Substitution treatment of injecting opioid users for prevention of HIV infection.

BACKGROUND: Injecting drug users are vulnerable to infection with HIV and other blood borne viruses as a result of collective use of injecting equipment as well as sexual behaviour.

OBJECTIVES: To assess the effect of oral substitution treatment for opioid dependent injecting drug users on rates of HIV infections, and high risk behaviours.

SEARCH STRATEGY: Multiple electronic databases were searched. Reference lists of retrieved studies, reviews and conference abstracts were handsearched.

SELECTION CRITERIA: Studies were required to consider the incidence of risk behaviours, or the incidence of HIV infection related to substitution treatment of opioid dependence. All types of original studies were considered.

DATA COLLECTION AND ANALYSIS: Each potentially relevant study was independently assessed by two reviewers. For studies that met the inclusion criteria, key information was extracted by one reviewer and confirmed by consultation between all four reviewers.

MAIN RESULTS: Twenty-eight studies, involving 7900 participants, were included. The majority were not randomised controlled studies. Issues of confounding and bias are discussed. The studies varied in several aspects limiting the extent of quantitative analysis.

REVIEWERS' CONCLUSIONS: Oral substitution treatment for opioid-dependent injecting drug users is associated with statistically significant reductions in illicit opioid use, injecting use and sharing of injecting equipment. It is also associated with reductions in the proportion of injecting drug users reporting multiple sex partners or exchanges of sex for drugs or money, but has little effect on condom use. It appears that the reductions in risk behaviours related to drug use do translate into reductions in cases of HIV infection. The lack of data from randomised controlled studies limits the strength of the evidence presented in this review. However, these findings add to the stronger evidence of effectiveness of substitution treatment on drug use, and treatment retention outcomes shown by other systematic reviews. On this basis, the provision of substitution treatment for opioid dependence in countries with emerging HIV and injecting drug use problems as well as in countries with established populations of injecting drug users should be supported.