THE EXTENT OF TRANSFUSION-ASSOCIATED HIV- INFECTION IN SWITZERLAND TO1994 - AN UPDATED ESTIMATE

Objective: The first report on transfusion-associated HIV infections w as published in the USA in 1982. The first case reports in Switzerland were published in 1986. So far there has never been a methodologicall y sound answer to the question of how many persons were infected with HIV by receiving transfusions in Switzerland before the introduction o f universal HIV blood donor screening. Methods: The following availabl e data sources were analyzed simultaneously: firstly, the results of t he look-back study conducted in 1993, secondly, the reports of HIV inf ections and AIDS cases in the national surveillance system, and, third ly, the claims for compensation for HIV-infected transfusion recipient s and hemophiliacs. Two methodologically different and independent est imates were obtained. Firstly, the coverage of the look-back study was estimated, which made it possible to calculate the total number of do cumentable transfusion-associated HIV infections in Switzerland. Secon dly, matching was performed on the cases in the look-back study and th e reports in the national surveillance system. Applying formulas of ca pture-recapture designs provided a second estimate of the total number of documentable transfusion-associated HIV infections. The claims for compensation were used to corroborate the estimates obtained. Results : The two methods produced almost identical figures which were corrobo rated by the number of claims for compensation. It is therefore estima ted that 80 to 100 persons in Switzerland may have been diagnosed as h aving HIV infection because of transfusions in Switzerland in the year s after 1980. The last five known infections occurred in 1986 (four) a nd, after termination of the look-back study, in 1994 (one). However, the estimate of 80 to 100 does not include individuals who were infect ed before 1986 and died soon - within weeks or a few months - after th e transfusion without diagnosis of HIV infection being possible. Concl usion: This estimate of the total number of transfusion-associated HIV infections in Switzerland is approximately half earlier published one s. In addition, the present study will probably reduce the remaining u ncertainties about the size of these iatrogenic HIV infections in the 1980s.