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Resumen Objetivos La diabetes mellitus incrementa los riesgos y complicaciones asociadas a la COVID-19. Una de las principales consecuencias de la pandemia ha sido la drástica reducción de las consultas presenciales. El objetivo de este estudio es evaluar el impacto que ha tenido la pandemia de COVID-19 en la gestión de la determinación de HbA1c y sus resultados en pacientes ambulatorios adultos y pediátricos con diabetes, teniendo en cuenta tanto la medición realizada en el laboratorio como las pruebas de laboratorio en el lugar de asistencia o point-of-care testing (POCT). Métodos Se realizó un estudio observacional retrospectivo que incluyó pacientes de las Unidades de Diabetes Pediátrica y de Adultos. A través del sistema de información del laboratorio, se extrajeron los resultados de HbA1c obtenidos en el laboratorio y los resultados de POCT en un periodo de tres años (2019–2021). Resultados El número de mediciones de HbA1c se redujo considerablemente tras el confinamiento. En poco tiempo, los pacientes pediátricos volvieron a recibir su asistencia médica habitual. El número de mediciones de HbA1c fue aumentando paulatinamente en los adultos, especialmente POCT. En general, los valores de HbA1c fueron inferiores en los pacientes pediátricos que en los adultos (p1c en niños (p1c. El porcentaje de resultados de HbA1c superiores al 8% se mantuvo estable durante el periodo de estudio. Conclusiones Los sistemas de monitorización continua de la glucosa y la telemedicina fueron cruciales, habiéndose producido incluso una mejoría respecto a los niveles de HbA1c. Durante el confinamiento, a los pacientes con mejor control metabólico, las pruebas analíticas se les realizaron en el laboratorio, mientras que a los pacientes con peor control o una situación clínica grave se les realizaron mediante POCT en las Unidades de Diabetes. En los pacientes adultos, el retorno a la asistencia habitual previa a la pandemia se produjo de forma lenta y gradual, ya que presentaban mayor riesgo de morbimortalidad asociado a la COVID-19. La coordinación entre todos los profesionales sanitarios fue esencial a la hora de garantizar la mejor atención posible, especialmente en escenarios complejos, como la pandemia de COVID-19.

Background Hematological parameters have many applications in athletes, from monitoring health to uncovering blood doping. This study aimed to deliver biological variation (BV) estimates for 9 hematological parameters by a Biological Variation Data Critical Appraisal Checklist (BIVAC) design in a population of recreational endurance athletes and to assess the effect of self-reported exercise and health-related variables on BV. Methods Samples were drawn from 30 triathletes monthly for 11 months and measured in duplicate for hematological measurands on an Advia 2120 analyzer (Siemens Healthineers). After outlier and homogeneity analysis, within-subject (CVI) and between-subject (CVG) BV estimates were delivered (CV-ANOVA and log-ANOVA, respectively) and a linear mixed model was applied to analyze the effect of exercise and other related variables on the BV estimates. Results CVI estimates ranged from 1.3% (95%CI, 1.2-1.4) for mean corpuscular volume to 23.8% (95%CI, 21.6-26.3) for reticulocytes. Sex differences were observed for platelets and OFF-score. The CVI estimates were higher than those reported for the general population based on meta-analysis of eligible studies in the European Biological Variation Database, but 95%CI overlapped, except for reticulocytes, 23.9% (95%CI, 21.6-26.5) and 9.7% (95%CI, 6.4-11.0), respectively. Factors related to exercise and athletes’ state of health did not appear to influence the BV estimates. Conclusions This is the first BIVAC-compliant study delivering BV estimates that can be applied to athlete populations performing high-level aerobic exercise. CVI estimates of most parameters were similar to the general population and were not influenced by exercise or athletes’ state of health.

Among medical specialties, laboratory medicine is the largest producer of structured data and must play a crucial role for the efficient and safe implementation of big data and artificial intelligence in healthcare. The area of personalized therapies and precision medicine has now arrived, with huge data sets not only used for experimental and research approaches, but also in the “real world”. Analysis of real world data requires development of legal, procedural and technical infrastructure. The integration of all clinical data sets for any given patient is important and necessary in order to develop a patient-centered treatment approach. Data-driven research comes with its own challenges and solutions. The Findability, Accessibility, Interoperability, and Reusability (FAIR) Guiding Principles provide guidelines to make data findable, accessible, interoperable and reusable to the research community. Federated learning, standards and ontologies are useful to improve robustness of artificial intelligence algorithms working on big data and to increase trust in these algorithms. When dealing with big data, the univariate statistical approach changes to multivariate statistical methods significantly shifting the potential of big data. Combining multiple omics gives previously unsuspected information and provides understanding of scientific questions, an approach which is also called the systems biology approach. Big data and artificial intelligence also offer opportunities for laboratories and the In Vitro Diagnostic industry to optimize the productivity of the laboratory, the quality of laboratory results and ultimately patient outcomes, through tools such as predictive maintenance and “moving average” based on the aggregate of patient results.

