Which techniques should be used to screen blood donations for hepatitis B surface antigen?
Preservation of all donor sera already tested for Hepatitis B surface antigen (HBsAg) by counterimmunoelectrophoresis (C.I.E.P.) allowed C.I.E.P., reversed passive haemagglutination (R.P.H.A.), and radioimmunoassay (R.I.A.) to be evaluated as screening techniques. Out of 165 811 donors tested for the first time 207 were found by C.I.E.P. to be positive for HBsAf-a prevalence of 0-12%. At the next donation 10 of those apparently negative on first screening were HBsAg positive by C.I.E.P., and nine of these were shown by retesting with R.P.H.A. and R.I.A. to have been positive at the earlier donation. These nine false negatives caused four cases of transfusion-transmitted HBsAg-positive hepatitis. On comparative screening of 22 239 donations C.I.E.P. detected 27 sera positive for HBsAg, R.P.H.A. 39, and R.I.A. 41. Thus R.I.A. increased the detection rate by more than half over C.I.E.P. From these 14 further false-negative donations by C.I.E.P. six cases-one fatal-of HBsAg-positive hepatitis occurred. The number of false positive reactions when using R.P.H.A. or R.I.A. for screening was less than 1%. As many as 700 donations in one day have been tested by R.P.H.A. or R.I.A. R.P.H.A. is faster and less expensive than R.I.A., but R.I.A. is more objective. Either R.P.H.A. or R.I.A. should replace C.I.E.P. as the routine method of screening donor sera for HBsAg.