COBAS® HIV-1/HIV-2 QUALITATIVE

Additional Manufacturer Narrative

THE REPORTED EVENT INVOLVED A COBAS 5800 ANALYZER (SERIAL NUMBER: (B)(6). THE INVESTIGATION DETERMINED THAT THE COBAS HIV-1/2 QUALITATIVE TEST AND COBAS HIV-1 QUANTITATIVE TEST PERFORMED WITHIN SPECIFICATIONS. A REVIEW OF THE PROVIDED DATA, INCLUDING CONTROL VALUES AND SAMPLE DATA, INDICATED THAT THE SAMPLE IN QUESTION APPEARED TO BE AT OR NEAR THE LIMIT OF DETECTION (LOD), AS EVIDENCED BY A VERY LATE CYCLE THRESHOLD (CT) VALUE. THIS PHENOMENON, WHICH CAN RESULT IN VARIABILITY BETWEEN POSITIVE AND NEGATIVE RESULTS, IS CONSISTENT WITH THE POISSON EFFECT AT LOW TARGET DNA CONCENTRATIONS. ADDITIONALLY, THE POSSIBILITY OF LOW-LEVEL CONTAMINATION FROM WORKFLOW CANNOT BE EXCLUDED. NO TRENDS OR SIMILAR ISSUES WERE IDENTIFIED IN THE COMPLAINT HISTORY ANALYSIS. THE INVESTIGATION CONCLUDED THAT THE OBSERVED VARIABILITY IS EXPECTED UNDER THESE CONDITIONS. LABORATORIES ARE ADVISED TO FOLLOW BEST PRACTICES TO MINIMIZE THE RISK OF CONTAMINATION.

Description of Event or Problem

THE INITIAL REPORTER ALLEGED DISCORDANT RESULTS BETWEEN THE COBAS HIV-1/2 QUALITATIVE TEST AND THE COBAS HIV-1 QUANTITATIVE TEST ON THE COBAS 5800. THE SAMPLE, IDENTIFIED AS (B)(6), WAS TESTED USING THE COBAS HIV-1/2 QUALITATIVE TEST ON (B)(6) 2024, GENERATING A REACTIVE RESULT FOR THE HIV-1 TARGET WITH A CYCLE THRESHOLD (CT) VALUE OF 41.71, NON-REACTIVE FOR THE HIV-2 TARGET, AND AN INTERNAL CONTROL (IC) CT VALUE OF 38.08. THE SAME SAMPLE WAS RETESTED ON (B)(6) 2024 USING THE COBAS HIV-1 QUANTITATIVE TEST, WHICH DID NOT DETECT THE TARGET. ADDITIONALLY, ANOTHER SPECIMEN (EDTA PLASMA) FROM THE SAME PATIENT WAS TESTED AT A DIFFERENT LABORATORY USING THE COBAS HIV-1/2 QUALITATIVE TEST ON A COBAS 5800 INSTRUMENT, AND NON-REACTIVE RESULTS WERE OBTAINED FOR BOTH HIV-1 AND HIV-2 TARGETS.