Risk of iatrogenic human immunodeficiency virus infection through transfusion of blood tested by inappropriately stored or expired rapid antibody assays in a Zambian hospital.

BACKGROUND

The purpose of this study was to estimate the risk of human immunodeficiency virus (HIV) infection via the transfusion of blood tested by inappropriately stored or expired rapid antibody assays in Zambia.

STUDY DESIGN AND METHODS

Surgical patients (n = 370) were tested with antibody assays (HIV-spot and HIV 1+2) that had expired 3 to 6 months previously. Blood donors (n = 211) were tested by inappropriately stored but non-expired HIV-spot assay. Serum samples from both groups were retested with enzyme immunoassays, and the seropositivity of samples was confirmed by immunoblotting.

RESULTS

Seroprevalence in surgical patients and blood donors was 19.8 and 11.6 percent, respectively. Sensitivity and specificity of HIV-spot (expired) were 88.2 and 98.1 percent; those of HIV 1+2 (expired) were 82.1 and 94.7 percent; and those of HIV-spot (non-expired) were 91.7 and 98.8 percent, respectively. The risk of HIV infection via the transfusion of blood tested by HIV-spot (expired), HIV-spot (nonexpired), or HIV 1+2 (expired) was calculated to be 1.4, 1.0, and 3.2 percent, respectively.

CONCLUSION

Manufacturers of the HIV-spot and HIV 1+2 assays claim sensitivity and specificity of 98.8 and 100 percent and 100 and 99.5 percent, respectively. In this study, sensitivity and specificity were 11 to 18 percent lower. Moreover, in-date reagents also performed less well than the manufacturers claimed, but the worst results were with expired or improperly stored reagents. According to the manufacturers of HIV-spot and HIV 1+2, the risk of HIV infection would be 0.2 and 0 percent, respectively. However, the risk of contracting HIV through transfusion is at least six times higher than expected.