NAT is administered at 12 and 24 weeks to reach the primary goal of therapy, which is to cure the infection by achieving a sustained virologic response (SVR), defined as undetectable HCV RNA in serum or plasma by an assay with a lower limit of detection ≤ 15 IU/mL 12 weeks (SVR12) or 24 weeks (SVR24) after treatment completion. An alternative endpoint of therapy is SVR12 or SVR24 of undetectable HCV core antigen at the end of treatment in patients who had detectable HCV core antigen prior to treatment. Another alternative endpoint that can be used where sensitive HCV RNA assays are not accessible or affordable is the use of SVR12 or SVR24 after the end of treatment as a qualitative HCV RNA assay with a lower limit of detection ≤ 1000 IU/mL (3.0 log10 IU/mL).
SVR is associated with an improvement in normalization of liver enzymes and improvement in liver function and fibrosis (this patient already has F2 stage fibrosis). In addition to intravenous drug addiction treatment, he should be counseled on minimizing alcohol consumption. In patients with cirrhosis, sustained SVR also reduces the risk of HCC and liver-related mortality especially in the presence hepatic comorbidities (eg, metabolic syndrome, NASH, harmful alcohol consumption and/or HBV coinfection). HCV therapy reduces all-cause mortality including those due to extrahepatic manifestations and prevents transmission through treatment as prevention.
Enzyme immunoassay can detect anti-HCV antibodies in recently acquired and chronic infections. Antibodies may not be detectable in the early phase of acute HCV infection or in immunosuppressed patients with chronic infection. Additionally, in patients with suspected HCV infection, either an HCV RNA or HCV core antigen in serum or plasma should be performed in addition to anti-HCV antibodies testing. Consequent to viral clearance either spontaneously or following pharmacologic treatment, anti-HCV antibodies persist in the serum but HCV RNA levels wane until they disappear in some patients and become undetectable. As anti-HCV antibodies persist, testing their levels is not helpful in assessing most cases of reinfection.
The Child-Pugh is a scoring system that is used to predict mortality in patients with end-stage liver disease. The score incorporates five measures of liver disease and assigns points to them: total bilirubin, albumin, PT or INR, encephalopathy, and ascites. The outcome defines the severity of hepatic cirrhosis by designating one of the three Child-Pugh classifications A, B, or C. Model for End-stage Liver Disease (MELD) is a similar widely used method to score end stage hepatic disease in patients who are waiting for liver transplant. It incorporates total bilirubin, creatinine, and INR.
The EASL guidelines state that patients with HCV infection who are on opioid substitute treatment and DAA-based anti-HCV therapy do not require dose alterations of methadone or buprenorphine. Prior to initiating DAAs, patients should be counseled on HCV transmission, risk factors for fibrosis progression, treatment, reinfection risk and harm reduction strategies. Once SVR is achieved, surveilling HCV reinfection biannually or annually by HCV RNA assessment should be done in persons who inject drugs and have ongoing risky behavior. Re-treatment should be offered if reinfection is identified during post-SVR follow-up.
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