IgM anti-HBc in acute and chronic hepatitis B virus (HBV) infection: diagnostic value and correlation with viral replication and disease activity.

IgM antibody to hepatitis B core antigen (IgM anti-HBc) was determined in 348 subjects with hepatitis B virus infection, in order to evaluate, in an area of high hepatitis D virus (HDV) endemicity, its usefulness in discriminating acute HBV hepatitis from HDV superinfection of HBsAg carriers, and to see whether in chronic HBV infection IgM anti-HBc can be related to viral replication, disease activity, or risk of neoplastic transformation. The positive predictive value (PV) of IgM anti-HBc for acute hepatitis was low at the standard 2.1 cut-off (35.2%), but a cut-off of 7 raised the positive PV, retaining a negative PV of above 90% and a sensitivity of 59.5%. No significant relationship was found in chronic infection between IgM anti-HBc, the level of HBV replication or the type of liver disease. Patients with HDV infection were mostly IgM anti-HBc negative. Hepatocellular carcinoma was not associated with a raised prevalence of IgM anti-HBc.