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. 2014 Jun 4;9(6):e97726.
doi: 10.1371/journal.pone.0097726. eCollection 2014.

Declining incidence of hepatitis C virus infection among people who inject drugs in a Canadian setting, 1996-2012

Jason Grebely  1 , Viviane Dias Lima  2 , Brandon D L Marshall  3 , M-J Milloy  4 , Kora DeBeck  5 , Julio Montaner  2 , Annick Simo  2 , Mel Krajden  6 , Gregory J Dore  1 , Thomas Kerr  2 , Evan Wood  2
Affiliations

Declining incidence of hepatitis C virus infection among people who inject drugs in a Canadian setting, 1996-2012

Jason Grebely et al. PLoS One. .

Abstract

Background: People 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.

Methods: Data 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.

Results: Among 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.

Conclusions: HCV 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.

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Conflict of interest statement

Competing Interests: JG is a consultant/advisor and has received research grants from Abbvie, Bristol Myers Squibb, Gilead, Janssen, and Merck. JM has received grants from Abbott, Boehringer-Ingelheim, Bristol-Myers Squibb, Gilead Sciences, Janssen, Merck and ViiV Healthcare. MK receives research grants from Merck, Gen-Probe (Hologic), Siemens and Roche. GD is a consultant/advisor and has received research grants from Abbvie, Bristol Myers Squibb, Gilead, Merck, Janssen and Roche. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

Figures

Figure 1
Figure 1. Participant disposition.
Figure 2
Figure 2. Trends in syringe borrowing and drug use at enrolment among HCV antibody negative PWID enrolled in the VIDUS cohort in Vancouver, Canada by year of enrollment.
Figure 3
Figure 3. Annual incidence density of HCV infection (per 100 person-years) among PWID in the VIDUS cohort between 1996 and 2012.
A) overall population (injecting at enrolment); B) those with person-years of injecting during follow-up. The circles indicate the HCV incidence density (per 100 person years) and the lines indicate the 95% confidence intervals (95% CI).
Figure 4
Figure 4. Incidence density of HCV infection (per 100 person-years) among PWID in the VIDUS cohort by year of study enrollment in: A) the overall population; B) those with person-years of injecting during follow-up; and calendar year of observation in: C) the overall population; and D) those with person-years of injecting during follow-up.
The circles indicate the HCV incidence density (per 100 person years) and the lines indicate the 95% confidence intervals (95% CI).
Figure 5
Figure 5. Incidence density of HCV infection (per 100 person-years) among PWID in the VIDUS cohort by calendar year of enrolment and calendar year of observation.
Each shaded area is a proportion relative to the largest incidence rate with 25.0 being 1 (full shading). The numeric values of the rates are used as the labels [95% CI]. Cells with N/A are blank.
Figure 6
Figure 6. Kaplan-Meier graphs of time to HCV seroconversion by calendar year of enrolment between 1996 and 2012 among PWID in the VIDUS cohort (truncated at 5 years of follow-up).
See this image and copyright information in PMC

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