Imperial College London

ProfessorMarie-ClaudeBoily

Faculty of MedicineSchool of Public Health

Professor of Mathematical Epidemiology
 
 
 
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Contact

 

+44 (0)20 7594 3263mc.boily

 
 
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Location

 

LG26Norfolk PlaceSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
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216 results found

Boily MC, Shannon K, 2017, Criminal law, sex work, HIV: need for multi-level research, Lancet HIV, Vol: 4, Pages: e98-e99, ISSN: 2405-4704

Journal article

Owen B, Elmes J, Silhol R, Dang Q, McGowan I, Shacklett B, Swann EM, van der Straten A, Baggaley RF, Boily MCet al., 2017, How common and frequent is heterosexual anal intercourse among South Africans? A systematic review and meta-analysis, Journal of International AIDS Society, Vol: 20, ISSN: 1758-2652

Background: HIV is transmitted more effectively during anal intercourse (AI) than vaginal intercourse (VI). However, patterns of heterosexual AI practice and its contribution to South Africa’s generalized epidemic remain unclear. We aimed to determine how common and frequent heterosexual AI is in South Africa.Methods: We searched for studies reporting the proportion practising heterosexual AI (prevalence) and/or the number of AI and unprotected AI (UAI) acts (frequency) in South Africa from 1990 to 2015. Stratified random-effects meta-analysis by subgroups was used to produce pooled estimates and assess the influence of participant and study characteristics on AI prevalence. We also estimated the fraction of all sex acts which were AI or UAI and compared condom use during VI and AI.Results: Of 41 included studies, 31 reported on AI prevalence and 14 on frequency, over various recall periods. AI prevalence was high across different recall periods for sexually active general-risk populations (e.g. lifetime = 18.4% [95%CI:9.4–27.5%], three-month = 20.3% [6.1–34.7%]), but tended to be even higher in higher-risk populations such as STI patients and female sex workers (e.g. lifetime = 23.2% [0.0–47.4%], recall period not stated = 40.1% [36.2–44.0%]). Prevalence was higher in studies using more confidential interview methods. Among general and higher-risk populations, 1.2–40.0% and 0.7–21.0% of all unprotected sex acts were UAI, respectively. AI acts were as likely to be condom protected as vaginal acts.Discussion: Reported heterosexual AI is common but variable among South Africans. Nationally and regionally representative sexual behaviour studies that use standardized recall periods and confidential interview methods, to aid comparison across studies and minimize reporting bias, are needed. Such data could be used to estimate the extent to which AI contributes to South Africa’s HIV epidemic.

Journal article

Brisson M, Benard E, Drolet M, Bogaards JA, Baussano I, Vanska S, Jit M, Boily MC, Smith MA, Berkhof J, Canfell K, Chesson HW, Burger EA, Choi YH, Freiesleben de Blasio B, De Vlas SJ, Guzzetta G, Hontelez JAC, Horn Jet al., 2016, Population-level impact, herd immunity, and eliminationafter human papillomavirus vaccination: a systematicreview and meta-analysis of predictions fromtransmission-dynamic models, Lancet Public Health, Vol: 1, Pages: e8-e17, ISSN: 2468-2667

BackgroundModelling studies have been widely used to inform human papillomavirus (HPV) vaccination policy decisions; however, many models exist and it is not known whether they produce consistent predictions of population-level effectiveness and herd effects. We did a systematic review and meta-analysis of model predictions of the long-term population-level effectiveness of vaccination against HPV 16, 18, 6, and 11 infection in women and men, to examine the variability in predicted herd effects, incremental benefit of vaccinating boys, and potential for HPV-vaccine-type elimination.MethodsWe searched MEDLINE and Embase for transmission-dynamic modelling studies published between Jan 1, 2009, and April 28, 2015, that predicted the population-level impact of vaccination on HPV 6, 11, 16, and 18 infections in high-income countries. We contacted authors to determine whether they were willing to produce new predictions for standardised scenarios. Strategies investigated were girls-only vaccination and girls and boys vaccination at age 12 years. Base-case vaccine characteristics were 100% efficacy and lifetime protection. We did sensitivity analyses by varying vaccination coverage, vaccine efficacy, and duration of protection. For all scenarios we pooled model predictions of relative reductions in HPV prevalence (RRprev) over time after vaccination and summarised results using the median and 10th and 90th percentiles (80% uncertainty intervals [UI]).Findings16 of 19 eligible models from ten high-income countries provided predictions. Under base-case assumptions, 40% vaccination coverage and girls-only vaccination, the RRprev of HPV 16 among women and men was 0·53 (80% UI 0·46–0·68) and 0·36 (0·28–0·61), respectively, after 70 years. With 80% girls-only vaccination coverage, the RRprev of HPV 16 among women and men was 0·93 (0·90–1·00) and 0·83 (0·75–1·00), respectiv

