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Marie-Claude Boily

Publications and source records attributed to Marie-Claude Boily.

10 recordsLinked to original sources
PubMed2006

The role of sexually transmitted infections in male circumcision effectiveness against HIV--insights from clinical trial simulation.

BACKGROUND: A landmark randomised trial of male circumcision (MC) in Orange Farm, South Africa recently showed a large and significant reduction in risk of HIV infection, reporting MC effectiveness of 61% (95% CI: 34%-77%). Additionally, two further randomised trials of MC in Kisumu, Kenya and Rakai, Uganda were recently stopped early to report 53% and 48% effectiveness, respectively. Since MC may protect against both HIV and certain sexually transmitted infections (STI), which are themselves cofactors of HIV infection, an important question is the extent to which this estimated effectiveness against HIV is mediated by the protective effect of circumcision against STI. The answer lies in the trial data if the appropriate statistical analyses can be identified to estimate the separate efficacies against HIV and STI, which combine to determine overall effectiveness. OBJECTIVES AND METHODS: Focusing on the MC trial in Kisumu, we used a stochastic prevention trial simulator (1) to determine whether statistical analyses can validly estimate efficacy, (2) to determine whether MC efficacy against STI alone can produce large effectiveness against HIV and (3) to estimate the fraction of all HIV infections prevented that are attributable to efficacy against STI when both efficacies combine. RESULTS: Valid estimation of separate efficacies against HIV and STI as well as MC effectiveness is feasible with available STI and HIV trial data, under Kisumu trial conditions. Under our parameter assumptions, high overall effectiveness of MC against HIV was observed only with a high MC efficacy against HIV and was not possible on the basis of MC efficacy against STI alone. The fraction of all HIV infections prevented which were attributable to MC efficacy against STI was small, except when efficacy of MC specifically against HIV was very low. In the three MC trials which reported between 48% and 61% effectiveness (combining STI and HIV efficacies), the fraction of HIV infections prevented in circumcised males which were attributable to STI was unlikely to be more than 10% to 20%. CONCLUSION: Estimation of efficacy, attributable fraction and effectiveness leads to improved understanding of trial results, gives trial results greater external validity and is essential to determine the broader public health impact of circumcision to men and women.

Journal Article↗
PubMed2006

Risk of HIV-1 transmission for parenteral exposure and blood transfusion: a systematic review and meta-analysis.

BACKGROUND: The role of iatrogenic transmission within the HIV/AIDS pandemic remains contentious. Estimates of the risk of HIV transmission from injections and blood transfusions are required to inform appropriate prevention policy. OBJECTIVES: Systematic review and meta-analysis of the literature on HIV-1 infectivity for parenteral transmission and blood transfusion. REVIEW METHODS: All identified studies with relevant transmission probability estimates up to May 2005 were included. STATISTICAL METHODS: When appropriate, summary estimates for accidental percutaneous and blood product exposures were derived. RESULTS: Infectivity estimates following a needlestick exposure ranged from 0.00 to 2.38% [weighted mean, 0.23%; 95% confidence interval (CI), 0.00-0.46%; n = 21]. Three estimates of infectivity per intravenous drug injection ranged from 0.63 to 2.4% (median, 0.8%); a summary estimate could not be calculated. The quality of the only estimate of infectivity per contaminated medical injection (1.9-6.9%) was assessed. Instead we propose a range of 0.24-0.65%. Infectivity estimates for confirmed contaminated blood transfusions range from 88.3 to 100.0% (weighted mean, 92.5%; 95% CI, 89.0-96.1%; n = 6). CONCLUSIONS: Infectivity estimates for infected blood transfusions are larger than for other modes of HIV transmission. Few studies on transmission risk per contaminated injection were found. However, transmission risk per needlestick injury, where needles are more likely to be rinsed or disinfected between recipients (especially for medical injections), may be representative of non-intravenous medical injections and lower than the risk from intravenous injections, which are likely to be deeper and to involve more fluids. Further work is needed to better estimate transmission probability related to contaminated injections and its likely contribution to overall HIV transmission.

HIV Infections↗
PubMed2006

Assessing HIV resistance in developing countries: Brazil as a case study.

