Progression of HIV infection in misusers of injected drugs who stop injecting or follow a programme of maintenance treatment with methadone.

OBJECTIVE

To see whether misusers of injected drugs who stop injecting or switch to a programme of maintenance treatment with methadone have a reduced risk of progression of HIV infection when compared with a group of persistent misusers.

DESIGN

Observational cohort study in HIV seropositive subjects with a current or past history of misusing injected drugs.

SETTING

HIV outpatient clinic at the University Hospital of Zurich, Switzerland.

PATIENTS: 297 Current and former parenteral drug misusers (median age 27) with asymptomatic HIV infection. During the observation period 80 subjects adhered to a programme of maintenance treatment with methadone, 124 continued with parenteral drug misuse, and 93 former misusers remained free of illicit drugs. No antiretroviral treatment was given during the study.

MAIN OUTCOME MEASURES: Probability of progression of HIV infection from asymptomatic to symptomatic (Centers for Disease Control stage IV) as calculated by life table analysis and compared in the three groups of patients by means of a log rank test, and predictors of disease progression as analysed with a Cox proportional hazards regression model.

RESULTS

The 297 patients were followed up for a median of 16 months. The median duration of injecting drug misuse before enrollment was 7.1 years. There were no significant differences among the three groups with respect to CD4+ counts at the beginning of the study (median 0.44 x 10(9)/l). Life table analysis showed a significantly lower probability of progression of HIV disease in both the methadone treated group and former drug misusers than in persistent injecting drug misusers. Multivariate regression analysis showed a relative risk of progression of the disease of 1.78 (95% confidence interval 1.20 to 2.67; p less than 0.01) in persistent injecting drug misusers, 0.48 (0.29 to 0.77; p less than 0.01) in the methadone treated group, and 0.66 (0.41 to 1.06; p = 0.085) in former drug misusers.

CONCLUSIONS

Stopping the misuse of injected drugs slows the progression of HIV disease in infected subjects. Drug treatment programmes are effective in secondary prevention of HIV associated morbidity.