An external quality control program distributes same control samples to various laboratories and evaluates results obtained with a common criterion. The aim of this work is to summarize the evolution ...of various types of external programs, to point out the progresses ant to preclude practical consequences of the participant laboratories.
The material consists on a brief revision of the different types of external programs that have been used for the last forty years. The method is the critical analysis of the strong and weak points of each program model, from the light of our experience. External quality assessment (EQA) programs were initiated at half the XX century, evidencing big discrepancies among laboratory results. EQA were developed in various countries and some mechanisms to harmonize them were proposed: to establish common performance specifications derived from biological variation, to use EQS as educational tool. Since the 2000 important advances were seen: to focus EQA to assure the adequate clinical use of laboratory tests, to use commutable controls, to harmonize the different EQA models, to promote a forum for co-operation and exchange of knowledge on quality-related matters for EQA organizers.
To participate in an EQA with commutable-reference method assigned values controls allows to know the real inaccuracy of results and their impact on patient' samples. To participate in a EQA with non commutable controls allows to know whether the individual laboratory performance agrees with that from other laboratories using same analytical method.
Resumen
Objectivos
Un programa de control externo distribuye las mismas muestras control entre varios laboratorios y evalúa los resultados obtenidos con un criterio común. El objetivo de este trabajo ...es resumir la evolución de los programas externos, poner de manifiesto los progresos conseguidos y deducir consecuencias prácticas para el laboratorio participante.
Métodos
El material es una breve revisión de los diferentes tipos de programas externos utilizados a lo largo de cuarenta años. El método es el análisis crítico de las ventajas e inconvenientes de cada modelo, a la luz de nuestra experiencia.
Resultados
A mitad del siglo XX se iniciaron los programas EQA, detectándose gran discrepancia entre resultados emitidos por distintos laboratorios. Se desarrollaron EQA en muchos países y se propusieron mecanismos para armonizarlos, como: establecer especificaciones derivadas de la variación biológica, promover el uso de métodos analíticos homogéneos, usar el EQA como herramienta educacional. A partir del 2000 se hacen importantes avances: asegurar el adecuado uso clínico de las pruebas del laboratorio, utilizar material control conmutable con el espécimen humano, armonizar los distintos modelos de EQA, promover una organización de cooperación entre organizadores de programas EQA.
Conclusiones
Participar en un EQA con controles conmutables y valores asignados por método de referencia certificado permite conocer la inexactitud real de los resultados y el impacto en las muestras de pacientes. Si se participa en programas con controles no conmutables solo se conoce si la prestación del laboratorio es similar a la de otros usuarios del mismo método analítico.
Internal quality control – past, present and future trends Ricós, Carmen; Fernandez-Calle, Pilar; Perich, Carmen ...
Advances in Laboratory Medicine / Avances en Medicina de Laboratorio,
10/2022, Letnik:
3, Številka:
3
Journal Article
Recenzirano
Odprti dostop
This paper offers an historical view, through a summary of the internal quality control (IQC) models used from second half of twentyth century to those performed today and wants to give a projection ...on how the future should be addressed.
The material used in this work study are all papers collected referring IQC procedures. The method used is the critical analysis of the different IQC models with a discussion on the weak and the strong points of each model.
First models were based on testing control materials and using multiples of the analytical procedure standard deviation as control limits. Later, these limits were substituted by values related with the intended use of test, mainly derived from biological variation. For measurands with no available control material methods based on replicate analysis of patient' samples were developed and have been improved recently; also, the sigma metrics that relates the quality desired with the laboratory performance has resulted in a highly efficient quality control model. Present tendency is to modulate IQC considering the workload and the impact of analytical failure in the patent harm.
This paper remarks the strong points of IQC models, indicates the weak points that should be eliminated from practice and gives a future projection on how to promote patient safety through laboratory examinations.
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.
This study was based on the results of the SEQC
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.
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.
The level of compliance to specifications remained independent from the specification used (SEQC
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.
Resumen
Objetivos
Los resultados de los programas de garantía externa de la calidad se evalúan frente a especificaciones generalmente basadas en los datos de variación biológica (VB). En este trabajo ...se pretende comprobar, por un lado, si el cumplimiento de especificaciones varía con la aplicación de nuevos valores de VB y, por otro lado, señalar qué patologías estarían comprometidas debido a una prestación analítica poco satisfactoria de sus mensurandos clave.
Métodos
El material utilizado son los resultados de los programas externos de la SEQC
ML
desde 2015 hasta 2022. El método es estimar la desviación del resultado individual respecto al valor diana considerado y calcular el porcentaje de resultados que cumplen la especificación pre-establecida.
Resultados
En 97 de los 133 mensurandos el cumplimiento se mantiene entre el 80 y el 100 % de los resultados obtenidos en los dos períodos estudiados. En 23 mensurandos el grado de cumplimiento oscila entre el 51 y el 79 % en los dos periodos. En ALT, AST y sodio el grado de cumplimiento es igual o menor al 50 % de los resultados en el primer período, quedando en este grupo únicamente el sodio en el segundo período.
Conclusiones
Para la mayoría de los mensurandos estudiados el cumplimiento se mantiene independiente de la especificación empleada (SEQC
ML
o EFLM). Los resultados de ion sodio están por debajo del valor diana, por lo que podrían darse casos de diagnóstico falso de hiponatremia. Los métodos de picrato alcalino no compensado sobreestiman la creatinina, pudiendo ocasionar falsa información de insuficiencia renal.
A major objective of the IFCC Committee on Education and Use of Biomarkers in Diabetes is to generate awareness and improvement of HbA1c assays through evaluation of the performance by countries and ...manufacturers.
