Background: In countries with generalized epidemics, national estimates of HIV prevalence levels and trends in the adult population are generally derived indirectly from surveillance of pregnant women attending selected antenatal care (ANC) clinics. ANC data however, come from a subset of the population and may not represent the true population prevalence.
Objective: To compare HIV seroprevalence estimates obtained from ANC sentinel surveillance surveys in Ethiopia, Kenya, Malawi, Tanzania, and Uganda with those from population-based Demographic and Health Surveys (DHS) and AIDS Indicator Surveys (AIS).
Methods: Geographic information system (GIS) methods were used to map sentinel surveillance sites and DHS/AIS survey clusters within a 15 km radius of the ANC surveillance sites. National DHS/AIS HIV prevalence estimates for women were compared with national prevalence estimates from ANC surveillance. DHS/AIS HIV prevalence estimates for women residing within 15 km of ANC sites were compared to those from ANC surveillance. These comparisons were also stratified by current pregnancy status, experience of recent child birth, and receiving ANC for the last birth.
Results: In four of the five countries, national DHS/AIS estimates of HIV prevalence were lower than the ANC surveillance estimates. Comparing women in the catchment areas of the ANC sites, the DHS/AIS estimates were similar to ANC surveillance estimates. ANC estimates were higher for younger women than DHS/AIS estimates for women in ANC catchment areas, but lower at older ages. In all cases, urban prevalence was higher than rural prevalence, but there were no consistent patterns by education.
Conclusions: ANC surveillance surveys tend to overestimate HIV prevalence compared to prevalence among women in the general population in DHS/AIS surveys. However, the ANC and DHS/AIS estimates are similar when restricted to women residing in catchment areas of ANC sites. Patterns by age and urban/rural residence suggest possible bias in the ANC estimates.
Key words: HIV, AIDS, prevalence, surveillance, estimates, surveys, sub-Saharan Africa