Venue-Based Recruitment of Women at Elevated Risk for HIV: An HIV Prevention Trials Network Study

Background: The challenge of identifying and recruiting U.S. women at elevated risk for HIV acquisition impedes prevention studies and services. HIV Prevention Trials Network (HPTN) 064 was a U.S. multisite, longitudinal cohort study designed to estimate HIV incidence among women living in communities with prevalent HIV and poverty. Venue-based sampling (VBS) methodologies and participant and venue characteristics are described. Methods: Eligible women were recruited from 10 U.S. communities with prevalent HIV and poverty using VBS. Participant eligibility criteria included age 18–44 years, residing in a designated census tract/zip code, and self-report of at least one high-risk personal and/or male sexual partner characteristic associated with HIV acquisition (e.g., incarceration history). Ethnography was conducted to finalize recruitment areas and venues. Results: Eight thousand twenty-nine women were screened and 2,099 women were enrolled (88% black, median age 29 years) over 14 months. The majority of participants were recruited from outdoor venues (58%), retail spaces (18%), and social service organizations (13%). The proportion of women recruited per venue category varied by site. Most participants (73%) had both individual and partner characteristics that qualified them for the study; 14% were eligible based on partner risk only. Conclusion: VBS is a feasible and effective approach to rapidly recruit a population of women at enhanced risk for HIV in the United States. Such a recruitment approach is needed in order to engage women most at risk and requires strong community engagement

Estimating Design Effect and Calculating Sample Size for Respondent-Driven Sampling Studies of Injection Drug Users in the United States

Respondent-driven sampling (RDS) has become increasingly popular for sampling hidden populations, including injecting drug users (IDU). However, RDS data are unique and require specialized analysis techniques, many of which remain underdeveloped. RDS sample size estimation requires knowing design effect (DE), which can only be calculated post hoc. Few studies have analyzed RDS DE using real world empirical data. We analyze estimated DE from 43 samples of IDU collected using a standardized protocol. We find the previous recommendation that sample size be at least doubled, consistent with DE = 2, underestimates true DE and recommend researchers use DE = 4 as an alternate estimate when calculating sample size. A formula for calculating sample size for RDS studies among IDU is presented. Researchers faced with limited resources may wish to accept slightly higher standard errors to keep sample size requirements low. Our results highlight dangers of ignoring sampling design in analysis

Number of casual male sexual partners and associated factors among men who have sex with men: Results from the National HIV Behavioral Surveillance system

Abstract Background In 2006, the majority of new HIV infections were in MSM. We sought to describe numbers of casual sex partners among US MSM. Methods Data are from the first MSM cycle of the National HIV Behavioral Surveillance system, conducted from 2003 to 2005. Relationships between number of casual male sex partners within the previous year and demographic information, self-reported HIV status, and risk behaviors were determined through regression models. Results Among 11,191 sexually active MSM, 76% reported a casual male partner. The median casual partner number was three. Lower number of casual partners was associated with black race, Hispanic ethnicity, and having a main sex partner in the previous year. Factors associated with a higher number included gay identity, exchange sex, both injection and non-injection drug use. Being HIV-positive was associated with more partners among non-blacks only. Age differences in partner number were seen only among chat room users. Conclusions MSM who were black, Hispanic or had a main sex partner reported fewer casual sex partners. Our results suggest specific populations of MSM who may benefit most from interventions to reduce casual partner numbers.</p

A Mathematical Model of Comprehensive Test-and-Treat Services and HIV Incidence among Men Who Have Sex with Men in the United States

<div><h3>Background</h3><p>Early diagnosis and treatment of HIV infection and suppression of viral load are potentially powerful interventions for reducing HIV incidence. A test-and-treat strategy may have long-term effects on the epidemic among urban men who have sex with men (MSM) in the United States and may achieve the 5-year goals of the 2010 National AIDS Strategy that include: 1) lowering to 25% the annual number of new infections, 2) reducing by 30% the HIV transmission rate, 3) increasing to 90% the proportion of persons living with HIV infection who know their HIV status, 4) increasing to 85% the proportion of newly diagnosed patients linked to clinical care, and 5) increasing by 20% the proportion of HIV-infected MSM with an undetectable HIV RNA viral load.</p> <h3>Methods and Findings</h3><p>We constructed a dynamic compartmental model among MSM in an urban population (based on New York City) that projects new HIV infections over time. We compared the cumulative number of HIV infections in 20 years, assuming current annual testing rate and treatment practices, with new infections after improvements in the annual HIV testing rate, notification of test results, linkage to care, initiation of antiretroviral therapy (ART) and viral load suppression. We also assessed whether five of the national HIV prevention goals could be met by the year 2015. Over a 20-year period, improvements in test-and-treat practice decreased the cumulative number of new infections by a predicted 39.3% to 69.1% in the urban population based on New York City. Institution of intermediate improvements in services would be predicted to meet at least four of the five goals of the National HIV/AIDS Strategy by the 2015 target.</p> <h3>Conclusions</h3><p>Improving the five components of a test-and-treat strategy could substantially reduce HIV incidence among urban MSM, and meet most of the five goals of the National HIV/AIDS Strategy.</p> </div

Annual number of new HIV infections over 20 years for MSM in New York City.

<p>Annual number of new HIV infections over 20 years for MSM in New York City.</p

Reduction in new infections from HIV annual testing, notification, linkage to care, treatment, and viral load suppression.

<p>Reduction in new infections from HIV annual testing, notification, linkage to care, treatment, and viral load suppression.</p

Sensitivity analyses for MSM in New York City.

<p>*The sensitivity analyses' results are compared to the current practice in which HIV-infected MSM aware of their infection use condoms for 75% of sex acts, compared with condom use for 50% of sex acts among persons who are HIV-infected but unaware of it. In addition, among HIV-infected MSM who achieve viral load suppression receiving ART in the current practice analysis, per-contact transmission risk is reduced 90% compared to HIV-infected MSM whose viral load is not suppressed.</p