215 results found
Dimitrov DT, Masse BR, Boily M-C, 2013, Beating the Placebo in HIV Prevention Efficacy Trials: The Role of the Minimal Efficacy Bound, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 62, Pages: 95-101, ISSN: 1525-4135
Baggaley RF, White RG, Hollingsworth TD, et al., 2013, Heterosexual HIV-1 Infectiousness and Antiretroviral Use: Systematic Review of Prospective Studies of Discordant Couples., Epidemiology, Vol: 1, Pages: 110-121
BACKGROUND: : Recent studies have estimated the reduction in HIV-1 infectiousness with antiretroviral therapy (ART), but high-quality studies such as randomized controlled trials, accompanied by rigorous adherence counseling, are likely to overestimate the effectiveness of treatment-as-prevention in real-life settings.METHODS: : We attempted to summarize the effect of ART on HIV transmission by undertaking a systematic review and meta-analysis of HIV-1 infectiousness per heterosexual partnership (incidence rate and cumulative incidence over study follow-up) estimated from prospective studies of discordant couples. We used random-effects Poisson regression models to obtain summary estimates. When possible, the analyses were further stratified by direction of transmission (man-to-woman or woman-to-man) and economic setting (high- or low-income countries). Potential causes of heterogeneity of estimates were explored through subgroup analyses.RESULTS: : Fifty publications were included. Nine allowed comparison between ART and non-ART users within studies (ART-stratified studies), in which summary incidence rates were 3.6/100 person-years (95% confidence interval = 2.0-6.5) and 0.2/100 person-years (0.07-0.7) for non-ART- and ART-using couples, respectively (P < 0.001), constituting a 91% (79-96%) reduction in per-partner HIV-1 incidence rate with ART use. The 41 studies that did not stratify by ART use provided estimates with high levels of heterogeneity (I statistic) and few reported levels of ART use, making interpretation difficult. Nevertheless, estimates tended to be lower with ART use. Infectiousness tended to be higher for low-income than high-income settings, but there was no clear pattern by direction of transmission (man-to-woman and woman-to-man).CONCLUSIONS: : ART substantially reduces HIV-1 infectiousness within discordant couples, based on observational studies, and could play a major part in HIV-1 prevention efforts. However, the non-zero risk from par
Owen BN, Brock PM, Baggaley RF, et al., 2012, Prevalence of heterosexual anal intercourse among youth: a systematic review and meta-analysis, 28th International Papillomavirus Conference
Mishra S, Steen R, Gerbase A, et al., 2012, Impact of High-Risk Sex and Focused Interventions in Heterosexual HIV Epidemics: A Systematic Review of Mathematical Models, PLOS One, Vol: 7, ISSN: 1932-6203
BackgroundThe core-group theory of sexually transmitted infections suggests that targeting prevention to high-risk groups (HRG) could be very effective. We aimed to quantify the contribution of heterosexual HRGs and the potential impact of focused interventions to HIV transmission in the wider community.MethodsWe systematically identified studies published between 1980 and 2011. Studies were included if they used dynamical models of heterosexual HIV transmission, incorporated behavioural heterogeneity in risk, and provided at least one of the following primary estimates in the wider community (a) the population attributable fraction (PAF) of HIV infections due to HRGs, or (b) the number per capita or fraction of HIV infections averted, or change in HIV prevalence/incidence due to focused interventions.FindingsOf 267 selected articles, 22 were included. Four studies measured the PAF, and 20 studies measured intervention impact across 265 scenarios. In low-prevalence epidemics (≤5% HIV prevalence), the estimated impact of sex-worker interventions in the absence of risk compensation included: 6–100% infections averted; 0.9–6.2 HIV infections averted per 100,000 adults; 11–94% and 4–47% relative reduction in prevalence and incidence respectively. In high-prevalence epidemics (>5% HIV prevalence), sex-worker interventions were estimated to avert 6.8–40% of HIV infections and up to 564 HIV infections per 100,000 adults, and reduce HIV prevalence and incidence by 13–27% and 2–14% respectively. In both types of epidemics, greater heterogeneity in HIV risk was associated with a larger impact on the fraction of HIV infections averted and relative reduction in HIV incidence.ConclusionFocused interventions, as estimated by mathematical models, have the potential to reduce HIV transmission in the wider community across low- and high-prevalence regions. However, considerable variability exists in estimated impact, suggesting that a
