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How To Collect and Evaluate Surveillance and Epidemiologic Data For Hepatitis C

How To Collect and Evaluate Surveillance and Epidemiologic Data For Hepatitis C. Miriam J. Alter, Ph.D. Division of Viral Hepatitis Centers for Disease Control and Prevention Atlanta, GA USA. Surveillance for Hepatitis C Virus Infection. Detect outbreaks Assess disease/infection burden

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How To Collect and Evaluate Surveillance and Epidemiologic Data For Hepatitis C

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  1. How To Collect and Evaluate Surveillance and Epidemiologic Data For Hepatitis C Miriam J. Alter, Ph.D. Division of Viral Hepatitis Centers for Disease Control and Prevention Atlanta, GA USA

  2. Surveillance for Hepatitis C Virus Infection Detect outbreaks Assess disease/infection burden Monitor trends Identification & follow-up of infected persons Develop, implement, evaluate prevent programs Guide allocation of resources Acute disease All infected persons

  3. Surveillance Components • Case reporting • Prevalence assessment and monitoring • Special studies

  4. Establishing Surveillance • Standardized case definitions • Reliable laboratory reporting • Infrastructure for identifying cases • Identify biases that affect interpretation of data • Generalizability of cases identified • Testing and reporting practices • Determine types of information to be collected

  5. Anti-HCV EIA RR Results by RIBA™ 3.0 and Population Tested RIBA 3.0 Source: LY Hwang, Houston; R. Gunn, San Diego; S. Harris, Austin; I. Weisfuse, NYC; CDC, Atlanta

  6. Proportion of Anti-HCV RR EIA Results Testing RIBA™ Positive by S/CO Ratio (N=765) (N=18) (N=21) (N=231) EIA S/CO Ratio Source: LY Hwang, Houston; R. Gunn, San Diego; S. Harris, Austin; I. Weisfuse, NYC; CDC, Atlanta

  7. ALT levels in HCV-infected persons Acute Hepatitis C ( n=267) 7 x ULN 15% 85% Chronic HCV infection (n=4702) 3% 97%

  8. Epidemiologic Studies • Identify persons at risk for infection • Determine amount of disease/infection attributable to each risk factor • Provide guidance for surveillance and prevention programs

  9. Types of Epidemiological Studies • Cohort (prospective) - direct estimate of risk • Presence of exposure determined in sample of population • Entire sample followed and incidence of disease compared for those with and without the exposure • Case control (retrospective) - indirect estimate of risk • Sample selected based on presence or absence of disease • Proportion of cases with history of exposure before onset of disease compared with controls • Cross-sectional or prevalence - associations • Presence of disease determined in sample of population • Proportion of cases with history of exposure compared with non-cases • Prevalence of disease compared for those with and without the exposure • Temporal sequence of exposure relative to disease unknown

  10. Cohort Studies • Directly measure relative risk and population attributable risk • Require large sample sizes, long follow-up, expensive • Only evaluate a single exposure

  11. Case Control Studies • Sample size, logistics, and expense reasonable • Odds ratio good estimate of risk if certain assumptions met • Frequency of disease in population small • <2% incidence/year • Cases and controls representative -- CRITICAL • Will not detect rare events

  12. Prevalence Studies • Logistics less complex, less expensive • Determining specific exposures preceding infection problematic when onset unknown or many years ago • Substantial differences in methodology • Population-based • Highly selected groups • Blood donors • Clinic patients • Inconsistent results among studies • Under-ascertain some risk factors • Cannot generalize to the rest of the population

  13. Disease vs asymptomatic Single source Referral (e.g., GI clinic) Clinics serving disadvantaged population Highly specialized setting for specific condition Case reports Blood donors Family member Cases of other types of viral hepatitis Single disease group Sources of Study Populations That Affect Reliable Interpretation of Results Controls Cases

  14. Risk Factors Associated With Acquiring HCV Infection, United States Cohort and Case Control Studies • Transfusion, transplant • Injecting drug use • Occupational blood exposure (needle sticks) • Birth to an infected mother • Infected sex partner • Multiple heterosexual partners

  15. Exposures Not Associated With Acquiring HCV Case Control Studies of Acute Hepatitis C, U.S.,1979-1985 Cases Controls Exposure (prior 6 months)n=148n=200 Medical care procedures 30.4% 29.5% Dental work 24.3% 23.5% Health care work (no blood contact) 4.1% 5.0% Ear piercing 2.7% 3.0% Tattooing 0.7% 0.5% Acupuncture 0 1.0% Incarceration 4.1% 1.0% Foreign travel 4.1% 2.5% Military service 1.3% 4.9% Source: JID 1982;145:886-93; JAMA 1989;262:1201-5.

  16. HCV Related to Health-Care ProceduresUnited States • Not associated with sporadic or background • Recognized primarily in context of outbreaks • Contaminated equipment • Hemodialysis • Unsafe injection practices • Plasmapheresis • Multiple dose medication vials • Hospitalized patients • Private practice • Home infusion therapy

  17. Cross-sectional/Prevalence Studies of HCV Variation of Results – Low Prevalence Countries Donors Patients College ExposureUS US AU UKGI Spinal VAStudents Injecting drug use + + + + ND + + + Transfusion + + + + ND - + + Tattooing - - + - + + + - Nasal cocaine use + - ND ND ND ND - - Ear/body piercing +/- + ND - - ND + - Acupuncture - - ND - - - - ND Incarceration - + - ND ND ND + +