Resumen Objetivos 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. Métodos El material usado es la recopilación bibliográfica de los distintos modelos de CIC publicados. El método de estudio ha sido el análisis crítico de dichos modelos, debatiendo los pros y contras de cada uno. Resultados Los primeros modelos se basaron en el análisis de materiales control y se fijaron como límites de aceptabilidad múltiplos de la desviación estándar del procedimiento analítico. Más adelante se sustituyeron estos límites por valores relacionados con el uso clínico de los exámenes del laboratorio, principalmente los derivados de la variación biológica. Para las pruebas sin material control estable se desarrollaron métodos basados en análisis replicados de especímenes de pacientes, que se han perfeccionado recientemente, así como la métrica sigma, que relaciona la calidad deseada con la prestación analítica para diseñar un protocolo de alta eficacia. La tendencia actual es matizar el control interno teniendo en cuenta la carga de trabajo y el impacto de un fallo analítico en la información sobre el paciente. Conclusiones Se indican los puntos fuertes resaltados a la luz de esta revisión, los puntos débiles que todavía se emplean y deberían eliminarse, así como se da una proyección de futuro encaminada a promover la seguridad de los exámenes del laboratorio.

Objectives 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. Methods 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. Results 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. Conclusions 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.

Objectives Trace elements (TrEL) are nutritionally essential components in maintaining health and preventing diseases. There is a lack of reliable biological variation (BV) data for TrELs, required for the diagnosis and monitoring of TrEL disturbances. In this study, we aimed to provide updated within- and between-subject BV estimates for zinc (Zn), copper (Cu) and selenium (Se). Methods Weekly serum samples were drawn from 68 healthy subjects (36 females and 32 males) for 10 weeks and stored at −80 °C prior to analysis. Serum Zn, Cu and Se levels were measured using inductively-coupled plasma mass spectrometry (ICP-MS). Outlier and variance homogeneity analyses were performed followed by CV-ANOVA (Røraas method) to determine BV and analytical variation estimates with 95% CI and the associated reference change values (RCV) for all subjects, males and females. Results Significant differences in mean concentrations between males and females were observed, with absolute and relative (%) differences for Zn at 0.5 μmol/L (3.5%), Cu 2.0 μmol/L (14.1%) and Se 0.06 μmol/L (6.0%). The within-subject BV (CVI [95% CI]) estimates were 8.8% (8.2–9.3), 7.8% (7.3–8.3) and 7.7% (7.2–8.2) for Zn, Cu and Se, respectively. Within-subject biological variation (CVI) estimates derived for male and female subgroups were similar for all three TrELs. Marked individuality was observed for Cu and Se. Conclusions The data of this study provides updated BV estimates for serum Zn, Cu and Se derived from a stringent protocol and state of the art methodologies. Furthermore, Cu and Se display marked individuality, highlighting that population based reference limits should not be used in the monitoring of patients.

AimsHyponatraemia is the most common body fluid disorders but often goes unnoticed. Our laboratory incorporated a standardised procedure to help clinicians detect moderate/severe hyponatraemia. The study aims were to evaluate the outcomes on patient care and clinicians’ satisfaction.MethodsThe study, observational and retrospective, included 1839 cases, adult and paediatric patients, with sodium concentration ResultsThe median hyponatraemia length decreased significantly from 4.95 hours (2.08–16.57) in the first period to 2.17 hours (1.06–5.39) in the second period. The lack of hyponatraemia patients follow-up was significantly less after the procedure implementation. The survey was answered by 92 (60 senior specialists and 32 residents) out of 110 clinicians surveyed. Ninety of them (98%) answered positively.ConclusionsWe have demonstrated the reduction in the time for diagnosing and management by physicians, the higher uniformity in the time required to solve hyponatraemia episodes following our laboratory procedure and the clinicians’ satisfaction.

Objectives The contribution of the clinical laboratory to diagnostics is increasingly important since a great deal of clinical decisions rely on laboratory test results. Content Parathyroid hormone (PTH) measurement presents a considerable analytical variability due to the heterogeneity of its circulating forms and the antigenic configuration of the different assays commercially available. Such variability may have an impact on pathological conditions associated with significant increases in circulating PTH, as it is the case of chronic kidney disease (CKD). Summary Despite the recent identification of new molecules involved in bone and mineral disorders associated with CKD, such as klotho or the fibroblastic factor 23 (FGF23), nephrologists still base their clinical decisions on PTH concentrations. The problem is that unawareness of these analytical considerations may cause errors in the clinical interpretation of test results. Outlook This systematic review addresses these issues from the clinical laboratory perspective and proposes new approaches related to PTH method selection and result expression. These new strategies will help laboratory medicine specialists and nephrologist better determine the status of CKD patients.

Resumen Introducción La aportación del Laboratorio Clínico en el ámbito diagnóstico es cada día mas importante porque gran parte de las decisiones clínicas que se adoptan se basan en nuestros resultados. Contenido La cuantificación en sangre de hormona paratiroidea (PTH) presenta una importante variabilidad analítica debido a la heterogeneidad de sus formas circulantes y a la configuración antigénica de los diferentes métodos disponibles. Esta circunstancia puede tener impacto en aquellas situaciones patológicas que cursan con valores circulantes de PTH excesivamente elevados, como sucede en la enfermedad renal crónica (ERC). Resumen A pesar de la identificación de otras moléculas involucradas en las alteraciones óseas y minerales asociadas a la ERC, como el klotho o el factor fibroblástico 23, los nefrólogos siguen basando sus decisiones terapéuticas en la PTH; el problema es que, el desconocimiento de estos aspectos analíticos en su cuantificación, puede inducir a errores en la interpretación clínica de sus resultados. Perspectiva Esta revisión aborda estas consideraciones desde el Laboratorio Clínico y plantea posibles estrategias futuras, que afectan tanto a la elección del método como a la expresión de los resultados de PTH, con la finalidad de acercarnos más a la realidad del paciente renal, en colaboración con el nefrólogo.

