Demographic and behavioral contextual risk groups among men who have sex with men participating in a phase 3 HIV vaccine efficacy trial: implications for HIV prevention and behavioral/biomedical intervention trials

Development and Validation of the Personalized Sexual Health Promotion (SexPro) HIV Risk Prediction Model for Men Who Have Sex with Men in the United States

Accurate HIV risk assessment among men who have sex with men (MSM) is important to help providers assess risk, and target HIV prevention interventions. We sought to develop an evidence-based HIV risk assessment tool for US MSM that is inclusive of Black MSM. Data from four large longitudinal cohorts of MSM were used to develop (EXPLORE), and validate (VAX004, HPTN061, and HVTN505). These data included visits in which participants self-reported HIV risk behavior and underwent HIV testing. We developed a pooled logistic model for incident HIV infection based on self-reported risk behaviors during the 6 months before each study visit. A total of 4069 MSM were used for the development cohort, and 8047 MSM in the three validation cohorts through 2013. The final model includes age (< 35, ≥ 35); Black race and Latino ethnicity; numbers of HIV-negative anal sex partners; number of insertive or receptive anal intercourse episodes; having 1 HIV-negative partner only; self-reported substance use; and bacterial sexually transmitted infection diagnosis. The model showed good discrimination in internal validation (C-statistic = 79.5). The external validation cohorts also showed good discrimination, with C-statistics of 73.1, 71.0, 71.9 in VAX004, HPTN061, and HVTN505 respectively, and acceptable calibration. We developed and validated an HIV risk assessment tool for MSM, which showed good predictive ability, including among the largest cohort of HIV-uninfected Black MSM in the US. This tool is available online (mysexpro.org) and can be used by providers to support targeting of HIV prevention interventions such as pre-exposure prophylaxis for MSM.

Voluntary medical male circumcision and HIV infection among men who have sex with men: Implications from a systematic review

Background:

With the rapidly-increased HIV epidemic among men who have sex with men worldwide, the effectiveness of voluntary medical male circumcision as the tool of HIV prevention still remains undetermined.

Purpose:

In the current study, we conducted a systematic review and meta-analysis to assess the association between voluntary medical male circumcision and HIV risk among men who have sex with men.

Methods and Conclusion:

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline, we conducted a comprehensive literature search through multiple databases. A total of 37 articles/abstracts were included in the analysis. We employed random-effects models and subgroup analyses based upon key study characteristics derived from empirical studies. A total of 117,293 men who have sex with men were included in the meta-analysis, and no randomized control trials have been identified. The odds of being HIV positive were 7% lower among men who have sex with men who were circumcised than among men who have sex with men who were uncircumcised (adjusted odds ratio, 0.93; 95% confidence interval, 0.88–0.99). The evidence for the potential protective effect of voluntary medical male circumcision was stronger among men who have sex with men in Asia and Africa (adjusted odds ratio, 0.62; 95% confidence interval, 0.53–0.73). Our meta-analyses may suggest a protective effect of voluntary medical male circumcision against HIV infection among men who have sex with men, especially in settings like Asia/Africa.

Developing a Mobile App (LYNX) to Support Linkage to HIV/Sexually Transmitted Infection Testing and Pre-Exposure Prophylaxis for Young Men Who Have Sex With Men: Protocol for a Randomized Controlled Trial

BACKGROUND

Young men who have sex with men (YMSM) in the United States have among the highest incidence of HIV and sexually transmitted infection (STI) and the lowest uptake of HIV and STI testing and pre-exposure prophylaxis (PrEP). Nearly universal mobile phone ownership among youth provides an opportunity to leverage mobile health apps to increase HIV/STI testing and PrEP uptake among YMSM.

OBJECTIVE

The goals of this project are to develop and refine LYNX, a novel mobile app to support linkage to HIV/STIs testing and PrEP services among YMSM in the United States, and to evaluate the acceptability and feasibility of LYNX in a pilot randomized controlled trial (RCT).

