Performance Evaluation of Two Automated Quantitative Fecal Occult Blood Tests

Abstract

Background: The performance of the fecal occult blood test (FOBT) has recently improved with the use of quantitative immunochemical assays. We evaluated the two latest immunochemical FOBTs: OC-Sensor PLEDIA (Eiken Chemical, Japan) and NS-Prime (Alfresa Pharma, Japan). Methods: The precision was evaluated by using the quality control materials at two levels and carry-over rates were measured at high and low concentrations of the sample, prepared from the calibrators. Linearity was measured by using five concentrations of human hemoglobin (0-1,000 ng/mL), prepared from erythrocyte lysates. Correlation between the two systems was analyzed by testing approximately 50 selected stool specimens per day and comparing the results obtained with those of the currently used analyzer, OC-Sensor DIANA (Eiken Chemical), for 10 consecutive working days. Results: The variation for repeatability, between-run, between-day, and intermediate precision at both levels was <5.0%, and carry-over rates were <0.01% for both systems. Linearity slopes were 0.857 and 0.594 for PLEDIA and NS-Prime, respectively, with r 2 >0.99 for both systems. In total, 499 stool specimens were analyzed, of which 127 (25.5%), 130 (26.1%), and 129 (25.9%) specimens tested positive by DIANA, PLEDIA, and NS-Prime, respectively. The agreement between PLEDIA and NS-Prime was 98.4%. Quantification by PLEDIA was linear to that by NS-Prime (y=1.0372x + 17.744; r²=0.9064). Conclusions: The analytical performances of PLEDIA and NS-Prime warrant their use as diagnostic tests. They showed excellent categorical agreement; however, the quantitative value obtained by NS-Prime was lower than that obtained by PLEDIA.