The Asian Epidemic Model: a process model for exploring HIV policy and program alternatives in Asia

Background Process models offer opportunities to explore the effectiveness of different program and policy alternatives by varying input behaviors and model parameters to reflect programmatic/policy effects. Methods Traditional theoretical HIV models set modeling parameters a priori and a small change in model parameters often gives widely varying results for the same behavioral inputs. The Asian Epidemic Model (AEM) has been designed to reflect the primary groups and transmission modes driving HIV transmission in Asia. The user adjusts AEM modeling parameters until HIV prevalence outputs from the model agree with observed epidemiological trends. Results The AEM projections resulting are closely tied to the epidemiological and behavioral data in the country. In Thailand and Cambodia, they have shown good agreement with observed epidemiological trends in surveillance populations and with changes in HIV transmission modes, AIDS cases, male/female ratios over time and other external validation checks. By varying the input behaviors and STI trends, one can examine the impact of different prevention efforts on the future course of the epidemic. Conclusions The AEM is a semi-empirical model, which has worked well in Asian settings. It provides a useful tool for policy and program analysis in Asian countries.