Male circumcision for HIV prevention in men in Rakai, Uganda: a randomised trial

BACKGROUND

Ecological and observational studies suggest that male circumcision reduces the risk of HIV acquisition in men. Our aim was to investigate the effect of male circumcision on HIV incidence in men.

METHODS

4996 uncircumcised, HIV-negative men aged 15-49 years who agreed to HIV testing and counselling were enrolled in this randomised trial in rural Rakai district, Uganda. Men were randomly assigned to receive immediate circumcision (n=2474) or circumcision delayed for 24 months (2522). HIV testing, physical examination, and interviews were repeated at 6, 12, and 24 month follow-up visits. The primary outcome was HIV incidence. Analyses were done on a modified intention-to-treat basis. This trial is registered with ClinicalTrials.gov, with the number NCT00425984.

FINDINGS

Baseline characteristics of the men in the intervention and control groups were much the same at enrollment. Retention rates were much the same in the two groups, with 90-92% of participants retained at all time points. In the modified intention-to-treat analysis, HIV incidence over 24 months was 0.66 cases per 100 person-years in the intervention group and 1.33 cases per 100 person-years in the control group (estimated efficacy of intervention 51%, 95% CI 16-72; p=0.006). The as-treated efficacy was 55% (95% CI 22-75; p=0.002); efficacy from the Kaplan-Meier time-to-HIV-detection as-treated analysis was 60% (30-77; p=0.003). HIV incidence was lower in the intervention group than it was in the control group in all sociodemographic, behavioural, and sexually transmitted disease symptom subgroups. Moderate or severe adverse events occurred in 84 (3.6%) circumcisions; all resolved with treatment. Behaviours were much the same in both groups during follow-up.

INTERPRETATION

Male circumcision reduced HIV incidence in men without behavioural disinhibition. Circumcision can be recommended for HIV prevention in men.

Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial

BACKGROUND

Randomised placebo-controlled trials have shown that daily oral pre-exposure prophylaxis (PrEP) with tenofovir-emtricitabine reduces the risk of HIV infection. However, this benefit could be counteracted by risk compensation in users of PrEP. We did the PROUD study to assess this effect.

METHODS

PROUD is an open-label randomised trial done at 13 sexual health clinics in England. We enrolled HIV-negative gay and other men who have sex with men who had had anal intercourse without a condom in the previous 90 days. Participants were randomly assigned (1:1) to receive daily combined tenofovir disoproxil fumarate (245 mg) and emtricitabine (200 mg) either immediately or after a deferral period of 1 year. Randomisation was done via web-based access to a central computer-generated list with variable block sizes (stratified by clinical site). Follow-up was quarterly. The primary outcomes for the pilot phase were time to accrue 500 participants and retention; secondary outcomes included incident HIV infection during the deferral period, safety, adherence, and risk compensation. The trial is registered with ISRCTN (number ISRCTN94465371) and ClinicalTrials.gov (NCT02065986).

FINDINGS

We enrolled 544 participants (275 in the immediate group, 269 in the deferred group) between Nov 29, 2012, and April 30, 2014. Based on early evidence of effectiveness, the trial steering committee recommended on Oct 13, 2014, that all deferred participants be offered PrEP. Follow-up for HIV incidence was complete for 243 (94%) of 259 patient-years in the immediate group versus 222 (90%) of 245 patient-years in the deferred group. Three HIV infections occurred in the immediate group (1·2/100 person-years) versus 20 in the deferred group (9·0/100 person-years) despite 174 prescriptions of post-exposure prophylaxis in the deferred group (relative reduction 86%, 90% CI 64-96, p=0·0001; absolute difference 7·8/100 person-years, 90% CI 4·3-11·3). 13 men (90% CI 9-23) in a similar population would need access to 1 year of PrEP to avert one HIV infection. We recorded no serious adverse drug reactions; 28 adverse events, most commonly nausea, headache, and arthralgia, resulted in interruption of PrEp. We detected no difference in the occurrence of sexually transmitted infections, including rectal gonorrhoea and chlamydia, between groups, despite a suggestion of risk compensation among some PrEP recipients.

INTERPRETATION

In this high incidence population, daily tenofovir-emtricitabine conferred even higher protection against HIV than in placebo-controlled trials, refuting concerns that effectiveness would be less in a real-world setting. There was no evidence of an increase in other sexually transmitted infections. Our findings strongly support the addition of PrEP to the standard of prevention for men who have sex with men at risk of HIV infection.

FUNDING

MRC Clinical Trials Unit at UCL, Public Health England, and Gilead Sciences.

On-Demand Preexposure Prophylaxis in Men at High Risk for HIV-1 Infection

BACKGROUND

Antiretroviral preexposure prophylaxis has been shown to reduce the risk of human immunodeficiency virus type 1 (HIV-1) infection in some studies, but conflicting results have been reported among studies, probably due to challenges of adherence to a daily regimen.

