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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TL;DR: The HATSIDU is a simple and usable index for the assessment of HIV/AIDS risk behaviour knowledge in a population with an average risk of HIV infection.
Abstract: SUMMARY Purpose: A short HIV/AIDS risk behaviour knowledge index based on questions about HIV transmission and prevention of HIV infection during sexual intercourse and intravenous drug use is proposed and implemented for an HIV average risk population in Munich. Methods: Knowledge levels about HIV/AIDS risk behaviour was assessed in a group of people (n=210) in sexually active age range of 18-49 years which was at an average risk of contracting HIV. Four questions about HIV transmission by unprotected vaginal, anal, or oral sexual intercourse, and by needle sharing, and two questions about HIV prevention by condom use, and the single use of needles and syringes were chosen from ten others for making a four level risk behaviour knowledge index (HIV/AIDS Transmission through Sex and Intravenous Drug Use, HATSIDU) internally consistent according to Cronbach's alpha. Results: HATSIDU index (mean 3.0, SD±1.18) was not associated (p>0.05) with sex and marital status, but depended (p Conclusion: The HATSIDU is a simple and usable index for the assessment of HIV/AIDS risk behaviour knowledge in a population with an average risk of HIV infection. Key words: HIV/AIDS, risk behaviour knowledge INTRODUCTION Knowledge about HIV/AIDS is one usable indirect criterion for the assessment of behavioural risk and preventative behaviour regarding HIV infection. HIV/AIDS knowledge has been investigated in various populations, for example school students (1, 2), adolescents (3), migrant farm workers (4), pregnant women (5), the mentally ill (6), and also in a group of intravenous drug users (IDUs) who have a high risk of contracting HIV (7). The HIV/AIDS risk behaviour knowledge scale was first developed by Kelly et al. (1989) (8) using a group of students, and homosexual men (men who have sex with men, MSM). The assessment of HIV knowledge or HIV risk behaviour knowledge in population is usually performed by summing up correct answers to questions about HIV transmission and prevention according to age, gender, national, social, and educational status in a knowledge score (4, 6, 8). The summing up of correct answers to questions about the possibility of HIV transmission by sexual intercourse, intravenous drug sharing, from an infected mother to her child, by hand shaking, or by using public places assumes that all questions are of equal significance and the answers fall in the same rank of importance. Therefore, respondents who correctly answered questions about HIV transmission by sex and drug use but gave incorrect answers for questions about kissing and hand shaking, would receive the same summed knowledge score as the respondents who failed in questions about HIV transmission by sex and intravenous drug use but answered correctly on kissing and hand contact, for example. Because of the equality of all items in constructing a summed knowledge score, HIV/AIDS knowledge can be investigated, but it is not really useful for the assessment of risk behaviour knowledge regarding HIV/AIDS. Assessment of risk behaviour knowledge means that ignorance of some risks has more impact on risk behaviour than others. For example, ignorance about condom use cannot be equated with misconceptions about HIV transmission through hairdressing or by the use of public toilets. Since 2004, 26 European Union/European Economic Area countries with exception of Poland and Estonia have been reporting statistics regarding transmission routes of HIV infection (9). HIV incidence in EU/EEA decreased in 2009 (5.7/100,000 population) compared to 2004 (6.5/100,000) and was accompanied by a 40% decrease of intravenous transmission of HIV by intravenous drug users (IDUs), but by a 24% increase in homosexually (MSM) transmitted HIV. …
13 citations
TL;DR: Men with multiple partners had unexpectedly high UAS frequency per partner, paired with low HIV testing rates, and the basic reproductive number (R0) over 3 months indicated rapid transmission over a wide range of values of per-act transmissibility.
