Hepatitis C : prevalence, risk factors and implications for screening

Abstract

Hepatitis C is a blood-borne virus that mainly affects the liver. The infection is often contracted early in life and remains as an asymptomatic slowly progressive disease. The World Health Organization (WHO) has set a goal to eliminate the hepatitis C virus (HCV) infection in 2030 and in order to reach that, anti-HCV screening is encouraged worldwide. In Sweden, treatment of HCV has been shown to be cost-effective, so the question is not if HCV should be treated but rather how those infected should be identified. The aim of this thesis was to study the prevalence, risk factors, and implications for hepatitis C screening in different groups of individuals.

In paper I 7,473 individuals were tested for HCV in a screening campaign. We found an anti-HCV prevalence of 1.8% and a prevalence of chronic hepatitis C of 1.4%. The majority were women transfused due to childbirth. Younger patients were significantly more often started on treatment but no correlation between treatment outcome and age at transfusion was found. Screening of individuals with earlier blood transfusion should be continued. In paper II 5,135 individuals, 4,108 pregnant women and 1,027 partners were tested for HCV at antenatal care clinics. We found an anti-HCV prevalence of 0.7% and a prevalence of chronic hepatitis C of 0.4%, in this group of young adults, mean age 30 years. In this study all were both tested for HCV and asked about different risk factors using a questionnaire. Based on our findings, risk factor-based screening at antenatal care clinics can be used to identify HCV infected women and partners who would benefit from subsequent therapy. The most relevant targeted screening model is to ask for previous or ongoing drug use, blood transfusions, origin in a high-prevalence country, and having a partner with HCV infection. In paper III the impact of kidney disease was investigated. Out of 42,522 diagnosed HCV individuals, 1,077 were found to have a concomitant chronic kidney disease (CKD), and 268 required haemodialysis. In the haemodialysis group, 17% of patients were treated for HCV and survival was significantly higher in the treated cohort compared to the untreated. This study demonstrates that patients with HCV have a higher risk of CKD and need for dialysis and that it is possible to treat patients on haemodialysis with interferon and ribavirin with improved survival. In paper IV we model the cost-effectiveness of universal screening of pregnant women compared to risk factor-based screening. This study is based on data from study II, including 4,108 pregnant women. The main finding of this study is that universal screening can be recommended instead of risk factor-based screening for cost-saving reasons in a Swedish setting, as long as the cost for the screening test is below the cost for the time spent on questions about risk factors at the antenatal care clinic.

To conclude, our studies have resulted in an increased knowledge about the prevalence of hepatitis C in Sweden. The screening strategies need to be renewed, with universal screening or improved risk factor-based screening in different groups of the population, including analysis of cost-effectiveness. To achieve the goal proposed by the WHO we need to identify and treat as many HCV-infected individuals as possible.