The epidemiology of hepatitis C infection in Ontario, 2004 Robert S. Remis MD, MPH, FRCPC Department of Public Health Sciences University of Toronto Ontario Ontrario Harm Reduction Distribution Program Toronto, Ontario March 4-6, 4 2007
Overview of presentation Background and mandate Study objectives Methods and data sources Estimates of prevalence, incidence and sequelae Study limitations Interpretation and recommendations
Background Hepatitis C prevalence estimated in Canada in 1998 but limited to transfusion-related related infection Modeling study under contract with Hepatitis C Program, Health Canada in 2003 using new methodology to model HCV incidence, prevalence and sequelae to 2002 In 2006, methods were refined and adapted to evaluate HCV epidemiology in Ontario under a mandate from Ontario Hepatitis C Secretariat
Study objectives HCV incidence and prevalence by exposure category, sex and age Proportion of infections diagnosed HCV-infection by stage of disease Morbidity Trends in serious sequelae
Methods 1 Estimate populations at risk Simulated population 1964-2024 from births, immigration and mortality Stratified by country of birth: Canada vs elsewhere Categorized into four subpopulations: injection drug users transfusion recipients haemophilia others
Methods 2 Model incidence & prevalence HCV incidence in each exposure category to derive prevalence For immigrants, prevalence at time of arrival Modeled transitions related to acquisition, antibody loss, progression through sequelae and mortality Parameter values adjusted to fit observed data Unique approach for each exposure category (for transfusion,1998 study)
Methods 3 Progression to serious sequelae Markov model through stages of HCV infection Stages: HCV infection, cirrhosis, liver failure, liver transplant, hepatocellular carcinoma Transitions stratified on sex, age and HIV status Parameter values from previous studies
Methods Integrated analytic HCV model Integrated Markov model from through birth or immigration, exposure, infection, progression and mortality Values written into spreadsheet (Excel) Model engine programmed in APL+ HIV infection incorporated into model for IDUs and hemophilia patients Hemophilia patients modeled entirely within Canadian-born population
Methods Other analyses To determine infections diagnosed, interpolated reported HCV diagnoses for missing periods Incidence estimated using two methods: HCV HCV incidence among susceptible IDUs and extrapolated Projected from acute HCV infections, adjusted for asymptomatic and unreported infections
Methods Sources of data HCV prevalence in source countries, WHO Populations 1960-2001, Statistics Canada Seroepidemiologic data from published and presented studies in Canada Proportions with respect to exposure category and place of birth, EHSSS Transition parameters, previous studies / Krahn Reported HCV diagnoses, Health Canada
HCV prevalence in Ontario among persons born in Canada, 2004 Population HCV prevalence rate IDU 32,310 58% HCV prevalence number Proportion 18,664 23% Ex-IDU 61,510 50% 30,832 38% IDU, total 93,820 49,496 51% Transfusion 807,245 1.35% 10,913 14% Hemophilia 790 54% 423 0.52% Other 7,622,462 0.26% 19,715 24% Total 8,524,318 0.94% 80,546 100%
HCV prevalence in Ontario among persons born elsewhere, 2004 Population HCV prevalence rate IDU 5,439 58% HCV prevalence number Proportion 3,179 11% Ex-IDU 11,480 50% 5,746 20% IDU, total 16,919 8,925 31% Transfusion 341,785 0.98% 3,347 11% Hemophilia Other 2,864,112 0.60% 17,183 58% Total 3,222,816 0.91% 29,455 100%
HCV prevalence in Ontario by exposure category, 2004 IDU Ex-IDU IDU, total Population 37,749 72,990 110,739 HCV prevalence rate 58% 50% HCV prevalence number 21,842 36,577 58,419 Proportion 23% 33% 53% Transfusion Hemophilia Other 1,149,030 790 10,486,574 1.24% 54% 0.35% 14,260 423 36,898 13% 0.38% 34% Total 11,747,134 0.94% 110,000 100%
Modeled number of HCV-infected persons by exposure category, Ontario, 2004 (n=110,000) IDU 20% Ex-IDU 36% Other 34% Transfusion 13% Hemophilia 0.5%
HCV incidence by place of birth and exposure category, Ontario, 2004 Born in Canada HCV incidence rate IDU 17% HCV incidence number Proportion Other 0.008% 583 20% Total 2,852 100% Born elsewhere Total 2,267 IDU 18% 410 85% Other 0.003% 74 80% 15% IDU 17% 2,677 80% Other 0.006% 656 20% Total 3,336 100%
Modeled incidence of HCV sequelae,, Ontario, 1964-2024 400 350 300 250 Cirrhosis Decomp HCC Transplant HCV deaths 200 150 100 50 0 1964 1969 1974 1979 1984 1989 1994 1999 2004 2009 2014 2019 2024
Modeled prevalence of HCV sequelae,, Ontario, 1964-2024 9,000 8,000 7,000 6,000 5,000 Cirrhosis Decomp HCC Transplant 4,000 3,000 2,000 1,000 0 1964 1969 1974 1979 1984 1989 1994 1999 2004 2009 2014 2019 2024
Annual reported cases of HCV infection, Ontario, 1992-2004 2004 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Cumulative reported cases of HCV infection, Ontario, 1992-2004 2004 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Modeled HCV infection among incarcerated persons, Ontario, 2004 Prison population: provincial 8,200, federal 5,600, total 13,800 Proportion with history IDU ~30% Provincial: HCV prevalence IDU 56%, other 0.10% Federal: HCV prevalence IDU 70%, other 1.0% HCV infections: provincial 1,383, federal 1,215, total 2,599 Crude HCV prevalance 17-19%; 19%; 98.3% IDU
Modeled HCV infection in the Aboriginal population, Ontario, 2004 Estimated population: 188,000 Proportion IDU 4.2% (male 6.0%, female 2.4%) Number IDU 7,896 (male 5,640, female 2,256) HCV prevalence: IDU 60%, other 0.50% HCV infections: IDU 4,738, other 901, total 5,638; thus, 84% of HCV infections from IDU HCV prevalance: : 3.0% (male 4.1%, female 1.9%)
Summary of findings About 110,000 persons in Ontario infected with HCV as of end 2004 3,300 persons infected each year, mostly through injection drug use Many (~32%) infection still not diagnosed Impact on health of persons in Ontario considerable Prevalence of serious HCV sequelae will continue to rise until 2024
Study limitations Current HCV estimates are hypotheses, not conclusions; the epidemiology of HCV infection in Ontario remains poorly defined Impact of more efficacious therapies not modeled EHSSS data likely biased: low participation rates and lack of data from Toronto Other routes may be over-estimated estimated Transition probabilities subject to uncertainty
Acknowledgements Hepatitis C Secretariat, Community Health Division, Ontario Ministry of Health and Long-Term Care Tom Smith, Janis Tripp Analytic Support Neil Hershfield Robert Palmer Public Health Division, Ontario Ministry of Health and Long-Term Care Marie Muir, Kristie Willson Public Health Agency of Canada Jun Wu