The cause for the discordant advia centaur xp hbsagii results is unknown.Siemens healthcare diagnostics is investigating.The information for use (ifu) states in the limitations section: "for diagnostic purposes, the advia centaur hbsagii test results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings.Heterophilic antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays.9 patients routinely exposed to animals or to animal serum products can be prone to this interference and anomalous values may be observed.Additional information may be required for diagnosis.".
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Siemens filed the initial mdr 1219913-2019-00048 on march 27, 2019.04/01/2019 additional information: the customer had a sample that recovered nonreactive with the advia centaur xp hbsag lot 201.The same sample recovered reactive with advia centaur xp hbsagii lot 150.When the sample was manually diluted with negative serum and tested with advia centaur xp hbsagii lot 150 the index value increased.The patient has myasthenia gravis (a chronic autoimmune neuromuscular disease) but no other medical information was available.The sample cannot be sent to siemens for evaluation due to china customs issues.The customer does not have any advia centaur xp hbsag reagents to do further testing.The advia centaur xp hbsagii assay is designed to detect mutant hbsag as outlined in the mutant hbsag detection section of the advia centaur xp/xpt hbsii instructions for use (ifu) (10635152 revision g, 2017-12).Since there was only one result with the advia centaur xp hbsag assay and no dilution data we cannot determine whether the initial nonreactive result was due to mutant hbsag, a testing error, or some unknown interferent.The relative clinical sensitivity and specificity section of the advia centaur xp hbsag instructions for use (ifu) (10629873 revision w, 2015-06) lists the 95% confidence interval (ci) for sensitivity as 99.24% - 100.00% so a certain number of false negative results can be expected for this assay.So, the one false negative sample seen by this customer does not indicate there is a product issue.Note that the advia centaur xp hbsagii assay is a qualitative assay, not a quantitative assay, and siemens makes no claims as to how dilutions will perform.The cause of the false negative result with the sample when using advia centaur xp hbsag lot 201 could not be determined but siemens cannot rule out mutant hbsag, pre-analytical factors, or a sample issue.Based on the investigation, no product problem was identified.The instrument is performing within specifications.No further evaluation of the device is required.
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