Laboratory-based HIV surveillance with information on exposure: importance of discriminating person-based from test-based results

Abstract

Within a surveillance programme in a Regional Public Health Laboratory anonym ous information on HIV test, requesting physician and tested individual is automatically selected, regardless of test result. Thereby, personal identifiers are transformed into unique but meaningless num eric codes. Besides, requesting physicians receive a questionnaire on indication for testing (response 87%). Between April 1989 and June 1993 12,219 HIV tests were performed in 10,972 individuals. The percentage of positive tests (2.1%) was twice the percentage of positive individuals (1%). No increase in num ber of new infections was observed over tim e. Of individuals, 41.6% were tested due to third party requests (mainly insurance): HIV was demonstrated once (0.03%). Among the rem ainder, with medical indications, seroprevalence was 1.4%. At relatively little expense, we were able to provide valid information about patterns of HIV-testing and HIV seroprevalences am ong people tested in routine medical practice. Prevention of double counts proved to be important. Extension to other Dutch areas is expected.