engleski

Performance characteristics and clinical usefulness of troponin I assays

Any condition resuting in myocardial cell damage can potentially increase cardiac troponin I levels. Therefor, low concentrations of troponin I have large clinical significance in diagnosis of pathological heart conditions. Materials and Methods A study was performed for the Axsym and Architect STAT Troponin I assays (Abbott Diagnostics). Axsym STAT Troponin I is a microparticle enzyme immunoassay (MEIA) ; Architect STAT Troponin I is a chemiluminiscent microparticle immunoassay (CMIA). Manufacturer's performance characteristics were verified according to NCCLS Protocol EP5-A2. A study was performed with STAT Troponin I Controls in two concentration levels ; n (Axsym)=20, n (Architect)=15 for each concentration level. According to do manufacturer's study, STAT Troponin I concentrations at 10 % CV were 0.16 µg/L for Axsym and 0.032 µg/L for Architect. Method comparison was performed on human serum (n=30) by linear regression analysis. Results Precision profile, including within-run precision CV%, for Axsym was 6.1 % (mean 0.28 µg/L) and 4.1 % (mean 1.14 µg/L), for Arcitect was 4.6 % (mean 0.14 µg/L) and 4.9 % (mean 0.56 µg/L) and within- laboratory precision for Axsym was 7.8 % and 5.3 %, for Architect was 5.6 % and 7.1 %. Comparison results all along measuring range (0.00-22.78 µg/L) showed r=0.92 (y=0.6138x+0.425). Conclusion STAT Troponin I CMIA has better analytical characteristics than MEIA. Methods are comparable because they are traceable to the same internal reference standard. As seen, analytical precision is not uniform among troponin I assays. The Commitee on Standardization of Markers of Cardiac Damage (C-SMCD) recommends a total precision CV% <10 at the myocardial infarction (MI) decision limit (0.028 µg/L). A failure to reach this goal could increase the risk of clinically misleading results. CMIA has advantage in clinical use because low concentrations of troponin I are significant in diagnosis of MI, angina, congestive heart failure, myocarditis.

myocardial cell damage; Troponin I assays; NCCLS Protocol EP5-A2; verification

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