Abstract: Objectives Survey data from men who have sex with men (MSM) in Asian cities indicate ongoing and drastic increases in HIV prevalence. It is unknown which behavioural factors are most important in driving these epidemics. We aimed to analyse detailed sexual behaviour data among MSM in Vietnam and to model HIV transmission using improved assumptions on sexual network structure. Setting Vietnam. Participants Internet-using men who had ever had sex (any type) with a man, aged ≥18 years and living in Vietnam. The study was cross-sectional, population-based and performed in 2012, using online respondent-driven sampling. The Internet-based survey instrument was completed by 982 participants, of which 857 were eligible. Questions included sociodemography and retrospective sexual behaviour, including number of unprotected anal sex (UAS) acts per partner. Primary and secondary outcome measures Estimated basic reproductive number over 3 months as a function of transmission risk per UAS act; frequency distributions of number of UAS partners and UAS acts during last 3 months. Results 36% (CI 32% to 42%) reported UAS at least once during the last 3 months. 36% (CI 32% to 41%) had ever taken an HIV test and received the result. UAS partner numbers and number of UAS acts were both highly skewed and positively correlated. Using a weighted configuration model, taking into account partner numbers, frequency of UAS and their correlations, we estimated the basic reproductive number (R0) over 3 months. The results indicated rapid transmission over a wide range of values of per-act transmissibility. Conclusions Men with multiple partners had unexpectedly high UAS frequency per partner, paired with low HIV testing rates. The study highlights the importance of collecting data on frequency of UAS acts and indicates the need to rapidly scale-up HIV prevention services and testing opportunities for MSM in Vietnam.
13 citations
TL;DR: This effective approach to HIV prevention, care, and treatment is illustrated through examples of community-based responses in Haiti, the United States, Africa, and other impoverished settings.
Abstract: The AIDS epidemic has been fueled by global inequities. Ranging from gender inequality and underdevelopment to homophobia impeding health care access for men who have sex with men (MSM), imbalanced resource allocations and social biases have potentiated the epidemic’s spread. However, recognition of culturally specific aspects of each microepidemic has yielded development of community-based organizations, which have resulted in locally effective responses to AIDS. This effective approach to HIV prevention, care and treatment is illustrated through examples of community-based responses in Haiti, the United States, Africa, and other impoverished settings.
13 citations
TL;DR: A mechanism by which surface bound HIV-1 particles function as signaling receptors that regulate T cell motility, cell-cell contact dynamics, and productive infection is described.
13 citations
Cites background from "HIV transmission risk through anal ..."
...During sexual transmission, HIV gains entry at mucosal sites (vaginal, penile, and anal mucosae) through breaks in the mucosal epithelial barrier to infect a founder population of susceptible targets (Baggaley et al., 2010; Haase, 2010, 2011; Tebit et al., 2012)....
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TL;DR: This study indicates that small reductions in the time to diagnosis, and thereby, beginning of treatment, may substantially reduce HIV prevalence and highlights the importance of HIV testing and condom-use interventions, and the role that casual and steady partners play in this, in order to turn the epidemiological trend in Sweden towards decreased HIV incidence.
13 citations
References
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TL;DR: A new quantity is developed, I 2, which the authors believe gives a better measure of the consistency between trials in a meta-analysis, which is susceptible to the number of trials included in the meta- analysis.
Abstract: Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice?
Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis.
Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4
Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted?
A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …
45,105 citations
TL;DR: A checklist contains specifications for reporting of meta-analyses of observational studies in epidemiology, including background, search strategy, methods, results, discussion, and conclusion should improve the usefulness ofMeta-an analyses for authors, reviewers, editors, readers, and decision makers.