METHODS

We conducted a double-blind, randomized trial of antiretroviral therapy for preexposure HIV-1 prophylaxis among men who have unprotected anal sex with men. Participants were randomly assigned to take a combination of tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) or placebo before and after sexual activity. All participants received risk-reduction counseling and condoms and were regularly tested for HIV-1 and HIV-2 and other sexually transmitted infections.

RESULTS

Of the 414 participants who underwent randomization, 400 who did not have HIV infection were enrolled (199 in the TDF-FTC group and 201 in the placebo group). All participants were followed for a median of 9.3 months (interquartile range, 4.9 to 20.6). A total of 16 HIV-1 infections occurred during follow-up, 2 in the TDF-FTC group (incidence, 0.91 per 100 person-years) and 14 in the placebo group (incidence, 6.60 per 100 person-years), a relative reduction in the TDF-FTC group of 86% (95% confidence interval, 40 to 98; P=0.002). Participants took a median of 15 pills of TDF-FTC or placebo per month (P=0.57). The rates of serious adverse events were similar in the two study groups. In the TDF-FTC group, as compared with the placebo group, there were higher rates of gastrointestinal adverse events (14% vs. 5%, P=0.002) and renal adverse events (18% vs. 10%, P=0.03).

CONCLUSIONS

The use of TDF-FTC before and after sexual activity provided protection against HIV-1 infection in men who have sex with men. The treatment was associated with increased rates of gastrointestinal and renal adverse events. (Funded by the National Agency of Research on AIDS and Viral Hepatitis [ANRS] and others; ClinicalTrials.gov number, NCT01473472.).

Theories of reasoned action and planned behavior as models of condom use: a meta-analysis

To examine how well the theories of reasoned action and planned behavior predict condom use, the authors synthesized 96 data sets (N = 22,594) containing associations between the models' key variables. Consistent with the theory of reasoned action's predictions, (a) condom use was related to intentions (weighted mean r. = .45), (b) intentions were based on attitudes (r. = .58) and subjective norms (r. = .39), and (c) attitudes were associated with behavioral beliefs (r. = .56) and norms were associated with normative beliefs (r. = .46). Consistent with the theory of planned behavior's predictions, perceived behavioral control was related to condom use intentions (r. = .45) and condom use (r. = .25), but in contrast to the theory, it did not contribute significantly to condom use. The strength of these associations, however, was influenced by the consideration of past behavior. Implications of these results for HIV prevention efforts are discussed.

Genital human papillomavirus infection: incidence and risk factors in a cohort of female university students

Incidence data on human papillomavirus (HPV) infection are limited, and risk factors for transmission are largely unknown. The authors followed 603 female university students in Washington State at 4-month intervals between 1990 and 2000. At each visit, a sexual and health questionnaire was completed and cervical and vulvovaginal samples were collected to detect HPV DNA. At 24 months, the cumulative incidence of first-time infection was 32.3% (95% confidence interval: 28.0, 37.1). Incidences calculated from time of new-partner acquisition were comparable for enrolled virgins and nonvirgins. Smoking, oral contraceptive use, and report of a new male sex partner--in particular, one known for less than 8 months before sex occurred or one reporting other partners--were predictive of incident infection. Always using male condoms with a new partner was not protective. Infection in virgins was rare, but any type of nonpenetrative sexual contact was associated with an increased risk. Detection of oral HPV was rare and was not associated with oral-penile contact. The data show that the incidence of HPV associated with acquisition of a new sex partner is high and that nonpenetrative sexual contact is a plausible route of transmission in virgins.

Global epidemiology of HIV among female sex workers: influence of structural determinants

Female sex workers (FSWs) bear a disproportionately large burden of HIV infection worldwide. Despite decades of research and programme activity, the epidemiology of HIV and the role that structural determinants have in mitigating or potentiating HIV epidemics and access to care for FSWs is poorly understood. We reviewed available published data for HIV prevalence and incidence, condom use, and structural determinants among this group. Only 87 (43%) of 204 unique studies reviewed explicitly examined structural determinants of HIV. Most studies were from Asia, with few from areas with a heavy burden of HIV such as sub-Saharan Africa, Russia, and eastern Europe. To further explore the potential effect of structural determinants on the course of epidemics, we used a deterministic transmission model to simulate potential HIV infections averted through structural changes in regions with concentrated and generalised epidemics, and high HIV prevalence among FSWs. This modelling suggested that elimination of sexual violence alone could avert 17% of HIV infections in Kenya (95% uncertainty interval [UI] 1-31) and 20% in Canada (95% UI 3-39) through its immediate and sustained effect on non-condom use) among FSWs and their clients in the next decade. In Kenya, scaling up of access to antiretroviral therapy among FSWs and their clients to meet WHO eligibility of a CD4 cell count of less than 500 cells per μL could avert 34% (95% UI 25-42) of infections and even modest coverage of sex worker-led outreach could avert 20% (95% UI 8-36) of infections in the next decade. Decriminalisation of sex work would have the greatest effect on the course of HIV epidemics across all settings, averting 33-46% of HIV infections in the next decade. Multipronged structural and community-led interventions are crucial to increase access to prevention and treatment and to promote human rights for FSWs worldwide.