Journal article

Jean K, Boily M-C, Danel C, Moh R, Badje A, Desgrees-du-Lou A, Eholie S, Lert F, Dray-Spira R, Anglaret X, Ouattara Eet al., 2016, What level of risk compensation would offset the preventive effect of early antiretroviral therapy? Simulations from the TEMPRANO trial, American Journal of Epidemiology, Vol: 184, Pages: 755-760, ISSN: 1476-6256

Whether risk compensation could offset the preventive effect of early initiation of antiretroviral therapy (ART) on human immunodeficiency virus (HIV) transmission remains unknown. Using virological and behavioral data collected 12 months after inclusion in the TEMPRANO randomized trial of early ART (Abidjan, Côte d'Ivoire, 2009–2012), we estimated the risk of HIV transmission and compared it between the intervention (early ART; n = 490) and control (deferred ART; n = 467) groups. We then simulated increases in various sexual risk behaviors in the intervention group and estimated the resulting preventive effect. On the basis of reported values of sexual behaviors, we estimated that early ART had an 89% (95% confidence interval: 81, 95) preventive effect on the cumulative risk of HIV transmission over a 1-month period. This preventive effect remained significant for a wide range of parameter combinations and was offset (i.e., nonsignificant) only for dramatic increases in different sexual behaviors simulated simultaneously. For example, when considering a 2-fold increase in serodiscordance and the frequency of sexual intercourse together with a 33% decrease in condom use, the resulting preventive effect was 47% (95% confidence interval: −3, 74). An important reduction of HIV transmission may thus be expected from the scale-up of early ART, even in the context of behavioral change.

Journal article

Menon S, Wusiman A, Boily MC, Kariisa M, Mabeya H, Luchters S, Forland F, Rossi R, Callens S, Vanden Broeck Det al., 2016, Epidemiology of HPV Genotypes among HIV Positive Women in Kenya: A Systematic Review and Meta-Analysis, PLOS One, Vol: 11, ISSN: 1932-6203

BACKGROUND: There is a scarcity of data on the distribution of human papillomavirus (HPV) genotypes in the HIV positive population and in invasive cervical cancer (ICC) in Kenya. This may be different from genotypes found in abnormal cytology. Yet, with the advent of preventive HPV vaccines that target HPV 16 and 18, and the nonavalent vaccine targeting 90% of all ICC cases, such HPV genotype distribution data are indispensable for predicting the impact of vaccination and HPV screening on prevention. Even with a successful vaccination program, vaccinated women will still require screening to detect those who will develop ICC from other High risk (HR) HPV genotypes not prevented by current vaccines. The aim of this review is to report on the prevalence of pHR/HR HPV types and multiple pHR/HR HPV genotypes in Kenya among HIV positive women with normal, abnormal cytology and ICC. METHODS: PUBMED, EMBASE, SCOPUS, and PROQUEST were searched for articles on HPV infection up to August 2nd 2016. Search terms were HIV, HPV, Cervical Cancer, Incidence or Prevalence, and Kenya. RESULTS: The 13 studies included yielded a total of 2116 HIV-infected women, of which 89 had ICC. The overall prevalence of pHR/HR HPV genotypes among HIV-infected women was 64% (95%CI: 50%-77%). There was a borderline significant difference in the prevalence of pHR/HR HPV genotypes between Female Sex workers (FSW) compared to non-FSW in women with both normal and abnormal cytology. Multiple pHR/HR HPV genotypes were highly prominent in both normal cytology/HSIL and ICC. The most prevalent HR HPV genotypes in women with abnormal cytology were HPV 16 with 26%, (95%CI: 23.0%-30.0%) followed by HPV 35 and 52, with 21% (95%CI: 18%-25%) and 18% (95%CI: 15%-21%), respectively. In women with ICC, the most prevalent HPV genotypes were HPV 16 (37%; 95%CI: 28%-47%) and HPV 18 (24%; 95%CI: 16%-33%). CONCLUSION: HPV 16/18 gains prominence as the severity of cervical disease increases, with HPV 16/18 accounting for

