Twin epidemics of new and prevalent hepatitis C infections in Canada: BC Hepatitis Testers Cohort

Abstract

BackgroundWe characterized the twin epidemics of new and prevalent hepatitis C virus (HCV) infections in British Columbia, Canada to inform prevention, care and treatment programs.MethodsThe BC Hepatitis Testers Cohort (BC-HTC) includes individuals tested for HCV, HIV or reported as a case of HBV, HCV, HIV or active TB between 1990–2013 linked with data on their medical visits, hospitalizations, cancers, prescription drugs and mortality. Prevalent infection was defined as being anti-HCV positive at first test. Those with a negative test followed by a positive test were considered seroconverters or new infections.ResultsOf 1,132,855 individuals tested for HCV, 64,634 (5.8 %) were positive and an additional 3092 cases tested positive elsewhere for a total of 67,726. Of 55,781 HCV positive individuals alive at the end of 2013, 7064 were seroconverters while 48,717 had prevalent infection at diagnosis. The HCV positivity rate (11.2 %) was highest in birth cohort 1945–1964 which declined over time. New infections were more likely to be male, 15–34 years of age (born 1965-1984), HIV- or HBV-coinfected, socioeconomically disadvantaged, have problematic drug and alcohol use and a mental health illness. The profile was similar for individuals with prevalent infection, except for lower odds of HBV-coinfection, major mental health diagnoses and birth cohort >1975.ConclusionsThe HCV positivity rate is highest in birth cohort 1945–1964 which represents most prevalent infections. New infections occur in younger birth cohorts who are commonly coinfected with HIV and/or HBV, socioeconomically marginalized, and living with mental illness and addictions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1683-z) contains supplementary material, which is available to authorized users.

The Population Level Cascade of Care for Hepatitis C in British Columbia, Canada: The BC Hepatitis Testers Cohort (BC-HTC)

“…Although literature and national modeling estimates suggest that 20–44% of HCV infections remain undiagnosed in Canada (Trubnikov et al, 2014), because of high HCV testing rates in BC and declining positivity among baby boomers (born 1945–64), (Janjua et al, 2016b, Consolacion et al, 2015) we used an undiagnosed estimate of 25%, bringing the anti-HCV prevalence in BC in 2012 to 73,203(1.6% of the population). Of these, 56% (40,656) had at least one HCV RNA test; 36% (26,300) had genotype testing; 12% (8532) had been dispensed treatment; and 7% (5197) were estimated to have achieved SVR (Fig.…”

“…The BC-HTC construction and data linkage has been described elsewhere (Janjua et al, 2016a, Janjua et al, 2016b). Briefly, the BC-HTC includes all individuals tested for HCV or HIV, or reported as a case of HBV, HCV, HIV or active tuberculosis (TB) in BC between 1990 and 2013 linked with data on medical visits, hospitalizations, cancers, prescription drugs, and deaths (BC Vital Statistics Agency, 2014, British Columbia Ministry of Health, 2014a, British Columbia Ministry of Health, 2014b, British Columbia Ministry of Health, 2014c, British Columbia Ministry of Health, 2014d, British Columbia Ministry of Health, 2014e).…”

Effect of opioid-substitution therapy and mental health counseling on HIV risk among hepatitis C-infected individuals

“…All prescriptions dispensed in BC are recorded in a centralized system called PharmaNet, irrespective of the payer. Detailed characteristics of the cohort, including linkage and related data, are presented elsewhere 15,16. Data linkages were approved by the data stewards of the BCCDC, BCCDC-PHL, BC Ministry of Health, BC Vital Statistics Agency, and BC Cancer Registry.…”

“…This stratification was done because our previous research showed differences in characteristics between these two populations 16. HCV + -prevalent and HCV + seroconverters are different in terms of demographic and risk factors.…”

“…HCV + seroconverters reflect ongoing risk activities, including IDU, while people with prevalent infection may not be engaged in high-risk activities, as shown in our previous work. HIV–HBV coinfection, major mental illness, illicit-drug use, problematic alcohol use, and socioeconomic deprivation are higher among HCV + seroconverters than HCV + -prevalent individuals 16. Therefore, transmission risk of HIV may be different in each of these groups, which were selected a priori for stratified analysis to account for differing baseline risk profiles of people.…”