Structural approaches to HIV prevention

Recognition that social, economic, political, and environmental factors directly affect HIV risk and vulnerability has stimulated interest in structural approaches to HIV prevention. Progress in the use of structural approaches has been limited for several reasons: absence of a clear definition; lack of operational guidance; and limited data on the effectiveness of structural approaches to the reduction of HIV incidence. In this paper we build on evidence and experience to address these gaps. We begin by defining structural factors and approaches. We describe the available evidence on their effectiveness and discuss methodological challenges to the assessment of these often complex efforts to reduce HIV risk and vulnerability. We identify core principles for implementing this kind of work. We also provide recommendations for ensuring the integration of structural approaches as part of combined prevention strategies.

Behavioural strategies to reduce HIV transmission: how to make them work better

This paper makes five key points. First is that the aggregate effect of radical and sustained behavioural changes in a sufficient number of individuals potentially at risk is needed for successful reductions in HIV transmission. Second, combination prevention is essential since HIV prevention is neither simple nor simplistic. Reductions in HIV transmission need widespread and sustained efforts, and a mix of communication channels to disseminate messages to motivate people to engage in a range of options to reduce risk. Third, prevention programmes can do better. The effect of behavioural strategies could be increased by aiming for many goals (eg, delay in onset of first intercourse, reduction in number of sexual partners, increases in condom use, etc) that are achieved by use of multilevel approaches (eg, couples, families, social and sexual networks, institutions, and entire communities) with populations both uninfected and infected with HIV. Fourth, prevention science can do better. Interventions derived from behavioural science have a role in overall HIV-prevention efforts, but they are insufficient when used by themselves to produce substantial and lasting reductions in HIV transmission between individuals or in entire communities. Fifth, we need to get the simple things right. The fundamentals of HIV prevention need to be agreed upon, funded, implemented, measured, and achieved. That, presently, is not the case.

Sexual behaviour in Britain: partnerships, practices, and HIV risk behaviours

BACKGROUND

Sexual behaviour is a major determinant of sexual and reproductive health. We did a National Survey of Sexual Attitudes and Lifestyles (Natsal 2000) in 1999-2001 to provide population estimates of behaviour patterns and to compare them with estimates from 1990-91 (Natsal 1990).

METHODS

We did a probability sample survey of men and women aged 16-44 years who were resident in Britain, using computer-assisted interviews. Results were compared with data from respondents in Natsal 1990.

FINDINGS

We interviewed 11161 respondents (4762 men, 6399 women). Patterns of heterosexual and homosexual partnership varied substantially by age, residence in Greater London, and marital status. In the past 5 years, mean numbers of heterosexual partners were 3.8 (SD 8.2) for men, and 2.4 (SD 4.6) for women; 2.6% (95% CI 2.2-3.1) of both men and women reported homosexual partnerships; and 4.3% (95% CI 3.7-5.0) of men reported paying for sex. In the past year, mean number of new partners varied from 2.04 (SD 8.4) for single men aged 25-34 years to 0.05 (SD 0.3) for married women aged 35-44 years. Prevalence of many reported behaviours had risen compared with data from Natsal 1990. Benefits of greater condom use were offset by increases in reported partners. Changes between surveys were generally greater for women than men and for respondents outside London.

INTERPRETATION

Our study provides updated estimates of sexual behaviour patterns. The increased reporting of risky sexual behaviours is consistent with changing cohabitation patterns and rising incidence of sexually transmitted infections. Observed differences between Natsal 1990 and Natsal 2000 are likely to result from a combination of true change and greater willingness to report sensitive behaviours in Natsal 2000 due to improved survey methodology and more tolerant social attitudes.

Sexual behaviour in context: a global perspective

Research aimed at investigating sexual behaviour and assessing interventions to improve sexual health has increased in recent decades. The resulting data, despite regional differences in quantity and quality, provide a historically unique opportunity to describe patterns of sexual behaviour and their implications for attempts to protect sexual health at the beginning of the 21st century. In this paper we present original analyses of sexual behaviour data from 59 countries for which they were available. The data show substantial diversity in sexual behaviour by region and sex. No universal trend towards earlier sexual intercourse has occurred, but the shift towards later marriage in most countries has led to an increase in premarital sex, the prevalence of which is generally higher in developed countries than in developing countries, and is higher in men than in women. Monogamy is the dominant pattern everywhere, but having had two or more sexual partners in the past year is more common in men than in women, and reported rates are higher in industrialised than in non-industrialised countries. Condom use has increased in prevalence almost everywhere, but rates remain low in many developing countries. The huge regional variation indicates mainly social and economic determinants of sexual behaviour, which have implications for intervention. Although individual behaviour change is central to improving sexual health, efforts are also needed to address the broader determinants of sexual behaviour, particularly those that relate to the social context. The evidence from behavioural interventions is that no general approach to sexual-health promotion will work everywhere and no single-component intervention will work anywhere. Comprehensive behavioural interventions are needed that take account of the social context in mounting individual-level programmes, attempt to modify social norms to support uptake and maintenance of behaviour change, and tackle the structural factors that contribute to risky sexual behaviour.