Journal article

Mitchell KM, Hoots B, Dimitrov D, Farley J, Gelman M, German D, Flynn C, Adeyeye A, Remien RH, Beyrer C, Paz-Bailey G, Boily M-Cet al., 2016, Potential Impact on HIV Incidence of Increasing Viral Suppression among HIV-positive MSM in Baltimore: Mathematical Modelling for HPTN 078, Conference on HIV Research for Prevention (HIV R4P), Publisher: Mary Ann Liebert, Pages: 64-64, ISSN: 1931-8405

Conference paper

Maheu-Giroux M, Vesga JF, Diabate S, Alary M, Boily M-Cet al., 2016, Modeling the HIV Epidemic in Cote d'Ivoire: Impact of Past Interventions, Conference on HIV Research for Prevention (HIV R4P), Publisher: MARY ANN LIEBERT, INC, Pages: 300-300, ISSN: 0889-2229

Conference paper

Mitchell KM, Prudden HJ, Washington R, Isac S, Rajaram SP, Foss AM, Terris-Prestholt F, Boily MC, Vickerman Pet al., 2016, Potential impact of pre-exposure prophylaxis for female sex workers and men who have sex with men in Bangalore, India: a mathematical modelling study, Journal of the International AIDS Society, Vol: 19, ISSN: 1758-2652

Introduction: In Bangalore, new HIV infections of female sex workers and men who have sex with men continue to occur, despite high condom use. Pre-exposure prophylaxis (PrEP) has high anti-HIV efficacy for men who have sex with men. PrEP demonstration projects are underway amongst Indian female sex workers. We estimated the impact and efficiency of prioritising PrEP to female sex workers and/or men who have sex with men in Bangalore.Methods: A mathematical model of HIV transmission and treatment for female sex workers, clients, men who have sex with men and low-risk groups was parameterised and fitted to Bangalore data. The proportion of transmission attributable (population attributable fraction) to commercial sex and sex between men was calculated. PrEP impact (infections averted, life years gained) and efficiency (life years gained/infections averted per 100 person years on PrEP) were estimated for different levels of PrEP adherence, coverage and prioritisation strategies (female sex workers, high-risk men who have sex with men, both female sex workers and high-risk men who have sex with men, or female sex workers with lower condom use), under current conditions and in a scenario with lower baseline condom use amongst key populations. Results: Population attributable fractions for commercial sex and sex between men have declined over time, and they are predicted to account for 19% of all new infections between 2016 and 2025. PrEP could prevent a substantial proportion of infections amongst female sex workers and men who have sex with men in this setting (23%/27% over 5/10 years, with 60% coverage and 50% adherence), which could avert 2.9%/4.3% of infections over 5/10 years in the whole Bangalore population. Impact and efficiency in the whole population was greater if female sex workers were prioritised. Efficiency increased, but impact decreased, if only female sex workers with lower condom use were given PrEP. Greater impact and efficiency was predicted for the

Journal article

Dimitrov DT, Boily MC, Hallett TB, Albert J, Boucher C, Mellors JW, Pillay D, van de Vijver DAet al., 2016, How Much Do We Know about Drug Resistance Due to PrEP Use? Analysis of Experts’ Opinion and Its Influence on the Projected Public Health Impact, PLOS One, Vol: 11, ISSN: 1932-6203

BACKGROUND: Randomized controlled trials reported that pre-exposure prophylaxis (PrEP) with tenofovir and emtricitabine rarely selects for drug resistance. However, drug resistance due to PrEP is not completely understood. In daily practice, PrEP will not be used under the well-controlled conditions available in the trials, suggesting that widespread use of PrEP can result in increased drug resistance. METHODS: We surveyed expert virologists with questions about biological assumptions regarding drug resistance due to PrEP use. The influence of these assumptions on the prevalence of drug resistance and the fraction of HIV transmitted resistance was studied with a mathematical model. For comparability, 50% PrEP-coverage of and 90% per-act efficacy of PrEP in preventing HIV acquisition are assumed in all simulations. RESULTS: Virologists disagreed on the following: the time until resistance emergence (range: 20-180 days) in infected PrEP users with breakthrough HIV infections; the efficacy of PrEP against drug-resistant HIV (25%-90%); and the likelihood of resistance acquisition upon transmission (10%-75%). These differences translate into projections of 0.6%- 1% and 3.5%-6% infected individuals with detectable resistance 10 years after introducing PrEP, assuming 100% and 50% adherence, respectively. The rate of resistance emergence following breakthrough HIV infection and the rate of resistance reversion after PrEP use is discontinued, were the factors identified as most influential on the expected resistance associated with PrEP. Importantly, 17-23% infected individuals could virologically fail treatment as a result of past PrEP use or transmitted resistance to PrEP with moderate adherence. CONCLUSIONS: There is no broad consensus on quantification of key biological processes that underpin the emergence of PrEP-associated drug resistance. Despite this, the contribution of PrEP use to the prevalence of the detectable drug resistance is expected to be small. However, i

