Quality specification and status of internal quality control of cardiac biomarkers in China from 2011 to 2016

Abstract

Background: This study aimed to investigate the status of internal quality control (IQC) for cardiac biomarkers from 2011 to 2016 so that we can have overall knowledge of the precision level of measurements in China and set appropriate precision specifications.

Methods: Internal quality control data of cardiac biomarkers, including creatinine kinase MB (CK-MB) (μg/L), CK-MB(U/L), myoglobin (Mb), cardiac troponin I (cTnI), cardiac troponin T (cTnT), and homocysteines (HCY), were collected by a web-based external quality assessment (EQA) system. Percentages of laboratories meeting five precision quality specifications for current coefficient of variations (CVs) were calculated. Then, appropriate precision specifications were chosen for these six analytes. Finally, the CVs and IQC practice were further analyzed with different grouping methods.

Results: The current CVs remained nearly constant for 6 years. cTnT had the highest pass rates every year against five specifications, whereas HCY had the lowest pass rates. Overall, most analytes had a satisfactory performance (pass rates >80%), except for HCY, if one-third TEa or the minimum specification were employed. When the optimal specification was applied, the performance of most analytes was frustrating (pass rates < 60%) except for cTnT. The appropriate precision specifications of Mb, cTnI, cTnT and HCY were set as current CVs less than 9.20%, 9.90%, 7.50%, 10.54%, 7.63%, and 6.67%, respectively. The data of IQC practices indicated wide variation and substantial progress.

Conclusion: The precision performance of cTnT was already satisfying, while the other five analytes, especially HCY, were still frustrating; thus, ongoing investigation and continuous improvement for IQC are still needed.

Keywords: analytical phase; biochemical markers; health care; quality control; quality indicators; quality specification.

Figure 1

Percentages of laboratories according to the number of concentration levels of quality control measurements performed within one analytical run for six items from 2011 to 2016

Figure 2

Percentages of laboratories using each type of test method for six items from 2011 to 2016. AECLA, acridinium‐ester‐labeled chemiluminescence immunoassay; ECLA, electrochemiluminescence assay; CLA, chemiluminescence immunoassay; DIGFA, dot immunogold filtration assay; CEA, chemiluminescent enzyme immunoassay; IFA, immunofluorescence method; CLMA, chemiluminescent microparticle immunoassay—AMPPD; MEIA, microparticle enzyme immunoassay; DCM, dry chemistry method; IIA, inhibition immunoassay; RM, rate method; IMT, immunoturbidimetry; FEIA, fluorescence enzyme immunoassay; and ECA, enzymatic cycling assay

Figure 3

Percentages of laboratories according to the control rules for six items from 2011 to 2016. 12s—one point out of 2 standard deviation (SD); 13s—one point outside 3 SD; 22s—(across runs) 2 consecutive values outside the same 2SD or (with run) 2 consecutive values outside the same 2 SD; R4s—The range (difference) between two controls within a run exceeds 4 SDs. This rule is only to be used within a run, not across runs; 41s—4 consecutive control values on one side of the mean and further than 1 SD from the mean. This can be within one control across 4 consecutive runs or within 2 controls across 2 consecutive runs; 10x—10 consecutive values on one side of the mean. This can be within one control across 10 consecutive runs or within 2 controls across 5 consecutive runs

Figure 4

Percentages of laboratories according to control frequency for six items from 2011 to 2016