Psychosocial correlates of heterosexual condom use: a meta-analysis

Despite increasing incidence of HIV/AIDS, there has been no systematic review of correlates of condom use among heterosexual samples. To rectify this, the present study used meta-analysis to quantify the relationship between psychosocial variables and self-reported condom use. Six hundred sixty correlations distributed across 44 variables were derived from 121 empirical studies. Variables were organized in terms of the labeling, commitment, and enactment stages of the AIDS Risk Reduction Model (Catania, Kegeles, & Coates, 1990). Findings showed that demographic, personality, and labeling stage variables had small average correlations with condom use. Commitment and enactment stage variables fared better, with attitudes toward condoms, behavioral intentions, and communication about condoms being the most important predictors. Overall, findings support a social psychological model of condom use highlighting the importance of behavior-specific cognitions, social interaction, and preparatory behaviors rather than knowledge and beliefs about the threat of infection.

Abstinence and safer sex HIV risk-reduction interventions for African American adolescents: a randomized controlled trial

CONTEXT

African American adolescents are at high risk of contracting sexually transmitted infection with human immunodeficiency virus (HIV), but which behavioral interventions to reduce risk are most effective and who should conduct them is not known.

OBJECTIVE

To evaluate the effects of abstinence and safer-sex HIV risk-reduction interventions on young inner-city African American adolescents' HIV sexual risk behaviors when implemented by adult facilitators as compared with peer cofacilitators.

DESIGN

Randomized controlled trial with 3-, 6-, and 12-month follow-up.

SETTING

Three middle schools serving low-income African American communities in Philadelphia, Pa.

PARTICIPANTS

A total of 659 African American adolescents recruited for a Saturday program.

INTERVENTIONS

Based on cognitive-behavioral theories and elicitation research, interventions involved 8 1-hour modules implemented by adult facilitators or peer cofacilitators. Abstinence intervention stressed delaying sexual intercourse or reducing its frequency; safer-sex intervention stressed condom use; control intervention concerned health issues unrelated to sexual behavior.

MAIN OUTCOME MEASURES

Self-reported sexual intercourse, condom use, and unprotected sexual intercourse.

RESULTS

Mean age of the enrollees was 11.8 years; 53% were female and 92.6% were still enrolled at 12 months. Abstinence intervention participants were less likely to report having sexual intercourse in the 3 months after intervention than were control group participants (12.5% vs 21.5%, P=.02), but not at 6- or 12-month follow-up (17.2% vs 22.7%, P=.14; 20.0% vs 23.1%, P=.42, respectively). Safer-sex intervention participants reported significantly more consistent condom use than did control group participants at 3 months (odds ratio [OR]=3.38; 95% confidence interval [CI], 1.25-9.16) and higher frequency of condom use at all follow-ups. Among adolescents who reported sexual experience at baseline, the safer-sex intervention group reported less sexual intercourse in the previous 3 months at 6- and 12-month follow-up than did control and abstinence intervention (adjusted mean days over prior 3 months, 1.34 vs 3.77 and 3.03, respectively; P< or =.01 at 12- month follow-up) and less unprotected intercourse at all follow-ups than did control group (adjusted mean days, 0.04 vs 1.85, respectively, P<.001, at 12-month follow-up). There were no differences in intervention effects with adult facilitators as compared with peer cofacilitators.

CONCLUSION

Both abstinence and safer-sex interventions can reduce HIV sexual risk behaviors, but safer-sex interventions may be especially effective with sexually experienced adolescents and may have longer-lasting effects.

Per-contact risk of human immunodeficiency virus transmission between male sexual partners

The risk of human immunodeficiency virus (HIV) transmission from various types of homosexual contact, including oral sex, is of biologic, epidemiologic, and public health importance. The per-contact risk of acquiring HIV infection from specific acts was estimated in a prospective cohort study of 2,189 high-risk homosexual and bisexual men, conducted in San Francisco, California; Denver, Colorado; and Chicago, Illinois, in 1992-1994. During 2,633 person-years of follow-up, 60 seroconversions were observed. The estimated per-contact risk of acquiring HIV from unprotected receptive anal intercourse (URA) was 0.82 percent (95% confidence interval: 0.24, 2.76 percent) when the partner was known to be HIV+ and 0.27 percent (95% confidence interval: 0.06, 0.49 percent) when partners of unknown serostatus were included. There was heterogeneity in per-contact risk, with nine seroconversions occurring after only one or two episodes of URA. The per-contact risk associated with unprotected insertive anal and receptive oral sex with HIV-positive or unknown serostatus partners was 0.06 and 0.04 percent, respectively. URA accounted for only 15 percent of all reported sexual activity by seroconverters. As lower-risk practices become more common, they may play a larger role in propagating the epidemic and should also be addressed by interventions targeting high-risk homosexual and bisexual men.

