11/1 - Epidemiological impact of ARV use

Baggaley, Ferguson and Garnett's review of mathematical models analyzing the impact of antiretroviral treatment on epidemiological trends highlights many of the uses and limitations of mathematical models. As the authors discussed, the effectiveness of both simple, linear models and more qualitative, comprehensive models is limited by the nature of the HIV epidemic and ARV treatment. While the use of antiretrovirals reduces the infectiousness of the individual by decreasing viral load, ARV's simultaneously increase the pool of infected people by extending the life expectancy of the infected population. These competing effects struck me as yet another complicating factor in the treatment of HIV/AIDS. I found the Salomon study in sub-Saharan Africa that was discussed by the authors to be particularly compelling, as the models used demonstrated the effectiveness of prevention strategies in the long-term as well as treatment strategies in the short-term, highlighting the crucial need for a combination of both approaches in any public health intervention.

I also found the author's discussion of the use of models to predict the spread of drug resistance to be very compelling. The authors stated that resistance testing is not currently a priority of the World Health Organization in resource poor areas, which I found very interesting, particularly considering the fact that the development of resistance is more likely in resource poor settings due to interruptions in drug supply and patient monitoring as well as incomplete patient education. It seems that drug resistance monitoring should be a high priority especially in resource poor settings, as resistance leads to the need for second-line drugs, which are substantially more expensive and more difficult to obtain in such areas.