HIV transmission risk through anal intercourse: systematic review, meta-analysis and implications for HIV prevention
01 Aug 2010-International Journal of Epidemiology (Oxford University Press)-Vol. 39, Iss: 4, pp 1048-1063
TL;DR: It was demonstrated that it would require unreasonably low numbers of AI HIV exposures per partnership to reconcile the summary per-act and per-partner estimates, suggesting considerable variability in AI infectiousness between and within partnerships over time.
Abstract: Background The human immunodeficiency virus (HIV) infectiousness of anal intercourse (AI) has not been systematically reviewed, despite its role driving HIV epidemics among men who have sex with men (MSM) and its potential contribution to heterosexual spread. We assessed the per-act and per-partner HIV transmission risk from AI exposure for heterosexuals and MSM and its implications for HIV prevention.
Methods Systematic review and meta-analysis of the literature on HIV-1 infectiousness through AI was conducted. PubMed was searched to September 2008. A binomial model explored the individual risk of HIV infection with and without highly active antiretroviral therapy (HAART).
Results A total of 62 643 titles were searched; four publications reporting per-act and 12 reporting per-partner transmission estimates were included. Overall, random effects model summary estimates were 1.4% [95% confidence interval (CI) 0.2–2.5)] and 40.4% (95% CI 6.0–74.9) for per-act and per-partner unprotected receptive AI (URAI), respectively. There was no significant difference between per-act risks of URAI for heterosexuals and MSM. Per-partner unprotected insertive AI (UIAI) and combined URAI–UIAI risk were 21.7% (95% CI 0.2–43.3) and 39.9% (95% CI 22.5–57.4), respectively, with no available per-act estimates. Per-partner combined URAI–UIAI summary estimates, which adjusted for additional exposures other than AI with a ‘main’ partner [7.9% (95% CI 1.2–14.5)], were lower than crude (unadjusted) estimates [48.1% (95% CI 35.3–60.8)]. Our modelling demonstrated that it would require unreasonably low numbers of AI HIV exposures per partnership to reconcile the summary per-act and per-partner estimates, suggesting considerable variability in AI infectiousness between and within partnerships over time. AI may substantially increase HIV transmission risk even if the infected partner is receiving HAART; however, predictions are highly sensitive to infectiousness assumptions based on viral load.
Conclusions Unprotected AI is a high-risk practice for HIV transmission, probably with substantial variation in infectiousness. The significant heterogeneity between infectiousness estimates means that pooled AI HIV transmission probabilities should be used with caution. Recent reported rises in AI among heterosexuals suggest a greater understanding of the role AI plays in heterosexual sex lives may be increasingly important for HIV prevention.
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University of Colorado Denver1, University of California, San Francisco2, Asociación Civil Impacta Salud y Educación3, Oswaldo Cruz Foundation4, Chiang Mai University5, Federal University of Rio de Janeiro6, University of Cape Town7, Brown University8, University of São Paulo9, National Institutes of Health10
TL;DR: Oral FTC-TDF provided protection against the acquisition of HIV infection among the subjects and Detectable blood levels strongly correlated with the prophylactic effect.
Abstract: The study subjects were followed for 3324 person-years (median, 1.2 years; maximum, 2.8 years). Of these subjects, 10 were found to have been infected with HIV at en rollment, and 100 became infected during follow-up (36 in the FTC–TDF group and 64 in the placebo group), indicating a 44% reduction in the incidence of HIV (95% confidence interval, 15 to 63; P = 0.005). In the FTC–TDF group, the study drug was detected in 22 of 43 of seronegative subjects (51%) and in 3 of 34 HIV-infected subjects (9%) (P<0.001). Nausea was reported more frequently during the first 4 weeks in the FTC–TDF group than in the placebo group (P<0.001). The two groups had similar rates of serious adverse events (P = 0.57). Conclusions Oral FTC–TDF provided protection against the acquisition of HIV infection among the subjects. Detectable blood levels strongly correlated with the prophylactic effect. (Funded by the National Institutes of Health and the Bill and Melinda Gates Foun dation; ClinicalTrials.gov number, NCT00458393.)
4,247 citations
TL;DR: It is shown that the high probability of transmission per act through receptive anal intercourse has a central role in explaining the disproportionate disease burden in MSM and prevention strategies that lower biological transmission and acquisition risks offer promise.
1,369 citations
TL;DR: The findings suggest that transgender women are a very high burden population for HIV and are in urgent need of prevention, treatment, and care services.