Background Many studies have assessed the biological variation (BV) of cardiac-specific troponins (cTn), reporting widely varying within-subject BV (CVI) estimates. The aim of this study was to provide meta-analysis-derived BV estimates for troponin I (cTnI) and troponin T (cTnT) for different sampling intervals and states of health. Methods Relevant studies were identified by a systematic literature search. Studies were classified according to their methodological quality by the Biological Variation Data Critical Appraisal Checklist (BIVAC). Meta-analyses of BIVAC-compliant studies were performed after stratification by cTn isoform, exclusion of results below the limit of detection, states of health, and sampling interval to deliver reference change values (RCV), index of individuality (II) and analytical performance specifications (APS) for these settings. Results Sixteen and 15 studies were identified for cTnI and cTnT, respectively, out of which 6 received a BIVAC grade A. Five studies had applied contemporary cTnI assays, but none contemporary cTnT. High-sensitivity (hs-) cTnI and cTnT delivered similar estimates in all settings. Long-term CVI estimates (15.1; 11.3%) derived from healthy individuals were higher than short-term (4.3%; 5.3%) for hs-cTnI and hs-cTnT, respectively, although confidence intervals overlapped. Estimates derived from diseased subjects were similar to estimates in healthy individuals for all settings. Conclusions This study provides robust estimates for hs-cTnI and hs-cTnT applicable for different clinical settings and states of health, allowing for the use of RCV both to aid in the diagnosis of myocardial injury and for prognosis. BV-based APS appear too strict for some currently available technologies.

Objectives Kidney markers are some of the most frequently used laboratory tests in patient care, and correct clinical decision making depends upon knowledge and correct application of biological variation (BV) data. The aim of this study was to review available BV data and to provide updated BV estimates for the following kidney markers in serum and plasma; albumin, creatinine, cystatin C, chloride, potassium, sodium and urea. Content Relevant studies were identified from a historical BV database as well as by systematic literature searches. Retrieved publications were appraised by the Biological Variation Data Critical Appraisal Checklist (BIVAC). Meta-analyses of BIVAC compliant studies with similar design were performed to deliver global estimates of within-subject (CVI) and between-subject (CVG) BV estimates. Out of the 61 identified papers, three received a BIVAC grade A, four grade B, 48 grade C, five grade D grade and one was not appraised as it did not report numerical BV estimates. Most studies were identified for creatinine (n=48). BV estimates derived from the meta-analysis were in general lower than previously reported estimates for all analytes except urea. For some measurands, BV estimates may be influenced by age or states of health, but further data are required. Summary This review provides updated global BV estimates for kidney related measurands. For all measurands except for urea, these estimates were lower than previously reported. Outlook For the measurands analyzed in this review, there are sufficient well-designed studies available to publish a trustworthy estimate of BV. However, for a number of newly appearing kidney markers no suitable data is available and additional studies are required.

Resumen 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.

Objetivos El objetivo de este estudio es conocer la evolución de la prestación analítica de los laboratorios participantes en los programas EQA de la SEQCML durante los 30 años de funcionamiento y compararla con la prestación obtenida en otros programas EQA para saber si los resultados son similares. Métodos Se evalúan los resultados obtenidos durante este periodo, aplicando las especificaciones de la calidad derivadas de la VB y del estado del arte. Además, se realiza una comparación con los resultados obtenidos por otras organizaciones de programas EQA. Resultados Se observa que los laboratorios participantes en los programas EQA-SEQCML han mejorado su prestación durante los 30 años de experiencia y que las especificaciones derivadas de la variación biológica son alcanzables. La comparación entre programas EQA es difícil, debido a: la falta de accesibilidad y a las diferencias en el diseño de estos programas (materiales control, cálculos empleados y especificaciones analíticas establecidas). Conclusiones Los datos de este estudio ponen de manifiesto que para algunas magnitudes biológicas los resultados obtenidos en los programas todavía no están armonizados, aunque se estan realizando esfuerzos para alcanzar la armonización. Los organizadores de programas EQA deberían sumarse al esfuerzo de armonización, facilitando la información sobre sus resultados para permitir su comparación.