Van de Velde N, Boily M-C, Drolet M, et al., 2012, Population-Level Impact of the Bivalent, Quadrivalent, and Nonavalent Human Papillomavirus Vaccines: A Model-Based Analysis, JNCI-JOURNAL OF THE NATIONAL CANCER INSTITUTE, Vol: 104, Pages: 1712-1723, ISSN: 0027-8874
Dimitrov D, Boily M-C, Marrazzo J, et al., 2012, Population-level benefits from providing effective HIV prevention means to pregnant women in high prevalence settings, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 15, Pages: 79-79
Mitchell KM, Foss AM, Prudden HJ, et al., 2012, Sexual mixing patterns between men who have sex with men in southern India: implications for modelling the HIV epidemic and predicting the impact of targeted oral pre-exposure prophylaxis, Publisher: JOHN WILEY & SONS LTD, Pages: 106-107
Malagon T, Drolet M, Boily M-C, et al., 2012, Cross-protective efficacy of two human papillomavirus vaccines: a systematic review and meta-analysis, LANCET INFECTIOUS DISEASES, Vol: 12, Pages: 781-789, ISSN: 1473-3099
Behanzin L, Diabate S, Minani I, et al., 2012, Decline in HIV Prevalence among Young Men in the General Population of Cotonou, Benin, 1998-2008, PLOS One, Vol: 7, ISSN: 1932-6203
ObjectiveTo assess changes in the prevalence of HIV and other sexually transmitted infections, as well as in different proximal and distal factors related to HIV infection, in the general population of Cotonou between 1998 and 2008, while an intensive preventive intervention targeting the sex work milieu was ongoing.MethodsA two-stage cluster sampling procedure was used to select the participants in each study. Subjects aged 15–49 who agreed to participate were interviewed and tested for HIV, syphilis, HSV-2, gonorrhoea and chlamydia. We used the Roa-Scott Chi-square test (proportions) and the Student’s t test (means) for bivariate comparisons, and adjusted logistic regression models taking into account the cluster effect for multivariate analyses.ResultsHIV prevalence decreased significantly in men (3.4% in 1998 versus 2.0% in 2008, p = 0.048), especially in those aged 15–29 (3.0% to 0.5%, p = 0.002). Among men, the prevalence of gonorrhoea decreased significantly (1.1% to 0.3%, p = 0.046) while HSV-2 prevalence increased from 12.0% to 18.1% (p = 0.0003). The proportion of men who reported condom use at least once (29.3% to 61.0%, p<0.0001) and of those having attained a secondary educational level or more (17.1% to 61.3%, p<0.0001) also increased significantly. There was an overall decrease in the prevalence of syphilis (1.5% to 0.6%, p = 0.0003).ConclusionThis is the first population-based study reporting a significant decline in HIV prevalence among young men in an African setting where overall prevalence has never reached 5%. The decline occurred while preventive interventions targeting the sex work milieu were ongoing and the educational level was increasing.
Boily M-C, Masse B, Alsallaq R, et al., 2012, HIV Treatment as Prevention: Considerations in the Design, Conduct, and Analysis of Cluster Randomized Controlled Trials of Combination HIV Prevention, PLOS Medicine, Vol: 9, ISSN: 1549-1277
Delva W, Eaton JW, Meng F, et al., 2012, HIV Treatment as Prevention: Optimising the Impact of Expanded HIV Treatment Programmes, PLOS Medicine, Vol: 9, ISSN: 1549-1277
Until now, decisions about how to allocate ART have largely been based on maximising the therapeutic benefit of ART for patients. Since the results of the HPTN 052 study showed efficacy of antiretroviral therapy (ART) in preventing HIV transmission, there has been increased interest in the benefits of ART not only as treatment, but also in prevention. Resources for expanding ART in the short term may be limited, so the question is how to generate the most prevention benefit from realistic potential increases in the availability of ART. Although not a formal systematic review, here we review different ways in which access to ART could be expanded by prioritising access to particular groups based on clinical or behavioural factors. For each group we consider (i) the clinical and epidemiological benefits, (ii) the potential feasibility, acceptability, and equity, and (iii) the affordability and cost-effectiveness of prioritising ART access for that group. In re-evaluating the allocation of ART in light of the new data about ART preventing transmission, the goal should be to create policies that maximise epidemiological and clinical benefit while still being feasible, affordable, acceptable, and equitable.
