Towards the elimination of hepatitis C : identifying the infected population, and remaining hepatitis C related risks after successful treatment

Abstract: Chronic Hepatitis C virus (HCV) infection can lead to liver fibrosis and cirrhosis with increased risk of hepatocellular carcinoma (HCC) and liver failure. The World Health Organisation (WHO) has set a goal to eliminate viral hepatitis as a global health threat by 2030. To reach this goal for HCV we need to prevent new infections and identify and treat the infected population. Individuals with pre-treatment cirrhosis still have an elevated risk for HCC after HCV cure. This thesis aims to assess the health outcomes after cured HCV infection, study HCV prevalence and find a way to identify undiagnosed infections.In Paper I, 97 patients were followed through clinical visits (n=54) or through national registers (n=43) to study the long-term outcomes after cure from HCV and to assess the presence and impact of occult HCV infection (OCI). Three non-cirrhotic patients were diagnosed with HCC 8-11 years after HCV cure. Two patients had OCI at 8-9 years after cure. They had liver fibrosis stage 2, but no association with HCC. In Paper II, pregnant women (n=4,108) and partners (n=1,027) at antenatal clinics in southern Stockholm and Örebro County were tested for HCV and interviewed about risk factors to assess prevalence and evaluate screening strategies to identify undiagnosed infections. Anti-HCV prevalence was 0.7% and 0.4% were viraemic. The most effective risk factor-based screening was to ask for drug use, country of birth, and having a partner with HCV. Paper III presents a nationwide register study of the risk of extrahepatic cancer (EHC) the first 3 years after HCV treatment with direct acting antiviral (DAAs). We compared 4,013 DAA-treated, with 3,071 interferon-treated and 12,601 untreated patients. No increased risk for EHC was found after adjustments for age and comorbidities. An increased EHC risk in DAA-treated compared with general population was seen. Paper IV presents a register based study of the risk of HCC and association with pre-treatment liver stiffness measurement (LSM) in 7,227 HCV infected patients cured by DAAs. We found that pre-treatment LSM values correlated well with HCC risk. The incidence rate for patients with LSM values ≥12.5 kPa and <12.5 kPa was 1.6 and 0.15/100 person years, respectively.To conclude, cured HCV infection usually leads to regression of fibrosis. The DAAs are safe and highly effective against HCV. However, the HCC risk remains elevated for many years after cure in cirrhotic and sometimes in non-cirrhotic patients. Furthermore, HCV screening of pregnant women and partners is useful to identify patients who would benefit from therapy.

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