SIEMENS HEALTHCARE DIAGNOSTICS, INC. ATELLICA IM TOXOPLASMA IGG (TOXO G); TOXOPLASMA GONDII IMMUNOASSAY
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Model Number N/A |
Device Problem
False Positive Result (1227)
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Patient Problems
No Known Impact Or Consequence To Patient (2692); No Clinical Signs, Symptoms or Conditions (4582)
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Event Date 06/30/2020 |
Event Type
malfunction
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Manufacturer Narrative
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The customer contacted the siemens customer care center (ccc) to report discordant, false reactive atellica im toxoplasma igg (toxo g) patient results.Siemens has reviewed atellica im toxo g patient data from 07-mar-2019 to 26-jun-2020 and reagent lot 260 is recovering comparably with previous reagent lots 247, 249, 251, 252, and 258.The calculated specificity observed for this customer is 99.2%.The instruction for use (ifu) initial relative specificity is 98.6%.Siemens is investigating.The instruction for use (ifu) states in the interpretation of results section: "results of this assay should always be interpreted in conjunction with the patient's medical history, clinical presentation, and other findings." the instruction for use (ifu) states in the limitations section: "specimens collected in the early stages of infection may have igg levels that are classified as negative." "in geographic regions that have an apparent low prevalence of toxoplasma igg in asymptomatic populations, the positive predictive value of any assay is reduced due to the increased possibility that a positive result is actually falsely positive.As with all in vitro diagnostic assays, each laboratory should determine its own reference range(s) for the diagnostic evaluation of patient results.".
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Event Description
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False reactive (positive) atellica im toxoplasma igg (toxo g) results were obtained on samples from the same patient and questioned by the physician(s).The reactive results were considered discordant compared to nonreactive (negative) alternate toxoplasma igg test method results performed at a national reference center (cnr).The nonreactive alternate toxoplasma igg (toxo g) results were reported to the physician(s) as corrected results.There are no reports that treatment was altered or prescribed or adverse health consequences due to the discordant, false reactive atellica im toxoplasma igg (toxo g) results.
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Manufacturer Narrative
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Siemens filed the initial mdr 1219913-2020-00181 report on 23-jul-2020 for false positive atellica im toxoplasma igg (toxo g) result.26-sep-2020 - additional information: siemens completed an internal study on atellica im system for toxoplasma igg (toxo g) assay.During the study toxo g reagent lots 258, 260 and 262 were used.Toxo g reagent lot 252 expired on august 9th, 2020 and was relabeled to reagent lot 997.Results generated with lot 997 were solely for informational purposes.Fifty (50) normal patient samples from siemens and fifty (50) patient samples from france were tested in replicates of 3 (n=3).The final interpretation was the same for all 50 samples from france and for 49/50 patient samples from siemens.The one siemens normal patient sample was reactive with reagent lots 997, 258 and 260 and equivocal with reagent lot 262.This is a cut off sample (10.0 iu/ml) and recovery was within acceptable precision at that level.Siemens continues to investigate.In section h6, the health effect - clinical code, clinical impact code and the component code were added.
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Manufacturer Narrative
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Siemens filed the initial mdr 1219913-2020-00181 report on 23-jul-2020 for false reactive (positive) atellica im toxoplasma igg (toxo g) result.Mdr 1219913-2020-00181 supplemental report 1 was filed on 19-oct-2020 for additional information.26-oct-2020 - additional information: siemens has concluded the investigation.The customer reported a false reactive (positive) atellica im toxoplasma igg (toxo g) patient result with reagent lot 260.The patient sample when tested on an alternate toxoplasma igg method was nonreactive (negative).A new sample was drawn and recovered reactive with reagent lot 260.The customer treated the sample with heterophilic blocking tube (hbt) and non-specific antibody blocking tubes (nabt) and the sample consistently recovered reactive (positive) on the atellica im toxoplasma igg (toxo g), however detailed results were not provided.Siemens reviewed the customer's calibration data.The data was comparable to product release specifications.The customer's quality control recovered within ranges.The atellica im toxoplasma igg (toxo g) siemens analytics service (sas) patient data was reviewed from march 2019 to june 2020.Reagent lot 260 recovered similarly with interpretation rates of previous reagent lots 247, 249, 251, 252, and 258.A review of internal data for mean control recovery comparing reagent lots 252 to 258, and reagent lots 258 to 260, showed the same trend; reagent lot 258 elevated compared to reagent lots 252 and 260.Further analysis of the siemens internal data (global and france only) for mean patient recovery across several reagent lots, verified that reagent lot 258 was elevated compared to reagent lots 252 and 260 globally and in france.The atellica im toxoplasma igg (toxo g) instructions for use (ifu) 10995430_en rev.02, 2019-08 interpretation of results section states the following: "the magnitude of the measured result above the cut-off value is not indicative of the total amount of antibody present in the sample." siemens initiated an internal study that included toxo g reagent lots 258, 260 and 262, fifty (50) normal patient samples from siemens and fifty (50) patient samples from france.The patient samples from france for the internal study were purchased by siemens from an approved supplier and french acquisition company (inospecimens niobank).All samples were tested in replicates of 3 (n=3).The final interpretation was the same for the patient samples across the reagent lots, except for one siemens sample that was near the cutoff of 10 iu/ml.The recovery for this sample was within acceptable precision at that level.Based on the information provided, the calculated specificity for this customer with reagent lot 260 is 127/128 = 0.992 x100 = 99.2%.The atellica im toxoplasma igg (toxo g) instructions for use (ifu) initial relative specificity results from the 3 studies range from 97.7%- 99.8%.The atellica im toxoplasma igg reagent lot 260 is performing as intended.A product performance issue has not been identified.The customer will verify reactive results that do not match with historical values with an alternate toxoplasma igg method.The customer is operational.The assay is performing within specifications.No further evaluation of the device is required.In section h6, the investigation finding and investigation conclusion codes were updated.
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