Analytical assessment of ortho clinical diagnostics high-sensitivity cardiac troponin I assay

Performance evaluation of a novel high-sensitivity cardiac troponin T assay: analytical and clinical perspectives

OBJECTIVES

To evaluate the analytical characteristics of a novel high-sensitivity cardiac troponin T (hs-cTnT) test on the automatic light-initiated chemiluminescent assay (LiCA®) system, and validated its diagnostic performance for non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

Studies included an extensive analytical evaluation and established the 99th percentile upper reference limit (URL) from apparently healthy individuals, followed by a diagnostic performance validation for NSTEMI.

RESULTS

Sex-specific 99th percentile URLs were 16.0 ng/L (1.7 % CV: coefficient of variation) for men (21-92 years) and 13.4 ng/L (2.0 % CV) for women (23-87 years) in serum, and 30.6 ng/L (0.9 % CV) for men (18-87 years) and 20.2 ng/L (1.4 % CV) for women (18-88 years) in heparin plasma. Detection rates in healthy individuals ranged from 98.9 to 100 %. An excellent agreement was identified between LiCA® and Elecsys® assays with a correlation coefficient of 0.993 and mean bias of -0.7 % (-1.8-0.4 %) across the full measuring range, while the correlation coefficient and overall bias were 0.967 and -1.1 % (-2.5-0.3 %) for the lower levels of cTnT (10-100 ng/L), respectively. At the specific medical decision levels (14.0 and 52.0 ng/L), assay difference was estimated to be <5.0 %. No significant difference was found between these two assays in terms of area under curve (AUC), sensitivity and specificity, negative predictive value (NPV) and positive predictive value (PPV) for the diagnosis of NSTEMI.

CONCLUSIONS

LiCA® hs-cTnT is a reliable 3rd-generation (level 4) high-sensitivity assay for detecting cardiac troponin T. The assay is acceptable for practical use in the diagnosis of NSTEMI.

The Clinical Validation of a Common Analytical Change Criteria for Cardiac Troponin for Ruling in an Acute Cardiovascular Outcome in Patients Presenting with Ischemic Chest Pain Symptoms

Serial cardiac troponin (cTn) testing on patients with symptoms suggestive of acute coronary syndrome (ACS) is primarily to identify those patients with evolving myocardial injury. With the improved analytical performance of the high-sensitivity cTn (hs-cTn) assays, different change criteria have been proposed that are mostly assay dependent. Here, we developed and compared a new Common Change Criteria (3C for the combined criteria of >3 ng/L, >30%, or >15% based on the initial cTn concentration of <10 ng/L, 10 to 100 ng/L, or >100 ng/L, respectively) method, versus the 2 h assay-dependent absolute change criteria endorsed by the European Society of Cardiology (ESC), versus the common relative >20% change criterion. These different analytical change criteria were evaluated in 855 emergency department (ED) patients with symptoms of ACS and who had two samples collected 3 h apart. The cTn concentrations were measured with four different assays (Abbott hs-cTnI, Roche hs-cTnT, Ortho cTnI-ES, and Ortho hs-cTnI). The outcomes evaluated were myocardial infarction (MI) and a composite outcome (MI, unstable angina, ventricular arrhythmia, heart failure, or cardiovascular death) within 7 days of ED presentation. The combined change criteria (3C) method yielded higher specificities (range: 93.9 to 97.2%) as compared to the >20% criterion (range: 42.3 to 88.1%) for all four assays for MI. The 3C method only yielded a higher specificity estimate for MI for the cTnI-ES assay (95.9%) versus the absolute change criteria (71.7%). Similar estimates were obtained for the composite outcome. There was also substantial agreement between hs-cTnT and the different cTnI assays for MI with the 3C method, with the percent agreement being ≥95%. The Common Change Criteria (3C) method combining both absolute and different percent changes may be used with cTnI, hs-cTnT, and different hs-cTnI assays to yield similar high-specificity (rule-in) estimates for adverse cardiovascular events for patients presenting to the ED with ACS symptoms.

