The impact of methadone maintenance therapy on hepatitis C incidence among illicit drug users

Abstract

Aims To determine the relationship between methadone maintenance therapy (MMT) and hepatitis C (HCV) seroconversion among illicit drug users. Design Generalized Estimating Equation model assuming a binomial distribution and a logit link function was used to examine for a possible protective effect of MMT use on HCV incidence. Setting Data from three prospective cohort studies of illicit drug users in Vancouver, Canada between 1996 and 2012. Participants 1004 HCV antibody negative illicit drug users stratified by exposure to MMT. Measurements Baseline and semi-annual HCV antibody testing and standardised interviewer administered questionnaire soliciting self-reported data relating to drug use patterns, risk behaviours, detailed sociodemographic data and status of active participation in an MMT program. Findings 184 HCV seroconversions were observed for an HCV incidence density of 6.32 [95% confidence interval [CI]: 5.44 – 7.31] per 100 person-years. After adjusting for potential confounders, MMT exposure was protective against HCV seroconversion (Adjusted Odds Ratio [AOR] = 0.47; 95% CI: 0.29 - 0.76). In sub-analyses, a dose-response protective effect of increasing MMT exposure on HCV incidence (AOR = 0.87; 95% CI: 0.78 – 0.97) per increasing 6-month period exposed to MMT was observed. Conclusion Participation in methadone maintenance treatment appears to be highly protective against hepatitis C incidence among illicit drug users. There appears to be a dose-response protective effect of increasing methadone exposure on hepatitis C incidence.

Assessing the impact and cost-effectiveness of needle and syringe provision and opioid substitution therapy on hepatitis C transmission among people who inject drugs in the UK: an analysis of pooled data sets and economic modelling

“…In total, we included 21 published studies 14,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] and seven unpublished studies [33][34][35][36][37]59,60 comprising 1827 HCV incident infections and 8789.7 person-years of follow-up. Overall HCV infection incidence ranged between 0.09 and 42 cases per 100 person-years across the studies.…”

“…Twenty-one of the included studies reported the impact of OST, 14,20,39,40,[45][46][47]49,[51][52][53]55,57,58 including seven unpublished estimates. [33][34][35][36][37]59,60 Seventeen studies reported the impact of NSPs, 14,20,[41][42][43][44]47,48,50,54,56,58 including five unpublished sources, [33][34][35]59,60 and four reported combined measures of NSPs with OST, 14,33,44,47 including one unpublished data source.…”

“…Of the 28 studies, we pooled data from a total of 17 studies to assess the impact of current OST use on HCV infection incidence, 14,39,40,[45][46][47]49,52,53,55,56,58 including five unpublished estimates. 33,36,37,59,60 Current use of OST was defined as reporting use of OST within the past 6 months (yes or no) 33,46,49,58,60 or as reporting use of OST either within 6 months or > 6 months ago, 36 use of methadone at the time of survey, 39,47,52,59 continuous use of OST throughout the follow-up period, 40,45,53 with one study defining continuous use as daily use of methadone (any dosage) in the past 6 months 14 or in the past month.…”

“…33,36,37,59,60 Current use of OST was defined as reporting use of OST within the past 6 months (yes or no) 33,46,49,58,60 or as reporting use of OST either within 6 months or > 6 months ago, 36 use of methadone at the time of survey, 39,47,52,59 continuous use of OST throughout the follow-up period, 40,45,53 with one study defining continuous use as daily use of methadone (any dosage) in the past 6 months 14 or in the past month. 37 One study used a 3-month time frame to measure the use of opioid agonist therapy maintenance treatment.…”

Hepatitis C Virus seroconversion among persons who inject drugs in relation to primary care physician visiting: The potential role of primary healthcare in a combined approach to Hepatitis C prevention

“…Access to substance use treatment is also considered key in harm reduction. For opiate users, receipt of opiate substitution treatment (OST) has been demonstrated to have positive impacts on risky injection behaviours (MacArthur, et al, 2014) and more recently, on HCV seroconversion (Nolan, et al, 2014;Tsui, Evans, Lum, Hahn, & Page, 2014), though limited evidence exists in support of other addiction treatment interventions (e.g., outpatient drug-free programs) (Hagan, Pouget, & Des Jarlais, 2011). In parallel, timely HCV screening, counseling and testing constitute essential actions for prevention (Centers for Disease Control and Prevention, 2012), as they have the potential to impact HCV acquisition and transmission rates by reducing high-risk drug use practices Bruneau, et al, 2014).…”