ESTIMATION OF HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) SEROINCIDENCE AMONG REPEAT ANONYMOUS TESTERS IN SAN-FRANCISCO

The authors approximated human immunodeficiency virus (HIV) seroincide nce in a population of men who have sex with men and who sought repeat ed anonymous HIV testing in San Francisco in 1995. The number of seroc onversions and person-years of observation were estimated using the da te and result of the current test and the self-reported date and resul t of the previous test. Estimates for HIV seroincidence (2.8 per 100 p erson-years, 95% confidence interval 2.3-3.4) and predictors of seroco nversion were similar to those estimated from a prospective study of m en who have sex with men conducted in San Francisco at the same time. While the limitations of self-reported data in a self-selected populat ion are recognized, data from repeat testers may provide a practical s urveillance tool.