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Till Bärnighausen, David Bloom and Salal Humair talk with ScienceWatch.com and answer a few questions about this month's Emerging Research Front paper in the field of Social Sciences, general.

Why do you think your paper is highly cited?

We think our paper is highly cited because it combined a simple insight with a simple mathematical model to quantify a large, yet hitherto ignored, effect of current antiretroviral treatment (ART) coverage on future resources required for ART. It shows that strategies to achieve universal coverage of people needing ART in developing countries are bound to fail if they do not account for feedback from current ART coverage levels to future ART need. This feedback occurs because ART is highly effective in reducing mortality in HIV-infected persons. 

A crucial resource in ART delivery is health workers. We believe that prior to this work, the number of health workers needed to provide universal ART coverage was considered to be directly proportional to the number of patients needing ART, regardless of current ART coverage.

Using a simple mathematical feedback model, we showed that twice the number of health workers currently employed in ART services would need to be added to the ART workforce every year to achieve universal ART coverage in sub-Saharan Africa within 10 years—unless either health-worker migration or mortality were decreased, HIV incidence were decreased, or the organization of ART delivery changed. The finding of a large impact of current ART coverage on future ART resource needs probably led to the paper's citation count.

Does it describe a new discovery, methodology, or synthesis of knowledge?

"Health policy makers need to devise strategies to either decrease health worker outflows, decrease the rate of new HIV infection, or improve the efficiency of ART delivery."

We quantified for the first time an important phenomenon in ART delivery, the resource implications of the feedback from current ART levels to future ART need, using a simple mathematical model. We showed that the impact of this feedback effect on the number of health workers required to achieve universal ART coverage becomes larger as ART coverage increases.

Would you summarize the significance of your paper in layman's terms?

ART programs fall victim to their own success. The more resources currently available for ART, i.e., the larger the number of people currently receiving treatment, the more resources are needed to increase coverage levels in the future. In some ways, universal coverage is a moving target; the closer you get, the harder it is to cover the remaining distance. Of course, the underlying reason for this moving target—ART substantially decreases mortality among HIV-infected persons—is highly desirable!

How did you become involved in this research, and how would you describe the particular challenges, setbacks, and successes that you've encountered along the way?

In 2007, the Council of Science Editors sponsored a Global Theme Issue on Poverty and Human Development, in which 235 scientific journals participated by publishing more than 1,000 articles simultaneously. The Global Theme Issues was launched at the National Institutes of Health where seven of the articles were presented, including ours, to highlight some of the most important research themes. 

Realizing that the problem we wanted to address needed a wide range of experience—economics, statistics, medicine, mathematical modeling, HIV research, and experience with ART delivery programs in the developing world—our only real challenge was in assembling the right team with shared goals and good communication. We successfully formed such a team across three continents (Africa, North America, and South Asia).

Where do you see your research leading in the future?

Since this paper, we have done more mathematical analysis to understand other properties of the model. The version of this paper containing the mathematical model has been published as a working paper in NBER.

We continue to work on mathematical models of health workers in ART and have developed models to investigate the financial sustainability of ART, the impact of prevention on long-term ART outcomes, and the effect of combinations of different HIV prevention interventions on health outcomes. All of these models utilize feedback mechanisms similar to the AIDS Patient Care & STDs paper.

Do you foresee any social or political implications for your research?

One political implication of our paper is immediate. Under present conditions it will be extremely difficult to add ART health workers at a rate that is sufficient to achieve the United Nations' goal of universal ART coverage. Health policy makers need to devise strategies to either decrease health-worker outflows, decrease the rate of new HIV infection, or improve the efficiency of ART delivery, if ambitious targets of ART coverage are to be achieved.

Till Bärnighausen, M.D., Sc.D.
Department of Global Health and Population
Harvard School of Public Health
Boston, MA, USA
and
Africa Centre for Health and Population Studies
University of KwaZulu-Natal
KwaZulu-Natal, South Africa

David E. Bloom, Ph.D.
Department of Global Health and Population
Harvard School of Public Health
Boston, MA, USA

Salal Humair, Ph.D.
Department of Global Health and Population
Harvard School of Public Health
Boston, MA, USA
and
School of Science and Engineering
Lahore University of Management Sciences
Lahore, Pakistan

KEYWORDS: SUB-SAHARAN AFRICA; ANTIRETROVIRAL THERAPY; DEVELOPING-COUNTRIES; SOUTH-AFRICA; HEALTH-WORKERS; HIV-INFECTION; PREVALENCE; CHALLENGES; MORTALITY; EPIDEMIC.

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• October 2010 - Emerging Research Fronts
• Till Bärnighausen, David Bloom and Salal Humair Discuss AIDS Patient Care & STDs