METHODS

This research protocol will be conducted in 3 phases: an iterative development phase with a series of 3 focus groups among 20 YMSM to refine the LYNX app; an open technical pilot among 15 YMSM to optimize usability of the app; and then a 6-month pilot RCT among 60 HIV-uninfected YMSM at risk for HIV acquisition. Developed using the Information, Motivation, and Behavioral skills theoretical model, the LYNX app includes an electronic diary to track sexual behaviors (information), a personalized risk score to promote accurate risk perception (information/motivation), testing reminders (motivation/behavioral skills), and access to home-based HIV/STI testing options and geospatial-based HIV/STI testing care sites (behavioral skills). Feasibility and acceptability will be assessed through app analytics of usage patterns and acceptability scales administered via computer-assisted self-interview at 3 and 6 months. We will also evaluate preliminary efficacy by comparing the proportion of YMSM who test at least once during the 6-month pilot and the proportion who successfully link to a PrEP provider in the intervention versus control groups.

RESULTS

Formative work is currently underway. The LYNX pilot RCT will begin enrollment in October 2018, with study results available in 2019.

CONCLUSIONS

The LYNX app is one of the first mobile apps designed to increase HIV/STI testing and PrEP uptake among YMSM. As low-perceived risk is a barrier to HIV/STI testing and PrEP use among youth, the personalized risk assessment and interactive sexual diary in LYNX could assist YMSM in better understanding their HIV risk and providing motivation to test for HIV/STIs and initiate PrEP. Coupled with community-based recruitment, this novel mobile app has great potential to reach and engage YMSM not currently involved in care and increase rates of HIV/STI testing and PrEP uptake in this vulnerable population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03177512; https://clinicaltrials.gov/ct2/show/NCT03177512 (Archived by WebCite at http://www.webcitation.org/73c917wAw).

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/10659.

Does per-act HIV-1 transmission risk through anal sex vary by gender? An updated systematic review and meta-analysis

Quantifying HIV-1 transmission risk per-act of anal intercourse (AI) is important for HIV-1 prevention. We updated previous reviews by searching Medline and Embase to 02/2018. We derived pooled estimates of receptive AI (URAI) and insertive AI (UIAI) risk unprotected by condoms using random-effects models. Subgroup analyses were conducted by gender, study design, and whether antiretroviral treatment (ART) had been introduced by the time of the study. Two new relevant studies were identified, one of which met inclusion criteria, adding three new cohorts and increasing number of individuals/partnerships included from 1869 to 14 277. Four studies, all from high-income countries, were included. Pooled HIV-1 risk was higher for URAI (1.25%, 95% CI 0.55%-2.23%, N = 5, I²  = 87%) than UIAI (0.17%, 95 % CI 0.09%-0.26%, N = 3, I²  = 0%). The sole heterosexual URAI estimate (3.38%, 95% CI 1.85%-4.91%), from a study of 72 women published in a peer-reviewed journal, was significantly higher than the men-who-have-sex-with-men (MSM) pooled estimate (0.75%, 95% CI 0.56%-0.98%, N = 4, P < 0.0001) and higher than the only other heterosexual estimate identified (0.4%, 95% CI 0.08%-2.0%, based on 59 women, excluded for being a pre-2013 abstract). Pooled per-act URAI risk varied by study design (retrospective-partner studies: 2.56%, 95% CI 1.20%-4.42%, N = 2 (one MSM, one heterosexual); prospective studies: 0.71%, 95% CI 0.51%-0.93%, N = 3 MSM, P < 0.0001). URAI risk was lower for studies conducted in the ART era (0.75%, 95% CI 0.52%-1.03%) than pre-ART (1.67%, 95% CI 0.44%-3.67%) but not significantly so (P = 0.537). Prevention messages must emphasize that HIV-1 infectiousness through AI remains high, even in the ART era. Further studies, particularly among heterosexual populations and in resource-limited settings, are required to elucidate whether AI risk differs by gender, region and following population-level ART scale-up.

Per-partner condom effectiveness against HIV for men who have sex with men

OBJECTIVE

Few studies have examined condom effectiveness for HIV prevention among MSM. We estimated condom effectiveness per partner in four cohorts of MSM during 1993-2003 (JumpStart, Vaccine Preparedness Study, VAX004 and Project Explore).

METHODS

We used logistic regression to estimate the increase in odds of new HIV infection per HIV-positive partner for condom-protected receptive anal intercourse (PRAI; partners with whom condoms were always used) and condomless (unprotected) receptive anal intercourse (URAI; partners with whom condoms were sometimes or never used). To estimate condom effectiveness for preventing HIV transmission, we applied the concept of excess odds, the odds ratio minus 1. The condom failure rate was estimated as the excess odds per PRAI partner divided by the excess odds per URAI partner. Condom effectiveness was then 1 minus the failure rate.

