men (MSM) in Rwanda.

• In the first capture, trained distributors provided branded keychains, one for MSM themselves and two for other MSM they knew, valued under $3 each. Example of a keychain pictured below.
• After a week, the second capture involved offering MSM-friendly services nationwide and using targeted questions to identify individuals from the first capture.
• The third capture employed respondent-driven sampling (RDS), again utilizing targeted questions to trace individuals from earlier captures. See Venn Diagram below.

Example of Key Chain used in First Capture

They assessed dependency between captures by testing for homophily in the RDS recruitment chain based on the capture history variable. They found a homophily value of 1.02, indicating nondependency as it was almost 1.

Using the latent-class model for capture-recapture (LCMCR) package in R v.4.0.5 for data analysis, the overall population size for MSM was approximately 18,100 MSM (95% credibility set: 11,300–29,700), equating to 0.7% of the total adult male population.

Venn Diagram - Number of MSM at each capture

Tuyishime E, Kayitesi C, Musengimana G, Malamba S, Moges H, Kankindi I, Escudero HR, Habimana Kabano I, Oluoch T, Remera E, Chukwu A. Population Size Estimation of Men Who Have Sex With Men in Rwanda: Three-Source Capture-Recapture Method. JMIR Public Health Surveill. 2023 Mar 27;9:e43114. doi: 10.2196/43114. PMID: 36972131; PMCID: PMC10131990.

RDS is a sampling method used when traditional probability sampling methods are not feasible. It is often used to sample key populations. In essence, RDS is an improved form of chain-referral sampling (also known as snowball sampling). It uses information about social networks and recruitment patterns of people included in the survey to determine the probability of each participant's inclusion in the sample.

The recruitment starts with initial participants called seeds who are chosen by researchers. The seeds recruit other members of the target population who in turn recruit other members. Data collected is analyzed through specialized methods and software to achieve population level (representative) estimates.

Advantages

• Access to hidden populations through peer recruitment.
• Cost-effective by relying on participants to recruit peers.
• Builds trust through peer-driven recruitment.
• Adjusts for biases (e.g., network size) with statistical methods.
• Dual incentives boost participation and recruitment.
• Scalable across various populations and regions.
• Collects additional data on social networks.

Weaknesses

• Relies on social networks, which may be fragmented.
• Recruitment bias if peers favor specific subgroups.
• Risk of inaccurate reporting (e.g., network size).
• Limited generalizability beyond the sampled group.
• Recruitment can be slow and subject to fatigue.
• Complex analysis and statistical adjustments required.

RDS Quality Checklist

• Describe formative research findings used to inform RDS study
• Describe the setting, locations, and relevant dates, including periods of recruitment and data collection
• Describe eligibility criteria and how participants were instructed to recruit others, number of coupons issued per person, any time limits for referral
• Describe methods of seed selection and state number at start of study and number added later
• State how recruiter–recruit relationship was tracked
• State if there was any variation in study procedures during data collection (e.g., changing numbers of coupons per recruiter, interruptions in sampling, or stopping recruitment chains)
• Report wording of personal network size question(s)
• Describe incentives for participants and recruitment
• Describe all statistical methods, including those to account for sampling strategy (e.g., the estimator used) and, if applicable, those used to control for confounding
• State data analysis software, version number, and specific analysis settings used
• Explain how seeds were handled in analysis
• Report unweighted sample size and percentages, estimated population proportions or means with estimated precision (e.g., 95% confidence interval)

• White RG, Hakim AJ, Salganik MJ, Spiller MW, Johnston LG, Kerr L, Kendall C, Drake A, Wilson D, Orroth K, Egger M, Hladik W. Strengthening the Reporting of Observational Studies in Epidemiology for respondent-driven sampling studies: "STROBE-RDS" statement. J Clin Epidemiol. 2015 Dec;68(12):1463-71. doi: 10.1016/j.jclinepi.2015.04.002. Epub 2015 May 1. PMID: 26112433; PMCID: PMC4669303.
• Biobehavioural survey guidelines for populations at risk for HIV. WHO 2017. https://www.who.int/publications/i/item/978-92-4-151301-2

Report from the Field

Can PhotoVoice change attitudes towards trans women?

Three in 10 of the 11.3% of trans women in Nepal living with HIV do not seek care. This is often due to the stigma of being Hijra, or “the third sex." The Fogarty-supported Sweekar program, meaning “acceptance” in Nepali, aims to increase both HIV testing and treatment adherence by examining and addressing stigma faced by trans women in Nepal.