Abstract: Summary Background Previous systematic reviews have identified a high prevalence of HIV infection in transgender women in the USA and in those who sell sex (compared with both female and male sex workers). However, little is known about the burden of HIV infection in transgender women worldwide. We aimed to better assess the relative HIV burden in all transgender women worldwide. Methods We did a systematic review and meta-analysis of studies that assessed HIV infection burdens in transgender women that were published between Jan 1, 2000, and Nov 30, 2011. Meta-analysis was completed with the Mantel-Haenszel method, and random-effects modelling was used to compare HIV burdens in transgender women with that in adults in the countries for which data were available. Findings Data were only available for countries with male-predominant HIV epidemics, which included the USA, six Asia-Pacific countries, five in Latin America, and three in Europe. The pooled HIV prevalence was 19·1% (95% CI 17·4–20·7) in 11 066 transgender women worldwide. In 7197 transgender women sampled in ten low-income and middle-income countries, HIV prevalence was 17·7% (95% CI 15·6–19·8). In 3869 transgender women sampled in five high-income countries, HIV prevalence was 21·6% (95% CI 18·8–24·3). The odds ratio for being infected with HIV in transgender women compared with all adults of reproductive age across the 15 countries was 48·8 (95% CI 21·2–76·3) and did not differ for those in low-income and middle-income countries compared with those in high-income countries. Interpretation Our findings suggest that transgender women are a very high burden population for HIV and are in urgent need of prevention, treatment, and care services. The meta-analysis showed remarkable consistency and severity of the HIV disease burden among transgender women. Funding Center for AIDS Research at Johns Hopkins and the Center for Public Health and Human Rights at the JHU Bloomberg School of Public Health.
1,142 citations
University College London1, University of Copenhagen2, University of St. Gallen3, University of Hamburg4, Hospital Clínico San Carlos5, University of Liverpool6, Universidad Miguel Hernández de Elche7, University of Victoria8, University of Zurich9, Karolinska University Hospital10, University of Bern11, Medical University of Vienna12, University Hospital of Basel13, Praxis14, Helsinki University Central Hospital15, Warwickshire Hospital16
TL;DR: Evaluating the rate of within-couple HIV transmission among serodifferent heterosexual and MSM couples during periods of sex without condoms and when the HIV-positive partner had HIV-1 RNA load less than 200 copies/mL found no phylogenetically linked transmissions.
Abstract: Importance A key factor in assessing the effectiveness and cost-effectiveness of antiretroviral therapy (ART) as a prevention strategy is the absolute risk of HIV transmission through condomless sex with suppressed HIV-1 RNA viral load for both anal and vaginal sex. Objective To evaluate the rate of within-couple HIV transmission (heterosexual and men who have sex with men [MSM]) during periods of sex without condoms and when the HIV-positive partner had HIV-1 RNA load less than 200 copies/mL. Design, Setting, and Participants The prospective, observational PARTNER (Partners of People on ART—A New Evaluation of the Risks) study was conducted at 75 clinical sites in 14 European countries and enrolled 1166 HIV serodifferent couples (HIV-positive partner taking suppressive ART) who reported condomless sex (September 2010 to May 2014). Eligibility criteria for inclusion of couple-years of follow-up were condomless sex and HIV-1 RNA load less than 200 copies/mL. Anonymized phylogenetic analysis compared couples’ HIV-1 polymerase and envelope sequences if an HIV-negative partner became infected to determine phylogenetically linked transmissions. Exposures Condomless sexual activity with an HIV-positive partner taking virally suppressive ART. Main Outcomes and Measures Risk of within-couple HIV transmission to the HIV-negative partner Results Among 1166 enrolled couples, 888 (mean age, 42 years [IQR, 35-48]; 548 heterosexual [61.7%] and 340 MSM [38.3%]) provided 1238 eligible couple-years of follow-up (median follow-up, 1.3 years [IQR, 0.8-2.0]). At baseline, couples reported condomless sex for a median of 2 years (IQR, 0.5-6.3). Condomless sex with other partners was reported by 108 HIV-negative MSM (33%) and 21 heterosexuals (4%). During follow-up, couples reported condomless sex a median of 37 times per year (IQR, 15-71), with MSM couples reporting approximately 22 000 condomless sex acts and heterosexuals approximately 36 000. Although 11 HIV-negative partners became HIV-positive (10 MSM; 1 heterosexual; 8 reported condomless sex with other partners), no phylogenetically linked transmissions occurred over eligible couple-years of follow-up, giving a rate of within-couple HIV transmission of zero, with an upper 95% confidence limit of 0.30/100 couple-years of follow-up. The upper 95% confidence limit for condomless anal sex was 0.71 per 100 couple-years of follow-up. Conclusions and Relevance Among serodifferent heterosexual and MSM couples in which the HIV-positive partner was using suppressive ART and who reported condomless sex, during median follow-up of 1.3 years per couple, there were no documented cases of within-couple HIV transmission (upper 95% confidence limit, 0.30/100 couple-years of follow-up). Additional longer-term follow-up is necessary to provide more precise estimates of risk.
1,039 citations
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TL;DR: The role of immune activation in the pathogenesis of non-AIDS clinical events (major causes of morbidity and mortality in people on antiretroviral therapy) is receiving increased recognition and breakthroughs in the prevention of HIV important to public health include male medical circumcision.
