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An approach for the calculation of preliminary measurement uncertainty values in clinical routine laboratories using
Simon Michaelis1, Laura Binder1, Christopher Schneider1
1Institute of Clinical Chemistry and Laboratory Medicine, General Hospital Hochsteiermark, Vordernberger Straße 42, 8700 Leoben, Austria.
Background:
The measurement uncertainty is an essential measure of quality in clinical routine laboratories. Its estimation is mandatory for the ISO 15189 accreditation. However, there is no in consensus on how to establish the MU. The study aimed to evaluate a procedure for calculating a preliminary MU based on already existing verification data and results from external quality assessment (EQA) schemes.
Methods:
Expanded measurement uncertainty (U) was calculated for 29 measurands using two different data sets applying the Nordtest protocol. One U was determined with internal quality control (IQC) data from one year (60 measurements/level; two levels) and six EQA-samples (MUIQC-scheme), the second U was performed with verification data according to the CLSI EP15-A3 guideline (25 measurements/level, 5x5-scheme; two levels) and four EQA samples (MUVerification-scheme). The difference between MUIQC and MUVerification (ΔU) was calculated. MUIQC and MUVerification were compared to published acceptance criteria (Rili-BAEK and Westgard).
Results:
For most measurands, U was higher for MUIQC (range 2.2 %-20.9 %) compared with MUVerification (range 2.2 %-13.0 %). The ΔU ranged between -1.8 %-13.8 %. Five measurands showed a ΔU of > 5 %, while seven measurands showed a higher U for MUVerification (ΔU-range -1.8 %--0.8 %). For all measurands, the U for MUIQC and MUVerification were within the Rili-BAEK and Westgard acceptance criteria.
Conclusion:
The use of verification data may serve as a suitable approach for the estimation of preliminary MU values in clinical routine laboratories.
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