In ancient Sanskrit texts, Hijra are described as capable of bestowing both blessings and curses. “Every temple you go to you see trans people's images. They're seen as mystic and people treat them with both respect and fear," said Dr. Erin Wilson, H2R faculty and senior research scientist, San Francisco Department of Public Health. In rural Nepal, however, most trans people experience exclusion from society and discrimination. For the Hijra, this means “they’re highly regarded in the moment in which they're giving a blessing, but, once that moment is over, they’re highly disregarded,” said Wilson.

Regrettably, such stigma can lead Hijra, who are part of the larger trans women population in Nepal, to not seek medical care. Wilson and her colleagues are working on a stigma reduction intervention for Nepal's trans women community to increase their healthcare uptake.

Training Opportunity

Mentoring the Mentors workshop in Nairobi, Kenya

The two-day workshop will be held on February 17 and 18, 2025 at the Fairview Hotel in Nairobi. 

The Kenya workshop will feature a keynote from Professor Moses Kamya from Makerere University in Kampala, Uganda, and include talks from UCSF-based and Kenya-based faculty. This will be an intensive and interactive meeting designed to provide faculty in HIV research with the tools for more effective mentoring in the context of African-based universities and research centers.

The workshop will discuss the mentor-mentee relationship, structuring the mentoring relationship, and barriers related to being an early career investigator.

IAS 2025

Scholarship and Abstract Submissions Close 22 January

Scholarship and abstract submissions for IAS 2025 close in just two weeks.

Submit an abstract or scholarship application today and take part in the world’s most influential meeting on HIV science and its applications.

IAS 2025 will take place in Kigali, Rwanda, from 13 to 17 July 2025.

Team Achievements

Publications

• Sadaat SI, Marr A, Mirzazadeh A, Suprasert B, Tate M, Wilson E, McFarland W. Uptake of COVID-19 Vaccination and Related Factors Among People who Inject Drugs, San Francisco, 2022. AIDS Behav. 2024 Dec 10. doi: 10.1007/s10461-024-04564-z. Epub ahead of print. PMID: 39656342.
• Chiu I, Cano D, Leathers M, Turner CM, Trujillo D, Sicro S, Arayasirikul S, Taylor KD, Wilson EC, McFarland W. HIV and hepatitis C virus infection and co-infection among trans women in San Francisco, 2020. PLoS One. 2024 Sep 23;19(9):e0307990. doi: 10.1371/journal.pone.0307990. PMID: 39312538; PMCID: PMC11419358.
• Wesson P, Graham-Squire D, Perry E, Assaf RD, Kushel M. Novel methods to construct a representative sample for surveying California's unhoused population: the California Statewide Study of People Experiencing Homelessness. Am J Epidemiol. 2024 Sep 11:kwae323. doi: 10.1093/aje/kwae323. Epub ahead of print. PMID: 39267209.
• Martignetti L, Knight R, Nafeh F, Atkinson K, Laurence G, Johnson CH, Werb D, Karamouzian M. Motivations for and perspectives of medication diversion among clients of a safer opioid supply program in Toronto, Canada. Int J Drug Policy. 2024 Dec 4;135:104665. doi: 10.1016/j.drugpo.2024.104665. Epub ahead of print. PMID: 39637492.

Presentation

Dr. Abubaker Saeed, H2R Graduate, Assistant Professor of Pharmacy Practice, Harvard.

• CAPS/DPS Town Hall INSIGHTS Lecture Series
• Talk: Impact of an Intervention to Reduce Pharmacists' Racial Bias Towards People of Color at Risk of HIV 
• Dr. Abubaker Saeed interests lie in the newly emerging field of pharmacoequity science, which addresses the lack of equitable access to and use of evidence-based medical treatments for disadvantaged populations. His research career focuses on the development and implementation of pharmacy-based interventions to reduce healthcare disparities in HIV treatment and prevention. Dr. Saeed worked as a university professor at different colleges of pharmacy, in both Sudan and Saudi Arabia.

One-the-Spot (SPOT) Award

Alex Marr, MPH, PhD.c., H2R mentor, for taking on significant challenges that advanced key projects and built team capacity. His expertise in bio-behavioral surveillance, data analysis, and curriculum development in Kenya, Namibia, the Middle East, and North Africa demonstrates his professionalism and collaborative spirit.

Data Corner & Consultation

Data Request

If you are a student, post-doc, researcher, faculty, physician, or health officer, it is never too late to start your H2R research or conduct secondary data analysis and write a paper for a health topic on H2R populations.

Submit your data request online to be involved in one of our past or current projects on an H2R population.

Office Hours

We have office hours for those who want to meet virtually or in person and consult with one of our team members about an H2R population study or method.



• Tuesdays (17:00 to 18:00 PT)
• Wednesdays (16:00 to 17:00 PT)

Call for content

We would love to highlight any work from you, our community.

Please send us any content or suggestions you may have for future issues at H2R@ucsf.edu.