RESULTS

The excess odds of HIV infection per HIV-positive partner were 83% for URAI and 7% for PRAI. The resulting failure rate (9%) indicated per-partner condom effectiveness of 91% (95% confidence interval 69-101).

CONCLUSION

The increase in odds of new HIV infection per HIV-positive partner for receptive anal intercourse was reduced by 91% for each partner with whom condoms were always used.

Age, race/ethnicity, and behavioral risk factors associated with per contact risk of HIV infection among men who have sex with men in the United States

OBJECTIVE

Young men who have sex with men (MSM) and MSM of color have the highest HIV incidence in the United States. To explore possible explanations for these disparities and known individual risk factors, we analyzed the per contact risk (PCR) of HIV seroconversion in the early highly active antiretroviral therapy era.

METHODS

Data from 3 longitudinal studies of MSM (HIV Network for Prevention Trials Vaccine Preparedness Study, EXPLORE behavioral efficacy trial, and VAX004 vaccine efficacy trial) were pooled. The analysis included visits where participants reported unprotected receptive anal intercourse (URA), protected receptive anal intercourse, or unprotected insertive anal intercourse (UIA) with an HIV seropositive, unknown HIV serostatus, or an HIV seronegative partner. We used regression standardization to estimate average PCRs for each type of contact, with bootstrap confidence intervals.

RESULTS

The estimated PCR was highest for URA with an HIV seropositive partner (0.73%; 95% bootstrap confidence interval [BCI]: 0.45% to 0.98%) followed by URA with a partner of unknown HIV serostatus (0.49%; 95% BCI: 0.32% to 0.62%). The estimated PCR for protected receptive anal intercourse and UIA with an HIV seropositive partner was 0.08% (95% BCI: 0.0% to 0.19%) and 0.22% (95% BCI: 0.05% to 0.39%), respectively. Average PCRs for URA and UIA with HIV seropositive partners were higher by 0.14%-0.34% among younger participants and higher by 0.08% for UIA among Latino participants compared with white participants. Estimated PCRs increased with the increasing number of sexual partners, use of methamphetamines or poppers, and history of sexually transmitted infection.

CONCLUSIONS

Susceptibility or partner factors may explain the higher HIV conversion risk for younger MSM, some MSM of color, and those reporting individual risk factors.

Predictors of screening for AIDS clinical trials among African-Americans and Latino/Hispanics enrolled in an efficacious peer-driven intervention: uncovering socio-demographic, health, and substance use-related factors that promote or impede screening

African-American and Latino/Hispanic persons living with HIV/AIDS are underrepresented in AIDS clinical trials (ACTs). The aim of this paper was to uncover factors, either unmodifiable or not directly targeted for change, that predicted screening for ACTs during an efficacious peer-driven intervention (N = 540 total; N = 351 in an intervention arm, N = 189 control). This paper focused on participants assigned to an intervention arm, 56 % of whom were screened for ACTs. We found a decreased odds of screening was associated with closer proximity to the screening site, gay/lesbian orientation, lower mental health symptoms, current injection drug use, more recent HIV diagnosis, lack of prior screening experience, and failure to attend all intervention sessions, but there were no gender or racial/ethnic differences. Efforts to reduce racial/ethnic disparities in ACTs can be enhanced by attending to these specific factors, which may interfere with programmatic efforts to increase African-American and Latino/Hispanic representation in ACTs.

Risk factors for HIV-1 seroconversion among Taiwanese men visiting gay saunas who have sex with men

Background

Men having sex with men (MSM) accounts for 33.6% of all reported cases of HIV-1 infection in Taiwan. The aim of this study was to investigate the epidemiology of HIV-1 infection among MSM in gay saunas in Taiwan.

Methods

Patrons of 5 gay saunas were recruited for a weekly volunteer counseling and testing program from 2001 to 2005. Questionnaires were collected for a risk factor analysis. HIV-1 subtypes were determined using DNA sequencing and phylogenetic analyses.