Genital herpes

Genital herpes is the main cause of genital ulcers worldwide; the prevalence of herpes simplex virus (HSV) type 2 infections in the general population ranges from 10% to 60%. Most genital herpes is caused by HSV-2, although HSV-1 accounts for about half of new cases in developed countries. The risk of HIV acquisition is three times higher in people with HSV-2. Neonatal herpes is an uncommon but serious complication of genital herpes. Most genital HSV-2 infections are unrecognised and undiagnosed; infected individuals, even with mild symptoms, shed HSV, and can infect sexual partners. Since clinical diagnosis is neither sensitive nor specific, virological and type-specific serological tests should be used routinely. Oral antiviral drugs for HSV infections are safe and effective and can be used both to treat episodes and to prevent recurrences. Antiviral treatment of the infected partners and condom use reduce the risk of sexual transmission of HSV-2.

Global perspectives on the sexual and reproductive health of adolescents: patterns, prevention, and potential

Worldwide, societal shifts and behavioural patterns exacerbated by unique developmental vulnerabilities create a confluence of factors that place today's adolescents at heightened risks for poor health outcomes. Country-level data show that continued investment in effective prevention and treatment strategies is essential to protect adolescents' sexual and reproductive health. Whereas strategies must be tailored to the developmental needs of this age group and their social contexts, effective approaches are multifaceted. All adolescents need access to quality youth-friendly services provided by clinicians trained to work with this population. Sex education programmes should offer accurate, comprehensive information while building skills for negotiating sexual behaviours. Girls and boys also need equal access to youth development programmes that connect them with supportive adults and with educational and economic opportunities. Although progress has been made since the 1994 International Conference on Population and Development, adolescents continue to be disproportionately burdened by threats to their sexual and reproductive health.

A longitudinal study of human immunodeficiency virus transmission by heterosexual partners. European Study Group on Heterosexual Transmission of HIV

BACKGROUND

Worldwide, the predominant mode of human immunodeficiency virus (HIV) transmission is heterosexual intercourse, but the risk of heterosexual transmission and the effectiveness of measures to prevent it are not well defined.

METHODS

We conducted a prospective study of HIV-negative subjects whose only risk of HIV infection was a stable heterosexual relationship with an HIV-infected partner. Every six months the subjects were interviewed, tested for HIV, and counseled about safe sexual practices.

RESULTS

A total of 304 HIV-negative subjects (196 women and 108 men) were followed for an average of 20 months. During the study, 130 couples (42.8 percent) ended their sexual relationships, most often because of the HIV-infected partner's illness or death. Of the 256 couples who continued to have sexual relations for more than three months after enrollment in the study, only 124 (48.4 percent) used condoms consistently for vaginal and anal intercourse. Among these couples, none of the seronegative partners became infected with HIV, despite a total of about 15,000 episodes of intercourse. Among the 121 couples who used condoms inconsistently, the rate of seroconversion was 4.8 per 100 person-years (95 percent confidence interval, 2.5 to 8.4). Eleven couples refused to answer questions about condom use. The risk of transmission increased with advanced stages of HIV infection in the index partners (P < 0.02) and with genital infection in the HIV-negative partners (P < 0.04). Withdrawal to avoid ejaculation in the vagina had a protective effect in uninfected women (P < 0.02).

CONCLUSIONS

Consistent use of condoms for heterosexual intercourse is highly effective in preventing the transmission of HIV. Among couples not using condoms regularly, the risk of HIV transmission varies widely.

Audio-computer interviewing to measure risk behaviour for HIV among injecting drug users: a quasi-randomised trial

BACKGROUND

We aimed to assess audio-computer-assisted self-interviewing (audio-CASI) as a method of reducing under-reporting of HIV risk behaviour among injecting drug users.

METHODS

Injecting drug users were interviewed at syringe-exchange programmes in four US cities. Potential respondents were randomly selected from participants in the syringe exchanges, with weekly alternate assignment to either traditional face-to-face interviews or audio-CASI. The questionnaire included items on sociodemographic characteristics, drug use, and HIV risk behaviours for 30 days preceding the interview. We calculated odds ratios for the difference in reporting of HIV risk behaviours between interview methods.

FINDINGS

757 respondents were interviewed face-to-face, and 724 were interviewed by audio-CASI. More respondents reported HIV risk behaviours and other sensitive behaviours in audio-CASI than in face-to-face interviews (odds ratios for reporting of rented or bought used injection equipment in audio-CASI vs face-to-face interview 2.1 [95% CI 1.4-3.3] p=0.001; for injection with borrowed used injection equipment 1.5 [1.1-2.2] p=0.02; for renting or selling used equipment 2.3 [1.3-4.0] p=0.003).

