Evaluación de los límites analíticos de desempeño del laboratorio del HIGA O. Alende de Mar del Plata / Evaluation of analytical limits of performance in the laboratory of HIGA O. Alende of Mar del Plata / Avaliação dos limites analíticos de desempeno do laboratório do HIGA O. Alende de Mar del Plata

Los límites analíticos de desempeño (LAD) forman parte del diseño del programa de control de calidad analítico. Los objetivos de este trabajo fueron determinar imprecisión (CV), error sistemático (ES) y error total (ET) de 14 analitos de Química Clínica en los sectores de planta y de guardia del laboratorio del HIGA O. Alende de Mar del Plata, evaluar su desempeño analítico según variabilidad biológica y comparar los datos obtenidos. Se realizó un estudio retrospectivo con el registro de controles de calidad y se utilizaron los LAD derivados de VB para obtener las especificaciones de calidad para CV, ES y ET. Respecto del CV, cumple con los criterios el 79% en el sector planta y el 64% en el de guardia. Y en cuanto al ET, cumple el 90% y el 75%, respectivamente. En conclusión, aunque la mayoría de los analitos evaluados cumplen al menos con los criterios mínimos establecidos, los resultados ponen de manifiesto la necesidad de mejorar el desempeño analítico. Detectar los tipos de errores presentes en el proceso de laboratorio es el primer paso para instaurar controles de procedimiento y análisis, soluciones que permitirán mejorar la calidad analítica, uno de los pilares que optimizan la seguridad del paciente.

The analytical limits of performance (ALP) are part of the programme design of analytical quality control. The goals of this study were to determine imprecision (VC), systematic error (SE) and total error (TE) of 14 clinical chemistry analytes in the routine and emergency laboratory of HIGA O. Alende of Mar del Plata, to evaluate their analytical performance in accordance with biological variability, and compare the data obtained. A retrospective study was performed using the record of quality controls. The ALP were obtained from BV to get the quality specifications for VC, SE and TE. Regarding VC, 78% of the analytes meet the criteria in the routine laboratory and 64% in the emergency. Regarding TE, in the routine laboratory, 90% meet the TE criteria, and 75% in the emergency. It can be concluded that, although most of the evaluated analytes meet at least the minimum established criteria, the results highlight the need to improve the analytical performance. Detecting the types of errors in the laboratory process is the first step to establish procedural and analysis controls. These are solutions that will improve the analytical quality, one of the pillars to optimize patient safety.

Os limites analíticos de desmpeño (LAD) são parte do desenho do programa de controle de qualidade analítico. Os objetivos deste estudo foram determinar a imprecisão (CV), o erro sistemático (ES) e o erro total (ET) de 14 analitos de Química Clínica nas áreas de planta e de plantão do laboratório HIGA O. Alende de Mar del Plata, avaliar seu desempenho analítico de acordo com a variabilidade biológica e comparar os dados obtidos. Um estudo retrospectivo foi realizado com o registro de controles de qualidade utilizando os LAD derivados de VB para obter as especificações de qualidade para CV, ES e ET. Quanto ao CV, 79% cumpre com os critérios no setor da planta e 64% no setor de plantão. E, quanto ao ET, cumpre 90% e 75% respectivamente. Em conclusão, embora a maioria dos analitos testados cumpra pelo menos com os critérios mínimos estabelecidos, os resultados destacam a necessidade de melhorar o desempenho analítico. Detectar os tipos de erros encontrados no processo de laboratório é o primeiro passo para estabelecer controles de procedimento e análise, soluções que permitirão melhorar a qualidade analítica, um dos pilares que otimizam a segurança do paciente.

