Impact of implementing a category 1 external quality assurance scheme for monitoring harmonization of clinical laboratories in Spain

Abstract

Background: The objective of the present study was to examine the evolution of the analytical performance specifications (APS) used in External Quality Assurance (EQA) schemes, as well as the efficacy of a category 1 EQA scheme in monitoring the harmonization of clinical laboratory results in Spain.

Methods: A review of the literature on the types of quality specifications used in schemes in other countries and their evolution was performed. In addition, a comparative analysis of the potential impact that different APS from eight countries had on clinical decision-making was made based on three measurands: sodium, thyroid-stimulating hormone (TSH), and activated partial thromboplastin time (aPTT).

Results: Harmonization of analytical methods was demonstrated by assessing whether average results deviated from the certified reference value of control materials within the APS derived from biological variation (BV). The APS used in EQA have evolved from state-of-the-art models to BV. Poor clinical decision-making would occur if the results accepted by some APS were applied.

Conclusions: In Spain, only 2 of the 18 measurands studied are considered to be well harmonized. Closer collaboration between laboratories and analytical system providers would be required to resolve discrepancies.

Keywords: analytical performance specifications; biological variation; external quality assurance schemes; harmonization; state of the art.

Figure 1:

Evolution of the type of APS used in EQA schemes. (A) 16 Europeans EQA schemes, 1996. (B) 10 international EQA schemes, 2017.

Figure 2:

Bias obtained for standardized analytes. (A) CK (2018). (B) Potasium (2015–2018). Green dotted lines indicate the acceptable upper and lower bias based on BV. The bias shown may be the desirable (d) or the optimum (o). The number of participating laboratories in each comparison group is indicated in brackets.

Figure 3:

Bias obtained for non-standardized analytes according to the instrument used. (A) Alkaline phosphatase (2018). (B) Proteins (2018). Green dotted lines indicate the acceptable upper and lower bias based on BV. The bias shown may be the desirable (d) or the optimum (o). The number of participating laboratories in each comparison group is indicated in brackets.

Figure 4:

ALT. Bias depends on the analytical method used. Green dotted lines indicate the acceptable upper and lower bias based on BV. The bias shown may be the desirable (d) or the optimum (o). The number of participating laboratories in each comparison group is indicated in brackets.

Figure 5:

Evolution of inter-laboratory imprecision (CV%) for glucose and sodium. (A) Glucose. (B) Sodium.