Evaluation of the Diagnostic Performance of three Rapid Diagnostic Tests for HBsAg screening for blood donation in Cameroon

Abstract

Background: Rapid Diagnostic Tests have been wildly reported for HBsAg screening in Cameroon. Aims and Objectives: The present study aimed at assessing the diagnostic performance and the limit of detection of three Rapid Diagnostic Tests used for HBsAg screening for blood donation in Cameroon. Study Design: A hospital-based cross-sectional study involving blood donors who met blood banks requirements was done. Setting: The study was carried out at Douala Laquintinie Hospital and Bamenda Regional Hospital. Materials and Methods: Ten mL of blood specimen was collected among blood donors who accepted to partake in the study by signing the inform consent. Laboratory processing was performed at the University of Buea. The limit of detection of the assays under evaluation was checked and the diagnostic performance assessed. The automated Architect HBsAg assay and the ELISA Biorex HBsAg were used as the reference standard. Statistics: Sensitivity, specificity was obtained by comparing the results of each of the assay to those of the reference standard. The limit of detection (LOD) of the three RDTs compared to the ELISA Biorex was assessed by preparing 14-fold Dilution of known positive control samples. Results: The limit of detection of the tests under evaluation was 0.18IU/mL whereas the one of the ELISA Biorex was 0.05IU/mL. Diaspot and Fastep obtained a sensitivity of 88.24% when compared to Architect and respectively 60.53% and 57.89% when compared to Biorex. Abon showed a lower sensitivity of 50.0% as compared to Biorex and 58.82% compare to Architect. Diaspot and Fastep had a specificity > 99% independent on the standard while Fastep had 98.62% using Biorex and 97.54% using Architect. Conclusion: Diaspot and Fastep feature the World Health Organization required specificity independent of the standard used while none of the tests reached the expected sensitivity and limit of detection.