Compliance to specifications in an external quality assurance program: did new biological variation estimates of the European Federation of Laboratory Medicine (EFLM) affect the quality of laboratory results?

Abstract

Objectives: The results of external quality assurance schemes are evaluated against specifications generally based on biological variation (BV) data. This study was carried out to determine whether new BV values affected the level of compliance to specifications. Our secondary objective was to identify the conditions that would be compromised as a result of poor analytical performance in disease associated markers.

Methods: This study was based on the results of the SEQC^ML External Quality Assurance scheme for the 2015-2022 period. Deviation of the individual result from the target value was estimated. Additionally, we calculated the percentage of results that met the pre-established specification.

Results: In 97 of the 133 analytes, the level of compliance was maintained in 80-90 % of the results obtained in the two study periods. In 23 analytes, the level of compliance ranged from 51 to 79 % in the two study periods. In ALT, AST and sodium, the level of compliance was ≤50 % of the results obtained in the first study period, with sodium being the only analyte that maintained this poor level of compliance in the second study period.

Conclusions: The level of compliance to specifications remained independent from the specification used (SEQC^ML or EFLM) for the majority of the analytes. The results for sodium ion were below the target value, which may lead to misdiagnosis of hyponatremia. Non-compensated alkaline picrate methods overestimate creatinine, which may produce false information suggestive of kidney failure.

Keywords: analytical performance specification; biological variation; external quality assurance.