Journal article

Mishra S, Boily MC, Schwartz S, Beyrer C, Blanchard JF, Moses S, Castor D, Phaswana-Mafuya N, Vickerman P, Drame F, Alary M, Baral SDet al., 2016, Data and methods to characterize the role of sex work and to inform sex work programs in generalized HIV epidemics: evidence to challenge assumptions, Annals of Epidemiology, Vol: 26, Pages: 557-569, ISSN: 1873-2585

In the context of generalized human immunodeficiency virus (HIV) epidemics, there has been limited recent investment in HIV surveillance and prevention programming for key populations including female sex workers. Often implicit in the decision to limit investment in these epidemic settings are assumptions including that commercial sex is not significant to the sustained transmission of HIV, and HIV interventions designed to reach "all segments of society" will reach female sex workers and clients. Emerging empiric and model-based evidence is challenging these assumptions. This article highlights the frameworks and estimates used to characterize the role of sex work in HIV epidemics as well as the relevant empiric data landscape on sex work in generalized HIV epidemics and their strengths and limitations. Traditional approaches to estimate the contribution of sex work to HIV epidemics do not capture the potential for upstream and downstream sexual and vertical HIV transmission. Emerging approaches such as the transmission population attributable fraction from dynamic mathematical models can address this gap. To move forward, the HIV scientific community must begin by replacing assumptions about the epidemiology of generalized HIV epidemics with data and more appropriate methods of estimating the contribution of unprotected sex in the context of sex work.

Journal article

Jean K, Boily MC, Danel C, Moh R, Badge A, Desgrées-du- Loû A, Eholié S, Lert F, Dray-Spira R, Anglaret X, Ouattara Eet al., What Level Of Risk Compensation Would Offset the Preventive Effect of Early ART? Simulations from the Temprano Trial (Abidjan, Côte d’Ivoire), American Journal of Epidemiology, ISSN: 1476-6256

Journal article

Dureau J, Kalogeropoulos K, Vickerman P, Pickles M, Boily M-Cet al., 2016, A Bayesian approach to estimate changes in condom use from limited human immunodeficiency virus prevalence data, Journal of the Royal Statistical Society Series C - Applied Statistics, Vol: 65, Pages: 237-257, ISSN: 0035-9254

Evaluation of large-scale intervention programmes against human immunodeficiency virus (HIV) is becoming increasingly important, but impact estimates frequently hinge on knowledge of changes in behaviour such as the frequency of condom use over time, or other self-reported behaviour changes, for which we generally have limited or potentially biased data. We employ a Bayesian inference methodology that incorporates an HIV transmission dynamics model to estimate condom use time trends from HIV prevalence data. Estimation is implemented via particle Markov chain Monte Carlo methods, applied for the first time in this context. The preliminary choice of the formulation for the time varying parameter reflecting the proportion of condom use is critical in the context studied, because of the very limited amount of condom use and HIV data available. We consider various novel formulations to explore the trajectory of condom use over time, based on diffusion-driven trajectories and smooth sigmoid curves. Numerical simulations indicate that informative results can be obtained regarding the amplitude of the increase in condom use during an intervention, with good levels of sensitivity and specificity performance in effectively detecting changes. The application of this method to a real life problem demonstrates how it can help in evaluating HIV interventions based on a small number of prevalence estimates, and it opens the way to similar applications in different contexts.

Journal article

Lemieux-Mellouki P, Drolet M, Brisson J, Franco EL, Boily M-C, Baussano I, Brisson Met al., 2015, Assortative mixing as a source of bias in epidemiological studies of sexually transmitted infections: the case of smoking and human papillomavirus, Epidemiology and Infection, Vol: 144, Pages: 1490-1499, ISSN: 1469-4409

Journal article

Brisson M, Laprise J-F, Chesson HW, Drolet M, Malagon T, Boily M-C, Markowitz LEet al., 2015, Health and Economic Impact of Switching From a 4-Valent to a 9-Valent HPV Vaccination Program in the United States, Journal of the National Cancer Institute, Vol: 108, ISSN: 0027-8874