Results

HIV-1 prevalence rates among MSM in gay saunas in 2001 through 2005 were 3.4%, 5.1%, 8.9%, 8.5%, and 8.3%, respectively. In total, 81 of 1, 093 (7.4%) MSM had HIV-1 infection. Fifty-two HIV-1 strains were genotyped, and all of them were subtype B. HIV-seropositive men were significantly younger than the seronegatives. Only 37.1% used condoms every time during sexual intercourse. A multivariate logistic regression analysis showed that the risk factors for HIV-1 were being uncircumcised (odds ratio (OR) = 2.19; 95% confidence interval (CI), 1.08~4.45); having sexual intercourse with at least 2 partners during each sauna visit (≥ 2 vs. ≤ 1, OR = 1.71; 95% CI, 1.02~2.89); and the role played during anal intercourse (versatile vs. an exclusively insertive role, OR = 2.76; 95% CI, 1.42~5.36).

Conclusions

Overall, 7.4% Taiwanese MSM participating in this study had HIV-1 subtype B infection. Uncircumcised, being versatile role during anal intercourse, and having sex with more than one person during each sauna visit were main risk factors for HIV-1 infection.

Male circumcision for prevention of homosexual acquisition of HIV in men

BACKGROUND

Previous systematic reviews found inconsistent effects of male circumcision on HIV acquisition in men who have sex with men (MSM). However, a number of new studies have become available in the three years since the last systematic review.

OBJECTIVES

To assess the effects of male circumcision for preventing HIV acquisition by men through sex with men.

SEARCH STRATEGY

In June 2010 we electronically searched the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, AIDS Education Global Information System, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform; hand-searched reference lists of relevant articles; and contacted relevant organisations and experts. We updated the search in March 2011.

SELECTION CRITERIA

We looked for randomised controlled trials (RCTs) and observational studies that assessed the effects of male circumcision on HIV acquisition in MSM.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility and methodological quality, and extracted data. We expressed study results as odds ratios (OR) with 95% confidence intervals (CI), and conducted random-effects meta-analysis.

MAIN RESULTS

We found no completed RCT and included 21 observational studies with 71,693 participants. The only eligible RCT is currently ongoing among MSM in China. The pooled effect estimate for HIV acquisition was not statistically significant (20 studies; 65,784 participants; OR 0.86, 95% CI 0.70 to 1.06) and showed significant heterogeneity (I²=53%). In a subgroup analysis, the results were statistically significant in studies of men reporting an insertive role (7 studies, 3465 participants; OR 0.27, 95% CI 0.17 to 0.44; I²=0%) but not in studies of men reporting a receptive role (3 studies, 1792 participants; OR 1.20, 95% CI 0.63 to 2.29; I² = 0%). There was no significant association between male circumcision and syphilis (8 studies; 34,999 participants: OR 0.96, 95% CI 0.82 to 1.13; I² = 0%), herpes simplex virus 1 (2 studies, 2740 participants; OR 0.90, 95% CI 0.53 to 1.52; I²=0%), or herpes simplex virus 2 (5 studies;10,285 participants; OR 0.86, 95% CI 0.62 to 1.21; I²=0%). The overall GRADE quality of evidence was low. None of the included studies assessed adverse effects associated with male circumcision.

AUTHORS' CONCLUSIONS

Current evidence suggests that male circumcision may be protective among MSM who practice primarily insertive anal sex, but the role of male circumcision overall in the prevention of HIV and other sexually transmitted infections among MSM remains to be determined. Therefore, there is not enough evidence to recommend male circumcision for HIV prevention among MSM at present. Further research should be of high quality and further explore interaction with the predominant sexual role.

Male circumcision to reduce the risk of HIV and sexually transmitted infections among men who have sex with men

PURPOSE OF REVIEW

The success of male circumcision in reducing HIV acquisition among African heterosexuals has led to renewed interest in this biological intervention for HIV/sexually transmissible infection (STI) prevention in men who have sex with men (MSM). This review summarizes the available data on the association of circumcision and HIV/STI among MSM populations.

RECENT FINDINGS

Results of observational studies indicate that circumcision has limited impact on HIV/STI acquisition among MSM populations overall. Longitudinal data suggest that circumcision may reduce the risk of incident syphilis, but there is little evidence of a protective effect for other STIs. The subgroup of MSM who predominantly practise the insertive role in anal intercourse may be at lower risk of HIV, although the relative inefficiency of HIV acquisition for insertive compared with receptive partners has resulted in imprecise estimates of effect.

SUMMARY

The evidence that circumcision reduces HIV and other STIs among MSM is weak and inconsistent. However, recent studies have found that circumcised MSM who predominantly take the insertive role in anal intercourse may be at a lower risk of HIV infection. Although MSM may be willing to undergo adult circumcision, should it be proven to reduce HIV acquisition risk, there is substantial potential that behavioural disinhibition could offset any benefits achieved by a circumcision intervention.