Myocardial Injury Thresholds for 4 High-Sensitivity Troponin Assays in a Population-Based Sample of US Children and Adolescents

BACKGROUND

Myocardial injury is an important pediatric diagnosis. Establishing normative data from a representative pediatric sample is vital to provide accurate upper reference limits (URLs) for defining myocardial injury using high-sensitivity cardiac troponin.

METHODS

Among participants 1 to 18 years of age in the 1999-2004 National Health and Nutrition Examination Survey, we measured high-sensitivity troponin T using one assay (Roche) and high-sensitivity troponin I using 3 assays (Abbott, Siemens, and Ortho). In a strictly defined healthy subgroup, we estimated 97.5th and 99th percentile URLs for each assay using the recommended nonparametric method.

RESULTS

Of 5695 pediatric participants, 4029 met criteria for the healthy subgroup (50% males; mean age 12.6 years). Our 99th percentile URL estimates for all 4 high-sensitivity troponin assays among children and adolescents were lower than the manufacturer-reported URLs (derived from adults). The 99th percentile URLs (95% CI) were 15 ng/L (95% CI, 12-17) for high-sensitivity troponin T, 16 ng/L (95% CI, 12-19) for high-sensitivity troponin I with the Abbott assay, 38 ng/L (95% CI, 25-46) for high-sensitivity troponin I with the Siemens assay, and 7 ng/L (95% CI, 5, 12) for high-sensitivity troponin I with the Ortho assay. The 95% CIs for age-, sex-, and race and ethnicity-specific 99th percentile URLs overlapped. However, the 97.5th percentile URL for each assay was measured with superior statistical precision (ie, tighter 95% CIs) and demonstrated differences by sex. For male compared with female children and adolescents, 97.5th percentile URLs were 11 ng/L (95% CI, 10-12) versus 6 ng/L (95% CI, 6-7) for high-sensitivity troponin T, 9 ng/L (95% CI, 7-10) versus 5 ng/L (95% CI, 4-6) for high-sensitivity troponin I with the Abbott assay, 21 ng/L (95% CI, 18-25) versus 11 ng/L (95% CI, 9-13) for high-sensitivity troponin I with the Siemens assay, and 4 ng/L (95% CI, 3-5) versus 2 ng/L (95% CI, 1-3) for high-sensitivity troponin I with the Ortho assay. In contrast to the 99th percentiles, the point estimates of 97.5th percentile pediatric URLs for high-sensitivity troponin were also much more stable to differences in the analytic approaches taken to estimate URLs.

CONCLUSIONS

Because myocardial infarction is rare in children and adolescents, the use of statistically more precise and reliable sex-specific 97.5th percentile high-sensitivity troponin URLs might be considered to define pediatric myocardial injury.

Age partitioned and continuous upper reference limits for Ortho VITROS High Sensitivity Troponin I in a healthy paediatric cohort

OBJECTIVES

In adults, the elevation of cardiac troponin (cTn) above the 99th percentile upper reference limit defines myocardial injury. The use and interpretation of cTn in a paediatric population, however, is difficult given the 99th percentile for different assays is not well established. Using paediatric blood samples from healthy neonates, infants and children we derived continuous and partitioned 97.5th and 99th percentiles for the Ortho VITROS hs-TnI assay.

METHODS

A total of 328 samples for infants, children and adolescents aged 0-17.8 years were obtained. Age partitioned reference limits were derived in accordance with CLSI EP28-A3C. Continuous reference limits were established as described previously by the HAPPI Kids Study team.

RESULTS

hs-TnI as measured by the Ortho VITROS Assay is highly elevated above the adult 99th percentile at birth and declines to lower levels within the first 6 months of life. The 99th centile upper reference limit for ages 0-3 months was 72 ng/L (90% CI: 52-91) and 9 ng/L (90% CI: 5.2-17.4) for ages 3 months to 18 years. Continuous upper 99th centile reference limits were comparable.

