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Our objective was to describe and compare the trends of incidence and prevalence of HIV-1 infection in intravenous drug users (IDUs) in Valencia, Spain in 1987-1992. A cohort study was carried out in AIDS Information Centers located in the Valencia Region (Spain). Point seroprevalence was calculated for in each year according to HIV status at the first contact. Incidence annual rates were calculated from those IDUs identified as seronegative in their first visit and who returned for a new testing. From a total of 4,207 IDUs who contacted these centers, 4,131 (98.2%) asked voluntarily for HIV-1 testing. The seroprevalence for the whole period was 48.4% (95% C.I., 46.88, 49.92). Follow-up information was available for 604 subjects of the total 2,130 subjects who were seronegative in their first visit. The incidence rate for the 1988-1992 period was 12.02/100 person-years (95% C.I., 9.62, 14.41). Prevalence showed an overall decreasing pattern with a minimum corresponding to the year 1992 (43.6%). Incidence rates increased mildly until 1990 (13.93 per 100 person-years), to stabilize beyond at approximately 10 per 100 person-years. Our incidence rates are very high regardless of the decline of prevalence. Effective risk reduction programs among IDUs have been almost nonexistent in Spain up to now and should become an immediate priority.

Background: In order to identify, in a sample of heroin intravenous drug users (IVDU), those factors associated with the predominant risk behaviour related to the transmission of HIV-1 infection--sharing of injection equipment--a cross-sectional survey was carried out in Valencia, Spain from 1987 to 1992., Methods: Informed consent and pertinent data were obtained from 3755 heroin IVDU recruited at two public AIDS Information Centres in two cities in the region of Valencia. Data were gathered on sociodemographic variables, and sexual and drug use behaviour by interview. The subjects were subsequently tested for HIV-1 antibody. A univariate analysis was carried out to identify variables that were significantly associated with sharing injection equipment. A logistic regression model was used to control for possible confounders., Results: The IVDU who were teenagers, prostitutes (OR = 1.95), who had antibodies to HIV-1 (OR = 1.30) or who had an IVDU steady partner were at significantly higher risk for sharing of injection equipment. Higher levels of education, condom use (OR = 0.65) and living in the smaller city (OR = 0.75) were inversely related to sharing injection equipment., Conclusions: Our results suggest that different subgroups of IVDU have different characteristics that place them at different risk for HIV-1 infection. These characteristics should guide the design and intensity of specific preventive interventions. Teenagers and IVDU with low educational levels should be targetted for special attention by health authorities.

Background: To contribute to the knowledge of the frequency and distribution of infection by the HIV-1 in intravenous drug consumers (IVDC) the prevalence of infection in those in whom the voluntary serologic testing was practised and tendency over 5 years were studied., Methods: The study included 2794 IVDC from centers of primary health care (70%) or those who attended directly (30%), from 1987 to 1991, to three Centers of Information and Prevention of AIDS located in the cities of Valencia, Alicante and Castellón in which the voluntary and free practice of the test of antibodies versus HIV-1 was performed. The serologic test (enzymoimmunoassay) was carried out in 2694 individuals whose positive results were confirmed by Western-blot. Risk factors of the infection in addition to sociodemographic data were collected by questionnaire., Results: The estimated global prevalence was of 49.9% with confidence intervals of 95% (CI 95%) of 48.1% to 51.7%. Differences were observed according to the city with the highest being Valencia (55.3%, CI 95%: 52.8%; 57.8%) in comparison with Alicante (43.7%. CI 95%: 40.5%; 46.9%) and Castellón (41.3%, CI 95%: 35.6%, 47%). A decrease in prevalence was detected during the period studied (chi 2 of tendency = 6.37; p = 0.011), with this decrease only being produced in Alicante and Castellón. No differences were found with regard to sex in contrast to those found according to age, from 35.3% in those under 20 years of age to 59.5% in those over 29 years (chi 2 of tendency = 80.62; p < 0.0001). Only in the youngest age groups was a decreased tendency in prevalence found. The IVDC attended reported interchanging of needles at the time of consultation in 16.9% (CI 95%: 15.5%; 18.3%) with a descending temporal tendency from 27.7% in 1987 to 2.8% in 1991 (chi 2 of tendency = 14.18; p = 0.0001). Only 18.7% (CI 95%: 17.2%; 20.2%) of the IVDC used condoms in more than 66% of their sexual encounters of vaginal coitus. No differences were found with respect to sex or year of consultation., Conclusions: The prevalence of infection by the HIV-1 in intravenous drug consumers requesting the serologic test is decreasing in the Community of Valencia. This reduction in frequency should be confirmed by estimated rate of incidence of seroconversion. The frequency of the use of condoms in intravenous drug consumers is low conditioning a high risk of extension of the epidemics by sexual transmission.