Background and Prevalence: Although hepatitis C virus (HCV) infection primarily affects the liver, other organ systems may become involved, which may result in a variety of clinical manifestations. The percentage of patients infected with chronic hepatitis C infection who develop some extrahepatic manifestation remains poorly defined. Nevertheless, some experts have estimated that approximately 40% of patients with HCV will develop at least one extrahepatic manifestation, but estimates of the specific extrahepatic conditions vary. Overall, there is a lack of strong evidence regarding the true prevalence of most of these extrahepatic conditions.
Need for Recognition: It is extremely important that clinicians consider the potential for HCV to cause extrahepatic manifestations in patients with chronic HCV infection (Figure 1). It is unclear how well clinicians recognize, diagnose, and treat such extrahepatic syndromes, especially since many patients with HCV infection may not have obvious manifestations of chronic liver disease. An awareness of the range of potential extrahepatic manifestations could facilitate earlier diagnosis and more appropriate and timely treatment of these disorders.
Quality of Evidence: Most of the literature on HCV-related extrahepatic manifestations consists of observational studies that have shown an association between a specific extrahepatic condition and the presence of HCV antibody and/or detection of HCV RNA. Most of these studies are prone to selection bias. A few studies have used large datasets, such as the Veterans Administration medical database, and these studies are most useful when the extrahepatic condition in question can be easily defined and the data is easily accessible (e.g., renal disease as determined by a creatinine level or glomerular filtration rate [GFR]). For extrahepatic conditions that require a clinical diagnosis, such as lichen planus, identifying the specific condition is much more difficult when utilizing larger datasets. Thus, it is important to keep in mind the original source and type of data when estimating prevalence of these extrahepatic conditions and considering the need for screening.