INTERPRETATION

Although validation of these self-reported behaviours was not possible, we propose that audio-CASI enables substantially more complete reporting of HIV risk behaviour. More complete reporting might increase understanding of the dynamics of HIV transmission and make the assessment of HIV-prevention efforts easier.

New heterosexually transmitted HIV infections in married or cohabiting couples in urban Zambia and Rwanda: an analysis of survey and clinical data

BACKGROUND

Sub-Saharan Africa has a high rate of HIV infection, most of which is attributable to heterosexual transmission. Few attempts have been made to assess the extent of HIV transmission within marriages, and HIV-prevention efforts remain focused on abstinence and non-marital sex. We aimed to estimate the proportion of heterosexual transmission of HIV which occurs within married or cohabiting couples in urban Zambia and Rwanda each year.

METHODS

We used population-based data from Demographic and Health Surveys (DHS) on heterosexual behaviour in Zambia in 2001-02 and in Rwanda in 2005. We also used data on the HIV serostatus of married or cohabiting couples and non-cohabiting couples that was collected through a voluntary counselling and testing service for urban couples in Lusaka, in Zambia, and Kigali, in Rwanda. We estimated the probability that an individual would acquire an incident HIV infection from a cohabiting or non-cohabiting sexual partner, and then the proportion of total heterosexual HIV transmission which occurs within married or cohabiting couples in these settings each year.

FINDINGS

We analysed DHS data from 1739 Zambian women, 540 Zambian men, 1176 Rwandan women, and 606 Rwandan men. Under our base model, we estimated that 55.1% to 92.7% of new heterosexually acquired HIV infections among adults in urban Zambia and Rwanda occurred within serodiscordant marital or cohabiting relationships, depending on the sex of the index partner and on location. Under our extended model, which incorporated the higher rates of reported condom use that we found with non-cohabiting partners, we estimated that 60.3% to 94.2% of new heterosexually acquired infections occurred within marriage or cohabitation. We estimated that an intervention for couples which reduced transmission in serodiscordant urban cohabiting couples from 20% to 7% every year could avert 35.7% to 60.3% of heterosexually transmitted HIV infections that would otherwise occur.

INTERPRETATION

Since most heterosexual HIV transmission for both men and women in urban Zambia and Rwanda takes place within marriage or cohabitation, voluntary counselling and testing for couples should be promoted, as should other evidence-based interventions that target heterosexual couples.

Condom use and the risk of genital human papillomavirus infection in young women

BACKGROUND

To evaluate whether the use of male condoms reduces the risk of male-to-female transmission of human papillomavirus (HPV) infection, longitudinal studies explicitly designed to evaluate the temporal relationship between condom use and HPV infection are needed.

METHODS

We followed 82 female university students who reported their first intercourse with a male partner either during the study period or within two weeks before enrollment. Cervical and vulvovaginal samples for HPV DNA testing and Papanicolaou testing were collected at gynecologic examinations every four months. Every two weeks, women used electronic diaries to record information about their daily sexual behavior. Cox proportional-hazards models were used to evaluate risk factors for HPV infection.

RESULTS

The incidence of genital HPV infection was 37.8 per 100 patient-years at risk among women whose partners used condoms for all instances of intercourse during the eight months before testing, as compared with 89.3 per 100 patient-years at risk in women whose partners used condoms less than 5 percent of the time (adjusted hazard ratio, 0.3; 95 percent confidence interval, 0.1 to 0.6, adjusted for the number of new partners and the number of previous partners of the male partner). Similar associations were observed when the analysis was restricted to high-risk and low-risk types of HPV and HPV types 6, 11, 16, and 18. In women reporting 100 percent condom use by their partners, no cervical squamous intraepithelial lesions were detected in 32 patient-years at risk, whereas 14 incident lesions were detected during 97 patient-years at risk among women whose partners did not use condoms or used them less consistently.

CONCLUSIONS

Among newly sexually active women, consistent condom use by their partners appears to reduce the risk of cervical and vulvovaginal HPV infection.

Relationship power, condom use and HIV risk among women in the USA

Women's ability to negotiate safer sexual practices, particularly condom use, is a vital component of HIV/STD prevention strategies. Gender-based power imbalances may constrain women's negotiation ability, yet few empirical studies have tested the hypothesis that sexual relationship power constitutes a key factor in condom use negotiation. In this investigation, a new measure - the Sexual Relationship Power Scale (SRPS) - was applied. Data were collected from 388, mostly Latina, women at an urban community health centre in Massachusetts. Women with high levels of relationship power were five times as likely as women with low levels to report consistent condom use, after controlling for sociodemographic and psychosocial variables (p < 0.05). Population attributable risk estimates indicate that 52% of the lack of consistent condom use among women can be attributed to low sexual relationship power. The strong association between the Sexual Relationship Power Scale and consistent condom use supports the hypothesis that relationship power plays a key role in safer sex decision making. These findings underscore the importance of including the issue of relationship power in the design and implementation of programmes that promote sexual and reproductive health, as well as research investigating condom use and HIV risk.