HIV Modelling Consortium Treatment as Prevention Editorial Writing Group, 2012, HIV treatment as prevention: models, data, and questions--towards evidence-based decision-making., PLOS Medicine, Vol: 9, ISSN: 1549-1277
Antiretroviral therapy (ART) for those infected with HIV can prevent onward transmission of infection, but biological efficacy alone is not enough to guide policy decisions about the role of ART in reducing HIV incidence. Epidemiology, economics, demography, statistics, biology, and mathematical modelling will be central in framing key decisions in the optimal use of ART. PLoS Medicine, with the HIV Modelling Consortium, has commissioned a set of articles that examine different aspects of HIV treatment as prevention with a forward-looking research agenda. Interlocking themes across these articles are discussed in this introduction. We hope that this article, and others in the collection, will provide a foundation upon which greater collaborations between disciplines will be formed, and will afford deeper insights into the key factors involved, to help strengthen the support for evidence-based decision-making in HIV prevention.
Dimitrov D, Boily M-C, Mâsse BR, et al., 2012, Impact of Pill Sharing on Drug Resistance Due to a Wide-Scale Oral Prep Intervention in Generalized Epidemics., J AIDS Clin Res, Vol: Suppl 5, ISSN: 2155-6113
BACKGROUND: The first antiretroviral drug (Truvada) to be used as a pre-exposure prophylaxis (PrEP) in preventing HIV transmission is about to be approved. Behavioral studies suggest that a portion of users may share anti-retroviral drugs with sex partners, family, or friends. Pill sharing will decrease PrEP efficacy and adherence level, and potentially create an environment favorable for the development of drug resistance. We aim to evaluate the potential impact of pill sharing on the PrEP effectiveness and on the rates of drug-resistance development in heterosexual populations. METHODS: A transmission dynamic model was used to assess the population-level impact of oral PrEP. The fractions of new HIV infections prevented (CPF), drug resistance prevalence and the proportion of new infections in which drug-resistant HIV is transmitted (TDR) are evaluated over fixed time periods. The influence of different factors on CPF and TDR is studied through simulations, using epidemic parameters representative of the countries in Sub-Saharan Africa. RESULTS: Without pill sharing, a 70% efficacious PrEP used consistently by 60% of uninfected individuals prevents 52.8% (95% CI 49.4%-56.4%) of all new HIV infections over ten years with drug-resistant HIV transmitted in 2.2% of the new infections. Absolute CPF may vary by 9% if up to 20% of the users share PrEP while the level of TDR and total resistance prevalence may increase by up to 6-fold due to pill sharing in some intervention scenarios. CONCLUSION: Pill sharing may increase the PrEP coverage level achieved in the population but it also affects the PrEP efficacy for the users who do not follow the prescribed schedule. More importantly, it creates a pool of untracked users who remain unreached by the effort to avoid sub-optimal PrEP usage by infected people. This increases substantially the potential risk of drug resistance in the population.
Boily MC, Brisson M, Mâsse B, et al., 2012, The role of mathematical models in vaccine development and public health decision making, Vaccinology: Principles and Practice, Pages: 480-508, ISBN: 9781405185745
Mohlala BKF, Gregson S, Boily M-C, 2012, Barriers to involvement of men in ANC and VCT in Khayelitsha, South Africa, Aids Care, Vol: 24, Pages: 972-977, ISSN: 1360-0451
We used qualitative methods to assess pregnant women and men's attitudes, feelings, beliefs, experiences and reactions to male partners' involvement in antenatal clinic (ANC) in Khayelitsha, Cape Town, South Africa. The aims of these studies were to determine barriers to male partners' attendance of ANC with their pregnant female partners and to identify possible strategies to overcome these barriers. Findings from the qualitative studies demonstrated that pregnant women were keen to invite their male sexual partners and that men would attend if invited. The main barrier to male participation was lack of awareness and the healthcare facility environment. The findings of these studies emphasized the need to increase awareness among men in Khayelitsha of the need for male attendance of ANC and the need to address the barriers to male attendance of ANC. It was clear that community sensitization programmes coupled with improvement of the health facility environment to be receptive to men are essential for increasing male attendance of ANC.