CONCLUSIONS

Partitioned and continuous 99th percentiles for hs-TnI were derived for the new Ortho VITROS assay in healthy neonates and older children. This will assist clinicians to appropriately assess for the presence of myocardial injury in this population.

Storage conditions, sample integrity, interferences, and a decision tool for investigating unusual high-sensitivity cardiac troponin results

The current definition of high-sensitivity cardiac troponin (hs-cTn) assays is laboratory-based and their analytical attributes and characteristics have drawn significant attention in the literature at least partly due to the lower concentration cut-offs and changes in concentrations (i.e., deltas) employed in different algorithms and pathways to manage patient care. We propose that pre-analytical conditions such as sample type, storage conditions, and other interferences may also have a significant impact on hs-cTn concentrations and clinical management. The purpose of this literature review is to provide a summary of important pre-analytical and interference studies affecting hs-cTn concentrations. A breakdown of the literature for the major diagnostic companies providing core laboratory instrumentation (i.e., Abbott, Beckman, Ortho, Roche, and Siemens) is also provided. Finally, three cases are highlighted where knowledge of pre-analytical factors aids the hs-cTn clinically discordant investigations. This review highlights the importance of pre-analytical variables, especially storage condition, sample handling, and blood tubes used (i.e., sample type) when interpreting hs-cTn assays. Additional studies are needed to further elaborate on pre-analytical variables (i.e., centrifugation, sample type, stability) and interferences for all hs-cTn assays in clinical use, as knowledge of these variables may aid in hs-cTn clinically discordant investigations.

Analytical and clinical performance evaluation of a new high-sensitivity cardiac troponin I assay

OBJECTIVES

To validate the analytical performance and diagnostic accuracy for non-ST-segment elevation myocardial infarction (NSTEMI) with a new high-sensitivity cardiac troponin I (hs-cTnI) assay on the automated light-initiated chemiluminescent assay (LiCA^®) platform.

METHODS

Comprehensive analytical validations were performed, and the 99th percentile upper reference limit (URL) from apparently healthy individuals were established. We evaluated the diagnostic performance of the assay for NSTEMI.

RESULTS

The limit of quantitation (LoQ) were 1.9 ng/L (20% CV) and 5.1 ng/L (10% CV). The sex-specific 99th percentile URLs were 17.6 ng/L (4.2% CV) for men (age 20-79y) and 14.2 ng/L (4.9% CV) for women (age 19-89y) in serum, 14.4 ng/L (4.9% CV) for men (age 19-88y) and 12.9 ng/L (5.2% CV) for women (age 19-87y) in plasma, respectively. Detection rates in healthy individuals were from 98.7 to 99.1%. The correlation coefficient and median bias between LiCA and Architect were 0.985 and 0.1% (-2.0-2.9%) in full analytical range of serum specimens. In lower range (<100 ng/L), LiCA had an overall positive bias 6.7% (-1.6-13.3%), R=0.949. At the specific medical decision levels (15.2, 26.2 and 64.0 ng/L), assay difference was estimated to be <10%. No significant differences on AUC, sensitivity and specificity, NPV and PPV were found between LiCA and Architect for the diagnosis of NSTEMI.

CONCLUSIONS

LiCA hs-cTnI is a precise, highly sensitive and specific assay that meets the requirement of a 3rd generation (level 4) high-sensitivity method. The diagnostic accuracy of LiCA assay for NSTEMI is comparable to the established Architect hs-cTnI assay.

0/2 h-Algorithm for Rapid Triage of Suspected Myocardial Infarction Using a Novel High-Sensitivity Cardiac Troponin I Assay

Background

We aimed to derive and validate a 0/2 h-algorithm using the new high-sensitivity cardiac troponin I (hs-cTnI)-VITROS assay (VITROS® Immunodiagnostic Products hs-Troponin I Reagent Pack, Ortho Clinical Diagnostics) for rapid rule-out/in of non-ST-segment elevation myocardial infarction (NSTEMI).

