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Markers of Hepatitis C Infection among Hemodialysis Patients with Acute and Chronic Infection: Implications for Infection Control Strategies in Hemodialysis Units

To evaluate strategies for screening patients on hemodialysis (HD) for markers of acute and chronic hepatitis C virus (HCV) infection, we studied sixty-nine patients at a single center over a 36-month period. Serum samples were tested for alanine aminotransferase (ALT) levels, anti-HCV and HCV RNA at 3–4 month intervals. Anti-HCV was tested for by EIA1, EIA2, and RIBA2. HCV RNA was detected by polymerase chain reaction (PCR). In addition, IgM antibody to the c33 antigen of HCV was detected by an experimental EIA. Of the 43 HD patients at the start of the study, anti-HCV was detected by EIA1 in 13 (30%). All EIA1 positive patients and 14 (47%) of the 30 EIA1 negative patients tested positive by EIA2. Thus, at the start of the study 27 (63%) of 43 patients tested positive for anti-HCV by EIA2. The presence of anti-HCV among EIA2 positive patients was confirmed by RIBA2 in all patients. Based on the PCR results, the sensitivity, specificity, positive predictive value and negative predictive value for EIA1 were 48%, 100%, 53% and 100%, respectively, and for EIA2 were 100%, 100%, 100% and 100%, respectively. During follow-up, 26 EIA2 negative patients began HD in the unit. Of the 42 EIA2 negative patients, five (12%) seroconverted for anti-HCV during follow-up. All five patients with new HCV infection tested positive for HCV RNA three months prior to the detection of anti-HCV by EIA2. In addition, IgM to c33 was detected three months prior to seroconversion for anti-HCV by conventional tests in the two patients in whom testing was performed. All patients in whom HCV RNA was detected remained HCV RNA positive through the course of the study. The HCV subtype testing revealed that 25 (86%) of 29 patients had HCV type II infection and the remainder had mixed infection with both type I and II. The results of this study demonstrate that EIA2 is a reliable predictor of HCV infection among HD patients, and that RIBA2 or PCR testing is not necessary in routine clinical practice. Further, clearance of viremia and recovery from HCV infection is unusual, and hence regular testing for HCV should be limited to patients who are EIA2 negative. Serum ALT levels and conventional anti-HCV tests are poor predictors of early HCV infection. The anti-c33 IgM test may have a role in the identification of individuals with early HCV infection.