Objectives Numerous biological variation (BV) studies have been performed over the years, but the quality of these studies vary. The objectives of this study were to perform a systematic review and critical appraisal of BV studies on glycosylated albumin and to deliver updated BV estimates for glucose and HbA1c, including recently published high-quality studies such as the European Biological Variation study (EuBIVAS). Methods Systematic literature searches were performed to identify BV studies. Nine publications not included in a previous review were identified; four for glycosylated albumin, three for glucose, and three for HbA1c. Relevant studies were appraised by the Biological Variation Data Critical Appraisal Checklist (BIVAC). Global BV estimates were derived by meta-analysis of BIVAC-compliant studies in healthy subjects with similar study design. Results One study received BIVAC grade A, 2B, and 6C. In most cases, the C-grade was associated with deficiencies in statistical analysis. BV estimates for glycosylated albumin were: CVI=1.4% (1.2–2.1) and CVG=5.7% (4.7–10.6), whereas estimates for HbA1c, CVI=1.2% (0.3–2.5), CVG=5.4% (3.3–7.3), and glucose, CVI=5.0% (4.1–12.0), CVG=8.1% (2.7–10.8) did not differ from previously published global estimates. Conclusions The critical appraisal and rating of BV studies according to their methodological quality, followed by a meta-analysis, generate robust, and reliable BV estimates. This study delivers updated and evidence-based BV estimates for glycosylated albumin, glucose and HbA1c.

Biological variation (BV) data have many applications in laboratory medicine. However, these depend on the availability of relevant and robust BV data fit for purpose. BV data can be obtained through different study designs, both by experimental studies and studies utilizing previously analysed routine results derived from laboratory databases. The different BV applications include using BV data for setting analytical performance specifications, to calculate reference change values, to define the index of individuality and to establish personalized reference intervals. In this review, major achievements in the area of BV from last decade will be presented and discussed. These range from new models and approaches to derive BV data, the delivery of high-quality BV data by the highly powered European Biological Variation Study (EuBIVAS), the Biological Variation Data Critical Appraisal Checklist (BIVAC) and other standards for deriving and reporting BV data, the EFLM Biological Variation Database and new applications of BV data including personalized reference intervals and measurement uncertainty.

Objectives Thyroid biomarkers are fundamental for the diagnosis of thyroid disorders and for the monitoring and treatment of patients with these diseases. The knowledge of biological variation (BV) is important to define analytical performance specifications (APS) and reference change values (RCV). The aim of this study was to deliver BV estimates for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), thyroglobulin (TG), and calcitonin (CT). Methods Analyses were performed on serum samples obtained from the European Biological Variation Study population (91 healthy individuals from six European laboratories; 21–69 years) on the Roche Cobas e801 at the San Raffaele Hospital (Milan, Italy). All samples from each individual were evaluated in duplicate within a single run. The BV estimates with 95% CIs were obtained by CV-ANOVA, after analysis of variance homogeneity and outliers. Results The within-subject (CV I ) BV estimates were for TSH 17.7%, FT3 5.0%, FT4 4.8%, TG 10.3, and CT 13.0%, all significantly lower than those reported in the literature. No significant differences were observed for BV estimates between men and women. Conclusions The availability of updated, in the case of CT not previously published, BV estimates for thyroid markers based on the large scale EuBIVAS study allows for refined APS and associated RCV applicable in the diagnosis and management of thyroid and related diseases.

Objectives Within- and between-subject biological variation (BV) estimates have many applications in laboratory medicine. However, robust high-quality BV estimates are lacking for many populations, such as athletes. This study aimed to deliver BV estimates of 29 routine laboratory measurands derived from a Biological Variation Data Critical Appraisal Checklist compliant design in a population of high-endurance athletes. Methods Eleven samples per subject were drawn from 30 triathletes monthly, during a whole sport season. Serum samples were measured in duplicate for proteins, liver enzymes, lipids and kidney-related measurands on an Advia2400 (Siemens Healthineers). After outlier and homogeneity analysis, within-subject (CVI) and between-subject (CVG) biological variation estimates were delivered (CV-ANOVA and log-ANOVA, respectively) and a linear mixed model was applied to analyze the effect of exercise and health related variables. Results Most CVI estimates were similar or only slightly higher in athletes compared to those reported for the general population, whereas two- to three-fold increases were observed for amylase, ALT, AST and ALP. No effect of exercise and health related variables were observed on the CVI estimates. For seven measurands, data were not homogeneously distributed and BV estimates were therefore not reported. Conclusions The observation of higher CVI estimates in athletes than what has been reported for the general population may be related to physiological stress over time caused by the continuous practice of exercise. The BV estimates derived from this study could be applied to athlete populations from disciplines in which they exercise under similar conditions of intensity and duration.

Background Analysis of acid-base status (ABS) is requested in a wide range of clinical scenarios, including in the assessment of athletes’ performance and follow up, but there is a lack of high-quality biological variation (BV) data. The aims of this study were to estimate the BV of ABS related parameters in athletes and to evaluate if variables related to exercise may influence the estimates. Material and methods Eleven samples from 30 triathletes were drawn, on a monthly basis. The samples were measured for pH, pCO2, bicarbonate, base excess, TCO2, Ca2+ and lactate. A CV-ANOVA was performed to calculate within-subject (CVI) estimates and a linear mixed model was applied to analyze the effect of the folowing variables on the BV; health status, sampling interval, intensity and duration of the exercise. Results For all ABS parameters except for lactate, higher CVI estimates were found in athletes than what have been reported for the general population. No significant effect of the exercise and sampling related variables were observed, except for Ca2+. Conclusion This difference founds in ABS parameters between athletes and the general population could be explained by the physiological stress during exercise. Laboratories attending this population could use these BV estimates to establish quality goals.

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.

