Declining Incidence of Hepatitis C Virus Infection among People Who Inject Drugs in a Canadian Setting, 1996-2012

Abstract

BackgroundPeople who inject drugs (PWID) are at high risk of hepatitis C virus (HCV) infection. Trends in HCV incidence and associated risk factors among PWID recruited between 1996 and 2012 in Vancouver, Canada were evaluated.MethodsData were derived from a long-term cohort of PWID in Vancouver. Trends in HCV incidence were evaluated. Factors associated with time to HCV infection were assessed using Cox proportional hazards regression.ResultsAmong 2,589, 82% (n = 2,121) were HCV antibody-positive at enrollment. Among 364 HCV antibody-negative participants with recent (last 30 days) injecting at enrollment, 126 HCV seroconversions were observed [Overall HCV incidence density: 8.6 cases/100 person-years (py); 95% confidence interval (95% CI): 7.2, 10.1; HCV incidence density among those with injecting during follow-up: 11.5 cases/100 py; 95% CI 9.7, 13.6]. The overall HCV incidence density declined significantly from 25.0/100 py (95% CI: 20.2, 30.3) in 1996–99, as compared to 6.0/100 py (95% CI: 4.1, 8.5) in 2000–2005, and 3.1/100 py (95% CI: 2.0, 4.8) in 2006–2012. Among those with injecting during follow-up, the overall HCV incidence density declined significantly from 27.9/100 py (95% CI: 22.6, 33.6) in 1996–99, as compared to 7.5/100 py (95% CI: 5.1, 10.6) in 2000–2005, and 4.9/100 py (95% CI: 3.1, 7.4) in 2006–2012. Unstable housing, HIV infection, and injecting of cocaine, heroin and methamphetamine were independently associated with HCV seroconversion.ConclusionsHCV incidence has dramatically declined among PWID in this setting. However, improved public health strategies to prevent and treat HCV are urgently required to reduce HCV-associated morbidity and mortality.

Information processing speed and attention in multiple sclerosis: Reconsidering the Attention Network Test (ANT)

“…These results were consistent with the findings reported by Urbanek et al (2010) based on proportional scores and Crivelli et al (2012) based on residualized scores. A small difference was also found on proportional scores relating to the orienting network, a result that has also been recently reported by Vazquez-Marrufo et al (2014) based on proportional scores.…”

Mixed HCV infection and reinfection in people who inject drugs—impact on therapy

“…1-3 HCV transmission is driven by a high incidence of infection among PWID, particularly among young PWID. [4][5][6] The majority of those infected fail to clear the virus and also fail to develop protective immunity. [7][8][9][10] As such, PWID are likely to be exposed to multiple HCV infections as a result of ongoing high-risk behaviours and might commonly harbour mixed HCV infections (that is, infection with two or more distinct viruses).…”

Methamphetamine injecting is associated with phylogenetic clustering of hepatitis C virus infection among street-involved youth in Vancouver, Canada

“…The lower proportion with clustering in this study compared to previous studies might be due to several different reasons. First, there was a lower prevalence of HCV among at-risk PWID in this study, partly related to a decreased HCV incidence observed among PWID in Vancouver over the past two decades (Grebely et al, 2014). Further, participants were sampled more broadly throughout the Greater Vancouver region compared to previous studies of long-term PWID in the Vancouver Downtown Eastside neighbourhood (a restricted geographical area known for having a highly concentrated population of PWID).…”

“…However, previous data have demonstrated that methamphetamine injection was independently associated with acquisition of HCV infection (Grebely et al, 2014; Hadland et al, 2014; Miller et al, 2009). Methamphetamine use in any form among street-involved youth in Vancouver has increased from 2.5% in 1999 to 10.5% in 2011, consistent with global trends (Lianping et al, 2013).…”

“…Further, HCV incidence remains high (7 to 25 cases per 100 person-years), particularly among young PWID and street-involved, at-risk youth (Grebely et al, 2014; Hadland et al, 2014; Page et al, 2013). Ongoing HCV transmission occurs, in part, because prevention measures that have been successful in preventing HIV infection, such as needle and syringe programs (NSP) and opioid substitution therapy (OST) have had less success in preventing HCV transmission (Nolan et al, 2014; Turner et al, 2011; White et al, 2014).…”