Proficiency testing of viral marker screening in African blood centers: A multinational study

A 2014 report revealed sensitivities of 92%, 87% and 90% to anti-HIV, HBsAg and anti-HCV, respectively, at African blood center laboratories but substantial international investments in national blood transfusion services (NBTS) have since been made. During 2017, we performed a proficiency testing study at 84 blood center laboratories in seven African countries, including 55 NBTS and 29 non-NBTS laboratories. A blinded panel of 25 plasma samples (including negatives and pedigreed positives for anti-HIV, HBsAg and anti-HCV) was shipped to each participating laboratory for routine testing. Assay types in use were “Rapid” and enzyme immunoassay generations 3 [EIA-3] and 4 [EIA-4]. Sensitivity and specificity to each assay target were estimated using two general estimating equation models that assumed binomial distributions and clustered assay targets by laboratory. Analogous multivariable models added laboratory type, assay type, and all two-way interactions. Mean (95% CI) sensitivity to anti-HIV was 97% (95%–98%), compared with 76% (71%–81%) for HBsAg and 80% (75%–86%) for anti-HCV. Mean (95% CI) specificity was 95% (93%–97%) for anti-HIV, 96% (93%–98%) for HBsAg, and 95% (90%–98%) for anti-HCV. Sensitivity to all targets was high at NBTS laboratories (> 92%) and when EIA-3 assays were used (> 97%). Lower sensitivities to HBsAg and anti-HCV were associated with non-NBTS laboratories and/or assay types other than EIA-3. We conclude that proficiency for HIV testing has improved but remains suboptimal for HBsAg and anti-HCV testing. Remediation measures and reassessment are planned for poorly performing laboratories.