Hepatitis C infection: recent insights relevant to transfusion safety

Prevalence, incidence, and risk factors for hepatitis C virus infection in hemodialysis patients

Hepatitis C virus (HCV) infection is common in dialysis patients and is associated with increased morbidity and mortality. We used the Dialysis Outcomes and Practice Patterns Study (DOPPS, 1996-2015) to assess trends in the prevalence, incidence, and risk factors for HCV infection as defined by a documented diagnosis or antibody positivity. Among prevalent hemodialysis patients, HCV prevalence was nearly 10% in 2012-2015. Prevalence ranged from 4% in Belgium to as high as 20% in the Middle East, with intermediate prevalence in China, Japan, Italy, Spain, and Russia. HCV prevalence decreased over time in most countries participating in more than one phase of DOPPS, and prevalence was around 5% among patients who had recently (<4 months) initiated dialysis. The incidence of HCV infection decreased from 2.9 to 1.2 per 100 patient-years in countries participating in the initial phase of DOPPS. Although most units reported no seroconversions, 10% of units experienced 3 or more cases over a median of 1.1 years. High HCV prevalence in the hemodialysis unit was a powerful facility-level risk factor for seroconversion, but the use of isolation stations for HCV-positive patients was not associated with significantly lower seroconversion rates. Overall, despite a trend toward lower HCV prevalence among hemodialysis patients, the prevalence of HCV infection remains higher than in the general population. Combined with a high prevalence of HCV infection among patients with Stage 5 CKD, high rates of HCV seroconversion in a subset of hemodialysis units may contribute to this disparity.

HCV NS3Ag: a reliable and clinically useful predictor of antiviral outcomes in genotype 1b hepatitis C virus-infected patients

Since hepatitis C virus (HCV) non-structural 3 (NS3) protease inhibitor (PI) combined with pegylated interferon/ribavirin (PR) has been approved for chronic HCV genotype (GT) 1b infection, a reliable and clinically useful predictor combining with serum HCV RNA to predict early virologic response, breakthrough, and relapse is important during HCV antiviral treatment. We evaluated the role of HCV NS3 antigen (HCV NS3Ag) on the prediction of virologic response in patients with HCV GT1b during PR or PR/simeprevir (triple) therapy. Three hundred patients were recruited, and HCV RNA and HCV NS3Ag were tested at baseline and weeks 2, 4, 12, 24, 48, and 72. NS3Ag and HCV RNA were significantly related (r(2) = 0.67) in the whole patient selection. The kinetic pattern of HCV RNA and HCV NS3Ag during triple treatment was similar. HCV NS3Ag levels in the triple group closely followed those of HCV RNA; the r(2) values were 0.756 (baseline), 0.837 (2 weeks), 0.989 (4 weeks), and 0.993 (12 weeks), respectively. For patients treated with PR, the positive and negative predictive values (PPVs and NPVs) for viral response were 96.31 % and 67.19 %, respectively, at week 4 by using the decrease of NS3Ag (dHCV NS3Ag) combined with HCV RNA. At week 12, the PPV was similar at 94.16 %, while the NPV reached 87.26 %. The PPV and NPV for the prediction of relapse and breakthrough were 90.6 % and 76.7 %, respectively. HCV NS3Ag is a valuable marker and could be a supplementary predictor of HCV RNA for the prediction of antiviral response, breakthrough, or relapse during HCV antiviral treatment.

Current testing strategies for hepatitis C virus infection in blood donors and the way forward

Screening tests for blood donations are based upon sensitivity, cost-effectiveness and their suitability for high-throughput testing. Enzyme immunoassay (EIAs) for hepatitis C virus (HCV) antibodies were the initial screening tests introduced. The ”first generation“ antibody EIAs detected seroconversion after unduly long infectious window period. Improved HCV antibody assays still had an infectious window period around 66 d. HCV core antigen EIAs shortened the window period considerably, but high costs did not lead to widespread acceptance. A fourth-generation HCV antigen and antibody assay (combination EIA) is more convenient as two infectious markers of HCV are detected in the same assay. Molecular testing for HCV-RNA utilizing nucleic acid amplification technology (NAT) is the most sensitive assay and shortens the window period to only 4 d. Implementation of NAT in many developed countries around the world has resulted in dramatic reductions in transfusion transmissible HCV and relative risk is now < 1 per million donations. However, HCV serology still continues to be retained as some donations are serology positive but NAT negative. In resource constrained countries HCV screening is highly variable, depending upon infrastructure, trained manpower and financial resource. Rapid tests which do not require instrumentation and are simple to perform are used in many small and remotely located blood centres. The sensitivity as compared to EIAs is less and wherever feasible HCV antibody EIAs are most frequently used screening assays. Efforts have been made to implement combined antigen-antibody assays and even NAT in some of these countries.