Background: Randomized clinical trials have shown the 9-valent human papillomavirus (HPV) vaccine to be highly effective against types 31/33/45/52/58 compared with the 4-valent. Evidence on the added health and economic benefit of the 9-valent is required for policy decisions. We compare population-level effectiveness and cost-effectiveness of 9- and 4-valent HPV vaccination in the United States.Methods: We used a multitype individual-based transmission-dynamic model of HPV infection and disease (anogenital warts and cervical, anogenital, and oropharyngeal cancers), 3% discount rate, and societal perspective. The model was calibrated to sexual behavior and epidemiologic data from the United States. In our base-case, we assumed 95% vaccine-type efficacy, lifelong protection, and a cost/dose of $145 and $158 for the 4- and 9-valent vaccine, respectively. Predictions are presented using the mean (80% uncertainty interval [UI] = 10th−90th percentiles) of simulations.Results: Under base-case assumptions, the 4-valent gender-neutral vaccination program is estimated to cost $5500 (80% UI = 2400–9400) and $7300 (80% UI = 4300−11 000)/quality-adjusted life-year (QALY) gained with and without cross-protection, respectively. Switching to a 9-valent gender-neutral program is estimated to be cost-saving irrespective of cross-protection assumptions. Finally, the incremental cost/QALY gained of switching to a 9-valent gender-neutral program (vs 9-valent girls/4-valent boys) is estimated to be $140 200 (80% UI = 4200−>1 million) and $31 100 (80% UI = 2100−>1 million) with and without cross-protection, respectively. Results are robust to assumptions about HPV natural history, screening methods, duration of protection, and healthcare costs.Conclusions: Switching to a 9-valent gender-neutral HPV vaccination program is likely to be cost-saving if the additional cost/dose of the 9-valent is less than $13. Giving females the 9-valent vaccine provides t

Journal article

Drolet M, Benard E, Boily M-C, Ali H, Baandrup L, Bauer H, Beddows S, Brisson J, Brotherton JML, Cummings T, Donovan B, Fairley CK, Flagg EW, Johnson AM, Kahn JA, Kavanagh K, Kjaer SK, Kliewer EV, Lemieux-Mellouki P, Markowitz L, Mboup A, Mesher D, Niccolai L, Oliphant J, Pollock KG, Soldan K, Sonnenberg P, Tabrizi SN, Tanton C, Brisson Met al., 2015, Population-level impact and herd effects following human papillomavirus vaccination programmes: a systematic review and meta-analysis, LANCET INFECTIOUS DISEASES, Vol: 15, Pages: 565-580, ISSN: 1473-3099

Journal article

Tavitian-Exley I, Vickerman P, Bastos FI, Boily M-Cet al., 2015, Influence of different drugs on HIV risk in people who inject: systematic review and meta-analysis, ADDICTION, Vol: 110, Pages: 572-584, ISSN: 0965-2140

Journal article

Boily M-C, Pickles M, Alary M, Baral S, Blanchard J, Moses S, Vickerman P, Mishra Set al., 2015, What Really Is a Concentrated HIV Epidemic and What Does It Mean for West and Central Africa? Insights From Mathematical Modeling, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 68, Pages: S74-S82, ISSN: 1525-4135

Journal article

Beyrer C, Crago A-L, Bekker L-G, Butler J, Shannon K, Kerrigan D, Decker MR, Baral SD, Poteat T, Wirtz AL, Weir BW, Barre-Sinoussi F, Kazatchkine M, Sidibe M, Dehne K-L, Boily M-C, Strathdee SAet al., 2015, An action agenda for HIV and sex workers, LANCET, Vol: 385, Pages: 287-301, ISSN: 0140-6736

Journal article

Shannon K, Strathdee SA, Goldenberg SM, Duff P, Mwangi P, Rusakova M, Reza-Paul S, Lau J, Deering K, Pickles MR, Boily M-Cet al., 2015, Global epidemiology of HIV among female sex workers: influence of structural determinants, LANCET, Vol: 385, Pages: 55-71, ISSN: 0140-6736

Journal article

Malagon T, Drolet M, Boily M-C, Laprise J-F, Brisson Met al., 2015, Changing Inequalities in Cervical Cancer: Modeling the Impact of Vaccine Uptake, Vaccine Herd Effects, and Cervical Cancer Screening in the Post-Vaccination Era, CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION, Vol: 24, Pages: 276-285, ISSN: 1055-9965