Biological variation (BV) data have many important applications in laboratory medicine. Concerns about quality of published BV data led the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) 1st Strategic Conference to indicate need for new studies to generate BV estimates of required quality. In response, the EFLM Working Group on BV delivered the multicenter European Biological Variation Study (EuBIVAS). This review summarises the EuBIVAS and its outcomes. Serum/plasma samples were taken from 91 ostensibly healthy individuals for 10 consecutive weeks at 6 European centres. Analysis was performed by Siemens ADVIA 2400 (clinical chemistry), Cobas Roche 8000, c702 and e801 (proteins and tumor markers/hormones respectively), ACL Top 750 (coagulation parameters), and IDS iSYS or DiaSorin Liaison (bone biomarkers). A strict preanalytical and analytical protocol was applied. To determine BV estimates with 95% CI, CV-ANOVA after analysis of outliers, homogeneity and trend analysis or a Bayesian model was applied. EuBIVAS has so far delivered BV estimates for 80 different measurands. Estimates for 10 measurands (non-HDL cholesterol, S100-β protein, neuron-specific enolase, soluble transferrin receptor, intact fibroblast growth-factor-23, uncarboxylated-unphosphorylated matrix-Gla protein, human epididymis protein-4, free, conjugated and %free prostate-specific antigen), prior to EuBIVAS, have not been available. BV data for creatinine and troponin I were obtained using two analytical methods in each case. The EuBIVAS has delivered high-quality BV data for a wide range of measurands. The BV estimates are for many measurands lower than those previously reported, having an impact on the derived analytical performance specifications and reference change values.

COVID-19@Spain and COVID@HULP Study., [Objective] To develop and validate a prediction model of mortality in patients with COVID-19 attending hospital emergency rooms., [Design] Multivariable prognostic prediction model., [Setting] 127 Spanish hospitals., [Participants] Derivation (DC) and external validation (VC) cohorts were obtained from multicentre and single-centre databases, including 4035 and 2126 patients with confirmed COVID-19, respectively., [Interventions] Prognostic variables were identified using multivariable logistic regression., [Main outcome measures] 30-day mortality., [Results] Patients’ characteristics in the DC and VC were median age 70 and 61 years, male sex 61.0% and 47.9%, median time from onset of symptoms to admission 5 and 8 days, and 30-day mortality 26.6% and 15.5%, respectively. Age, low age-adjusted saturation of oxygen, neutrophil-to-lymphocyte ratio, estimated glomerular filtration rate by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, dyspnoea and sex were the strongest predictors of mortality. Calibration and discrimination were satisfactory with an area under the receiver operating characteristic curve with a 95% CI for prediction of 30-day mortality of 0.822 (0.806–0.837) in the DC and 0.845 (0.819–0.870) in the VC. A simplified score system ranging from 0 to 30 to predict 30-day mortality was also developed. The risk was considered to be low with 0–2 points (0%–2.1%), moderate with 3–5 (4.7%–6.3%), high with 6–8 (10.6%–19.5%) and very high with 9–30 (27.7%–100%)., [Conclusions] A simple prediction score, based on readily available clinical and laboratory data, provides a useful tool to predict 30-day mortality probability with a high degree of accuracy among hospitalised patients with COVID-19., This work was supported by Fundación SEIMC/GeSIDA. The funders had no role in study design, data collection, data interpretation or writing of the manuscript. JB, JRB, IJ, JC, JP and JRA received funding for research from Plan Nacional de I+D+i 2013‐2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, cofinanced by the European Development Regional Fund “A way to achieve Europe”, Operative program Intelligent Growth 2014‐2020. Spanish AIDS Research Network (RIS) (RD16/0025/0017 (JB), RD16/0025/0018 (JRA), RD16CIII/0002/0006 (IJ)). Spanish Network for Research in Infectious Diseases (REIPI) (RD16/0016/0001 (JRB), RD16/0016/0005 (JC) and RD16/0016/0009 (JP)).

Objective We aimed to evaluate the results of key performance indicators (KPIs) for a period of over three years, as well as their effectiveness as an improvement tool, to provide information about Point-of-Care Testing (POCT) management system performance and quality assurance. Design and methods KPIs regarding the global POCT process, extra-analytical phase, quality assurance and staff training and competency were evaluated for blood gases, HbA1c, sweat test and non-connected and connected glucose in an ISO 22870 accredited network. We established the definition of every KPI and its corresponding target. The results of KPIs from all clinical settings were appraised every month during the study period, taking corrective actions when necessary. Results Annual global results were generally acceptable. However, some clinical areas displayed deviations in specific months. The monitoring of these KPIs allowed us to detect the deviations immediately and identify their causes. These included errors in patient identification, consumables, strips, reagents, analyzers, calibration, internal and external quality control, sample management, connectivity, and operator identification strategy, among others. Conclusions The evaluation of these KPIs over time has shown their appropriateness. This set of quality indicators could be a useful tool for laboratory medicine leading POCT networks for better and safer patient care.

