Performance of a semi-quantitative whole blood test for human heart-type fatty acid-binding protein (H-FABP)

Objectives: We evaluated the accuracy of visually reading the whole blood Rapicheck H-FABP panel test using the quantitative plasma H-FABP concentration as the reference. Subjects and methods: Consecutive patients with chest pain (n = 237) who were suspected of having acute myocardial infarction were recruited. The appearance of an evident test line within 5 min was given a grade of +3 (strongly positive), appearance within 15 min +2 (moderately positive) and the appearance of a weak test line within 15 min +1 (weakly positive). Results and discussion: The concordance rates were 91.8% for positive, 70.1% for negative and 80.2% for overall. Plasma H-FABP concentrations were above the cut-off value for 9.2% of negative (0) results. Fifty percent of weakly positive (+1) and 25.0% of moderately positive (+2) results had H-FABP concentrations lower than the cut-off value. All of the strongly positive (+3) were above the cut-off value. These results suggested that the false-positive and false-negative results of Rapicheck H-FABP were caused by over or underestimation in visual reading when the plasma H-FABP concentration was near the cut-off concentration. Conclusions: Low accuracy of visual reading of Rapicheck H-FABP was due to poor estimation by manual reading around the cut-off value.