Validation of the Modes of Transmission Model as a Tool to Prioritize HIV Prevention Targets: A Comparative Modelling Analysis

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Abstract

Background

The static Modes of Transmission (MOT) model predicts the annual fraction of new HIV infections acquired across subgroups (MOT metric), and is used to focus HIV prevention. Using synthetic epidemics via a dynamical model, we assessed the validity of the MOT metric for identifying epidemic drivers (behaviours or subgroups that are sufficient and necessary for HIV to establish and persist), and the potential consequence of MOT-guided policies.

Methods and Findings

To generate benchmark MOT metrics for comparison, we simulated three synthetic epidemics (concentrated, mixed, and generalized) with different epidemic drivers using a dynamical model of heterosexual HIV transmission. MOT metrics from generic and complex MOT models were compared against the benchmark, and to the contribution of epidemic drivers to overall HIV transmission (cumulative population attributable fraction over t years, PAF _t). The complex MOT metric was similar to the benchmark, but the generic MOT underestimated the fraction of infections in epidemic drivers. The benchmark MOT metric identified epidemic drivers early in the epidemics. Over time, the MOT metric did not identify epidemic drivers. This was not due to simplified MOT models or biased parameters but occurred because the MOT metric (irrespective of the model used to generate it) underestimates the contribution of epidemic drivers to HIV transmission over time (PAF _5–30). MOT-directed policies that fail to reach epidemic drivers could undermine long-term impact on HIV incidence, and achieve a similar impact as random allocation of additional resources.

Conclusions

Irrespective of how it is obtained, the MOT metric is not a valid stand-alone tool to identify epidemic drivers, and has limited additional value in guiding the prioritization of HIV prevention targets. Policy-makers should use the MOT model judiciously, in combination with other approaches, to identify epidemic drivers.

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Most cited references 26

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Towards an improved investment approach for an effective response to HIV/AIDS.

Bernhard Schwartländer, John Stover, Timothy Hallett … (2011)

Substantial changes are needed to achieve a more targeted and strategic approach to investment in the response to the HIV/AIDS epidemic that will yield long-term dividends. Until now, advocacy for resources has been done on the basis of a commodity approach that encouraged scaling up of numerous strategies in parallel, irrespective of their relative effects. We propose a strategic investment framework that is intended to support better management of national and international HIV/AIDS responses than exists with the present system. Our framework incorporates major efficiency gains through community mobilisation, synergies between programme elements, and benefits of the extension of antiretroviral therapy for prevention of HIV transmission. It proposes three categories of investment, consisting of six basic programmatic activities, interventions that create an enabling environment to achieve maximum effectiveness, and programmatic efforts in other health and development sectors related to HIV/AIDS. The yearly cost of achievement of universal access to HIV prevention, treatment, care, and support by 2015 is estimated at no less than US$22 billion. Implementation of the new investment framework would avert 12·2 million new HIV infections and 7·4 million deaths from AIDS between 2011 and 2020 compared with continuation of present approaches, and result in 29·4 million life-years gained. The framework is cost effective at $1060 per life-year gained, and the additional investment proposed would be largely offset from savings in treatment costs alone. Copyright © 2011 Elsevier Ltd. All rights reserved.

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"Know your epidemic, know your response": a useful approach, if we get it right.

T Halperin, David Wilson (2008)

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HIV and other sexually transmitted infections in a cohort of women involved in high-risk sexual behavior in Kampala, Uganda.

Judith Vandepitte, Justine Bukenya, Helen A Weiss … (2011)

Uganda has long been successful in controlling the HIV epidemic; however, there is evidence that HIV prevalence and incidence are increasing again. Data on the HIV/STI epidemic among sex workers are so far lacking from Uganda. This paper describes the baseline epidemiology of HIV/STI in a newly established cohort of women involved in high-risk sexual behavior in Kampala, Uganda. Women were recruited from red-light areas in Kampala. Between April 2008 and May 2009, 1027 eligible women were enrolled. Sociodemographic and behavioral information were collected; blood and genital samples were tested for HIV/STI. Risk factors for HIV infection were examined using multivariate logistic regression. HIV seroprevalence was 37%. The prevalence of Neisseria gonorrhoeae was 13%, Chlamydia trachomatis, 9%; Trichomonas vaginalis, 17%; bacterial vaginosis, 56% and candida infection, 11%. Eighty percent had herpes simplex virus 2 antibodies (HSV-2), 21% were TPHA-positive and 10% had active syphilis (RPR+TPHA+). In 3% of the genital ulcers, Treponema pallidum (TP) was identified, Haemophilus ducreyi in 6%, and HSV-2 in 35%. Prevalent HIV was independently associated with older age, being widowed, lack of education, sex work as sole income, street-based sex work, not knowing HIV-status, using alcohol, and intravaginal cleansing with soap. HIV infection was associated with N. gonorrhoeae, T. vaginalis, bacterial vaginosis, HSV-2 seropositivity and active syphilis. Prevalence of HIV/STI is high among women involved in high-risk sexual behavior in Kampala. Targeted HIV prevention interventions including regular STI screening, voluntary HIV testing and counseling, condom promotion, and counseling for reducing alcohol use are urgently needed in this population.

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Author and article information

Contributors

Julian W. Tang: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2014

Publication date (Electronic): 9 July 2014

Volume: 9

Issue: 7

Electronic Location Identifier: e101690

Affiliations

[1 ]Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom

[2 ]St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Canada

[3 ]Centre for Global Public Health, Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada

Alberta Provincial Laboratory for Public Health/University of Alberta, Canada

Author notes

* E-mail: sharmistha.mishra08@ 123456imperial.ac.uk

Competing Interests: The authors have declared that no competing interests exist.

Conceived and designed the experiments: S. Mishra MCB MP JFB. Analyzed the data: S. Mishra. Wrote the paper: S. Mishra. Conceived of the study and designed the analysis: S. Mishra MCB MP JFB. Designed, developed, and analyzed the models: S. Mishra. Interpreted results and provided critical review and editing of manuscript: S. Mishra MCB ZS MP S. Moses JFB. Contributed to model design: MP.

Article

Publisher ID: PONE-D-13-48134

DOI: 10.1371/journal.pone.0101690

PMC ID: 4090151

PubMed ID: 25014543

SO-VID: 715e4980-9d6f-46a8-beb0-a0e149f98084

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 15 November 2013

Date accepted : 10 June 2014

Page count

Pages: 14

Funding

The study was funded by the HIV Modelling Consortium, with support provided from a grant by the Bill & Melinda Gates Foundation. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Validation of the Modes of Transmission Model as a Tool to Prioritize HIV Prevention Targets: A Comparative Modelling Analysis

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Abstract

Background

Methods and Findings

Conclusions

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PLOS Climate

Most cited references 26

Towards an improved investment approach for an effective response to HIV/AIDS.

"Know your epidemic, know your response": a useful approach, if we get it right.

HIV and other sexually transmitted infections in a cohort of women involved in high-risk sexual behavior in Kampala, Uganda.

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