Methods

The final diagnosis was centrally adjudicated by 2 independent cardiologists according to the fourth universal definition of myocardial infarction (MI) among 1888 patients presenting to the emergency department with acute chest pain. hs-cTnI-VITROS concentrations were measured at presentation and at 2 h in a blinded fashion. The optimal assay-specific thresholds for the hs-cTnI-VITROS 0/2 h-algorithm were derived in a randomly selected 70% of the cohort and validated in the remaining 30%.

Results

NSTEMI was the final diagnosis in 216/1322 (16.3%) patients of the derivation cohort. Rule-out was defined as baseline hs-cTnI concentrations of &lt;1 ng/L in patients presenting with chest pain onset &gt;3 h or a baseline hs-cTnI concentration of &lt;2 ng/L and an absolute change of &lt;3 ng/L within 2 h. Thresholds for rule-in were either ≥40 ng/L at presentation or an absolute change within 2 h of ≥ 5ng/L. In the derivation cohort, these thresholds ruled-out 50.8% of patients with a negative predictive value (NPV) and sensitivity of 99.7% (95% Confidence Interval (CI), 98.8–99.9%) and 99.1% (95% CI, 96.7–99.9%), and ruled-in 17.9% with a positive predictive value (PPV) of 79.2% (95% CI, 74.3–83.5%). In the validation cohort, NSTEMI was the final diagnosis in 91/566 (16.1%) patients. The derived 0/2 h-algorithm ruled-out 46.3% of patients with a NPV and sensitivity of 100% (95% CI, 95.6–100%) and 100% (95% CI, 96.0–100%), and ruled-in 18.9% with a PPV of 73.8% (95% CI, 66.1–80.3%) in the validation cohort.

Conclusion

hs-cTnI-VITROS concentrations at presentation combined with absolute changes within the first 2 h allowed safe rule-out and accurate rule-in of NSTEMI in two-thirds of unselected patients presenting with acute chest pain to the emergency department.

Trial registration

www.clinicaltrials.gov: NCT0047058

Pre-analytical considerations in biomarker research: focus on cardiovascular disease

Clinical biomarker research is growing at a fast pace, particularly in the cardiovascular field, due to the demanding requirement to provide personalized precision medicine. The lack of a distinct molecular signature for each cardiovascular derangement results in a one-size-fits-all diagnostic and therapeutic approach, which may partially explain suboptimal outcomes in heterogeneous cardiovascular diseases (e.g., heart failure with preserved ejection fraction). A multidimensional approach using different biomarkers is quickly evolving, but it is necessary to consider pre-analytical variables, those to which a biological sample is subject before being analyzed, namely sample collection, handling, processing, and storage. Pre-analytical errors can induce systematic bias and imprecision, which may compromise research results, and are easy to avoid with an adequate study design. Academic clinicians and investigators must be aware of the basic considerations for biospecimen management and essential pre-analytical recommendations as lynchpin for biological material to provide efficient and valid data.

Analytical assessment and performance of the 0/3h algorithm with novel high sensitivity cardiac troponin I

BACKGROUND

Recently, Ortho Clinical Diagnostics have launched a high sensitivity cardiac troponin I assay adapted on Vitros3600 / 5600. We aimed at evaluating the analytical and clinical performances using the 0/3-hour algorithm, of the Ortho hs-cTnI assay on the Vitros 3600® (Ortho Clinical Diagnostics, Illkirch, France) analyzer with comparison to Roche hs-cTnT assay on the Cobas8000/e801® module (Roche diagnostics, Meylan, France) and the Abbott STAT hs-cTnI assay on the Alinity i® (Abbott, Rungis, France) analyzer.

