Risk factors in transmission of non-A, non-B posttransfusion hepatitis. The role of hepatitis B antibody in donor blood.

Risk of developing icteric hepatitis in a transfusion study involving cardiac surgery patients was 0.2 per cent per unit of blood transfused with the ratio of icteric to anicteric cases being 1:4. Risk of developing hepatitis was proportional to the number of units transfused: one to four units, 4 per cent; six to ten units, 8 per cent; 11 to 20 units, 19 per cent; greater than 21 units, 42 per cent. The prevalence of type B hepatitis was low (6 per cent), with the vast majority of patients being shown to have non-A non-B hepatitis. However, a greater incidence of hepatitis type B serologic events was observed among recipients of anti-HBs positive blood than those transfused only with units not containing antibody (p = 0.04. A significantly greater incidence of non-A, non-B hepatitis was observed among patients transfused with blood containing anti-HBs when compared with a group who received blood without antibody (p less than 0.01). Caution should be exercised in interpretation of this difference because patients transfused with blood containing anti-HBs received significantly more units of blood. However, utilization of stepwise regression analysis to unconfound the two dependent variables suggest that the use of blood containing anti-HBs increases the hepatitis risk (p = 0.06) although the number of units transfused was the more significant factor (p less than 0.001). Additional data from carefully designed studies are needed to determine if donor blood containing anti-HBs significantly increases the risk of transmitting non-A, non-B hepatitis.