The customer from outside the united states reported one (1) false negative (non-reactive) hiv ag/ab combo (chiv) result was obtained on an advia centaur cp.The result was considered discordant compared to a result from alternate methods.The non-reactive result was not reported to the physician.The reactive results obtained from the alternate instruments were considered correct.Siemens has evaluated the instrument, reagent and sample data.Reagent issues were ruled out based on review of qc which showed recovery within acceptable ranges and no issues were reported with other patient samples.Based on the available information, the cause of the discordant result is unable to be determined.The calculated values for anti-hiv and/or p24 antigen in each specimen as determined by assays from different manufacturers can vary due to differences in assay methods and reagent specificity.Sample return for further investigation is not possible as sample is not available.The customer is operational.The limitations section of the advia centaur cp hiv ag/ab combo (chiv) instructions for use (ifu) states the following: ¿the calculated values for anti-hiv and/or p24 antigen in a given specimen as determined by assays from different manufacturers can vary due to differences in assay methods and reagent specificity.The results reported by the laboratory to the physician must include the identity of the assay used.Values obtained with different assay methods cannot be used interchangeably.The reported antibody level and/or p24 antigen cannot be correlated to an endpoint titer.¿ additionally, the limitations section of the ifu states: ¿currently available assays for the detection of p24 antigen and/or antibodies to hiv-1 and/or hiv-2 may not detect all infected individuals.A negative test result does not exclude the possibility of exposure to or infection with hiv.Hiv antibodies and/or p24 antigen may be undetectable in some stages of the infection and in some clinical conditions.¿.
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