Evaluating the Chain of Addiction Care (CAC)

People who (have) inject(ed) drugs (PWID) are at high risk for hepatitis C infection. Establishing adequate linkage to care in this population can be a challenge. Many of these patients receive opioid substitution, hepatitis C treatment possibly influences pharmacokinetics of those substitutes. This protocol describes a study on hepatitis C in people who (have) inject(ed) drugs (PWID), consisting of two substudies. 1) An exploratory, observational study in which we evaluate the decentralised hepatitis C care pathway in addiction care centres. 2) An observational pharmacokinetic study in hepatitis C patients on opioid substitution therapy (OST) embedded within the first study. Rationale: 1) Many PWIDs are lost during the process of testing and linkage to care and do therefore not receive adequate hepatitis C treatment. Decentralising care in addiction care centres deems hospital visits unnecessary, an approach that has become increasingly popular in this population over the last few years. This practice however has not yet been evaluated in the Netherlands. 2) In the Netherlands the PWID population is often treated for opioid addiction by opioid substitution therapy (OST) with methadone (MET) or buprenorphine (BUP). There is evidence that liver inflammation has a negative effect on pharmacokinetics of drugs. Consequently, we hypothesize that HCV treatment results in reduced liver inflammation and a decrease in MET and/or BUP levels, which is clinically relevant in the PWID/OST population. Objective: 1) to evaluate the feasibility of a decentralised hepatitis C care pathway (the Chain of Addiction Care (CAC) pathway) in several addiction care centres in the east of the Netherlands. 2. to measure the impact of hepatitis C clearance on MET (+metabolites) and BUP (+metabolites) levels and craving in patients on OST. Study design: This is an exploratory, observational study with a pharmacokinetic observational study embedded within the same population.