Hepatitis B result combinations used to define hepatitis B status

HBsAg: Hepatitis B surface antigen. Anti-HBs: antibody to hepatitis B surface antigen. Anti-HBc: antibody to hepatitis B core antigen.Note to Table 1: There are several potential explanations for results being recorded as missing, with varied consequences for the analysis. Tests may have been undertaken but the data not available electronically and therefore not included in the exported dataset, or tests may not have been carried out in error or intentionally. The latter is particularly likely where previous test results are known so that clinicians may have been able to infer the current HBV status, but the details of these are not included in the dataset. In other situations, clinicians or the laboratory may have limited the tests requested, for example if HBsAg and anti-HBc were both detectable an anti-HBs test might have been deemed unnecessary. Some missing results are less critical to the analysis than others, in that the result would not change the allocated category. All those with missing HBsAg results have been put in the unclassifiable category.