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: This study demonstrates that health of the index, anal intercourse and bleeding as a result of intercourse are the major determinants of sexual transmission of HIV to women in couples.
Abstract: OBJECTIVE: Since heterosexual transmission of HIV in the United States is occurring at an increasing rate, especially among black and Hispanic couples and those in which one member has a history of intravenous drug use, we sought to study the heterosexual transmission of HIV in couples. DESIGN: Multiple logistic regression analysis of risks for HIV infection in female partners. METHODS: We enrolled 158 non-intravenous drug user (IVDU) steady heterosexual partners of HIV-infected individuals (indexes) in this study. Of these, 93% were women, 54% were Hispanic whites, 23% were black and 65.6% were partners of IVDU. RESULTS: In a multiple logistic regression analysis of risks for HIV infection in female partners, the strongest predictors of transmission were AIDS or AIDS-related complex (ARC) in the index [adjusted odds ratios (OR), 16.81; P < 0.001 and 12.53; P = 0.003, respectively], a history of anal intercourse (adjusted OR, 10.81; P < 0.001) and bleeding as a result of intercourse (adjusted OR, 4.90; P < 0.05). Female-to-male transmission was detected in seven out of 11 couples at risk. Ethnicity, number of episodes of vaginal intercourse, number of other sexual partners and history of sexually transmitted infections were not significantly associated with transmission to women. CONCLUSION: Our study demonstrates that health of the index, anal intercourse and bleeding as a result of intercourse are the major determinants of sexual transmission of HIV to women in couples.
106 citations
TL;DR: The data suggest that heterosexual transmission of HIV can occur during routine vaginal intercourse but that it usually does not occur until the hemophiliac has severe immune deficiency late in the course of HIV infection.
Abstract: We evaluated risk factors for human immunodeficiency virus (HIV) seropositivity in the wives/female sexual partners of hemophiliacs. One of the 6 seropositive women has developed the acquired immunodeficiency syndrome (AIDS). At least three of the others seroconverted during 1985-86, after more than four years of regular sexual contact with a seropositive hemophiliac. HIV seropositivity was present in at least 5 (50%) of the 10 female partners of hemophiliacs with severe depletion of T-helper cells (less than 100/microliters), including 3 (43%) of the 7 female partners of hemophiliacs with AIDS. All 4 HIV seropositive women with available data had vaginal intercourse without a condom, but risk of seropositivity did not appear to be affected by the frequency of vaginal intercourse or by hysterectomy. Other sexually transmitted diseases, anal intercourse, or vaginal intercourse during menstrual periods were not necessary for HIV infection. These data suggest that heterosexual transmission of HIV can occur during routine vaginal intercourse but that it usually does not occur until the hemophiliac has severe immune deficiency late in the course of HIV infection.
101 citations
TL;DR: Both anal intercourse and dry sex were common in this sample of female sex workers in Kenya, and although perceived as high risk practices, were not adequately protected with condom use.
Abstract: Objective: To examine the practices of anal intercourse and dry sex within a cohort of female sex workers (FSWs) in Kenya, focusing on the prevalence and perceived risk of the practices, demographic and behavioural correlates, and association with sexually transmitted infections (STI). Methods: A survey was conducted among FSWs in Meru, Kenya, with 147 participants randomly sampled from an existing cohort of self identified FSWs. Results: 40.8% of participants reported ever practising anal intercourse and 36.1% reported ever practising dry sex. Although the majority of women surveyed believed anal intercourse and dry sex to be high risk practices for HIV infection compared with vaginal sex, about one third of women reported never or rarely using condoms during anal intercourse, and about 20% never or rarely using condoms during dry sex. Reported consistent condom use was lower with both of these practices than with penile-vaginal intercourse. Anal intercourse was associated with experience of recent forced sexual intercourse, while dry sex was not. Anal intercourse was almost always initiated by clients, whereas dry sex was likely to be initiated by the women themselves. Sex workers reported charging higher fees for both practices than for vaginal intercourse. Both practices were associated with reported symptoms and diagnoses of STI. Conclusions: Both anal intercourse and dry sex were common in this sample, and although perceived as high risk practices, were not adequately protected with condom use. Education and other interventions regarding these high risk sexual behaviours need to be translated into safer practices, particularly consistent condom use, even in the face of financial vulnerability.
98 citations
TL;DR: In this article, the authors examined the occurrence of anal intercourse in samples drawn from community and clinic settings and found that men used condoms during 67% and women 50% of the anal intercourse occasions and that anal intercourse was associated with younger age, being unmarried, having a history of STI, exchanging sex, using substances, having been tested for HIV and testing HIV positive.
Abstract: Background: Anal intercourse is an efficient mode of HIV transmission and may play a role in the heterosexual HIV epidemics of southern Africa. However, little information is available on the anal sex practices of heterosexual individuals in South Africa. Purpose: To examine the occurrence of anal intercourse in samples drawn from community and clinic settings. Methods: Anonymous surveys collected from convenience samples of 2593 men and 1818 women in two townships and one large city sexually transmitted infection (STI) clinic in Cape Town. Measures included demographics, HIV risk history, substance use and 3-month retrospective sexual behaviour. Results: A total of 14% (n = 360) men and 10% (n = 172) women reported engaging in anal intercourse in the past 3 months. Men used condoms during 67% and women 50% of anal intercourse occasions. Anal intercourse was associated with younger age, being unmarried, having a history of STI, exchanging sex, using substances, having been tested for HIV and testing HIV positive. Conclusions: Anal intercourse is reported relatively less frequently than unprotected vaginal intercourse among heterosexual individuals. The low prevalence of anal intercourse among heterosexual individuals may be offset by its greater efficiency for transmitting HIV. Anal sex should be discussed in heterosexual HIV prevention programming.
96 citations