Evaluating the effect of interventions to prevent HIV and other sexually transmitted infections on HIV transmission remains an elusive goal for most programs because of the prohibitive costs and methodological difficulties associated with field-based impact evaluation.
In response to these challenges, FHI has developed the AVERT computer model, which uses information that is readily available to many programs to derive estimates of the reductions in HIV infections achieved through interventions. This model enables users with little experience in modeling to develop estimates of program impact.
AVERT does this by providing estimates of the impact of intervention results, such as increased condom use, improved treatment of sexually transmitted diseases or changes in sexual behaviors (e.g., reducing the number of sex partners), in reducing HIV transmission through sexual intercourse. The program calculates how many fewer infections would be averted in a given time period–typically one year–following intervention. A validation exercise showed that AVERT's estimates were very close to the actual results of a randomized controlled study conducted in Cameroon.
For a detailed description of the model, see T Rehle, T Saidel, S Hassig, P Bouey, E Gaillard and D Sokal, Avert: a user-friendly model to estimate the impact of HIV/sexually transmitted disease prevention interventions in HIV transmission, in AIDS 1998, 12(suppl. 2):S27-S35.
Version 1.0 of AVERT is programmed for use in a DOS environment with an IBM-compatible microcomputer. The model is public domain software that may be freely copied. AVERT was developed under the AIDS Control and Prevention (AIDSCAP) and Implementing AIDS Prevention and Care (IMPACT) projects of Family Health International with the support of the United States Agency for International Development (USAID). The AVERT manual and software can be downloaded from FHI's Web site.
