Death from liver disease in a cohort of injecting opioid users in a Swedish city in relation to registration for opioid substitution therapy.

Abstract

Injecting opioid users are at elevated risk of death. Although liver disease (especially hepatitis C) is common, its impact on mortality is low in active injectors. Because opioid substitution therapy (OST) reduces the risk of death from directly drug related causes, we hypothesised that the proportion of liver-related deaths would increase in subjects receiving OST. We investigated liver-related mortality in a cohort of injecting opioid users attending a needle exchange program (NEP) in a Swedish city in relation to OST exposure. Participants enrolled in the NEP between 1987 and 2011 with available national identity numbers, and registered use of opioids, were included. Linkage based on national identity numbers was performed with national registers for death, emigration and prescription of OST. Participants were categorised as non-OST recipients until the registered date of first OST prescription, and hence as OST recipients. Hazard ratios were calculated by Cox regression for overall and liver-related mortality in relation to OST, with OST as a time-dependent variable. Among 4494 NEP participants, 1488 opioid users were identified; 711/1488 had been prescribed OST. During a follow-up period of 15 546 person-years 368 deaths occurred. Sixteen deaths were caused by liver disease; 10 of these occurred in OST recipients. The risk of liver-related death was significantly increased in OST receiving participants (hazard ratio 3.08, 95% confidence interval [1.09, 8.68], P = 0.03). Liver related mortality among opioid users was significantly elevated in OST recipients, showing the long-term importance of chronic liver disease in this population. [Jerkeman A, Håkansson A, Rylance R, Wagner P, Alanko Blomé M, Björkman P. Death from liver disease in a cohort of injecting opioid users in a Swedish city in relation to registration for opioid substitution therapy. Drug Alcohol Rev 2017;36:424-431].