Adherence to combination therapy: influence on sustained virologic response and economic impact

Estimating the incidence of new hepatitis C virus (HCV) infection accurately is very difficult [1,2]. Many patients who have acute HCV infection are asymptomatic and therefore are not identified [2]. Underreporting of diagnosed cases is also believed to be common, and individuals who are at high risk of infection may not have access to health care, decreasing the likelihood of a timely diagnosis [2]. Mathematical modeling suggests that the annual incidence of acute HCV infection in the United States decreased from all average of approximately 230,000 new cases per year in the 1980s to 38,000 cases per year in the 1990s [3]. Currently, approximately 35,000 new HCV infections are estimated to occur each year in the United States [1]. Although the incidence of HCV infection might be declining, the known prevalence of liver disease caused by HCV is increasing because of the significant lag between infection, diagnosis of existing Symptomatic cases. and clinical manifestation of liver disease [2]. Between 1990 and 2015, the Centers for Disease Control and Prevention projects a fourfold increase ill the number of adults diagnosed with long-standing HCV infection [4]. With the progressive liver fibrosis of chronic HCV infection leading to cirrhosis, end-stage liver disease, hepatocellular carcinoma, and possible liver transplantation.. a significant and continued increase in the health and economic burden of the disease is anticipated over the next 10 to 20 years [2,4,5]. Based on a cohort simulation model, the direct medical care costs of HCV infection from the years 2010 through 2019 in the United States were projected to be $10.7 billion (range, $6.7-14.1 billion), and societal costs related to deaths before the age of 65 from decompensated cirrhosis and hepatocellular carcinoma were projected to be approximately $21 and $54 billion, respectively [5]. Thus, improving the efficacy of anti-HCV therapy has the potential to significantly reduce the morbidity, mortality, and health care utilization associated with the disease.