Is opioid substitution treatment beneficial if injecting behaviour continues?

BACKGROUND Opioid substitution treatment (OST) is recognised as an effective treatment for opioid dependence. Still, a subgroup of OST users continues to inject drugs. This study examines health risks and criminal activity in a population of needle exchange programme (NEP) participants by comparing those identified as current OST users to (i) those identified as former OST users and (ii) those with no OST experience. METHODS This was a semi-annual cross-sectional study conducted from 2002 to 2011. NEP participants were interviewed in Oslo, Norway (n=1760); 341 were identified as current OST users, 356 as former OST users and 1063 had no OST experience. The associations between OST status and health risk and criminal activity were assessed through univariate and multiple logistic regression analyses. RESULTS Among NEP participants, those currently in OST had fewer non-fatal overdoses (OR=0.5 [95% CI 0.3, 0.9]) compared to former OST users and those never in OST. Additionally, they were less likely to have injected frequently (OR=0.4 [95% CI 0.3, 06]), to have used heroin daily or almost daily (OR=0.3 [95% CI 0.2, 0.4]), and to have committed theft (OR=0.6 [95% CI 0.4, 1.0]) and engaged in drug dealing (OR=0.7 [95% CI 0.5, 0.9]) in the past month. Overall, there was a high level of polysubstance use and no group differences on this measure. CONCLUSIONS NEP participants who are currently in OST have substantially reduced health risks and criminal activity than other NEP participants. The high level of polysubstance use nevertheless poses a public health challenge.