Sexual mixing patterns and sex-differentials in teenage exposure to HIV infection in rural Zimbabwe

BACKGROUND

HIV-1 prevalence typically rises more rapidly at young ages in women than in men in sub-Saharan Africa. Greater susceptibility to infection on exposure in women is believed to be a contributory factor as is greater exposure to previously infected sexual partners of the opposite sex. We investigated the latter hypothesis using data from a field study in rural Manicaland, Zimbabwe.

METHODS

Quantitative data on onset and degree of sexual activity, numbers of partners, concurrent partnerships, condom use, and partner characteristics were used in conjunction with epidemiological data on age and sex specific prevalence of HIV infection to do statistical analyses of association between key variables. Mathematical models and qualitative data were used to aid analysis and interpretation.

FINDINGS

Older age of sexual partner was associated with increased risk of HIV-1 infection in men (odds ratio 1.13 [95% CI 1.02-1.25]) and women (1.04 [1.01-1.07]). Young women form partnerships with men 5-10 years older than themselves, whereas young men have relationships with women of a similar age or slightly younger. Greater number of lifetime partners is also associated with increased risk of HIV (1.03 [1.00-1.05]). Young men report more partners than do women but infrequent coital acts and greater use of condoms. These behaviour patterns are underpinned by cultural factors including the expectation that women should marry earlier than men. A strong gender effect remains after factors that affect exposure to infected partners are controlled for (6.04 [1.49-24.47]).

INTERPRETATION

The substantial age difference between female and male sexual partners in Manicaland is the major behavioural determinant of the more rapid rise in HIV prevalence in young women than in men. Theoretical studies have suggested that this difference is an important determinant of observed epidemiological patterns but the study reported in this paper provides clear empirical evidence of association.

Sexual behaviour in Britain: early heterosexual experience

BACKGROUND

Relatively high rates of teenage conception and sexually transmitted infection among young people in Britain have focused attention on early sexual behaviour and its determinants. We report the results of the second National Survey of Sexual Attitudes and Lifestyles (Natsal 2000).

METHODS

We did a probability sample survey between 1999 and 2001, of men and women aged 16-44 years in Britain. Participants were interviewed using a combination of computer-assisted face-to-face and self-completion questionnaires, and asked questions regarding first heterosexual intercourse, communication about sex, pregnancy, and sexually transmitted infections (STIs).

FINDINGS

We recruited 11161 men and women to the survey (4762 men, 6399 women). The proportion of those aged 16-19 years at interview reporting first heterosexual intercourse at younger than 16 years was 30% for men and 26% for women; median age was 16 years. The proportion of women reporting first intercourse before 16 years increased up to, but not after, the mid-1990s. There has been a sustained increase in condom use and a decline in the proportion of men and women reporting no contraceptive use at first intercourse with decreasing age at interview. Among 16-24 year olds, non-use of contraception increased with declining age at first intercourse; reported by 18% of men and 22% of women aged 13-14 years at occurrence. Early age at first intercourse was significantly associated with pregnancy under 18 years, but not with occurrence of STIs. Low educational attainment was associated with motherhood before 18 years, but not abortion.

INTERPRETATION

The increase in the proportion of women reporting first intercourse before age 16 years does not appear to have continued throughout the past decade. Only a small minority of teenagers have unprotected first intercourse, and early motherhood is more strongly associated with educational level than with family background. Factors most strongly associated with risk behaviour and adverse outcomes have considerable potential for preventive intervention.

Sexual behavior of HIV discordant couples after HIV counseling and testing

BACKGROUND AND OBJECTIVES

Sexual behavior following voluntary HIV counseling and testing (VCT) is described in 963 cohabiting heterosexual couples with one HIV positive and one HIV negative partner ('discordant couples'). Biological markers were used to assess the validity of self-report.

METHODS

Couples were recruited from a same-day VCT center in Lusaka, Zambia. Sexual exposures with and without condoms were recorded at 3-monthly intervals. Sperm detected on vaginal smears, pregnancy, and sexually transmitted diseases (STD) including HIV, gonorrhea, syphilis, and Trichomonas vaginalis were assessed.

RESULTS

Less than 3% of couples reported current condom use prior to VCT. In the year after VCT, > 80% of reported acts of intercourse in discordant couples included condom use. Reporting 100% condom use was associated with 39-70% reductions in biological markers; however most intervals with reported unprotected sex were negative for all biological markers. Under-reporting was common: 50% of sperm and 32% of pregnancies and HIV transmissions were detected when couples had reported always using condoms. Positive laboratory tests for STD and reported extramarital sex were relatively infrequent. DNA sequencing confirmed that 87% of new HIV infections were acquired from the spouse.

CONCLUSIONS

Joint VCT prompted sustained but imperfect condom use in HIV discordant couples. Biological markers were insensitive but provided evidence for a significant under-reporting of unprotected sex. Strategies that encourage truthful reporting of sexual behavior and sensitive biological markers of exposure are urgently needed. The impact of prevention programs should be assessed with both behavioral and biological measures.