Journal article

Mitchell KM, Foss AM, Ramesh BM, Washington R, Isac S, Prudden HJ, Deering KN, Blanchard JF, Moses S, Lowndes CM, Boily M-C, Alary M, Vickerman Pet al., 2014, Relationship between exposure to the Avahan intervention and levels of reported condom use among men who have sex with men in southern India, BMC Public Health, Vol: 14, ISSN: 1471-2458

BackgroundThe Avahan intervention promotes consistent (100%) condom use amongst men who have sex with men in southern India. We assessed how condom use varies with intervention exposure for men who have sex with men in Bangalore.MethodsSelf-reported condom use and intervention exposure data were derived from a cross-sectional survey. Consistent condom use and condom use at last sex act with all, main, and casual male sex partners were assessed. Binary and continuous variables reflecting intervention exposure (including contact(s) with intervention staff, receiving condoms and seeing condom demonstrations) were used. Multivariable logistic regression was employed to assess the relationship between condom use with each type of partner and each exposure variable independently, controlling for socio-demographic and behavioural factors associated with condom use or intervention exposure.ResultsCondom use with all partners was higher among those who had ever been contacted by, received condoms from, or seen a condom demonstration by intervention staff (adjusted odds ratio >2, p < 0.02 for all). Consistent condom use with all types of partner increased with the number of condom demonstrations seen in the last month (adjusted odds ratio = 2.1 per demonstration, p < 0.025), while condom use at last sex act with a casual (but not main) partner increased with the number of condoms received from the intervention (adjusted odds ratio = 1.4 per condom, p = 0.04).ConclusionsDirect contact with Avahan program staff is associated with increased reported condom use among men who have sex with men in Bangalore. Reported consistent condom use and condom use at last sex act are associated with contacts involving demonstrations of correct condom use, and with receiving condoms, respectively.Keywords: Consistent condom use; Condom use at last sex act; Condom demonstration; Key population; Bangalore; Cross-secti

Journal article

Vassall A, Chandrashekar S, Pickles M, Beattie TS, Shetty G, Bhattacharjee P, Boily M-C, Vickerman P, Bradley J, Alary M, Moses S, CHARME India Group, Watts Cet al., 2014, Community mobilisation and empowerment interventions as part of HIV prevention for female sex workers in southern India: a cost-effectiveness analysis, PLOS One, Vol: 9, ISSN: 1932-6203

BackgroundMost HIV prevention for female sex workers (FSWs) focuses on individual behaviour change involving peer educators, condom promotion and the provision of sexual health services. However, there is a growing recognition of the need to address broader societal, contextual and structural factors contributing to FSW risk behaviour. We assess the cost-effectiveness of adding community mobilisation (CM) and empowerment interventions (eg. community mobilisation, community involvement in programme management and services, violence reduction, and addressing legal policies and police practices), to core HIV prevention services delivered as part of Avahan in two districts (Bellary and Belgaum) of Karnataka state, Southern India.MethodsAn ingredients approach was used to estimate economic costs in US$ 2011 from an HIV programme perspective of CM and empowerment interventions over a seven year period (2004–2011). Incremental impact, in terms of HIV infections averted, was estimated using a two-stage process. An ‘exposure analysis’ explored whether exposure to CM was associated with FSW’s empowerment, risk behaviours and HIV/STI prevalence. Pathway analyses were then used to estimate the extent to which behaviour change may be attributable to CM and to inform a dynamic HIV transmission model.FindingsThe incremental costs of CM and empowerment were US$ 307,711 in Belgaum and US$ 592,903 in Bellary over seven years (2004–2011). Over a 7-year period (2004–2011) the mean (standard deviation, sd.) number of HIV infections averted through CM and empowerment is estimated to be 1257 (308) in Belgaum and 2775 (1260) in Bellary. This translates in a mean (sd.) incremental cost per disability adjusted life year (DALY) averted of US$ 14.12 (3.68) in Belgaum and US$ 13.48 (6.80) for Bellary - well below the World Health Organisation recommended willingness to pay threshold for India. When savings from ART are taken into account, investments in CM an

Journal article

Laprise J-F, Drolet M, Boily M-C, Jit M, Sauvageau C, Franco EL, Lemieux-Mellouki P, Malagon T, Brisson Met al., 2014, Comparing the cost-effectiveness of two- and three-dose schedules of human papillomavirus vaccination: A transmission-dynamic modelling study, VACCINE, Vol: 32, Pages: 5845-5853, ISSN: 0264-410X

Journal article

Panovska-Griffiths J, Vassall A, Prudden HJ, Lepine A, Boily M-C, Chandrashekar S, Mitchell K, Beattie TS, Alary M, Martin NK, Vickerman Pet al., 2014, Optimal allocation of resources in female sex worker targeted HIV prevention interventions: Model insights from Avahan in South India, PLOS One, Vol: 9, ISSN: 1932-6203