Running in place: implications of HIV incidence estimates among urban men who have sex with men in the United States and other industrialized countries

Attempts to document changing HIV incidence rates among MSM are compromised by issues of generalizability and statistical power. To address these issues, this paper reports annualized mean HIV incidence rates from the entire published incidence literature on MSM from Europe, North America and Australia for the period 1995-2005. Publications that met the entry criteria were coded for region of the world, sampling method and year of study. From these reports, we calculated a mean incidence rate with confidence intervals for these variables. Although no differences in mean incidence rates were found for MSM from 1995 to 2005, HIV incidence rates are lower in Australia than either North America or Europe. We calculated a mean incidence rate of 2.39% for MSM in the United States, which if sustained within a cohort of MSM, would yield HIV prevalence rate of approximately 40% at age 40. These extrapolations overlap published HIV prevalence rates for MSM younger than age 40 in the United States. HIV incidence rates in the 2-3% range will adversely affect the health of gay male communities for decades to come. This analysis suggests that greater attention should be devoted to the question of how best to design prevention interventions that will lower HIV incidence rates among gay men.

Differential HIV risk behavior among men who have sex with men seeking health-related mobile van services at diverse gay-specific venues

Distinguishing between gay venues may provide important information to better understand patterns of environmental influence and HIV/STI behavioral risk among MSM. Massachusetts MSM accessing State Health Department mobile van services (n = 214) at Gay Pride events, bars/clubs, and private safer sex parties completed a one-time, cross-sectional survey via ACASI. In the past 12 months, private safer sex party attendees reported a higher mean number of anonymous partners, were more likely to report meeting sex partners via the Internet, and were more likely to report sex while drunk; in logistic regression analyses, they were less likely to report both unprotected insertive and receptive anal sex in the past year relative to men from other venues. Private safer sex parties may represent a strategy used by some MSM to reduce HIV/STI risk. Differentiating risk behavior by venue type provides valuable information with which to effectively target interventions to reach MSM at greatest risk.

Behavioral interventions to reduce risk for sexual transmission of HIV among men who have sex with men

BACKGROUND

Men who have sex with men (MSM) remain at great risk for HIV infection. Program planners and policy makers need descriptions of interventions and quantitative estimates of intervention effects to make informed decisions concerning prevention funding and research. The number of intervention strategies for MSM that have been examined with strong research designs has increased substantially in the past few years.

OBJECTIVES

1. To locate and describe outcome studies evaluating the effects of behavioral HIV prevention interventions for MSM.2. To summarize the effectiveness of these interventions in reducing unprotected anal sex.3. To identify study characteristics associated with effectiveness.4. To identify gaps and indicate future research, policy, and practice needs.

SEARCH STRATEGY

We searched electronic databases, current journals, manuscripts submitted by researchers, bibliographies of relevant articles, conference proceedings, and other reviews for published and unpublished reports from 1988 through December 2007. We also asked researchers working in HIV prevention about new and ongoing studies.

SELECTION CRITERIA

Studies were considered in scope if they examined the effects of behavioral interventions aimed at reducing risk for HIV or STD transmission among MSM. We reviewed studies in scope for criteria of outcome relevance (measurement of at least one of a list of behavioral or biologic outcomes, e.g., unprotected sex or incidence of HIV infections) and methodologic rigor (randomized controlled trials or certain strong quasi-experimental designs with comparison groups).

DATA COLLECTION AND ANALYSIS

We used fixed and random effects models to summarize rate ratios (RR) comparing intervention and control groups with respect to count outcomes (number of occasions of or partners for unprotected anal sex), and corresponding prevalence ratios (PR) for dichotomous outcomes (any unprotected anal sex vs. none). We used published formulas to convert effect sizes and their variances for count and dichotomous outcomes where necessary. We accounted for intraclass correlation (ICC) in community-level studies and adjusted for baseline conditions in all studies. We present separate results by intervention format (small group, individual, or community-level) and by type of intervention delivered to the comparison group (minimal or no HIV prevention in the comparison condition versus standard or other HIV prevention in the comparison condition). We examine rate ratios stratified according to characteristics of participants, design, implementation, and intervention content. For small group and individual-level interventions we used a stepwise selection process to identify a multivariable model of predictors of reduction in occasions of or partners for unprotected anal sex. We used funnel plots to examine publication bias, and Q (a chi-squared statistic with degrees of freedom = number of interventions minus 1) to test for heterogeneity.