METHODS

Imprecision studies, linearity, limit of detection, and the interference to hemolysis were performed for Ortho hs-cTnI assay. The concordance study was based on results of troponin obtained from 160 patients with chest pain to the emergency department. Testing was performed simultaneously measuring the Roche hs-cTnT and the Ortho hs-cTnI, then on remaining sample the concentration of Abbott hs-cTnI (n = 150). We applied the 0/3h algorithm to rule out/rule in, in acute myocardial infarction.

RESULTS

Analytical performances were acceptable and in accordance with manufacturer's data. For late presenters 100, 92.8 and 88.8% patients could be rule-out with Roche, Ortho and Abbott assay, respectively with one NSTEMI missed with both hs-TnI assays. Applying the hs-cTn cut-offs from 0/3-hour algorithm, 107 (66.8%) could be rule out with Roche hs-cTnT with no AMI missed (sensitivity 100% [95%CI: 90.5 to 100] and NPV 100%); 89 with Ortho hs-cTnI (sensitivity 97.3% [95%CI: 85.8-99.9] and NPV 98.8% [95%CI:92.7-99.8]); and 61 with Abbott hs-cTnI (sensitivity 97% [95%CI: 84.2-99.9] and NPV 98.4% [95%CI: 89.8-99.7]). For rule-in, 23.7% (n = 37) from the total population would be designated in this group, with a specificity of 86.9% (95%CI: 79.7-92.4) and PPV of 69.8% (95%CI: 59.4-78.5) vs specificity of 72.3% (95%CI:63.5-80.0) and PPV of 51.4% (95%CI: 44.1-58.2)with Roche hs-cTnT vs Ortho hs-cTnI respectively; and with Abbott, 33 patients had constitued this group with a specificity of 52.1% (95%CI:42.7-61.4) and PPV of 36.4% (95%CI: 32.0-41.0).

CONCLUSION

In conclusion, according to ESC guidelines, our results indicate that the Ortho hs-cTnI assay for the Vitros 3600 instrument is a method that may be used in the clinical practice using 0/3-hour algorithm.

Independent and combined effects of biotin and hemolysis on high-sensitivity cardiac troponin assays

OBJECTIVES

This study compared the independent and combined effects of hemolysis and biotin on cardiac troponin measurements across nine high-sensitivity cardiac troponin (hs-cTn) assays.

METHODS

Parallel cTn measurements were made in pooled lithium heparin plasma spiked with hemolysate and/or biotin using nine hs-cTn assays: Abbott Alinity, Abbott ARCHITECT i2000, Beckman Access 2, Ortho VITROS XT 7600, Siemens Atellica, Siemens Centaur, Siemens Dimension EXL cTnI, and two Roche Cobas e 411 Elecsys Troponin T-hs cTnT assays (outside US versions, with and without increased biotin tolerance). Absolute and percent cTn recovery relative to two baseline concentrations were determined in spiked samples and compared to manufacturer's claims.

RESULTS

All assays except the Ortho VITROS XT 7600 showed hemolysis and biotin interference thresholds equivalent to or greater than manufacturer's claims. While imprecision confounded analysis of Ortho VITROS XT 7600 data, evidence of biotin interference was lacking. Increasing biotin concentration led to decreasing cTn recovery in three assays, specifically both Roche Cobas e 411 Elecsys Troponin T-hs assays and the Siemens Dimension EXL. While one of the Roche assays was the most susceptible to biotin among the nine studied, a new version showed reduced biotin interference by approximately 100-fold compared to its predecessor. Increasing hemolysis also generally led to decreasing cTn recovery for susceptible assays, specifically the Beckman Access 2, Ortho VITROS XT 7600, and both Roche Cobas e 411 Elecsys assays. Equivalent biotin and hemolysis interference thresholds were observed at the two cTn concentrations considered for all but two assays (Beckman Access 2 and Ortho VITROS XT 7600). When biotin and hemolysis were present in combination, biotin interference thresholds decreased with increasing hemolysis for two susceptible assays (Roche Cobas e 411 Elecsys and Siemens Dimension EXL).