  18. History of Tattooing and Acute Hepatitis C1982-2000, United States Time period of History of tattooing prior 6 mo reported caseNAll patientsNo IDU/BT Total (95% CI) 1856 3.2% (2.5-3.8) 1.5% (0.9-2.1) 1982-1986 839 2.7% 1.8% 1987-1990 625 2.7% 1.1% 1991-2000 392 4.3% 1.5% Source: CDC Sentinel Counties Study

  19. History of Body Piercing Acute Hepatitis B and Acute Hepatitis C1996-2000, United States History of piercing* prior 6 mo TypeNAll patientsNo IDU Acute hepatitis B 603 2.3% 1.5% Acute hepatitis C 134 3.7% 1.0% * Other than ears Source: CDC Sentinel Counties Study

  20. Tattoos and HCV InfectionCross-sectional, GI Clinic, Albuquerque, 95-96 • 40% Hispanic, 40% indigent • Cases – referred for positive HCV test • Controls – gastroesophageal reflux disease • HCV status not ascertained Positive (total tested) Adj. (95% ExposureCasesControlsORCI) IDU or BT 87% (477) NA Tattooed Subset (no IDU/BT) 43% (58) 16% (58) 5.9 (1.1-30.7) Of total cases 5% (477)* 1% (58) *Attributable fraction 0.8% (estimated from data) Balasekaran et al. Am J Gastro 1999;94:1341-6

  21. LimitationsBalasekaran et al. Am J Gastro 1999;94:1341-6 • Representativeness • Cases not representative of all persons with HCV • Controls not representative of nondiseased persons • Is prevalence of characteristic under study same in control group as in the general population? • Possible selection bias from using a single disease group • Not tested for HCV • History of incarceration not ascertained • Even if tattooing associated with HCV in this group, accounts for <1% of infections

  22. Tattoos and HCV InfectionPrevalence, Orthopedic Spinal Clinic, Dallas, TX 91-92 • Over represented blacks, hisp, men, middle/low income • 43/626 HCV positive (6.9% sample; 2.8% standardized) % HCV positive Adj. (95% ExposureYesNoOR CI)AR* Tattoo 22% 3.5% NA 41% Commercial parlor 33% 3.5% 6.5 (2.9-14.8) (30%) Beer drinker 12% 5% 4.0 (1.8-8.7) 23% Injection drug use 37.5% 5% NA 17% >1 yr 58% 5% 23.0 (7.5-70.6) (14%) Male Ancillary HCW 32% 6% 9.6 (3.8-24.3) 8% Transfusion 4% 7.5% NS -- *Attributable risk % adjusted for other risk factors and standardized to population Source: Haley et al. Medicine 2001;80:134-51.

  23. LimitationsHaley et al. Medicine 2001;80:134-151 • Population not representative • Inconsistent with virtually all other studies • Dose response relationships inconsistent for tattooing, but not for IDU • IDU likely under-reported • >50% of HCV-positives admit to IDU when re-interviewed after receiving results • Some factors likely surrogates for known risks • Male ancillary HCW (why not females?) • Beer drinking (why not other forms of alcohol?)

  24. HCV and HBV Among College Students 18-35 yrs old, U.S., 2000-2001 % Positive CharacteristicTotal Tested (%)HCV HBV Transfusion Yes 337 (4.5) 6.2* 11.8* No 7236 (95.5) 0.7 5.6 IDU Yes 116 (1.5) 22.4* 17.1* No 7718 (98.5) 0.6 5.7 Tattoo Yes 1430 (20.5) 0.3† 5.3 No 5533 (79.5) 0.5 6.2 Body piercing Yes 1202 (17.4) 0.4† 3.7 No 5701 (82.6) 0.4 6.5 Snorted drugs Yes 617 (9.1) 0.6† 6.8 No 6179 (90.9) 0.4 5.9 * p<.001 † excluding IDU and transfusion Hwang et al., unpublished data

  25. Geographic Differences in HCV Transmission Patterns Importance of Exposures by HCV Endemicity Exposures among prevalent infectionsLowModerateHigh Injecting drug use ++++ ++ + Transfusions (unscreened) +++ +++ +++ Health-care related Contaminated equipment +/- ++++ ++++ Unsafe injections +/- ++++ ++++ Folk medicine - ++ No data

  26. HCV Related to Therapeutic and Cosmetic Procedures in Moderate/High Endemic Countries • Associated with “background” infections in some studies • unsafe therapeutic injections • hospitalization, surgery, dental work • Control populations may not have been representative • Acupuncture (one village in Japan) • Geographic clustering by age, town, region • considerable variation within and between countries

  27. Health-Care Procedures and HCV InfectionModerate Endemic Countries SurgeryDental CountryHCV PosHCV NegHCV PosHCV Neg Case-Control Italy 17%* 2% 22%* 11% Cross-Sectional Italy 56%* 36% 91%* 80% 77% 57% 90% 90% Taiwan 13% 3% 24% 28% Pakistan No data 33% 39% Japan 32%* 10% No data * P<.05, independent of other risk factors

  28. Cosmetic Procedures and HCV InfectionModerate Endemic Countries Tattooing Body Piercing Country (author)HCV PosHCV NegHCV PosHCV Neg Case control Taiwan (Chen) 0% 0% 0% 1% Cross sectional Taiwan (Sun) 3% 1% -- -- (Ho) 21% 34% 78% 83%* Japan (Kiyosawa) 1% 0% -- -- 3% 0% -- -- Pakistan (Luby) 7% 0% 7% 0% Korea (Kim) 11% 7% 14% 20% * Ear piercing women only

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