It should first be pointed out that decisions about treatment of chronic hepatitis B are not typically based on liver biopsy findings. Rather, they are based on factors related to measures of viral replication (hepatitis B virus [HBV] DNA) and disease activity (alanine aminotransferase activities), as summarized in a recent practice guideline issued by the American Association for the Study of Liver Diseases.^[1] Thus, treatment is generally recommended for patients with serum HBV DNA levels > 10⁵ copies/mL and elevated serum aminotransferases.

Liver histology plays a much more important role in making decisions about treatment of hepatitis C, but there are no precise guidelines about which Knodell or METAVIR scores merit therapy. The recent National Institutes of Health Consensus Statement on Management of Hepatitis C states: "Liver biopsy is useful in defining baseline abnormalities of liver disease and in enabling patients and healthcare providers to reach a decision regarding antiviral therapy."^[2] This document further indicates that patients with no fibrosis and minimal necroinflammatory changes may not need treatment and should be monitored periodically. I would personally interpret this statement to refer to METAVIR or Knodell scores of up to 2.

The Knodell, METAVIR, Ishak, and other similar systems for scoring the necroinflammatory and fibrotic changes of hepatitis C are summarized by Brunt.^[3] Features that are typically assessed include portal and lobular inflammation, interface hepatitis (formerly piecemeal necrosis), and fibrosis. The degree of fibrosis best reflects progression of hepatitis C and begins with portal expansion, extending to bridging fibrosis and eventually cirrhosis.

The decision to initiate treatment in a patient with hepatitis C is a complex one that involves assessment of disease severity, but also includes hepatitis C virus genotype, patient motivation, symptoms, severity of comorbid illness, and the patient's age.^[2]