Objective: To evaluate the risk of developing AIDS and to identify early markers of disease progression in injecting drug users (IDU).
Design: Prospective study.
Setting: Sixteen centres throughout Italy.
Patients, participants: Four hundred and sixty-eight IDU for whom it was possible to estimate the date of HIV seroconversion.
Main outcome measures: Progression to AIDS.
Results: Twenty-six subjects developed AIDS during a median follow-up period of 42 months. The risk of developing AIDS was 21% within 7 years following seroconversion. Age greater than 25 years at seroconversion was associated with more rapid disease progression. Progression was similar for men and women. Continued drug injection did not accelerate progression to AIDS. Among the laboratory markers studied, CD4+ cell count at the first HIV-positive test was the best predictor of disease progression. Results were confirmed using multivariate analysis.
Conclusions: Our findings indicate the importance of the role played by age in accelerated disease progression, which may be determined by a more rapid decline in CD4+ cell number in older HIV-infected IDU.