Increased transmission of resistant HIV has been raised as a potential consequence of expanded access to antiretroviral therapy. We review how limitations in resources and health care infrastructure may impact the transmission of resistant HIV, and we examine data from Brazil as a case study. We introduce a biological and clinical framework to identify the major determinants of transmitted resistance and to discuss how these determinants may be affected by a lack of infrastructure. We then use our framework to examine HIV resistance data from Brazil. This country was chosen as a case study due to its extensive experience delivering antiretroviral drugs and because of the availability of data on the prevalence of resistant HIV there. The data from Brazil show that antiretroviral therapy can be delivered in a resource-limited setting without resulting in widespread transmission of resistant virus. While the Brazilian experience does not necessarily generalize to countries with less health care infrastructure, neither theory nor data support a foregone conclusion that resistance will necessarily dominate HIV epidemics in the developing world to a greater extent than it does in the developed world.

Anti-Retroviral Agents↗
PubMed2005

The impact of the transmission dynamics of the HIV/AIDS epidemic on sexual behaviour: a new hypothesis to explain recent increases in risk taking-behaviour among men who have sex with men.

Increases in sexually transmitted infections and related high-risk behaviours have been reported among men who have sex with men (MSM) in industrialised countries when effective antiretroviral therapy against HIV infection has become widely available, in the mid-nineties. The reasons for these increases are not fully understood and often conflicting. Prevention fatigue, relapses to unsafe sex, as well as optimism toward the risk of developing AIDS among people living with HIV are not unique to the era of antiretroviral therapy (ART). This has led researchers to highlight the need to investigate other potential reasons that could explain the increase in high-risk taking following the ART introduction. We put forward the hypothesis that the change in the transmission dynamics of the HIV/AIDS epidemic before and after the introduction of ART has contributed to this change in high-risk behaviour. It is suggested that a decline in sexual risk activities has occurred at the population-level following the initial spread of the HIV/AIDS epidemic because AIDS mortality and severe morbidity disproportionately depleted the pool of high-risk taking individuals. As a result, non-volitional changes may have occurred at the individual-level over time because the depletion of this pool of high-risk individuals made it more difficult for the remaining high-risk taking individuals to find partners to engage in risky sex with. Following its introduction, ART has facilitated the differential replenishment of the pool of individuals willing to engage in high-risk taking behaviours because ART reduces AIDS mortality, and morbidity. Consequently, high-risk taking individuals who had previously reduced their level of risky sex non-volitionally (i.e., as a result of the reduced availability of high-risk partners) were able to resume their initial high-risk practices as the pool of high-risk taking individuals replenished over time. Thus, a fraction of the recently reported increase in high-risk sexual activities may be secondary to the fact that those MSM who were unable to engage in their desired high-risky sexual activities (because of reduced availability) are now able to revert to them as the availability of men willing to engage in risky sexual behaviours increases partly due to ART. Therefore, we suggest that a fraction of the changes in individual behaviour are non-volitional and can be explained by a change in "sexual partner availability" due to the transmission dynamics of HIV/AIDS before and after ART. The hypothesis is formulated and explained using simple social network diagrams and the Theory of Planned Behaviour. We also discuss the implication of this hypothesis for HIV prevention.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Changes in the transmission dynamics of the HIV epidemic after the wide-scale use of antiretroviral therapy could explain increases in sexually transmitted infections: results from mathematical models.

BACKGROUND: Recent increases in bacterial sexually transmitted infections (STI) and risk behavior have coincided with the introduction of antiretroviral therapy (ART) in homosexual communities of industrialized countries. The reasons for these increases are not fully understood. GOAL: The goal of this study was to understand the various effects of ART on risk behaviors and STI. OBJECTIVE: The objective of this study was to assess the independent impact of the change in the transmission dynamics of HIV/AIDS as a result of the wide-scale use of ART on a bacterial STI. STUDY DESIGN: We developed a mathematical model of bacterial STI and treated/untreated HIV/AIDS infection for an open homosexual population. At the individual level, we assume that susceptible and healthy HIV-positive individuals do not increase their risk behavior as a result of ART over time. However, individuals with AIDS, who are successfully treated with ART, can resume sexual activity. The impact of the wide-scale use of ART on risky behavior, STI, and HIV/AIDS was evaluated over a wide range of assumptions on treatment use, ART efficacy, and population characteristics. RESULTS: Over 10 years, 0% to 55% new bacterial STI could be attributed to the wide-scale use of ART as a result of more modest increases (0-25%) in risky sex occurring at the population level rather than at the individual level. These increases have a negative impact on HIV if coverage is too low. Increasing treatment coverage helps to prevent more HIV infections despite larger increases in risky sex and STI that is predicted to ensue. CONCLUSION: Taking the differential impact of wide-scale use of ART into account helps to interpret recent behavioral and STI trends. Our results have implications for prevention strategies and for the formulation of public health policies. A better understanding of the differential impact of ART on sexual network over time is required.

Antiretroviral Therapy, Highly Active↗