Standardization in laboratory medicine: Two years’ experience from category 1 EQA programs in Spain

Abstract

IntroductionStandardization is the ability to obtain interchangeable results leading to same medical interpretation. External quality assessment (EQA) is the main support of the on-going harmonization initiatives. Aim of study was to evaluate results obtained from two years category 1 EQA program experience in Spain and determine the impact of applying this type of EQA program on the analytical standardization.Materials and methodsAccording to the analytical method, traceability and instrument different groups were established which results were evaluated by calculating mean, coefficient of variation and percent of deviation to the reference value. Analytical performance specifications used to the results' evaluation were derived from biological variation for bias and from the inter-laboratory coefficients of variation found in a previous pilot study.ResultsOnly creatinine measured by enzymatic methods gave excellent results, although few laboratories used this method. Creatine kinase and GGT gave good precision and bias in all, but one instrument studied. For the remaining analytes (ALT, ALP, AST, bilirubin, calcium, chloride, glucose, magnesium, potassium, sodium, total protein and urate) some improvement is still necessary to achieve satisfactory standardization in our setting.ConclusionsThe two years of category 1 EQA program experience in Spain have manifested a lack of standardization of 17 most frequent biochemistry tests used in our laboratories. The impact of the information obtained on the lack of standardization is to recommend abandoning methods such as ALT, AST without exogenous pyridoxal phosphate, Jaffe method for creatinine, and do not use non-commutable calibrators, such as aqueous solutions for calcium and sodium.

La trazabilidad en las mediciones del laboratorio clínico: impacto en la calidad y seguridad del paciente

“…La implementación y efecto de estas iniciativas ha sido monitoreada en años posteriores en algunos países europeos, mediante la utilización de muestras conmutables en ensayos de aptitud, cuyo valor esperado es obtenido mediante procedimientos de medida de referencia. En estos seguimientos, se ha observado que algunos laboratorios aún utilizan métodos no trazables para alfa-amilasa [24,25] y LDH, y que también se pueden obtener resultados variables en ALT y AST, incluso en el mismo tipo de instrumentos [24,25]. También se ha evidenciado que la diferencia entre laboratorios para bilirrubina, cloro, glucosa, hierro, magnesio y fósforo está más relacionada con el instrumento de medición que con el método de medición [26], similar a lo observado con fosfatasa alcalina en algunos estudios [25,27].…”

Big data and reference intervals: rationale, current practices, harmonization and standardization prerequisites and future perspectives of indirect determination of reference intervals using routine data

“…The implementation of the Dutch External Quality Assessment (EQA) Program "SKML Combi New Style" in 2005, using commutable and targeted sera, has proven to be very effective in reducing median interlaboratory coefficients of variation for electrolytes, substrates and enzymes in the Netherlands [50]. A comparability study between analytical methods in Spain, using also commutable materials from SKML, shows that standardization is still lacking [51,52]. Ricos et al [51] have already recommended the change to pyridoxal phosphate methods for alanine aminotransferase and aspartate aminotransferase measurements, the use of enzymatic method for creatinine measurement, the change to pyruvate to lactate methods for lactate dehydrogenase measurement and the use of commutable calibrators for electrolytes.…”

“…A comparability study between analytical methods in Spain, using also commutable materials from SKML, shows that standardization is still lacking [51,52]. Ricos et al [51] have already recommended the change to pyridoxal phosphate methods for alanine aminotransferase and aspartate aminotransferase measurements, the use of enzymatic method for creatinine measurement, the change to pyruvate to lactate methods for lactate dehydrogenase measurement and the use of commutable calibrators for electrolytes. These recommendations are important to recall.…”

EQA/PT scheme to improve the equivalence of enzymatic results between mutual recognition laboratories in Beijing

“…At present, standardization has become the goal of global efforts in laboratory medicine 3,4 . The external quality assessment (EQA)/proficiency testing (PT), as a management tool to monitor and verify the performance of participating laboratories, plays an important role in promoting clinical laboratory standardization 5–9 …”