214 results found
Dimitrov D, Boily M-C, Brown ER, et al., 2013, Analytic Review of Modeling Studies of ARV Based PrEP Interventions Reveals Strong Influence of Drug-Resistance Assumptions on the Population-Level Effectiveness, PLOS One, Vol: 8, ISSN: 1932-6203
BackgroundFour clinical trials have shown that oral and topical pre-exposure prophylaxis (PrEP) based on tenofovir may be effective in preventing HIV transmission. The expected reduction in HIV transmission and the projected prevalence of drug resistance due to PrEP use vary significantly across modeling studies as a result of the broad spectrum of assumptions employed. Our goal is to quantify the influence of drug resistance assumptions on the predicted population-level impact of PrEP.MethodsAll modeling studies which evaluate the impact of oral or topical PrEP are reviewed and key assumptions regarding mechanisms of generation and spread of drug-resistant HIV are identified. A dynamic model of the HIV epidemic is developed to assess and compare the impact of oral PrEP using resistance assumptions extracted from published studies. The benefits and risks associated with ten years of PrEP use are evaluated under identical epidemic, behavioral and intervention conditions in terms of cumulative fractions of new HIV infections prevented, resistance prevalence among those infected with HIV, and fractions of infections in which resistance is transmitted.ResultsPublished models demonstrate enormous variability in resistance-generating assumptions and uncertainty in parameter values. Depending on which resistance parameterization is used, a resistance prevalence between 2% and 44% may be expected if 50% efficacious oral PrEP is used consistently by 50% of the population over ten years. We estimated that resistance may be responsible for up to a 10% reduction or up to a 30% contribution to the fraction of prevented infections predicted in different studies.ConclusionsResistance assumptions used in published studies have a strong influence on the projected impact of PrEP. Modelers and virologists should collaborate toward clarifying the set of resistance assumptions biologically relevant to the PrEP products which are already in use or soon to be added to the arsenal against
Ralph LJ, McCoy SI, Hallett T, et al., 2013, Next steps for research on hormonal contraception and HIV, LANCET, Vol: 382, Pages: 1467-1469, ISSN: 0140-6736
Cohen MS, Smith MK, Muessig KE, et al., 2013, Antiretroviral treatment of HIV-1 prevents transmission of HIV-1: where do we go from here?, LANCET, Vol: 382, Pages: 1515-1524, ISSN: 0140-6736
Hontelez JAC, Lurie MN, Baernighausen T, et al., 2013, Elimination of HIV in South Africa through Expanded Access to Antiretroviral Therapy: A Model Comparison Study, PLOS MEDICINE, Vol: 10, ISSN: 1549-1277
Smit M, Smit C, Geerlings S, et al., 2013, Changes in First-Line cART Regimens and Short-Term Clinical Outcome between 1996 and 2010 in The Netherlands, PLOS One, Vol: 8, ISSN: 1932-6203
Objectives: Document progress in HIV-treatment in the Netherlands since 1996 by reviewing changing patterns of cART useand relating those to trends in patients’ short-term clinical outcomes between 1996 and 2010.Design and Methods: 1996–2010 data from 10,278 patients in the Dutch ATHENA national observational cohort wereanalysed. The annual number of patients starting a type of regimen was quantified. Trends in the following outcomes weredescribed: i) recovery of 150 CD4 cells/mm3 within 12 months of starting cART; ii) achieving viral load (VL) suppression#1,000 copies/ml within 12 months of starting cART; iii) switching from first-line to second-line regimen within three yearsof starting treatment; and iv) all-cause mortality rate per 100 person-years within three years of starting treatment.Results: Between 1996 and 2010, first-line regimens changed from lamivudine/zidovudine-based or lamivudine/stavudinebasedregimens with unboosted-PIs to tenofovir with either emtricitabine or lamivudine with NNRTIs. Mortality rates did notchange significantly over time. VL suppression and CD4 recovery improved over time, and the incidence of switching due tovirological failure and toxicity more than halved between 1996 and 2010. These effects appear to be related to the use ofnew regimens rather than improvements in clinical care.Conclusion: The use of first-line cART in the Netherlands closely follows changes in guidelines, to the benefit of patients.While there was no significant improvement in mortality, newer drugs with better tolerability and simpler dosing resulted inimproved immunological and virological recovery and reduced incidences of switching due to toxicity and virologicalfailure.
