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In the present study data on the incidence of HBV and HCV were used to indicate the prevalence of and trends in risk behavior, assuming that drug users (DUs) who become infected with HBV or HCV are also at risk for infection with HIV. In addition, we determined to that extent the transmission patterns of HIV, HBV and HCV differed. DUs were selected from a cohort study in Amsterdam, had at least one follow-up visit between December 1985 and September 1989 and reported never to have had homosexual contacts. Among 305 DUs, of whom 70% injected recently, the prevalence of HIV, HBV and HCV were 31%, 68% and 65% respectively. These prevalences were strongly interrelated and the same risk factors were found. The cumulative incidence of either HIV or HBV or HCV was 30% among prevalent HIV-negatives. Despite a previously reported reduction in risk behavior, only the HIV incidence tended to decrease initially, and after 1986 the incidences of HIV, HBV and HCV remained disturbingly high and stable (mean: 4, 9 and 10 per 100 person-years, respectively). As at present HBV appears to be transmitted more heterosexually than HIV in our study group and the HIV-epidemic may follow the HBV-epidemic in its transmission patterns, preventive activities targeted at both injecting and sexual behavior should be expanded.

The impact of human immunodeficiency virus (HIV) infection and other risk factors on mortality was studied in a cohort of Dutch injection drug users and drug users who did not inject. Participants were recruited between 1985 and 1992 and followed up through 1993. Vital status was ascertained through repeat visit information, supplemented by population register data. A total of 77 deaths were recorded among 632 drug users, for a mortality rate per 1,000 person-years of 7 for HIV-negative noninjection drug users, 18 for HIV-negative injection drug users, and 64 for HIV-positive injection drug users. In multivariate analyses, limited to injection drug users, a positive HIV serostatus, age above 40 years, and using benzodiazepines several times daily were significantly associated with an elevated risk of death, both for death from all causes and for death preceding acquired immunodeficiency syndrome (AIDS) diagnosis (pre-AIDS). For pre-AIDS death, the adjusted relative risk associated with HIV infection was 2.2 (95% confidence interval 1.3-3.7). Only 38% of HIV-infected injection drug users who died were diagnosed with AIDS. However, 76% of HIV-infected injection drug users who died without AIDS diagnosis had evidence of immunosuppression (CD4 count < 500/microliters). Daily use of methadone and participation in needle and syringe exchange schemes were not associated with lower mortality rates. This study illustrates in a group of injection drug users with a 30% HIV seroprevalence and a high background mortality the profound influence on mortality that HIV infection has gained.

We studied the prevalence and risk factors for thrombocytopenia among 299 drug users and 461 homosexual men. The prevalence of thrombocytopenia was 3.3% in HIV-negative homosexual men, 8.7% in HIV-negative drug users, 16.4% in HIV-positive homosexual men, and 36.9% in HIV-positive drug users. With multivariate logistic regression HIV-seropositivity (odds ratio 3.3), a history of injecting drugs (OR 3.9), an increased number of lymphocytes (OR 0.44), an increased number of neutrophils (OR 0.53) and a larger mean platelet volume (OR 2.8) were independently and significantly associated with thrombocytopenia. The results obtained with linear regression analysis were consistent with the results of the logistic regression. The higher prevalence of thrombocytopenia among drug users was related to a history of intravenous drug use but not to recent injecting. The mechanisms causing thrombocytopenia among HIV-positives and HIV-negatives seem to be related, but HIV-infection seems to enhance thrombocytopenia in an independent way.

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