Evaluating large-scale HIV prevention interventions: study design for an integrated mathematical modelling approach

Abstract

Background: There is an urgent need to evaluate HIV prevention interventions, thereby improving our understanding of what works, under which circumstances and what is cost-effective.

Objectives: To describe an integrated mathematical evaluation framework designed to assess the population-level impact of large-scale HIV interventions and applied in the context of Avahan, the Indian AIDS Initiative, in Southern India. The Avahan Initiative is a large-scale HIV prevention intervention, funded by the Bill & Melinda Gates Foundation, which targets high-risk groups in selected districts of the six states most affected by the HIV/AIDS epidemic (Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh, Nagaland and Manipur) and along the national highways.

Methods: One important component of the M&E of Avahan relies on an integrated mathematical framework that combines empirical biological and behavioural data from different sub-populations in the intervention areas, with the use of tailor-made transmission dynamics models embedded within a Bayesian framework.

Results: We first give an overview of the Avahan Initiative and the objectives of the monitoring and evaluation of the intervention. We discuss the rationale for choosing this evaluation design compared to other possible designs. We describe the different components of the evaluation framework and discuss its advantages and challenges, with illustrated examples.

Conclusions: This is the first time such an approach is applied on such a large scale. Lessons learnt from the CHARME project could help the design of future evaluations of large-scale interventions in other settings while the results of the evaluation will be of programmatic and public health relevance.