BackgroundThe Avahan programme has provided HIV prevention activities, including condom promotion, to female sex workers (FSWs) in southern India since 2004. Evidence suggests Avahan averted 202,000 HIV infections over 4 years. For replicating this intervention elsewhere, it is essential to understand how the intervention’s impact could have been optimised for different budget levels.MethodsBehavioural data were used to determine how condom use varied for FSWs with different levels of intervention intensity. Cost data from 64 Avahan districts quantified how district-level costs related to intervention scale and intensity. A deterministic model for HIV transmission amongst FSWs and clients projected the impact and cost of intervention strategies for different scale and intensity, and identified the optimal strategies that maximise impact for different budget levels.ResultsAs budget levels increase, the optimal intervention strategy is to first increase intervention intensity which achieves little impact, then scale-up coverage to high levels for large increases in impact, and lastly increase intensity further for small additional gains. The cost-effectiveness of these optimal strategies generally improves with increasing resources, while straying from these strategies can triple costs for the same impact. Projections suggest Avahan was close to being optimal, and moderate budget reductions (≥20%) would have reduced impact considerably (>40%).DiscussionOur analysis suggests that tailoring the design of HIV prevention programmes for FSWs can improve impact, and that a certain level of resources are required to achieve demonstrable impact. These insights are critical for optimising the use of limited resources for preventing HIV.

Journal article

Mountain E, Pickles M, Mishra S, Vickerman P, Alary M, Boily M-Cet al., 2014, The HIV care cascade and antiretroviral therapy in female sex workers: implications for HIV prevention, EXPERT REVIEW OF ANTI-INFECTIVE THERAPY, Vol: 12, Pages: 1203-1219, ISSN: 1478-7210

Journal article

Mountain E, Mishra S, Vickerman P, Pickles M, Gilks C, Boily M-Cet al., 2014, Antiretroviral therapy uptake, attrition, adherence and outcomes among HIB-infected female sex workers: a systematic review and meta-analysis, PLOS One, Vol: 9, ISSN: 1932-6203

PurposeWe aimed to characterize the antiretroviral therapy (ART) cascade among female sex workers (FSWs) globally.MethodsWe systematically searched PubMed, Embase and MEDLINE in March 2014 to identify studies reporting on ART uptake, attrition, adherence, and outcomes (viral suppression or CD4 count improvements) among HIV-infected FSWs globally. When possible, available estimates were pooled using random effects meta-analyses (with heterogeneity assessed using Cochran's Q test and I2 statistic).Results39 studies, reporting on 21 different FSW study populations in Asia, Africa, North America, South America, and Central America and the Caribbean, were included. Current ART use among HIV-infected FSWs was 38% (95% CI: 29%–48%, I2 = 96%, 15 studies), and estimates were similar between high-, and low- and middle-income countries. Ever ART use among HIV-infected FSWs was greater in high-income countries (80%; 95% CI: 48%–94%, I2 = 70%, 2 studies) compared to low- and middle-income countries (36%; 95% CI: 7%–81%, I2 = 99%, 3 studies). Loss to follow-up after ART initiation was 6% (95% CI: 3%–11%, I2 = 0%, 3 studies) and death after ART initiation was 6% (95% CI: 3%–11%, I2 = 0%, 3 studies). The fraction adherent to ≥95% of prescribed pills was 76% (95% CI: 68%–83%, I2 = 36%, 4 studies), and 57% (95% CI: 46%–68%, I2 = 82%, 4 studies) of FSWs on ART were virally suppressed. Median gains in CD4 count after 6 to 36 months on ART, ranged between 103 and 241 cells/mm3 (4 studies).ConclusionsDespite global increases in ART coverage, there is a concerning lack of published data on HIV treatment for FSWs. Available data suggest that FSWs can achieve levels of ART uptake, retention, adherence, and treatment response comparable to that seen among women in the general population, but these data are from only a few research settings. More routine programme data on HIV treatment among FSWs across settings should be collected and disseminated

Journal article

Vassall A, Pickles M, Chandrashekar S, Boily M-C, Shetty G, Guinness L, Lowndes CM, Bradley J, Moses S, Alary M, Vickerman Pet al., 2014, Cost-effectiveness of HIV prevention for high-risk groups at scale: an economic evaluation of the Avahan programme in south India, LANCET GLOBAL HEALTH, Vol: 2, Pages: E531-E540, ISSN: 2214-109X

