COMMUNITY-ACQUIRED PNEUMONIA IN A COHORT OF FORMER INJECTION-DRUG USERS WITH AND WITHOUT HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION - INCIDENCE, ETIOLOGIES, AND CLINICAL ASPECTS

Although the association among bacterial pneumonia, human immunodefici ency virus (HIV) infection, and injection-drug use seems to have been well established, accurate estimates of the risk of community-acquired pneumonia among HN-positive and HIV-negative injection-drug users (ID Us) are still needed. To estimate the incidence of pneumonia in a comm unity of former IDUs, we followed 4,236 persons between 1991 and 1994; 1,114 (26.3%) were HIV-positive and 3,122 (73.7%) were HIV-negative. All patients were evaluated for pneumonia by standard criteria, a seru m sample was obtained from each participant at least once a year, and laboratory values were monitored. Overall, 149 episodes of pneumonia o ccurred among HIV-positive patients and 61 among HIV-negative patients ; incidence rates were 90.5 and 14.2 (per 1,000 person-years), respect ively. The most common etiologic agents were Streptococcus pneumoniae, Chlamydia pneumoniae, and Haemophilus influenzae. Among the HIV-posit ive former IDUs, there was a 1.37-fold increase in the relative risk o f pneumonia for every decrease of 100/mm(3) in the CD4 cell count (95% confidence interval, 1.16-1.61). The incidence of community-acquired pneumonia was markedly higher among HIV-positive participants than amo ng HIV-negative ones, a finding similar to that concerning the general population.