The current risk of retroviral infections transmitted by transfusion in patients who have undergone multiple transfusions. Cooleycare Cooperative Group.

BACKGROUND

To conduct a multicenter, prospective survey within the program of the Cooleycare Cooperative Group to evaluate the rate of transfusion-transmitted infections with human immunodeficiency virus (HIV) and human T-lymphotropic virus (HTLV) in a cohort of patients who were homozygous for beta thalassemia and underwent multiple transfusions during the 6-year follow-up.

PATIENTS AND METHODS

One thousand three hundred eighty-four patients with beta thalassemia from 36 centers were enrolled from December 1989 to March 1990. Serum samples were tested at regular intervals during the period from December 1989 to March 1996 for anti-HIV and anti-HTLV antibodies in 1 laboratory. Samples from 1073 and 1001 of the 1384 patients were available for evaluation also during the periods from December 1992 to March 1993 and December 1995 to March 1996, respectively. The risk of acquiring infection was calculated by the ratio between the number of patients who experienced seroconversion and the number of red blood cell units administered to the patients during the study period.

RESULTS

The prevalence of HIV infection found in the period from December 1989 to March 1990 was 2.9% (40 of 1384 patients). During follow-up, 1 of 1001 patients showed anti-HIV seroconversion. The incidence of HIV infection was 1.7 per 10,000 person-years (upper boundary of the 95% confidence interval, 5 per 10,000). The risk of HIV infection was 1 in 190,000 U (upper boundary of the 95% confidence interval, 1 in 67,000). At baseline, 4 patients were infected with HTLV (3 with HTLV-1 and 1 with HTLV-2). No seroconversions were observed during follow-up; the risk of HTLV infection was less than 1 in 190,000 U.

CONCLUSION

The application of reliable screening procedures for donor selection reduced the transmission of transfusion-associated HIV infection in 1989-1995 to fewer than 2 cases in 10,000 person-years or 1 case per 190,000 units of red blood cells.