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Incidence and Etiology of Poor Duplicate Ortho High-Sensitivity Cardiac Troponin I Results in a Community Hospital Emergency Department

Open AccessPublished:October 10, 2022DOI:https://doi.org/10.1016/j.cjco.2022.10.002
      To the Editor:
      The prevalence of nonreproducible false-positive results obtained with the Ortho high-sensitivity cardiac troponin I (hs-cTnI) assay (Ortho Clinical Diagnostics, Raritan, NJ) is higher, compared to that obtained with other cardiac troponin assays in patients with an acute phase response, in both the academic and community hospital settings.
      • Kavsak P.A.
      • Mondoux S.
      • Worster A.
      • et al.
      Misclassification of myocardial injury by a high-sensitivity cardiac troponin I assay.
      • Kavsak P.A.
      • Um K.
      • Mondoux S.
      • et al.
      Important differences between manufacturers when transitioning from a contemporary cardiac troponin assay to a high-sensitivity cardiac troponin assay.
      • Kavsak P.A.
      • Mondoux S.E.
      • Martin J.
      • et al.
      Disagreement between cardiac troponin tests yielding a higher incidence of myocardial injury in the emergency setting.
      This difference is in contrast to testing performed in patients with a suspected acute coronary syndrome, for whom Ortho hs-cTnI concentrations are typically lower than Abbott hs-cTnI (Abbott Laboratories, Chicago, IL) concentrations.
      • Kavsak P.A.
      • Mondoux S.
      • Worster A.
      • et al.
      Misclassification of myocardial injury by a high-sensitivity cardiac troponin I assay.
      Initial estimates of poor reproducibility for Ortho hs-cTnI concentrations, in samples collected from emergency department (ED) patients for whom the ED physician requested hs-cTnI testing, was approximately 5%.
      • Kavsak P.A.
      • Mondoux S.E.
      • Martin J.
      • et al.
      Disagreement between cardiac troponin tests yielding a higher incidence of myocardial injury in the emergency setting.
      Here, we describe and report on the number of poor duplicate results obtained with the Ortho hs-cTnI assay (laboratory algorithm) over 1 year, from ED patients presenting to a community hospital within our hospital network.
      • Kavsak P.A.
      • Um K.
      • Mondoux S.
      • et al.
      Important differences between manufacturers when transitioning from a contemporary cardiac troponin assay to a high-sensitivity cardiac troponin assay.
      Briefly, duplicate testing (laboratory initiative) for the Ortho hs-cTnI assay was performed with the average result reported if the 2 results met the prespecified criteria for agreement (Supplemental Table S1).
      • Kavsak P.A.
      • Mondoux S.E.
      • Martin J.
      • et al.
      Disagreement between cardiac troponin tests yielding a higher incidence of myocardial injury in the emergency setting.
      ,
      • Lafrenière M.A.
      • Tandon V.
      • Ainsworth C.
      • et al.
      Storage conditions, sample integrity, interferences, and a decision tool for investigating unusual high-sensitivity cardiac troponin results.
      Samples yielding poor repeat measurements were not reported for the Ortho hs-cTnI assay, with the sample sent immediately for testing with the Abbott hs-cTnI assay.
      • Kavsak P.A.
      • Um K.
      • Mondoux S.
      • et al.
      Important differences between manufacturers when transitioning from a contemporary cardiac troponin assay to a high-sensitivity cardiac troponin assay.
      ,
      • Kavsak P.A.
      • Mondoux S.E.
      • Martin J.
      • et al.
      Disagreement between cardiac troponin tests yielding a higher incidence of myocardial injury in the emergency setting.
      Data were obtained from January 14, 2021 to February 8, 2022 from the laboratory information system on samples from ED patients that were not reported with the Ortho hs-cTnI assay due to poor reproducibility. The patient list was cross-checked with the non-reported Ortho hs-cTnI concentrations, the Abbott hs-cTnI results, and other variables, including patient disposition (admit or discharged home), with the primary impression of the ED physician on the patient condition being recorded.
      Over 13 months, 3350 patients had hs-cTnI assays ordered from an ED location. A total of 44 patients (1.3%; 95% confidence interval: 1.0-1.8) had samples (n = 48) that yielded poor duplicate Ortho hs-cTnI assay results. The median age of these patients was 70 years (interquartile range: 59-75), with 48% being female and 59% being discharged home. The median imprecision from the duplicate Ortho hs-cTnI assay concentrations was 28% (interquartile range: 22%-42%), with 43 of the 44 patients yielding at least one Ortho hs-cTnI assay concentration above the sex-specific 99th percentile (compared to 6 with the Abbott hs-cTnI assay). Most of the patients (75%) had an ED diagnosis with an infective etiology (Supplemental Table S2), with 4 patients having serial samples with poor reproducibility with the Ortho hs-cTnI assay (Table 1).
      Table 1Patients with poor reproducible Ortho hs-cTnI results that were not reported on serial sampling
      Age, ySexBlood drawOrtho result 1, ng/LOrtho result 2, ng/LAbsolute difference, Ortho 2nd from 1stPercent difference, Ortho 2nd from 1st, %Abbott reported

      result,

      ng/L
      ED physician primary impressionDisposition
      69FFirst46.069.023.05012PneumoniaDischarged
      Second31.386.555.217612
      60MFirst34.360.225.97611Rule out ACSDischarged
      Second8.914.05.15712
      52MFirst16.645.929.31775COVID-19Admitted
      Second44.664.720.1455
      61MFirst21.926.64.7217Chest infectionDischarged
      Second27.138.111.0419
      Patients with Ortho hs-cTnI assay (Ortho Clinical Diagnostics, Raritan, NJ) concentration results that have poor reproducibility (ie, difference > 3 ng/L or > 20% between values) that were not reported on serial sampling (Ortho female 99th ≤ 9 ng/L; Ortho male 99th ≤ 13 ng/L). The corresponding concentrations measured with Abbott hs-cTnI assay (Abbott Laboratories, Chicago, IL) were reported in the patient medical record (Abbott female 99th: ≤16 ng/L; Abbott male 99th ≤ 34 ng/L). Bolded hs-cTnI concentrations are those values that are above the 99th percentile.
      Abbott, Abbott hs-cTnI assay; ACS, acute coronary syndrome; ED, emergency department; F, female; hs-cTnI, high-sensitivity cardiac troponin I; M, male; Ortho, hs-cTnI assay.
      Duplicate testing will detect poor reproducible Ortho hs-cTnI results which, if reported, could lead to a misclassification of acute myocardial injury. The majority of these poor duplicate results are from patients with an infection.

      Ethics Statement

      Ethics approval: HiREB 2179.

      Acknowledgements

      We thank the laboratory staff within the Hamilton Regional Laboratory Medicine Program for performing the duplicate testing for the Ortho hs-cTnI assay.

      Funding Sources

      The authors have no funding sources to declare.

      Disclosures

      P.A.K. has received grants/reagents/honoraria from and/or served as advisor/consultant to the following: Abbott Laboratories, Abbott Point of Care, Beckman Coulter, Ortho Clinical Diagnostics, Quidel, Randox Laboratories, Roche Diagnostics, Siemens Healthcare Diagnostics, and Thermo Fisher Scientific. McMaster University has filed patents with P.A.K. listed as an inventor in the acute cardiovascular biomarker field. The other authors have no conflicts of interest to disclose.

      Supplementary Material

      References

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