Application of biological variation - a review

Ovaj rad sadrži opsežan pregled sastavnica biološke varijacije (BV), tj. intraindividualne (nasumična fluktuacija analita oko osnovne vrijednosti svakog pojedinca) i interindividualne (ukupna varijacija od osnovnih vrijednosti različitih osoba) varijacije, zatim ukratko objašnjava procjenu veličine intraindividualne i interindividualne BV u zdravih i oboljelih ispitanika, podrobno obrađuje osam složenijih primjena procjena BV, te govori o zanimljivim detaljima koji izazivaju najviše rasprava. Cilj rada je raspraviti kako pomoću današnje tehnologije doći do specifikacija kvalitete dobivenih na temelju BV u zdravih pojedinaca te u kojim se slučajevima koristiti podacima od oboljelih ispitanika. Konačno, u radu se promiče daljnji razvoj primjene BV, poput upozoravanja liječnika o promjenama u bolesnikovu stanju.This paper introduces an extensive revision of the types of components of biological variation (BV), i.e. intraindividual (random fluctuation of analytes around the setting point of each individual) and interindividual (overall variation from the different person\u27s setting point), briefly explains estimation of the magnitude of within- and between subject BV in healthy and non-healthy subjects, details the eight common applications of BV estimates and discusses the most debated points of interests. The aim is to discuss how quality specifications derived from BV determined in healthy individuals are attainable with current technology and in what cases data from non-healthy subjects should be used. Finally, the paper promotes further development of BV application, such as notifying doctors about changes in patient status

Application of biological variation - a review

Ovaj rad sadrži opsežan pregled sastavnica biološke varijacije (BV), tj. intraindividualne (nasumična fluktuacija analita oko osnovne vrijednosti svakog pojedinca) i interindividualne (ukupna varijacija od osnovnih vrijednosti različitih osoba) varijacije, zatim ukratko objašnjava procjenu veličine intraindividualne i interindividualne BV u zdravih i oboljelih ispitanika, podrobno obrađuje osam složenijih primjena procjena BV, te govori o zanimljivim detaljima koji izazivaju najviše rasprava. Cilj rada je raspraviti kako pomoću današnje tehnologije doći do specifikacija kvalitete dobivenih na temelju BV u zdravih pojedinaca te u kojim se slučajevima koristiti podacima od oboljelih ispitanika. Konačno, u radu se promiče daljnji razvoj primjene BV, poput upozoravanja liječnika o promjenama u bolesnikovu stanju.This paper introduces an extensive revision of the types of components of biological variation (BV), i.e. intraindividual (random fluctuation of analytes around the setting point of each individual) and interindividual (overall variation from the different person\u27s setting point), briefly explains estimation of the magnitude of within- and between subject BV in healthy and non-healthy subjects, details the eight common applications of BV estimates and discusses the most debated points of interests. The aim is to discuss how quality specifications derived from BV determined in healthy individuals are attainable with current technology and in what cases data from non-healthy subjects should be used. Finally, the paper promotes further development of BV application, such as notifying doctors about changes in patient status

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

Introduction: Standardization 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 methods: According 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\u27 evaluation were derived from biological variation for bias and from the inter-laboratory coefficients of variation found in a previous pilot study. Results: Only 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. Conclusions: The 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

External quality control in laboratory medicine. Progresses and future

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

Control externo de la calidad en medicina del laboratorio. Avances y futuro

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

Internal quality control – past, present and future trends

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

Modelos para estimar la variación biológica y la interpretación de resultados seriados: bondades y limitaciones

La variación biológica (VB) tiene múltiples aplicaciones en diversos campos del laboratorio clínico. Hay dos formas de relacionar el concepto de VB y los modelos estadísticos. Por un lado existen modelos para el cálculo de estimados de VB (intra e inter individual) y por otro, existen modelos que tienen en cuenta la VB y otros factores para la definición de rangos que ayudan a la interpretación de resultados seriados en un mismo individuo. Dentro de los modelos estadísticos dirigidos al cálculo de los estimados de VB existen dos tipos: A. Métodos directos. Estudios prospectivos, diseñados exclusivamente para el cálculo de estimados de VB: i. Modelo clásico: desarrollado por Harris y Fraser, revisado por EFLM-BVWG. ii. Modelos de efectos mixtos iii. Modelo bayesiano. B. Métodos indirectos. Estudios retrospectivos basados en extraer estimados de VB a partir de resultados que provienen de grandes bases de datos. Big-data. Ambos tipos presentan una serie de características que es importante conocer porque pueden condicionar su aplicabilidad en diferentes situaciones o poblaciones. Entre los modelos para definir rangos que ayudan a la interpretación de resultados seriados en un individuo encontramos: A. Valor de referencia del cambio (VRC). B. Red de datos bayesiana. En resumen, esta revisión pretende dar un enfoque general sobre los modelos para definir los componentes de VB así como otros para aplicarlos en el seguimiento de pacientes, que deberían ser explorados en el futuro para personalizar y mejorar la información aportada por el laboratorio clínico, aprovechando al máximo los recursos disponibles

Control interno de la calidad – bases del pasado, situación presente y futuras tendencias

Este artículo ofrece una síntesis de los modelos de control interno de la calidad analítica usados, desde mediados del siglo XX hasta los que están en vigor actualmente y pretende dar una proyección de cómo debería ser el futuro en esta materia concreta

Models to estimate biological variation components and interpretation of serial results: strengths and limitations

Biological variation (BV) has multiple applications in a variety of fields of clinical laboratory. The use of BV in statistical modeling is twofold. On the one hand, some models are used for the generation of BV estimates (within- and between-subject variability). Other models are built based on BV in combination with other factors to establish ranges of normality that will help the clinician interpret serial results for the same subject. There are two types of statistical models for the calculation of BV estimates: A. Direct methods, prospective studies designed to calculate BV estimates; i. Classic model: developed by Harris and Fraser, revised by the Working Group on Biological Variation of the European Federation of Laboratory Medicine. ii. Mixed-effect models. iii. Bayesian model. B. Indirect methods, retrospective studies to derive BV estimates from large databases of results. Big data. Understanding the characteristics of these models is crucial as they determine their applicability in different settings and populations. Models for defining ranges that help in the interpretation of individual serial results include: A. Reference change value and B. Bayesian data network. In summary, this review provides an overview of the models used to define BV components and others for the follow-up of patients. These models should be exploited in the future to personalize and improve the information provided by the clinical laboratory and get the best of the resources available