Fresh whole blood and lyophilized hemolysate specimens manufactured from the same pool were used by 17 external quality assessment organizers to evaluate analytical performance of 2166 laboratories. Results were evaluated per country, per manufacturer, and per manufacturer and country combined according to criteria of the IFCC model for quality targets.
At the country level with fresh whole blood specimens, 6 countries met the IFCC criterion, 2 did not, and 2 were borderline. With lyophilized hemolysates, 5 countries met the criterion, 2 did not, and 3 were borderline. At the manufacturer level using fresh whole blood specimens, 13 manufacturers met the criterion, 8 did not, and 3 were borderline. Using lyophilized hemolysates, 7 manufacturers met the criterion, 6 did not, and 3 were borderline. In both country and manufacturer groups, the major contribution to total error derived from between-laboratory variation. There were no substantial differences in performance between groups using fresh whole blood or lyophilized hemolysate samples.
The state of the art is that 1 of 20 laboratories does not meet the IFCC criterion, but there are substantial differences between country and between manufacturer groups. Efforts to further improve quality should focus on reducing between-laboratory variation. With some limitations, fresh whole blood and well-defined lyophilized specimens are suitable for purpose.
Biological variation data (BV) can be used for different applications, but this depends on the availability of robust and relevant BV data. In this study, we aimed to summarize and appraise BV ...studies for tumor markers, to examine the influence of study population characteristics and concentrations on BV estimates and to discuss the applicability of BV data for tumor markers in clinical practice.
Studies reporting BV data for tumor markers related to gastrointestinal, prostate, breast, ovarian, haematological, lung, and dermatological cancers were identified by a systematic literature search. Relevant studies were evaluated by the Biological Variation Data Critical Appraisal Checklist (BIVAC) and meta-analyses were performed for BIVAC compliant studies to deliver global estimates of within-subject (CV
) and between-subject (CV
) BV with 95% CI.
The systematic review identified 49 studies delivering results for 22 tumor markers; four papers received BIVAC grade A, 3 B, 27 C and 15 D. Out of these, 29 CV
and 29 CV
estimates met the criteria to be included in the meta-analysis. Robust data are lacking to conclude on the relationship between BV and different disease states and tumor marker concentrations.
This review identifies a lack of high-quality BV studies for many tumor markers and a need for delivery of BIVAC compliant studies, including in different disease states and tumor marker concentrations. As of yet, the state-of-the-art may still be the most appropriate model to establish analytical performance specifications for the majority of tumor markers.
Abstract
Objectives
The estimates of biological variation (BV) have traditionally been determined using direct methods, which present limitations. In response to this issue, two papers have been ...published addressing these limitations by employing indirect methods. Here, we present a new procedure, based on indirect methods that analyses data collected within a multicenter pilot study. Using this method, we obtain CV
I
estimates and calculate confidence intervals (CI), using the EFLM-BVD CV
I
estimates as gold standard for comparison.
Methods
Data were collected over a 18-month period for 7 measurands, from 3 Spanish hospitals; inclusion criteria: patients 18–75 years with more than two determinations. For each measurand, four different strategies were carried out based on the coefficient of variation ratio (rCoeV) and based on the use of the bootstrap method (OS1, RS2 and RS3). RS2 and RS3 use symmetry reference change value (RCV) to clean database.
Results
RS2 and RS3 had the best correlation for the CV
I
estimates with respect to EFLM-BVD. RS2 used the symmetric RCV value without eliminating outliers, while RS3 combined RCV and outliers. When using the rCoeV and OS1 strategies, an overestimation of the CV
I
value was obtained.
Conclusions
Our study presents a new strategy for obtaining robust CV
I
estimates using an indirect method together with the value of symmetric RCV to select the target population. The CV
I
estimates obtained show a good correlation with those published in the EFLM-BVD database. Furthermore, our strategy can resolve some of the limitations encountered when using direct methods such as calculating confidence intervals.
Biological variation gives valuable information about how the living organism regulates its constituents within and between subjects; this information on the behavior of body components allows us to ...derive consequences concerning reference populations and intervals. With a more pragmatic approach biological variation has three uses: setting the appropriate analytical performance specification for each analyte to limit the amount of error that laboratory could introduce in its measurements, to help distinguish health from disease, and to implement internal quality control with the automatic verification of results.
Resumen
Introducción
El objetivo de este estudio es comprobar la evolución de las especificaciones de la prestación analítica (EPA) utilizadas en programas de garantía externa de la calidad (EQA) y ...el papel de un programa de categoría 1 en la vigilancia de la estandarización de la prestación de los laboratorios clínicos en España.
Métodos
Se ha revisado la bibliografía sobre tipos de especificaciones de la calidad usados en programas de otros países y se ha comprobado su evolución; se ha comparado el posible impacto de distintas EPA empleadas en ocho países en la toma de decisiones clínicas con tres ejemplos de magnitudes: sodio, tirotropina (TSH) y tiempo de tromboplastina parcial activado (TTPA).
Resultados
Se ha evidenciado la estandarización entre métodos analíticos comprobando si los resultados medios se desvían respecto al valor de referencia certificado del control dentro de las EPA derivadas de la variación biológica (VB). Las EPA usadas en EQA han evolucionado desde el estado del arte hacia la VB. Si se aplican los resultados que se aceptarían con algunas EPA se podrían producir decisiones clínicas erróneas.
Conclusiónes
En España, solo 2 de las 18 magnitudes biológicas estudiadas se pueden considerar bien estandarizadas. Sería necesaria una colaboración más estrecha entre los laboratorios y proveedores de sistemas analíticos para resolver las discrepancias.
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