Epidemiology of Hepatitis C Infection in Canada Robert S. Remis MD, MPH, FRCPC Department of Public Health Sciences University of Toronto 1st Canadian Conference on Hepatitis C Montreal, Quebec May 1-4, 2001

instructional media centre, Laboratories Branch – 2001Acknowledgements Hepatitis C Transfusion Working Group, June 1998  Robert S. Hogg, Murray D. Krahn, Robert W.H. Palmer, Jutta K. Preiksaitis, Morris Sherman in collaboration with in collaboration with  JoAnne Chiavetta, PhD, Martin Tepper MD, Shimian Zou MD and Bob Slinger MD HCV-HIV Study, February 2000-March 2001  Marcel DuBois, Chris Archibald, Jennifer Geduld  Morris Sherman, Kevin Craib, Shimian Zou Others  Michel Alary, Kevin Craib, Elaine Whittingham

instructional media centre, Laboratories Branch – 2001 Background Importance of hepatitis C was underestimated due to delay in recognizing infection  difficulties in developing diagnostic tools  long latency from infection to disease Need to better evaluate extent and distribution of HCV infection in Canada  develop appropriate guidelines for primary prevention  develop guidelines for HCV testing  assess burden of infection and disease in short and long term  plan appropriate health services and support programs

instructional media centre, Laboratories Branch – 2001 Overview of presentation 1. Review of literature (published & unpublished) 2. Hepatitis C transmitted by blood transfusion 3. Hepatitis C prevalence and incidence in Canada 4. Estimating number of persons in Canada with dual HCV-HIV infection 5. Conclusions

instructional media centre, Laboratories Branch – 2001 Selected seroepidemiologic studies among IDUs

instructional media centre, Laboratories Branch – 2001 Selected seroepidemiologic studies among prisoners

instructional media centre, Laboratories Branch – 2001 Selected seroepidemiologic studies among patient populations

instructional media centre, Laboratories Branch – 2001 Selected seroepidemiologic studies among various patient populations

instructional media centre, Laboratories Branch – 2001 Hepatitis C infection due to blood transfusion: Methods Model 1For each year, number of transfused units x HCV risk per unit Used survival function to calculate number of recipients surviving to July 1998 Model 2Estimated number of HCV-infected persons in Canada as of July 1998 Calculated proportion and number due to blood transfusion Model 3Estimated number of persons transfused in Canada Calculated proportion and number with HCV infection

instructional media centre, Laboratories Branch – 2001 Modeled HCV risk and number of HCV-infected transfusion recipients, 1980–1991

instructional media centre, Laboratories Branch – 2001 Modeled HCV risk per transfusion episode and number of HCV-infected transfusion recipients,

instructional media centre, Laboratories Branch – 2001 Modeled number of surviving HCV-infected transfusion recipients by period of transfusion,1980–1992

instructional media centre, Laboratories Branch – 2001 Modeled number of surviving HCV-infected transfusion recipients by period of transfusion (n=34,800)

instructional media centre, Laboratories Branch – 2001 Modeled number of surviving HCV-infected transfusion recipients by period of transfusion 1980– , ,700 5,290 7,660 15,370

instructional media centre, Laboratories Branch – 2001 Hepatitis C prevalence and incidence, 1998: Methods  From HCV transfusion Model 2, estimated prevalent HCV infections  Interpolated to each provinces  Using population-based data (limited)  Estimating relative population prevalence from first-time blood donors

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-infected persons by province, 1998 (n=240,000) Modeled number of HCV-infected persons by province, 1998 (n=240,000) ,800 4,300 4,800 6,200 25,400 36,200 52, ,200

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-infected persons by province (n=240,000)

instructional media centre, Laboratories Branch – 2001 Hypothetical number of HCV-infected persons in Canada by mode of transmission

instructional media centre, Laboratories Branch – 2001 Annual incidence of HCV infection in Canada: Preliminary perspectives Method 1Observed incidence among populations in sentinel surveillance study projected from proportion symptomatic to all HCV infections Method 2Observed HCV incidence among susceptible IDUs in study cohorts projected from proportion IDU to all HCV infections (90,000 IDU - 68,000 HCV) x 20% Preliminary estimate: 3, ,000 new HCV infections per year

instructional media centre, Laboratories Branch – 2001 HCV infections in Canada: Interpretation  Estimates are subject to considerable uncertainty due to very limited Canadian data from representative study populations (only one study, in Quebec)  HCV prevalence appears highest in British Columbia, Ontario and Alberta. Four provinces, British Columbia, Ontario, Quebec and Alberta account for ~92% of HCV infections in Canada  The majority (>50%) of prevalent HCV infections in Canada are among IDUs, where HCV prevalence is >100-fold greater than other Canadians taken as a whole

instructional media centre, Laboratories Branch – 2001 Estimating the number of persons in Canada with dual HCV-HIV infection: Methods 1. Estimate the number of HIV-infected persons by HIV- defined exposure category and geographic region 2.Estimate HCV prevalence in each group (obtain data from available studies and review by expert consensus panel) 3.Multiply number by HCV prevalence 4.Plausible limits of outcome using Monte Carlo simulation 5.Special analysis for Aboriginal population and prisoners to estimate persons in each HIV-defined exposure category and then as above

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-HIV infected persons by exposure category, 1999

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-HIV infected persons by exposure category, 1999 (n=11,194)

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-HIV infected persons by geographic region, 1999 (n=11,194)

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-HIV infected Aboriginal people by exposure category, 1999 (n=1,477)

instructional media centre, Laboratories Branch – 2001 Modeled number of HCV-HIV infected prisoners by exposure category, 1999 (n=611)

instructional media centre, Laboratories Branch – 2001 Conclusions  Current estimates of HCV infections must be considered as hypotheses, not as conclusions; the epidemiology of HCV infection in Canada remains largely unknown.  Population-based studies are necessary  Burden of HCV infection is greatest in four provinces which account for most HCV infections in Canada  Most new HCV infections are probably among IDUs but a substantial proprtion, possibility as many as 40%, are not related to injection  Transmission of HCV (probability, determinants) in other populations needs further elucidation