MAIN RESULTS

We found 44 studies evaluating 58 interventions with 18,585 participants. Formats included 26 small group interventions, 21 individual-level interventions, and 11 community-level interventions. Sixteen of the 58 interventions focused on HIV-positives. The 40 interventions that were measured against minimal to no HIV prevention intervention reduced occasions of or partners for unprotected anal sex by 27% (95% confidence interval [CI] = 15% to 37%). The other 18 interventions reduced unprotected anal sex by 17% beyond changes observed in standard or other interventions (CI = 5% to 27%). Intervention effects were statistically homogeneous, and no independent variable was statistically significantly associated with intervention effects at alpha=.05. However, a multivariable model selected by backward stepwise elimination identified four study characteristics associated with reduction in occasions of or partners for unprotected anal sex among small group and individual-level interventions at alpha=.10. The most favorable reductions in episodes of or partners for unprotected anal sex (33% to 35% decreases) were observed among studies with count outcomes, those with shorter intervention spans (<=1 month), those with better retention in the intervention condition than in the comparison condition, and those with minimal to no HIV prevention intervention delivered to the comparison condition. Because there were only 11 community-level studies we did not search for a multivariable model for community-level interventions. In stratified analyses including only one variable at a time, the greatest reductions (40% to 54% decreases) in number of episodes of or partners for unprotected anal sex among community-level interventions were observed among studies where groups were assigned randomly rather than by convenience, studies with shorter recall periods and longer follow-up, studies with more than 25% non-gay identifying MSM, studies in which at least 90% of participants were white, and studies in which the intervention addressed development of personal skills.

AUTHORS' CONCLUSIONS

Behavioral interventions reduce self-reported unprotected anal sex among MSM. These results indicate that HIV prevention for this population can work and should be supported. Results of previous studies provide a benchmark for expectations in new studies. Meta-analysis can inform future design and implementation in terms of sample size, target populations, settings, goals for process measures, and intervention content. When effects differ by design variables, which are deliberately selected and planned, awareness of these characteristics may be beneficial to future designs. Researchers designing future small group and individual-level studies should keep in mind that to date, effects of the greatest magnitude have been observed in studies that used count outcomes and a shorter intervention span (up to 1 month). Among small group and individual-level studies, effects were also greatest when the comparison condition included minimal to no HIV prevention content. Nevertheless, statistically significant favorable effects were also seen when the comparison condition included standard or other HIV prevention content. Researchers choosing the latter option for new studies should plan for larger sample sizes based on the smaller expected net intervention effect noted above. When effects differ by implementation variables, which become evident as the study is conducted but are not usually selected or planned, caution may be advised so that future studies can reduce bias. Because intervention effects were somewhat stronger (though not statistically significantly so) in studies with a greater attrition in the comparison condition, differential retention may be a threat to validity. Extra effort should be given to retaining participants in comparison conditions. Among community-level interventions, intervention effects were strongest among studies with random assignment of groups or communities. Therefore the inclusion of studies where assignment of groups or communities was by convenience did not exaggerate the summary effect. The greater effectiveness of interventions including more than 25% non-gay identifying MSM suggests that when they can be reached, these men may be more responsive than gay-identified men to risk reduction efforts. Non-gay identified MSM may have had less exposure to previous prevention messages, so their initial exposure may have a greater impact. The greater effectiveness of interventions that include efforts to promote personal skills such as keeping condoms available and behavioral self-management indicates that such content merits strong consideration in development and delivery of new interventions for MSM. And the finding that interventions were most effective for majority white populations underscores the critical need for effective interventions for MSM of African and Latino descent. Further research measuring the incidence of HIV and other STDs is needed. Because most studies were conducted among mostly white men in the US and Europe, more evaluations of interventions are needed for African American and Hispanic MSM as well as MSM in the developing world. More research is also needed to further clarify which behavioral strategies (e.g., reducing unprotected anal sex, having oral sex instead of anal sex, reducing number of partners, avoiding serodiscordant partners, strategic positioning, or reducing anal sex even with condom use) are most effective in reducing transmission among MSM, the messages most effective in promoting these behaviors, and the methods and settings in which these messages can be most effectively delivered.