Evaluation of analytical quality of cardiac biomarkers in the emergency laboratory by sigma metrics

Abstract

Aim: The analytic quality of cardiac biomarkers were investigated consecutive six months by sigma metric method in our emergency laboratory. Total allowable error ratio (TEa%)'s of AAB, BV, RCPA, Ricos, and Rilibak were used for calculation. Sigma levels are compared and used to decide which TEa% is appropriate for our laboratory for more accurate results. Material and Method: Sigma levels were calculated for cardiac biomarkers which include Troponin I (cTnI), Troponin T (cTnT), CKMB mass, Myoglobin (Mb) and NT-proBNP in our emergency laboratory department between December 2017 and May 2018. The internal quality control (IQC) and external quality control (EQC) assessment results and TEa%'s of AAB, BV, RCPA, Ricos, and Rilibak were used to calculate sigma metrics. The sigma metrics for tests were calculated by "Sigma = (TEa% − Bias%) / CV%" formula. Results: Considering different TEa% 's, it is evaluated that CKMB mass sigma level is at the "world-class quality". On the contrary, cTnT sigma level is found to be at the level of "poor quality". For AAB, BV, RCPA, Ricos and Rilibak, different sigma levels are observed. Discussion: Due to using different TEa%'s for each test, different sigma levels were determined. On the other hand, because of the "poor quality" level of cTnT sigma value, decision is taken for the improvement of cTnT in our laboratory. In addition, it is observed that there is no specified TEa% for whole blood samples. Therefore, it is concluded that, for more accurate and consistent evaluations, specified matrix of TEa% values are required for whole blood samples.