CONCLUSIONS

Both Roche Cobas e 411 Elecsys as well as Ortho VITROS XT assays were susceptible to interference from in vitro hemolysis at levels routinely encountered in clinical laboratory samples (0-3 g/L free hemoglobin), leading to falsely low cTn recovery up to 3 ng/L or 13%. While most assays are not susceptible to biotin at levels expected with over-the-counter supplementation, severely reduced cTn recovery is possible at biotin levels of 10-2000 ng/mL (41-8,180 nmol/L) for some assays. Due to potential additive effects, analytical interferences should not be considered in isolation.

Disagreement between Cardiac Troponin Tests Yielding a Higher Incidence of Myocardial Injury in the Emergency Setting

Differences in patient classification of myocardial injury between high-sensitivity cardiac troponin (hs-cTn) assays have largely been attributed to assay design and analytical sensitivity aspects. Our objective was to compare Ortho Clinical Diagnostics' (OCD) hs-cTnI assay to OCD's contemporary/conventional assay (cTnI ES) and another hs-cTnI assay (Abbott hs-cTnI) in samples obtained from different emergency departments (EDs). Two different sample types were evaluated (lithium heparin and ethylenediaminetetraacetic acid (EDTA) plasma) in a non-selected ED population (study 1, n = 469 samples) and in patients for which ED physicians ordered cardiac troponin testing (study 2, n = 1147 samples), from five different EDs. The incidence of injury in study 1 was higher with the OCD hs-cTnI assay (30.9%; 95% CI: 26.9 to 35.2) compared to that of the Abbott hs-cTnI (17.3%; 95% CI: 14.1 to 21.0) and the OCD cTnI ES (15.4%; 95% CI: 12.4 to 18.9) assays, with repeat testing identifying 4.8% (95% CI: 3.0 to 7.5) of the OCD hs-cTnI results with poor reproducibility. In study 2, 4.6% (95% CI: 3.5 to 6.0) of the results were not reported for the OCD hs-cTnI assay (i.e., poor reproducibility) with 12.7% (95%CI: 8.7 to 17.8) of the OCD hs-cTnI results positive for injury being negative for injury with the Abbott hs-cTnI assay. In summary, the OCD hs-cTnI assay yields higher rates of biochemical injury with a higher rate of poor reproducible results in different ED populations.

Acute Phase Response and Non-Reproducible Elevated Concentrations with a High-Sensitivity Cardiac Troponin I Assay

High-sensitivity cardiac troponin (hs-cTn) testing has enabled physicians to make earlier diagnostic and prognostic decisions in the hospital setting than previous cardiac troponin assays. Analytical improvements have permitted one to measure cardiac troponin precisely in the nanogram per litre (ng/L) range with hs-cTn assays which has resulted in fast 0/1-h and 0/2-h algorithms for ruling-in and ruling-out myocardial infarction. Although analytical interferences that affect the reporting of hs-cTn are uncommon, not all hs-cTn assays are designed the same nor have undergone the same clinical and analytical validations. Here, after investigating an initial case of discrepant hs-cTnI results, we report that patients with an acute phase response (e.g., patients with inflammatory or infectious illnesses) can yield high and non-reproducible results with the Ortho Clinical Diagnostics hs-cTnI assay. Compared to Abbott Diagnostics hs-cTnI, Ortho Clinical Diagnostics hs-cTnI assay misclassifies biochemical injury in approximately 10% of the population being assessed for myocardial injury with imprecise results in approximately half of this population (i.e., 5%). In conclusion, caution is warranted in interpreting Ortho Clinical Diagnostics hs-cTnI alone in patients being evaluated for myocardial injury, especially in patients whose primary presentation is related to an acute phase response and not an acute coronary syndrome symptom.