UCSF

Background

Following World Health Organization recommendations that a quality control (QC) system be implemented in African blood centers, a pilot study of the performance of human immunodeficiency virus antibody (anti-HIV), hepatitis B surface antigen (HBsAg), and hepatitis C virus antibody (anti-HCV) testing by several Sub-Saharan African blood centers was initiated.

Study design and methods

A reference laboratory sent a panel of 25 samples to six African blood center laboratories. The panel included eight negative samples; four anti-HIV-1–, one anti-HIV-2–, four anti-HCV–, and five HBsAg-positive samples; and three samples consisting of mixtures of two sera to mimic coinfections. Sensitivity, specificity, and overall quality (correct positive or negative status) scores were calculated.

Results

From the 21 sets of results obtained (seven for each virus), eight were from rapid tests (two for HIV, three for HBV, and three for HCV) and 13 were from enzyme immunoassays (EIAs; all HIV EIAs were antigen/antibody combination assays). Overall assay sensitivity was 98% for HIV, 75% for HBV, and 88% for HCV; agreement between blood centers using the same assay was good. Sensitivity of rapid tests was notably poorer than EIAs, with overall sensitivity quality scores of 64.5% for rapid tests (20% for HBsAg rapid tests) compared to 100% for EIAs. The overall specificity quality scores were 98.3 and 94.5% for EIAs and rapid tests, respectively.

Conclusions

This pilot QC study organized for blood centers of Sub-Saharan Africa showed the feasibility of the approach despite some logistic constraints. Although interlaboratory variability was small, the poor performance of rapid tests, especially for HBsAg, raises policy questions about their use as the only screening assay.