Journal article

Mitchell KM, Foss AM, Prudden HJ, Mukandavire Z, Pickles M, Williams JR, Johnson HC, Ramesh BM, Washington R, Isac S, Rajaram S, Phillips AE, Bradley J, Alary M, Moses S, Lowndes CM, Watts CH, Boily M-C, Vickerman Pet al., 2014, Who mixes with whom among men who have sex with men? Implications for modelling the HIV epidemic in southern India, Journal of Theoretical Biology, Vol: 355, Pages: 140-150, ISSN: 1095-8541

In India, the identity of men who have sex with men (MSM) is closely related to the role taken in anal sex(insertive, receptive or both), but little is known about sexual mixing between identity groups. Both rolesegregation (taking only the insertive or receptive role) and the extent of assortative (within-group)mixing are known to affect HIV epidemic size in other settings and populations. This study explores howdifferent possible mixing scenarios, consistent with behavioural data collected in Bangalore, south India,affect both the HIV epidemic, and the impact of a targeted intervention. Deterministic models describingHIV transmission between three MSM identity groups (mostly insertive Panthis/Bisexuals, mostlyreceptive Kothis/Hijras and versatile Double Deckers), were parameterised with behavioural data fromBangalore. We extended previous models of MSM role segregation to allow each of the identity groups tohave both insertive and receptive acts, in differing ratios, in line with field data. The models were used toexplore four different mixing scenarios ranging from assortative (maximising within-group mixing) todisassortative (minimising within-group mixing). A simple model was used to obtain insights into therelationship between the degree of within-group mixing, R0 and equilibrium HIV prevalence underdifferent mixing scenarios. A more complex, extended version of the model was used to compare the predicted HIV prevalence trends and impact of an HIV intervention when fitted to data from Bangalore.With the simple model, mixing scenarios with increased amounts of assortative (within-group) mixingtended to give rise to a higher R0 and increased the likelihood that an epidemic would occur. When thecomplex model was fit to HIV prevalence data, large differences in the level of assortative mixing wereseen between the fits identified using different mixing scenarios, but little difference was projected infuture HIV prevalence trends. An oral pre-exposure prophylaxis (P

Journal article

Williams JR, Alary M, Lowndes CM, Behanzin L, Labbe A-C, Anagonou S, Ndour M, Minani I, Ahoussinou C, Zannou DM, Boily M-Cet al., 2014, Positive Impact of Increases in Condom Use among Female Sex Workers and Clients in a Medium HIV Prevalence Epidemic: Modelling Results from Project SIDA1/2/3 in Cotonou, Benin, PLOS One, Vol: 9, ISSN: 1932-6203

BackgroundA comprehensive, HIV prevention programme (Projet Sida1/2/3) was implemented among female sex workers (FSWs) in Cotonou, Benin, in 1993 following which condom use among FSWs increased threefold between 1993 and 2008 while FSW HIV prevalence declined from 53.3% to 30.4%.ObjectiveEstimate the potential impact of the intervention on HIV prevalence/incidence in FSWs, clients and the general population in Cotonou, Benin.Methods and FindingsA transmission dynamics model parameterised with setting-specific bio-behavioural data was used within a Bayesian framework to fit the model and simulate HIV transmission in the high and low-risk population of Cotonou and to estimate HIV incidence and infections averted by SIDA1/2/3. Our model results suggest that prior to SIDA1/2/3 commercial sex had contributed directly or indirectly to 93% (84–98%) of all cumulative infections and that the observed decline in FSWs HIV prevalence was more consistent with the self-reported post-intervention increase in condom use by FSWs than a counterfactual assuming no change in condom use after 1993 (CF-1). Compared to the counterfactual (CF-1), the increase in condom use may have prevented 62% (52–71%) of new HIV infections among FSWs between 1993 and 2008 and 33% (20–46%) in the overall population.ConclusionsOur analysis provides plausible evidence that the post-intervention increase in condom use during commercial sex significantly reduced HIV prevalence and incidence among FSWs and general population. Sex worker interventions can be effective even in medium HIV prevalence epidemics and need to be sustained over the long-term.

Journal article

Mishra S, Pickles M, Blanchard JF, Moses S, Shubber Z, Boily M-Cet al., 2014, Validation of the Modes of Transmission Model as a Tool to Prioritize HIV Prevention Targets: A Comparative Modelling Analysis, PLOS ONE, Vol: 9, ISSN: 1932-6203

Journal article

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