Resumen Objetivos A lo largo de los años se han publicado numerosos artículos sobre variación biológica (VB) de diferente calidad. Los objetivos de este trabajo fueron realizar una revisión sistemática y una evaluación crítica de los estudios de VB para albúmina glicosilada y proporcionar datos actualizados de VB para glucosa y HbA1c, incluyendo prestigiosos estudios recientemente publicados como el Estudio de Variación Biológica Europea (EuBIVAS). Métodos Se hizo una búsqueda bibliográfica sistemática para identificar estudios sobre VB, encontrándose 9 estudios no incluidos en la primera revisión: 4 para albúmina glicosilada, 3 para glucosa y 3 para HbA1c. Se realizó una evaluación crítica de los estudios relevantes, utilizando la herramienta Biological Variation Data Critical Appraisal Checklist (BIVAC). Se obtuvieron los estimados globales de VB mediante meta-análisis de los estudios que cumplían los requisitos BIVAC, realizados en individuos sanos con estudios de diseño similar. Resultados Un estudio recibió el grado A, dos el B y 6 el C. en la mayoría de los casos el grado C se asoció a deficiencias en el análisis estadístico de los datos. Los estimados de VB para albúmina glicosilada fueron: CVI = 1,4%(1,2–2,1) y CVG = 5,7%(4,7–10,6); para HbA1c, CVI = 1,2%(0,3–2,5), CVG = 5,4%(3,3–7,3) y para glucosa, CVI = 5,0%(4,1–12,0), CVG = 8,1%(2,7–10,8) no difirieron de los estimados globales previamente descritos. Conclusiones La evaluación crítica y clasificación de los estudios de VB a tenor de su calidad metodológica, seguido de un meta-análisis, genera estimados de VB robustos y fiables. Este estudio proporciona datos de VB para albúmina glicolisada, glucosa y HbA1c actualizados y basados en la evidencia científica.

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.

Twenty years have passed since the identification of klotho and the fibroblast growth factor 23 (FGF23), the regulatory binomial of phosphate homeostasis. Being kidney the main source of klotho as well as a target organ in the phosphate regulation, most studies involving klotho and FGF23 had a “nephrocentric” focus. Considering that circulating FGF23 can reach exaggerated levels at the end stage of chronic kidney disease (CKD), the bias of this approach allowed to recognize the harmful “off target” klotho-independent effect of FGF23. All of these findings have caused a revolution on our previous knowledge about mineral homeostasis and currently, we are facing a new scenario in the clinical management of CKD, where FGF23 emerges simultaneously as an early biomarker of phosphate retention but also as a therapeutic target. In this review, we describe the disturbances of FGF23 in the CKD and we focus on how the maintenance of circulating FGF23 into a supraphysiological adaptive range from the initial stages of CKD and the control of “unlimited hyperphosphatonism” generated by the resistance to FGF23 action at end stages should emerge as new treatment paradigms in CKD-MBD. The recent development of an automated FGF23 assay, already validated for clinical use, should be the starting point to individualize all our knowledge from epidemiological studies and will allow us to use it properly for the patient’s personalized care. Then, now we are in the momentum to assess the discriminating thresholds to distinguish the physiological adaptive FGF23 elevation related to each CKD stage from the exaggerated increase that would be interpreted as a poor regulatory compensation that will requires the adoption of therapeutic intervention. Resumen: Ya han transcurrido veinte años desde la identificación del klotho y del Factor de crecimiento fibroblástico 23 (FGF23), el binomio regulador de la homeostasis del fosfato. Al ser el riñón la principal fuente de klotho y el órgano diana regulador del fosfato, la mayoría de estudios sobre klotho y FGF23 tuvieron una vertiente “nefrocéntrica”. Gracias al sesgo de este enfoque, los exagerados niveles circulantes de FGF23 observados en la enfermedad renal crónica (ERC) permitieron reconocer el efecto nocivo “off target” independiente de klotho que ejerce el FGF23. Todo esto ha revolucionado nuestra visión previa sobre la homeostasis mineral y a día de hoy, nos encontramos ante un nuevo escenario en el abordaje clínico del paciente renal, en el que el FGFG23 emerge como marcador precoz de retención de fosfato y simultáneamente como diana terapéutica. En esta revisión se abordan las alteraciones del FGF23 en la ERC y se plantea cómo el mantenimiento del FGF23 circulante en rango adaptativo suprafisiológico desde los estadios iniciales de ERC y el control del “hiperfosfatonismo ilimitado”, generado por la resistencia a la acción del FGFG23 en los estadios avanzados, deberían emerger como nuevos paradigmas de tratamiento en la CKD-MBD. El reciente desarrollo de un método automatizado para cuantificar FGF23, validado para uso clínico, marca el punto de partida para individualizar todo lo que sabemos por los estudios epidemiológicos y utilizarlo adecuadamente desde la cabecera del paciente. Ahora nos toca establecer los límites que discriminen el incremento adaptativo fisiológico de FGF23, para cada estadio de ERC, frente al aumento exagerado reflejo de una maladaptacion y que requiera la adopción de medidas terapéuticas.

The purpose of this study is to understand the evolution of the analytical performance of the laboratories participating in the Spanish society of laboratory medicine (SEQCML) external quality assurance (EQA) programmes during its 30 years of operation and to compare it with the performance of other EQA programmes to establish whether the results are similar. The results obtained during this period are evaluated by applying the biological variability (BV) and state of the art-derived quality specifications. In addition, the results are compared with those obtained by other EQA programme organisations. It is noted that the laboratories participating in the EQA–SEQCML programmes have improved their performance over 30 years of experience and that the specifications derived from biological variation are achievable. It is difficult to compare EQA programmes, due to lack of accessibility and the differences in the design of these programmes (control materials, calculations used and analytical specifications established). The data from this study show that for some biological magnitudes the results obtained by the programmes are not yet harmonised, although efforts are being made to achieve this. Organisers of EQA programmes should also join the harmonisation effort by providing information on their results to enable comparison.

