Proficiency in testing for hepatitis B surface antigen: experience with Ausria II.

Eight hepatitis B surface antigen (HBsAg) proficiency panels were tested using a radioimmunoassay (RIA) test kit during 1978 and 1979 by routine processing laboratories within the 57 American Red Cross Blood Services Regions. The test results were analyzed and it was found that lot-to-lot variability in the reagents may result in a measurable loss of sensitivity of the test leading to an increased error rate. On the basis of these studies, it is recommended that the positive to negative (P/N) ratio for validation of the test be raised to at least 25.