KIT COBAS 58/68/8800 MPX 480T US

Additional Manufacturer Narrative

THE REPORTED EVENT OCCURRED ON A COBAS 8800 ANALYZER (SERIAL NUMBER: (B)(6). THE INVESTIGATION DETERMINED THAT THE KIT COBAS 58/68/8800 MPX 480T US-IVD ASSAY PERFORMED WITHIN SPECIFICATIONS. A REVIEW OF BATCH DATA CONFIRMED VALID CONTROL PERFORMANCE, AND NO ISSUES WERE IDENTIFIED WITH THE REAGENT LOT (M07839) OR THE SYSTEM. ANALYSIS OF THE PCR AMPLIFICATION CURVES FOR THE SERUM AND PLASMA SAMPLES VERIFIED THE ACCURACY OF THE RESULT INTERPRETATION. THE DISCREPANT RESULTS WERE ATTRIBUTED TO A VERY LOW VIRAL LOAD NEAR OR BELOW THE ASSAY'S LIMIT OF DETECTION, WHICH CAN RESULT IN VARIABILITY BETWEEN REACTIVE AND NON-REACTIVE OUTCOMES. THIS IS CONSISTENT WITH THE ASSAY'S PERFORMANCE CHARACTERISTICS AS DESCRIBED IN THE INSTRUCTIONS FOR USE (IFU). THERE WAS NO EVIDENCE OF OFF-LABEL USE OR PRODUCT QUALITY ISSUES. THE DEVICE REMAINS IN OPERATION AT THE CUSTOMER SITE.

Description of Event or Problem

THE INITIAL REPORTER ALLEGED DISCREPANT RESULTS FOR HEPATITIS B VIRUS (HBV) TESTING USING THE KIT COBAS 58/68/8800 MPX 480T US-IVD ASSAY ON THE COBAS 8800 ANALYZER. THE DISCREPANCY INVOLVED ONE PATIENT'S SERUM AND PLASMA SAMPLES TESTED IN BATCH ID 14736. THE SERUM SAMPLE TESTED NON-REACTIVE FOR HBV, WHILE THE PLASMA SAMPLE TESTED REACTIVE. BOTH SAMPLES WERE RECEIVED IN PRIMARY TUBES AND PROCESSED WITHOUT ALIQUOTING. THE PLASMA SAMPLE EXHIBITED AN HBV CYCLE THRESHOLD (CT) VALUE OF 36.76 AND AN INTERNAL CONTROL (IC) CT VALUE OF 40.1, WHILE THE SERUM SAMPLE SHOWED NO HBV SIGNAL AND AN IC CT VALUE OF 38.28. THE RESULTS WERE INTERPRETED BASED ON WEAK, NON-SIGMOIDAL POLYMERASE CHAIN REACTION (PCR) CURVES, WITH THE PLASMA SAMPLE MEETING THE CRITERIA FOR A REACTIVE RESULT AND THE SERUM SAMPLE BEING NON-REACTIVE.