Bradley J, Rajaram SP, Moses S, et al., 2012, Why do condoms break? A study of female sex workers in Bangalore, south India, SEXUALLY TRANSMITTED INFECTIONS, Vol: 88, Pages: 163-170, ISSN: 1368-4973
Boily M-C, Alary M, Baggaley RF, 2012, Neglected Issues and Hypotheses Regarding the Impact of Sexual Concurrency on HIV and Sexually Transmitted Infections, AIDS AND BEHAVIOR, Vol: 16, Pages: 304-311, ISSN: 1090-7165
Deering KN, Bhattacharjee P, Bradley J, et al., 2011, Condom use within non-commercial partnerships of female sex workers in southern India, BMC Public Health, Vol: 11, ISSN: 1471-2458
BackgroundAlthough female sex workers (FSWs) report high levels of condom use with commercial sex clients, particularly after targeted HIV preventive interventions have been implemented, condom use is often low with non-commercial partners. There is limited understanding regarding the factors that influence condom use with FSWs’ non-commercial partners, and of how programs can be designed to increase condom use with these partners. The main objectives of this study were therefore to describe FSWs’ self-reported non-commercial partners, along with interpersonal factors characterizing their non-commercial partnerships, and to examine the factors associated with consistent condom use (CCU) within non-commercial partnerships.MethodsThis study used data collected from cross-sectional questionnaires administered to 988 FSWs in four districts in Karnataka state in 2006-07. We used bivariate and multivariable logistic regression analysis to examine the relationship between CCU (i.e., ‘always’ compared to ‘never’, ‘sometimes’ or ‘frequently’) with non-commercial partners of FSWs (including the respondents’ husband or main cohabiting partner [if not married] and their most recent non-paying partner [who is neither a husband nor the main cohabiting partner, and with whom the FSW had sex within the previous year]) and interpersonal factors describing these partnerships, as well as social and environmental factors. Weighting and survey methods were used to account for the cluster sampling design.ResultsOverall, 511 (51.8%) FSWs reported having a husband or cohabiting partner and 247 (23.7%) reported having a non-paying partner. CCU with these partners was low (22.6% and 40.3% respectively). In multivariable analysis, the odds of CCU with FSWs’ husband or cohabiting partner were 1.8-fold higher for FSWs whose partner knew she was a sex worker (adjusted odds ratio [AOR]: 1.84, 95% confidence intervals[CI]: 1.0
Deering KN, Boily M-C, Lowndes CM, et al., 2011, A dose-response relationship between exposure to a large-scale HIV preventive intervention and consistent condom use with different sexual partners of female sex workers in southern India, BMC Public Health, Vol: 11 Suppl 6, ISSN: 1471-2458
BackgroundThe Avahan Initiative, a large-scale HIV preventive intervention targeted to high-risk populations including female sex workers (FSWs), was initiated in 2003 in six high-prevalence states in India, including Karnataka. This study assessed if intervention exposure was associated with condom use with FSWs’ sexual partners, including a dose-response relationship.MethodsData were from a cross-sectional study (2006-07) of 775 FSWs in three districts in Karnataka. Survey methods accounted for the complex cluster sampling design. Bivariate and multivariable logistic regression was used to separately model the relationships between each of five intervention exposure variables and five outcomes for consistent condom use (CCU= always versus frequently/sometimes/never) with different sex partners, including with: all clients; occasional clients; most recent repeat client; most recent non-paying partner; and