Abstract: ObjectiveBecause of the pressure for timely, informed decisions in public health
and clinical practice and the explosion of information in the scientific literature,
research results must be synthesized. Meta-analyses are increasingly used
to address this problem, and they often evaluate observational studies. A
workshop was held in Atlanta, Ga, in April 1997, to examine the reporting
of meta-analyses of observational studies and to make recommendations to aid
authors, reviewers, editors, and readers.ParticipantsTwenty-seven participants were selected by a steering committee, based
on expertise in clinical practice, trials, statistics, epidemiology, social
sciences, and biomedical editing. Deliberations of the workshop were open
to other interested scientists. Funding for this activity was provided by
the Centers for Disease Control and Prevention.EvidenceWe conducted a systematic review of the published literature on the
conduct and reporting of meta-analyses in observational studies using MEDLINE,
Educational Research Information Center (ERIC), PsycLIT, and the Current Index
to Statistics. We also examined reference lists of the 32 studies retrieved
and contacted experts in the field. Participants were assigned to small-group
discussions on the subjects of bias, searching and abstracting, heterogeneity,
study categorization, and statistical methods.Consensus ProcessFrom the material presented at the workshop, the authors developed a
checklist summarizing recommendations for reporting meta-analyses of observational
studies. The checklist and supporting evidence were circulated to all conference
attendees and additional experts. All suggestions for revisions were addressed.ConclusionsThe proposed checklist contains specifications for reporting of meta-analyses
of observational studies in epidemiology, including background, search strategy,
methods, results, discussion, and conclusion. Use of the checklist should
improve the usefulness of meta-analyses for authors, reviewers, editors, readers,
and decision makers. An evaluation plan is suggested and research areas are
explored.
17,663 citations
TL;DR: The problem of making a combined estimate has been discussed previously by Cochran and Yates and Cochran (1937) for agricultural experiments, and by Bliss (1952) for bioassays in different laboratories as discussed by the authors.
Abstract: When we are trying to make the best estimate of some quantity A that is available from the research conducted to date, the problem of combining results from different experiments is encountered. The problem is often troublesome, particularly if the individual estimates were made by different workers using different procedures. This paper discusses one of the simpler aspects of the problem, in which there is sufficient uniformity of experimental methods so that the ith experiment provides an estimate xi of u, and an estimate si of the standard error of xi . The experiments may be, for example, determinations of a physical or astronomical constant by different scientists, or bioassays carried out in different laboratories, or agricultural field experiments laid out in different parts of a region. The quantity xi may be a simple mean of the observations, as in a physical determination, or the difference between the means of two treatments, as in a comparative experiment, or a median lethal dose, or a regression coefficient. The problem of making a combined estimate has been discussed previously by Cochran (1937) and Yates and Cochran (1938) for agricultural experiments, and by Bliss (1952) for bioassays in different laboratories. The last two papers give recommendations for the practical worker. My purposes in treating the subject again are to discuss it in more general terms, to take account of some recent theoretical research, and, I hope, to bring the practical recommendations to the attention of some biologists who are not acquainted with the previous papers. The basic issue with which this paper deals is as follows. The simplest method of combining estimates made in a number of different experiments is to take the arithmetic mean of the estimates. If, however, the experiments vary in size, or appear to be of different precision, the investigator may wonder whether some kind of weighted meani would be more precise. This paper gives recommendations about the kinds of weighted mean that are appropriate, the situations in which they
4,335 citations
TL;DR: The viral load is the chief predictor of the risk of heterosexual transmission of HIV-1, and transmission is rare among persons with levels of less than 1500 copies of HIV -1 RNA per milliliter.
Abstract: Background and Methods We examined the influence of viral load in relation to other risk factors for the heterosexual transmission of human immunodeficiency virus type 1 (HIV-1). In a community-based study of 15,127 persons in a rural district of Uganda, we identified 415 couples in which one partner was HIV-1–positive and one was initially HIV-1–negative and followed them prospectively for up to 30 months. The incidence of HIV-1 infection per 100 person-years among the initially seronegative partners was examined in relation to behavioral and biologic variables. Results The male partner was HIV-1–positive in 228 couples, and the female partner was HIV-1–positive in 187 couples. Ninety of the 415 initially HIV-1–negative partners seroconverted (incidence, 11.8 per 100 person-years). The rate of male-to-female transmission was not significantly different from the rate of female-to-male transmission (12.0 per 100 person-years vs. 11.6 per 100 person-years). The incidence of seroconversion was highest among ...
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TL;DR: A theoretical strategy of universal voluntary HIV testing and immediate treatment with ART, combined with present prevention approaches, could have a major effect on severe generalised HIV/AIDS epidemics.
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