Background
Fifteen million adults in the World Health Organization European Region are estimated to have active hepatitis C infection. Intravenous drug use is a major hepatitis C transmission route in this region, and people who inject drugs (PWID) constitute a high-risk and high-prevalence population. A systematic review was conducted to assess levels of hepatitis C treatment uptake among PWID in Europe.

Methods
Searches in MEDLINE and EMBASE were carried out for articles in any language published between 1 January 2000 and 31 December 2012. Articles were included in the review if they presented original research findings about hepatitis C treatment uptake levels among people who reported injecting drugs currently or formerly, as well as those who reported using drugs currently or formerly (mode of consumption not specified). Treatment uptake data were extracted if uptake was measurable in relation to the number of patients who either: (a) tested HCV antibody-positive; (b) tested positive for HCV-RNA; or (c) tested positive for HCV-RNA and met additional treatment criteria.

Results
Twenty-five articles from 12 countries were included in the review. Among groups of drug-using study participants who were hepatitis C antibody-positive, the median treatment uptake level was 17%, and among those who were hepatitis C RNA-positive, the median was 30%. In the 11 studies reporting specifically on treatment uptake among current and former injecting drug users, hepatitis C RNA-positive study populations had a median treatment uptake level of 32%. Only one study reported on treatment uptake for current drug users.

Conclusions
This systematic review indicates that hepatitis C treatment uptake is relatively low among drug users in several European countries, and also points to considerable knowledge gaps regarding treatment uptake levels in this population. There was large variability in treatment uptake levels, suggesting that there may be major differences between and within countries in relation to treatment availability, drug-using populations in need of treatment, and the existence of integrated health care services targeting drug users. Stronger national hepatitis C treatment policies are needed, along with efforts to increase knowledge and reduce misconceptions among physicians regarding the feasibility and importance of treating drug users who have hepatitis C.