Background Objective interpretation of laboratory test results used to diagnose and monitor diabetes mellitus in part requires the application of biological variation data (BVD). The quality of published BVD has been questioned. The aim of this study was to quality assess publications reporting BVD for diabetes-related analytes using the Biological Variation Data Critical Appraisal Checklist (BIVAC); to assess whether published BVD are fit for purpose and whether the study design and population attributes influence BVD estimates and to undertake a meta-analysis of the BVD from BIVAC-assessed publications. Methods Publications reporting data for glucose, HbA1c, adiponectin, C-peptide, fructosamine, insulin like growth factor 1 (IGF-1), insulin like growth factor binding protein 3 (IGFBP-3), insulin, lactate and pyruvate were identified using a systematic literature search. These publications were assessed using the BIVAC, receiving grades A, B, C or D, where A is of highest quality. A meta-analysis of the BVD from the assessed studies utilised weightings based upon BIVAC grades and the width of the data confidence intervals to generate global BVD estimates. Results BIVAC assessment of 47 publications delivered 1 A, 3 B, 39C and 4 D gradings. Publications relating to adiponectin, C-peptide, IGF-1, IGFBP-3, lactate and pyruvate were all assessed as grade C. Meta-analysis enabled global BV estimates for all analytes except pyruvate, lactate and fructosamine. Conclusions This study delivers updated and evidence-based BV estimates for diabetes-related analytes. There remains a need for delivery of new high-quality BV studies for several clinically important analytes.

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.

BACKGROUND The European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) European Biological Variation Study (EuBIVAS) has been established to deliver rigorously determined biological variation (BV) indices. EuBIVAS determined BV for serum creatinine using the enzymatic and alkaline picrate measurement methods. METHOD In total, 91 healthy individuals (38 males, 53 females; age range, 21–69 years) were bled for 10 consecutive weeks at 6 European laboratories. An equivalent protocol was followed at each center. Sera were stored at −80 °C before analysis. Analyses for each patient were performed in duplicate within a single run on an ADVIA 2400 system (San Raffaele Hospital, Milan). The data were subjected to outlier and homogeneity analysis before performing CV-ANOVA to determine BV and analytical variation (CVA) estimates with confidence intervals (CI). RESULTS The within-subject BV estimates [CVI (95% CI)] were similar for enzymatic [4.4% (4.2–4.7)] and alkaline picrate [4.7% (4.4–4.9)] methods and lower than the estimate presently available online (CVI = 5.9%). No significant male/female BV differences were found. Significant differences were observed in mean creatinine values between men and women and between Turkish individuals and those of other nationalities. Between-subject BV (CVG) estimates, stratified accordingly, produced CVG values similar to historical BV data. CVA was 1.1% for the enzymatic and 4.4% for alkaline picrate methods, indicating that alkaline picrate methods fail to fulfill analytical performance specifications for imprecision (CVAPS). CONCLUSIONS The serum creatinine CVI obtained by EuBIVAS specifies a more stringent CVAPS than previously identified. The alkaline picrate method failed to meet this CVAPS, raising questions regarding its future use.

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.

Background Interpretation of the complete blood count (CBC) parameters requires reliable biological variation (BV) data. The aims of this study were to appraise the quality of publications reporting BV data for CBC parameters by applying the BV Data Critical Appraisal Checklist (BIVAC) and to deliver global BV estimates based on BIVAC compliant studies. Methods Relevant publications were identified by a systematic literature search and evaluated for their compliance with the 14 BIVAC criteria, scored as A, B, C or D, indicating decreasing compliance. Global CVI and CVG estimates with 95% CI were delivered by a meta-analysis approach using data from BIVAC compliant papers (grades A–C). Results In total, 32 studies were identified; four received a BIVAC grade A, 2 B, 20 C and 6 D. Meta-analysis derived CVI and CVG estimates were generally lower or in line with those published in a historical BV database available online. Except for reticulocytes, CVI estimates of erythrocyte related parameters were below 3%, whereas platelet (except MPV and PDW) and leukocyte related parameters ranged from 5% to 15%. Conclusions A systematic review of CBC parameters has provided updated, global estimates of CVI and CVG that will be included in the newly published European Federation of Clinical Chemistry and Laboratory Medicine BV Database.

BACKGROUND: The European Biological Variation Study (EuBIVAS) was created by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group on Biological Variation to establish high-quality biological variation (BV) estimates for clinically important measurands. In this study, the aim was to deliver reliable BV estimates for the biointact parathyroid hormone (PTH 1-84). METHODS: Serum samples were obtained from a population of 91 healthy individuals (38 men, 43 pre-menopausal women, and 10 post-menopausal women; 21–69 years) from 5 European countries, with all samples stored at −80 °C prior to analysis. PTH 1-84 analysis was performed at the San Raffaele Hospital (Milan, Italy) on the Roche Cobas e801. All samples from each individual were analysed in duplicate within a single run. CV-ANOVA was applied, after analysis of variance homogeneity and outliers, to obtain BV estimates for PTH 1-84 with 95% CIs. RESULTS: The within-subject BV [CV(I) (95% CI)] estimates were significantly different between men and women [13.0% (12.1–14.2%) and 15.2% (14.3–16.3%), respectively], while the between-subject estimates [CV(G) (95% CI)] were similar (men: 26.8% (21.4–35.1%), pre-menopausal women: 27.8% (22.7–36.1%)], allowing for delivery of updated analytical performance specifications and reference change values. CONCLUSIONS: Updated BV estimates for serum PTH 1-84 based on the large-scale EuBIVAS may be beneficial for the diagnosis and management of parathyroid glands and bone turnover pathologies.

