Evaluation of the demand for tests for the detection of human immunodeficiency virus antibodies in Cataluna (Spain)

Registration of cases of AIDS in Catalonia has been the most importance source of data on geographic prevalence characteristics of patients and clinical aspects of the disease. But the long and variable incubation period and problems inherent in registration suggest the need for a more dynamic and timely means of monitoring the epidemic. Complementary systems of surveillance focused on infection by HIV rather than cases of AIDS are needed. The objectives of these study were to estimate the prevalence of HIV infection in the population screened for HIV antibodies in Catalonia study their epidemiologic profile and detect possible changes in prevalence and distribution of risk factors in the population. 17 public hospitals in which 92% of declared cases of AIDS in Catalonia had been diagnosed were included in the study. 4 periods of 15 days each were designated for 1989 and 27-item anonymous questionnaires concerning demographic and epidemiologic characteristics of patients for whom ELISA tests were requested were evaluated for each of the 4 periods. In the 4 study periods the numbers of tests and completed questionnaires respectively were 1240 and 974 1252 and 1982 1061 and 963 and 1170 and 1041. 4723 tests and 4060 questionnaires were included in all for a response rate of 86% overall. 33012 serologic tests were performed during 1989 with an overall prevalence of 20.7% positive. The monthly proportion positive ranged from 18.9%- 22.5%. During the 4 study periods 50.8% of requests were from men and 47.2% from women. In 1.9% the sex was not stated. 21.3% of requests for tests were for heterosexual IV drug users .8% for homosexual or bisexual IV drug users 4.1% for homosexuals or bisexuals 5.7% for heterosexuals with high risk sexual behaviors 5.5% for transfusion recipients .4% for recipients of blood products .2% for organ recipients 3.7% for children of individuals at risk and 58.3% for individuals for whom no risk factor was specified. 21% of requests were for individuals aged 25-29 and 47% were for persons aged 20-34. Characteristics of seropositive persons were assessed for the 3889 surveys from institutions with response rates of at least 65%. The prevalence of positive results was 34.3% for the males and 13.6% for the females. 37.2% of this subpopulation was aged 25-29. Among the 1571 patients in the 4 study periods for whom routes of transmission were identified 68% were IV drug users. 76% of all IV drug users tested had positive results. Given the impossibility of extrapolating from these results it is evident that other systems of epidemiologic surveillance are needed.