Multicentre evaluation of a new point-of-care test for the determination of CK-MB in whole blood.
BACKGROUND
The point-of-care (POC) test Roche CARDIAC CK-MB is a new assay which has been developed for the existing Roche Cardiac reader system.


METHODS
We performed a multicentre evaluation at six sites to assess the analytical performance of the POC CK-MB assay and to compare it with a quantitative laboratory CK-MB assay.


RESULTS
Within-series coefficients of variation (CV) resulting from 34 ten-fold measurements with patient samples ranged from 4.3% to 16.4%. Using quality control material, the mean CV values for day-to-day imprecision were 6.5% for the low level control and 8.4% for the high level control. Based upon 847 pairs of values, the mean relative bias of three independently calibrated lots of the POC CK-MB assay ranged from -6% to -11% in method comparisons with the lab CK-MB assay. The mean relative lot-to-lot differences of POC CK-MB were between -2% and +1%. No interference was observed with lipaemic blood (triglyceride concentrations up to 8.1 mmol/L), icteric blood (bilirubin concentrations up to 513 micromol/L), haemolytic blood (haemoglobin concentrations up to 0.12 mmol/L), biotin (up to 30 mg/L) and rheumatoid factor (up to 119 IU/mL), or with 53 standard or cardiological drugs even in toxic concentrations. There was no influence on the results by varying haematocrit values in the range from 21% to 54%. A slight interference with human anti-mouse antibodies type 2 was found. No significant influence on the results with POC CK-MB was found by using sample volumes between 135 and 165 microL. High CK-MB concentrations above the measuring range of POC CK-MB (1-40 microg/L) did not lead to false low results due to potential high-dose hook effect. No significant effect of sample age on recovery occurred up to a sample age of 24 h. No cross-reactivity was found between the POC CK-MB assay and either CK-MM or CK-BB. A substudy with healthy individuals confirmed the reference limits of 3.8 microg/L for females and 6.7 microg/L for males.


CONCLUSIONS
The POC CK-MB assay showed a very good analytical performance with an excellent concordance with the calibration and reference laboratory method. It should be therefore suitable for its intended use in POC settings. Clin Chem Lab Med 2008;46:630-8.
Giannitsis
Evangelos
E
Abteilung für Kardiologie, Angiologie und Pulmonologie, Universitätsklinikum Heidelberg, Heidelberg, Germany.
Baum
Hannsjörg
H
Bertsch
Thomas
T
Juchum
Martin
M
Müller-Bardorf
Margit
M
Jørgensen
Bo
B
Böhmer
Agathe
A
Rebmann
Martina
M
Schäffler
Jürgen
J
Schwab
Michael
M
Zerback
Rainer
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood*; D002138:Calibration; D019963:Clinical Chemistry Tests / Q000379:methods*; D052279:Creatine Kinase, MB Form / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D019095:Point-of-Care Systems / Q000592:standards*; D015203:Reproducibility of Results
D015415:Biomarkers; D052279:Creatine Kinase, MB Form