To fight the virus SARS-CoV-2 spread to Europe from China and to give support to the collapsed public health system, the Spanish Health Authorities developed a field hospital located in the facilities of Madrid exhibition centre (IFEMA) to admit and treat patients diagnosed with SARS-CoV-2 infectious disease (COVID-19). The Department of Laboratory Medicine of La Paz University Hospital in Madrid (LMD-HULP) was designated to provide laboratory services. Due to the emergency, the IFEMA field hospital had to be prepared for patient admission in less than 1 week and the laboratory professionals had to collaborate in a multidisciplinary group to assure that resources were available to start on time. The LMD-HULP participated together with the managers in the design of the tests portfolio and the integration of the healthcare information systems (IS) (hospital IS, laboratory IS and POCT management system). Laboratorians developed a strategy to quickly train clinicians and nurses on test requests, sample collection procedures and management/handling of the POCT blood gas analyser both by written materials and training videos. The IFEMA´s preanalytical unit managed 3782 requests, and more than 11,000 samples from March 27th to April 30th. Furthermore, 1151 samples were measured by blood gas analysers. In conclusion, laboratory professionals must be resilient and have to respond timely in emergencies as this pandemic. The lab’s personnel selection, design and monitoring indicators to maintain and further improve the quality and value of laboratory services is crucial to support medical decision making and provide better patient care.

Background With increased interest in lipoprotein(a) (Lp[a]) concentration as a target for risk reduction and growing clinical evidence of its impact on cardiovascular disease (CVD) risk, rigorous analytical performance specifications (APS) and accuracy targets for Lp(a) are required. We investigated the biological variation (BV) of Lp(a), and 2 other major biomarkers of CVD, apolipoprotein A-I (apoA-I) and apolipoprotein B-100 (apoB), in the European Biological Variation Study population. Method Serum samples were drawn from 91 healthy individuals for 10 consecutive weeks at 6 European laboratories and analyzed in duplicate on a Roche Cobas 8000 c702. Outlier, homogeneity, and trend analysis were performed, followed by CV-ANOVA to determine BV estimates and their 95% CIs. These estimates were used to calculate APS and reference change values. For Lp(a), BV estimates were determined on normalized concentration quintiles. Results Within-subject BV estimates were significantly different between sexes for Lp(a) and between women aged 50 years for apoA-I and apoB. Lp(a) APS was constant across concentration quintiles and, overall, lower than APS based on currently published data, whereas results were similar for apoA-I and apoB. Conclusion Using a fully Biological Variation Data Critical Appraisal Checklist (BIVAC)–compliant protocol, our study data confirm BV estimates of Lp(a) listed in the European Federation of Clinical Chemistry and Laboratory Medicine database and reinforce concerns expressed in recent articles regarding the suitability of older APS recommendations for Lp(a) measurements. Given the heterogeneity of Lp(a), more BIVAC-compliant studies on large numbers of individuals of different ethnic groups would be desirable.

BACKGROUND The European Biological Variation Study (EuBIVAS) was established to deliver rigorously determined data for biological variation (BV). Here, EuBIVAS-based BV estimates are provided for α1-acid glycoprotein, α1-antitrypsin, albumin, β2-microglobulin, ceruloplasmin, complement component 3, complement component 4, C-reactive protein (CRP), cystatin C, haptoglobin, IgA, IgG, IgM, soluble transferrin receptor (sTfR), and transferrin (Trf), together with their associated analytical performance specifications (APSs) and reference change values (RCVs). METHOD Serum samples from weekly blood samplings of 91 healthy study participants (38 males and 53 females, ages 21–69 years old) over 10 consecutive weeks in 6 European laboratories were stored at −80 °C before duplicate analysis on a Roche Cobas c702. Outlier and variance homogeneity analyses were performed followed by CV-ANOVA on trend-corrected data if relevant, to determine BV and analytical variation estimates with CI and the associated RCV. RESULTS For the acute phase proteins, several participants experienced mild inflammatory episodes during the study, requiring exclusion of 7% of the 25290 results. Within-subject BV (CVI) estimates for specific proteins obtained in our study were lower than those available in the online 2014 BV database, except for Trf, whereas between-subject BV (CVG) estimates were similar. CVI and CVG estimates for sTfR, which have not previously been published, were 6.0% and 19.1%, respectively. CONCLUSIONS In addition to new BV estimates for sTfR, this EuBIVAS substudy generated more demanding APS for frequently requested plasma specific proteins. APS for CRP should not be calculated from BV data except when CRP is used as a risk factor for cardiovascular disease.

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' 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.