Male circumcision for the prevention of HSV-2 and HPV infections and syphilis

BACKGROUND

Male circumcision significantly reduced the incidence of human immunodeficiency virus (HIV) infection among men in three clinical trials. We assessed the efficacy of male circumcision for the prevention of herpes simplex virus type 2 (HSV-2) and human papillomavirus (HPV) infections and syphilis in HIV-negative adolescent boys and men.

METHODS

We enrolled 5534 HIV-negative, uncircumcised male subjects between the ages of 15 and 49 years in two trials of male circumcision for the prevention of HIV and other sexually transmitted infections. Of these subjects, 3393 (61.3%) were HSV-2-seronegative at enrollment. Of the seronegative subjects, 1684 had been randomly assigned to undergo immediate circumcision (intervention group) and 1709 to undergo circumcision after 24 months (control group). At baseline and at 6, 12, and 24 months, we tested subjects for HSV-2 and HIV infection and syphilis, along with performing physical examinations and conducting interviews. In addition, we evaluated a subgroup of subjects for HPV infection at baseline and at 24 months.

RESULTS

At 24 months, the cumulative probability of HSV-2 seroconversion was 7.8% in the intervention group and 10.3% in the control group (adjusted hazard ratio in the intervention group, 0.72; 95% confidence interval [CI], 0.56 to 0.92; P=0.008). The prevalence of high-risk HPV genotypes was 18.0% in the intervention group and 27.9% in the control group (adjusted risk ratio, 0.65; 95% CI, 0.46 to 0.90; P=0.009). However, no significant difference between the two study groups was observed in the incidence of syphilis (adjusted hazard ratio, 1.10; 95% CI, 0.75 to 1.65; P=0.44).

CONCLUSIONS

In addition to decreasing the incidence of HIV infection, male circumcision significantly reduced the incidence of HSV-2 infection and the prevalence of HPV infection, findings that underscore the potential public health benefits of the procedure. (ClinicalTrials.gov numbers, NCT00425984 and NCT00124878.)

Condom effectiveness in reducing heterosexual HIV transmission

BACKGROUND

The amount of protection that condoms provide for HIV and other sexually transmitted diseases is unknown. Cohort studies of sexually active HIV serodiscordant couples with follow-up of the seronegative partner, provide a situation in which a seronegative partner has known exposure to the disease and disease incidence can be estimated. When some individuals use condoms and some do not, namely some individuals use condoms 100% of the time and some never use (0%) condoms, condom effectiveness can be estimated by comparing the two incidence rates. Condom effectiveness is the proportionate reduction in disease due to the use of condoms.

OBJECTIVES

The objective of this review is to estimate condom effectiveness in reducing heterosexual transmission of HIV.

SEARCH STRATEGY

Studies were located using electronic databases (AIDSLINE, CINAHL, Embase, and MEDLINE) and handsearched reference lists.

SELECTION CRITERIA

For inclusion, studies had to have: (1) data concerning sexually active HIV serodiscordant heterosexual couples, (2) a longitudinal study design, (3) HIV status determined by serology, and (4) contain condom usage information on a cohort of always (100%) or never (0%) condom users.

DATA COLLECTION AND ANALYSIS

Studies identified through the above search strategy that met the inclusion criteria were reviewed for inclusion in the analysis. Sample sizes, number of seroconversions, and the person-years of disease-free exposure time were recorded for each cohort. If available, the direction of transmission in the cohort (male-to-female, female-to-male), date of study enrollment, source of infection in the index case, and the presence of STDs was recorded. Duplicate reports on the same cohort and studies with incomplete or nonsepecific information were excluded. HIV incidence was estimated from the cohorts of "always" users and for the cohorts of "never" users. Effectiveness was estimated from these two incidence estimates.

MAIN RESULTS

Of the 4709 references that were initially identified, 14 were included in the final analysis. There were 13 cohorts of "always" users that yielded an homogeneous HIV incidence estimate of 1.14 [95% C.I.:.56, 2.04] per 100 person-years. There were 10 cohorts of "never" users that appeared to be heterogeneous. The studies with the longest follow-up time, consisting mainly of studies of partners of hemophiliac and transfusion patients, yielded an HIV incidence estimate of 5.75 [95% C.I.: 3.16, 9.66] per 100 person-years. Overall effectiveness, the proportionate reduction in HIV seroconversion with condom use, is approximately 80%.

REVIEWER'S CONCLUSIONS

This review indicates that consistent use of condoms results in 80% reduction in HIV incidence. Consistent use is defined as using a condom for all acts of penetrative vaginal intercourse. Because the studies used in this review did not report on the "correctness" of use, namely whether condoms were used correctly and perfectly for each and every act of intercourse, effectiveness and not efficacy is estimated. Also, this estimate refers in general to the male condom and not specifically to the latex condom, since studies also tended not to specify the type of condom that was used. Thus, condom effectiveness is similar to, although lower than, that for contraception.