687 citations
References
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TL;DR: HIV prevalence and risk behavior in a sample of truck drivers visiting commercial sex workers at truck stops may have facilitated the spread of HIV infection throughout southern Africa.
Abstract: BackgroundAlthough the role of mobile populations in the spread of HIV has been documented in several countries, there are few data on HIV among truck drivers in South Africa and the sex workers with whom they interact.GoalTo determine HIV prevalence and risk behavior in a sample of truck drivers vi
192 citations
TL;DR: It would be beneficial to track the prevalence of heterosexual anal and oral sex and associated condom use on a more frequent basis.
Abstract: Background. Heterosexual anal and oral sex are related to the acquisition of sexually transmitted infections, including human immunodeficiency virus infection. We examined the correlates of heterosexual anal and oral sex in the general population, using data from the National Survey of Family Growth. Methods. The sample included 12,571 men and women aged 15‐44 years (79% response rate). Results. One-third of men and women had ever had anal sex, and three-quarters had ever had oral sex. Condom use during last oral or anal sex was relatively uncommon. In separate models for men and women, having ever had anal sex was associated with white race, age of 20‐44 years, and having had a nonmonogamous sex partner. White race,ageof20‐44years,beingmarried,andhavinghighernumbersoflifetimesexpartnerswererelatedtohavingever given oral sex in men and women. Giving oral sex was associated with having a nonmonogamous sex partner in men. Ever receiving oral sex was associated with white race and a nonmonogamous sex partner in men and women. Conclusions. It would be beneficial to track the prevalence of heterosexual anal and oral sex and associated
182 citations
TL;DR: In this article, the impact of highly active antiretroviral therapy on the HIV-1 epidemic among men who have sex with men in the Netherlands has been quantified.
Abstract: Objective: Reducing viral load, highly active antiretroviral therapy has the potential to limit onwards transmission of HIV-1 and thus help contain epidemic spread. However, increases in risk behaviour and resurgent epidemics have been widely reported post-highly active antiretroviral therapy. The aim of this study was to quantify the impact that highly active antiretroviral therapy had on the epidemic. Design: We focus on the HIV-1 epidemic among men who have sex with men in the Netherlands, which has been well documented over the past 20 years within several long-standing national surveillance programs. Methods: We used a mathematical model including highly active antiretroviral therapy use and estimated the changes in risk behaviour and diagnosis rate needed to explain annual data on HIV and AIDS diagnoses. Results: We show that the reproduction number R(t), a measure of the state of the epidemic, declined early on from initial values above two and was maintained below one from 1985 to 2000. Since 1996, when highly active antiretroviral therapy became widely used, the risk behaviour rate has increased 66%, resulting in an increase of R(t) to 1.04 in the latest period 2000-2004 (95% confidence interval 0.98-1.09) near or just above the threshold for a self-sustaining epidemic. Hypothetical scenario analysis shows that the epidemiological benefits of highly active antiretroviral therapy and earlier diagnosis on incidence have been entirely offset by increases in the risk behaviour rate. Conclusion: We provide the first detailed quantitative analysis of the HIV epidemic in a well defined population and find a resurgent epidemic in the era of highly active antiretroviral therapy, most likely predominantly caused by increasing sexual risk behaviour.
181 citations
TL;DR: A review of preclinical and clinical research on the development of microbicides formulated to prevent vaginal HIV transmission yielded 118 studies, with most of them finding microbicide compounds to be safe and well tolerated but not demonstrating efficacy in preventing HIV transmission.
Abstract: Summary Worldwide, nearly half of all individuals living with HIV are now women, who acquire the virus largely by heterosexual exposure. With an HIV vaccine likely to be years away, topical microbicide formulations applied vaginally or rectally are being investigated as another strategy for HIV prevention. A review of preclinical and clinical research on the development of microbicides formulated to prevent vaginal HIV transmission yielded 118 studies: 73 preclinical and 45 clinical. Preclinical research included in-vitro assays and cervical explant models, as well as animal models. Clinical research included phase I and II/IIb safety studies, and phase III efficacy studies. Whereas most phase I and phase II clinical trials have found microbicide compounds to be safe and well tolerated, phase III trials completed to date have not demonstrated efficacy in preventing HIV transmission. Topical microbicides are grouped into five classes of agents, based on where they disrupt the pathway of sexual transmission of HIV. These classes include surfactants/membrane disruptors, vaginal milieu protectors, viral entry inhibitors, reverse transcriptase inhibitors, and a fifth group whose mechanism is unknown. The trajectory of microbicide development has been toward agents that block more specific virus–host cell interactions. Microbicide clinical trials face scientifically and ethically complex issues, such as the choice of placebo gel, the potential for viral resistance, and the inclusion of HIV-infected participants. Assessment of combination agents will most likely advance this field of research.
176 citations