HIV seroprevalence in the population treated in a hospital emergency department: analysis by pooled batches of serum

The current number of Human Immunodeficiency Virus (HIV) infected people is not known in Spain as there is no national registry. This study has aimed to estimate the prevalence of HIV infection in the population treated in a hospital emergency department (ER) as an epidemic and risk of exposure indicator during healthcare activity and to assess the differences observed regarding previous estimates. We conducted a cross-sectional study of all the sera received in the ER anonymously. The final size of the pools was 5 sera. HIV antibody screening was performed using the 4th generation ELFA technique and confirmation was performed by Western Blot. Seven out of the 270 pools made from 1,347 sera obtained were reactive. The individualized analysis confirmed 6 sera to be positive and 1 serum to be false positive. The observed prevalence was 0.52% (95% CI 0.10-0.94). Prevalence fell 0.87% in comparison to the years 1990-1991, although this was not statistically significant (p = 0.08). The implementation of HIV antibodies detection through a system of pooled batches in samples collected in the ER make it possible to assess the prevalence of infection with this virus, decreasing costs with regard to individualized analysis of sera in both economic terms as well as samples handling.