Screening for Hepatitis C Virus Infection: Table 7. Summary of Findings of Evidence Synthesis on Screening for Hepatitis C Infection

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Table 7. Summary of Findings of Evidence Synthesis on Screening for Hepatitis C Infection *

Key Question	Level and Type of Evidence^a	Overall Evidence for the Link^b	Findings
1. Does screening for HCV reduce the risk for or rate of harm and premature death and disability?	None.	N/A	No direct evidence regarding benefits of screening in the general population.
2. Can clinical or demographic characteristics identify a subgroup of asymptomatic patients at higher risk for infection?	II-3. Cross-sectional studies	Good for persons with intravenous drug use, high-risk sexual behaviors, and transfusions prior to 1992. Fair for other risk factors.	Intravenous drug use is the most important risk factor for HCV infection. High-risk sexual behaviors are another important risk factor. Transfusions prior to 1992 remain a risk factor. Other risk factors have inconsistent associations with HCV infection. No prospective study has applied a screening strategy in the general population and measured what proportion of patients was identified correctly.
3. What are the test characteristics of HCV antibody testing?	Studies of diagnostic test characteristics.	Fair	Using viremia as the reference standard, sensitivity of third-generation ELISA testing appears to be 94% or higher. Limited data found a specificity of 97% or greater using viremia as the reference standard.
4. What is the predictive value of a positive screening test, and what are the harms associated with screening for HCV infection?	II-3. Cross-sectional studies.	Good for positive predictive values. Poor for harms.	Large population-based studies found that the positive predictive value for viremia of positive results on ELISA with confirmatory positive results on RIBA was 73%-86%. There are almost no data on the harms of screening.
5a. What are the test characteristics of the work-up for treatable disease?	One good systematic review.	Fair	Blood tests have only modest value in predicting fibrosis on liver biopsy.
5b. In patients found to be positive for HCV, what proportion of patients would qualify for antiviral treatment?	II-3. Cohort studies and cross-sectional studies.	Fair	30-40% of patients referred for treatment received treatment.
6. What are the harms associated with the work-up for active HCV disease?	II-2. Cohort studies	Fair	In the highest-quality trial, the risk of major complications (bleeding, death, perforation) from liver biopsy was approximately 1%-2%, with mortality less than 0.3%. The risks may be lower in patients undergoing liver biopsy specifically for evaluation of HCV infection.
7a. How well does antiviral treatment reduce the rate of viremia, improve transaminase levels, and improve histology?	I. Well-designed randomized clinical trials.	Good	Newer treatments have achieved sustained virologic response rates of 54-60%. (54-60% with pegylated interferon + ribavirin) compared with older treatments. Trials were performed in patients referred for treatment.
7b. How well does antiviral treatment improve health outcomes in asymptomatic patients with HCV infection?	I, II-2. Cohort studies and clinical trials.	Fair	Limited data, primarily from Japan, has found improved clinical outcomes in patients receiving antiviral treatment. Data on long-term quality of life outcomes is sparse.
7c. How well do counseling and immunizations improve outcomes in asymptomatic patients with HCV infection or prevent spread of disease?	II-3. Case-control and cross-sectional studies.	Poor	There is insufficient evidence to estimate the effects of counseling or immunizations on intermediate or clinical outcomes.
8. What are the harms (including intolerance to treatment) associated with antiviral intervention?	I. Well-designed randomized clinical trials.	Good	Common adverse events with interferon-based therapy are self-limited influenza-like symptoms, which occur in 50%-60%. Major complications occur in 1%-2% of patients. Withdrawals due to adverse events occurred in 14%-22% of patients on pegylated interferon plus ribavirin combination therapy.
9. Have improvement in intermediate outcomes been shown to reduce the risk or rate of harm from HCV infection?	II-2. Fair-quality cohort studies and clinical trials.	Fair	There is some evidence that intermediate outcomes are associated with improved clinical outcomes, but methodologic concerns limit interpretation of this data.
* ELISA = enzyme-linked immunoassay; HCV = hepatitis C virus; NA = not applicable; RIBA = recombinant immunoblot assay ^a Evidence codes are based on study design categories.³⁵ I = evidence obtained from at least one properly randomized, controlled trial; II-1 = evidence obtained from well-designed controlled trials without randomization; ll-2 = evidence obtained from well-designed cohort or case-control analytic studies; ll-3 = evidence obtained from multiple time series or dramatic uncontrolled experiments. ^b Based on criteria developed by the U.S. Preventive Services Task Force.³⁵

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