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Epidemiology of new versus prevalent hepatitis C infections in Canada: BC Hepatitis Testers Cohort

Introduction

n BC, at least 50,000 people are currently living with active hepatitis C (HCV) infection.[1,2] Left untreated, individuals with HCV have 5 times higher risk of dying from any cause and 20 times higher risk of dying from liver-related causes than uninfected persons.[3]

Newer, well-tolerated drugs (direct acting antivirals) have improved treatment success with cure rates approaching 95% while also reducing side effects. This presents new opportunities to prevent progressive liver disease in the population.  However, treatment alone may not be sufficient for all individuals living with HCV. Some individuals may benefit from complementary programs to prevent liver damage and/or reinfection with HCV.

A large data platform, the BC Hepatitis Testers Cohort (BC-HTC), has been assembled to assess and monitor HCV disease burden, including important co-infections such as HIV, tuberculosis, and hepatitis B and risk factors for liver damage and HCV re-infection.[4]

Based on the BC-HTC, the epidemiology of new and prevalent HCV infection has been described for BC.

Methods

The BC-HTC includes all individuals, since about 1990, that have either tested for HCV or HIV at the BCCDC Public Health Laboratory, or have been reported to public health as a case of HCV, HBV, HIV/AIDS, or active TB. This cohort of over 1 million people is linked with medical visits, hospitalizations, prescription drugs, cancers, and deaths.[4]

We compared two groups of HCV positive cases in terms of age, gender, markers of substance use and mental illness, and social and material deprivation.

HCV positive cases are divided into prevalent cases (those that tested HCV positive at their first test on record), and seroconverters (those that tested positive after a prior negative test). In seroconverters, infection occurred in the interval between the prior negative and first positive test, which suggests that there were risk factors for HCV acquisition during that time. In prevalent cases the timing of infection is unknown but more likely to be decades ago, based on previous explorations of HCV testing patterns.

Summary of evidence

Of the 1,132,855 individuals in the cohort, 67,726 were HCV cases as of the end of 2013. Of these, 11,954 (17.7%) had died.

Comparing the HCV groups, select findings include (see below infographic):

Prevalent cases: Older; more stable living conditions; more liver disease and age-related health issues

  • 88% of all cases. the majority of which (73%) were born before 1965
  • high rates of liver-related illness and death
  • lower prevalence of illicit drug use, mental illness, and HIV coinfection at time of HCV diagnosis
  • lower prevalence of problem alcohol use than seroconverters. However, even low to moderate alcohol use has implications for liver disease progression in HCV infected persons.

Seroconverters: Younger; living with multiple vulnerabilities

  • 12% of all cases, the majority of which (74%) were born after 1965
  • more likely to be coinfected with HIV and be socioeconomically marginalized at time of diagnosis
  • high proportion of this group are living with serious mental illness and/or had evidence of illicit drug use

Infographic: The twin HCV epidemics in Canada

Implications for practice

There are clear differences between older individuals diagnosed with HCV at first test (prevalent cases), compared with younger individuals diagnosed with HCV following previous negative test(s) (seroconverters).

Seroconverters can benefit from a comprehensive approach that integrates:

  • harm reduction
  • treatment and support for mental illness and dependence/addictions
  • treatment for HCV and co-infections, like HIV
  • stable housing and income

This approach will not only prevent HCV reinfection, but will also improve quality and quantity of life.

In contrast, prevalent cases have comparatively lower rates of illicit drug use, mental illness, alcohol use, and HIV coinfection. However, they require immediate linkage to care and assessment for treatment to prevent end-stage liver disease and premature death. Even the moderate prevalence of problem alcohol use suggests that awareness of HCV and strategies to reduce liver damage in infected persons requires improvement.

For further information

See the full publication for more details: http://www.biomedcentral.com/1471-2334/16/334
See the BC-HTC website for further information (patients and health care providers): http://hepatitiseducation.med.ubc.ca/

Acknowledgements

Dr. Naveed Janjua, Dr. Jason Wong, and Maria Alvarez, Clinical Prevention Services, BCCDC

References

  1. British Columbia Centre for Disease Control. British Columbia Annual Summary of Reportable Diseases 2014. Available at: http://www.bccdc.ca/resource-gallery/Documents/Statistics%20and%20Research/Statistics%20and%20Reports/Epid/Annual%20Reports/AR2014FinalSmall.pdf
  2. Janjua N, Kuo M, Yu A, Wong S, Alvarez M, Krajden M. The BC Hepatitis Testers Cohort: The population level hepatitis C Cascade of Care in British Columbia, Canada. Conference Presentation at: EASL: The International Liver Congress 2016. Barcelona, Spain. April 13-17, 2016.
  3. Yu YW, Spinelli JJ, Cook DA, Buxton JA, Krajden M. Mortality among British Columbians testing for hepatitis C antibody. 2013. BMC Infectious Diseases. DOI: 10.1186/1471-3458-13-291. Available at: http://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-13-291
  4. Janjua NZ, Kuo M, Chong M, Yu A, Alvarez M, Cook D, Armour R, Aiken C, Li K, Mussavi Rizi SA, Woods R, Godfrey D, Wong J, Gilbert M, Tyndall MW, Krajden M. Assessing Hepatitis C Burden and Treatment Effectiveness through the British Columbia Hepatitis Testers Cohort (BC-HTC): Design and Characteristics of Linked and Unlinked Participants. 2016. PLOS ONE. Available at: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0150176

Categories: Trend watch

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