the husband or cohabiting partner. Linear tests for trends were conducted for three continuous intervention exposure variables.ResultsFSWs reported highest CCU with all clients (81.7%); CCU was lowest with FSWs’ husband or cohabiting partner (9.6%). In multivariable analysis, the odds of CCU with all clients and with occasional clients were 6.3-fold [95% confidence intervals, CIs: 2.8-14.5] and 2.3-fold [95% CIs: 1.4-4.1] higher among FSWs contacted by intervention staff and 4.9-fold [95% CIs: 2.6-9.3] and 2.3-fold [95% CIs: 1.3-4.1] higher among those who ever observed a condom demonstration by staff, respectively, compared to those who had not. A significant dose-response relationship existed between each of these CCU outcomes and increased duration since first contacted by staff (P=0.001; P=0.006) and numbers of condom demonstrations witnessed (P=0.004; P=0.026); a dose-response relationship was also observed between condom use with all clients and number of times contacted by staff (P=0.047). Intervention exposure was not associated with higher odd
Boily M-C, Dimitrov D, Karim SSA, et al., 2011, The future role of rectal and vaginal microbicides to prevent HIV infection in heterosexual populations: implications for product development and prevention, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: 646-653, ISSN: 1368-4973
Dimitrov DT, Boily M-C, Baggaley RF, et al., 2011, Modeling the gender-specific impact of vaginal microbicides on HIV transmission, JOURNAL OF THEORETICAL BIOLOGY, Vol: 288, Pages: 9-20, ISSN: 0022-5193
Boily M-C, Mâsse BR, Dimitrov D, 2011, Oral antiretroviral pre-exposure prophylaxis reduces the risk of HIV acquisition among men who have sex with men., Evid Based Med, Vol: 16, Pages: 146-147
Brisson M, van de Velde N, Franco EL, et al., 2011, Incremental Impact of Adding Boys to Current Human Papillomavirus Vaccination Programs: Role of Herd Immunity, JOURNAL OF INFECTIOUS DISEASES, Vol: 204, Pages: 372-376, ISSN: 1537-6613
Mohlala BKF, Boily M-C, Gregson S, 2011, The forgotten half of the equation: randomized controlled trial of a male invitation to attend couple voluntary counselling and testing, AIDS, Vol: 25, Pages: 1535-1541, ISSN: 0269-9370
Mishra S, Boily MC, Steen R, et al., 2011, IMPACT OF TARGETED INTERVENTIONS IN HIV EPIDEMICS AS PREDICTED BY MATHEMATICAL MODELS: A SYSTEMATIC REVIEW, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A35-A35, ISSN: 1368-4973
Pickles M, Boily MC, Vickerman P, et al., 2011, TIME EVOLUTION OF THE FRACTION OF NEW HIV INFECTIONS DUE TO PRIMARY INFECTION AMONG HIGH RISK GROUPS IN SOUTHERN INDIA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A50-A51, ISSN: 1368-4973
Boily MC, 2011, USE OF TRANSMISSION DYNAMICS MODELS TO DESIGN AND EVALUATE THE IMPACT OF LARGE SCALE HIV/STI PREVENTION INTERVENTION: HOW, WHY AND WHEN?, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A4-A4, ISSN: 1368-4973
Dureau J, Boily MC, Vickerman P, et al., 2011, WHAT HAS BEEN THE EFFECT OF THE AVAHAN HIV INTERVENTION ON CONDOM USE AMONG FEMALE SEX WORKERS? INSIGHTS FROM A FULLY BAYESIAN INFERENCE METHODOLOGY, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A197-A198, ISSN: 1368-4973
Pickles M, Ramesh BM, Adhikary R, et al., 2011, QUANTIFYING SOCIAL DESIRABILITY BIASES IN REPORTED CONDOM USE AMONG FEMALE SEX WORKERS IN SOUTHERN INDIA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A162-A162, ISSN: 1368-4973
Dimitrov D, Boily MC, Masse B, 2011, IMPACT OF PILL SHARING ON DRUG-RESISTANCE AND POPULATION-LEVEL EFFECTIVENESS OF A WIDE-SCALE ORAL PREP INTERVENTION IN RESOURCE-CONSTRAINED SETTINGS, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A35-A35, ISSN: 1368-4973
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