Celum C, Hallett TB, Baeten JM, 2013, HIV-1 Prevention With ART and PrEP: Mathematical Modeling Insights Into Resistance, Effectiveness, and Public Health Impact, JOURNAL OF INFECTIOUS DISEASES, Vol: 208, Pages: 189-191, ISSN: 0022-1899
Hallett TB, Eaton JW, 2013, A Side Door Into Care Cascade for HIV-Infected Patients?, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 63, Pages: S228-S232, ISSN: 1525-4135
Vesga JF, Boily MC, Hallett TB, 2013, ESTIMATING THE IMPACT OF ANTIRETROVIRAL THERAPY AND CONDOMS IN THE HIV EPIDEMIC OF BOGOTA, COLOMBIA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A281-A281, ISSN: 1368-4973
Alsallaq R, Buttolph J, Cleland C, et al., 2013, ESTIMATING THE IMPACT OF COMBINED PREVENTION INTERVENTIONS TARGETING 15-24 YEARS-OLD MEN AND WOMEN IN NYANZA, KENYA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A269-A269, ISSN: 1368-4973
Elmes J, Nhongo K, Hallett T, et al., 2013, THE SOCIAL ORGANISATION OF SEX WORK IN RURAL EASTERN ZIMBABWE AND ITS IMPLICATIONS FOR HIV INFECTION, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A179-A180, ISSN: 1368-4973
Elmes J, Nhongo K, Hallett T, et al., 2013, THE PRICE OF SEX: INSIGHTS INTO THE DETERMINANTS OF THE PRICE OF COMMERCIAL SEX AMONG FEMALE SEX WORKERS IN RURAL ZIMBABWE, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A39-A39, ISSN: 1368-4973
Estill J, Egger M, Blaser N, et al., 2013, Cost-effectiveness of point-of-care viral load monitoring of antiretroviral therapy in resource-limited settings: mathematical modelling study, AIDS, Vol: 27, Pages: 1483-1492, ISSN: 0269-9370
Estill J, Egger M, Johnson LF, et al., 2013, Monitoring of Antiretroviral Therapy and Mortality in HIV Programmes in Malawi, South Africa and Zambia: Mathematical Modelling Study, PLOS ONE, Vol: 8, ISSN: 1932-6203
Cremin I, Alsallaq R, Dybul M, et al., 2013, The new role of antiretrovirals in combination HIV prevention: a mathematical modelling analysis, AIDS, Vol: 27, Pages: 447-458, ISSN: 0269-9370
Alsallaq RA, Baeten JM, Celum CL, et al., 2013, Understanding the Potential Impact of a Combination HIV Prevention Intervention in a Hyper-Endemic Community, PLOS ONE, Vol: 8, ISSN: 1932-6203
Chemaitelly H, Shelton JD, Hallett TB, et al., 2013, Only a fraction of new HIV infections occur within identifiable stable discordant couples in sub-Saharan Africa, AIDS, Vol: 27, Pages: 251-260, ISSN: 0269-9370
Butler AR, Smith JA, Polis CB, et al., 2013, Modelling the global competing risks of a potential interaction between injectable hormonal contraception and HIV risk, AIDS, Vol: 27, Pages: 105-113, ISSN: 0269-9370
Background: Some, but not all, observational studies have suggested an increase in the risk of HIV acquisition for women using injectable hormonal contraception (IHC).Methods: We used country-level data to explore the effects of reducing IHC use on the number of HIV infections, the number of live births and the resulting net consequences on AIDS deaths and maternal mortality for each country.Results: High IHC use coincides with high HIV incidence primarily in southern and eastern Africa. If IHC increases the risk of HIV acquisition, this could generate 27 000–130 000 infections per year globally, 87–88% of which occur in this region. Reducing IHC use could result in fewer HIV infections but also a substantial increase in live births and maternal mortality in countries with high IHC use, high birth rates and high maternal mortality: mainly southern and eastern Africa, South-East Asia, and Central and South America. For most countries, the net impact of reducing IHC use on maternal and AIDS-related deaths is dependent on the magnitude of the assumed IHC–HIV interaction.Conclusions: If IHC use increases HIV acquisition risk, reducing IHC could reduce new HIV infections; however, this must be balanced against other important consequences, including unintended pregnancy, which impacts maternal and infant mortality. Unless the true effect size approaches a relative risk of 2.19, it is unlikely that reductions in IHC could result in public health benefit, with the possible exception of those countries in southern Africa with the largest HIV epidemics.
Wheelock A, Eisingerich AB, Ananworanich J, et al., 2013, Are Thai MSM Willing to Take PrEP for HIV Prevention? An Analysis of Attitudes, Preferences and Acceptance, Plos One, Vol: 8(1)e54288
Eaton JW, Hallett TB, Epstein H, 2012, What Might be the Impact of Sexual Partnership "Concurrency'' Behavior Change Communication Campaigns?, SEXUALLY TRANSMITTED DISEASES, Vol: 39, Pages: 899-899, ISSN: 0148-5717
Case KK, Ghys PD, Gouws E, et al., 2012, Understanding the modes of transmission model of new HIV infection and its use in prevention planning, BULLETIN OF THE WORLD HEALTH ORGANIZATION, Vol: 90, Pages: 831-838, ISSN: 0042-9686
Hontelez JAC, Lurie MN, Baernighausen T, et al., 2012, Treatment as prevention for HIV in South Africa: different models show consistency in occurrence, but difference in timing of elimination and the overall impact of the intervention, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 15, Pages: 113-116
Gomez GB, Borquez A, Caceres CF, et al., 2012, The Potential Impact of Pre-Exposure Prophylaxis for HIV Prevention among Men Who Have Sex with Men and Transwomen in Lima, Peru: A Mathematical Modelling Study, PLOS MEDICINE, Vol: 9, ISSN: 1549-1676
Escaleira F, Birger R, Hallett T, et al., 2012, Cost-effectiveness of test and treat prevention in a high HIV prevalence US city, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 15, Pages: 256-257
Smit M, Smit C, Cremin I, et al., 2012, Could better tolerated HIV drug regimens improve patient outcome?, AIDS, Vol: 26, Pages: 1953-1959, ISSN: 0269-9370
Estill J, Aubriere C, Egger M, et al., 2012, Viral load monitoring of antiretroviral therapy, cohort viral load and HIV transmission in Southern Africa: a mathematical modelling analysis, AIDS, Vol: 26, Pages: 1403-1413, ISSN: 0269-9370
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.
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.
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
Johnson LF, Hallett TB, Rehle TM, et al., 2012, The effect of changes in condom usage and antiretroviral treatment coverage on human immunodeficiency virus incidence in South Africa: a model-based analysis, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 9, Pages: 1544-1554, ISSN: 1742-5689
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