Requerimientos de calidad en hemostasia: Variabilidad biológica versus estado actual de la metodología / Quality requirements in hemostasis: Biological variability versus the state of art / Requisitos de qualidade em hemostasia: Variabilidade Biológica versus o Estado atual da metodología

El objetivo del trabajo fue comparar los requerimientos de calidad (RC) de Variabilidad Biológica (VB) con el Estado Actual de la Metodología (EA) en ocho analitos de hemostasia. Se determinó el EA calculando el Coeficiente de Variación promedio ponderado (CVpp) de al menos 6 evaluaciones externas: RIQAS (ET1) y CAP (ET2). Los datos de Error Total aceptable (ETa) por VB mínimo (VBm) y deseable (VBd) se calcularon a partir de los CV intra e inter individuos reportados en www.westgard.com. Los datos obtenidos: Tiempo de Protrombina (TP segundos): ETVBm 7,9%, ETVBd 5,3%, ET1 19%, ET2 13%; Tiempo parcial de tromboplastina activada: (APTT segundos): ETVBm 6,7%, ETVBd 4,5%, ET1 23%, ET2 11%. INR: ETVBm 7,9%, ETVBd 5,3%, ET1 20%, ET2 16%; Fibrinógeno: ETVBm 20,4%, ETVBd13,6%, ET 10%, ET2 16%, FVIII: ETVBm13,3%, ETVBd 8,9%, ET1 30%, ET2 45%, FVII ETVBm16,1%, ETVBd 10,7%, ET1 31%, ET2 42%, Proteína C cromogénica (PCc) ETVBm 28%, ETVBd 18,7%, ET1 36%, ET2 25%; Proteína S libre (PSl ): ETVBm 31,1%, ETVBd 20,7%, ET1 18%, ET2 28%; Antitrombina cromogénica (ATc): ETVBm 12,5%, ETVBd 8,9%, ET1 18%, ET2 28%. Los únicos analitos que cumplen con el requerimiento de calidad de VBm o VBd son: fibrinógeno, PC y PS. Si bien cada laboratorio puede decidir las especificaciones de calidad que desea aplicar, la cuestión a debatir es: "cuál es el requerimiento de calidad deseable para la utilidad clínica de estos ensayos".

The aim of this work was to compare the quality requirements of biological variability (BV) with the state of the art (SA) in eight hemostasis analytes. SA was determined by calculating the weighted average coefficient of vari ation (CVwa) of at least 6 external evaluations: RIQAS (ET1) and CAP (ET2). Data acceptable total error (TEa) for minimum and desirable biological variability (VBm y VBd) was calculated from the coefficient of variation (CV) within-subject and between subject www.westgard.com reported. The following was the data : Prothrombin time ( PT second): ETVBm 7.9%, ETVBd 5.3%, ET1 19%, ET2 13%; Activated partial thromboplastin time (second APTT): ETVBm 6.7%, ETVBd 4.5%, ET1 23%, ET2 11%; INR: ETVBm 7.9%, ETVBd 5.3%, ET1 20%, ET2 16%; Fibrinogen: ETVBm 20.4% ETVBd 13.6% ET1 20%, ET2 16%, FVIII: ETVBm 13.3%, ETVBd 8.9%, ET1 30%, ET2 45% ; FVII: ETVBm 16.1%, ETVBd 10.7%, ET1 31%, ET2 42%; chromogenic Protein C (PCc): ETVBm 28%, ETVBd 18.7%, ET1 36%, ET2 25%; free Protein S (PSf ): ETVBm 31.1% ETVBd 20.7%, ET1 18%, ET2 28%; chromogenic Antithrombin (ATc): ETVBm 12.5%, ETVBd8.9%, ET1 18%, ET2 28%.The only analytes that meet the VBm or VBd quality requirement are fibrinogen, PC and PS. While each laboratory can decide the quality specifications it wants to apply, the issue to be discussed is: "what is the desirable quality requirement for clinical usefulness of these tests?"

O objetivo do trabalho foi comparar os requisitos de qualidade (RQ) de variabilidade biológica (VB) com o estado atual da metodologia (EA) em oito analitos de hemostasia. Foi determinada a EA através do cálculo do coeficiente de variação médio ponderado (CVmp) de pelo menos 6 avaliações externas: RIQAS (ET1) e CAP (ET2). Os dados de erro total admissível (ETa) para VB mínimo desejável (VBm) e (VBd) foram calculados a partir do CV intra e inter indivíduos reportados em www.westgard.com. Os dados obtidos: Tempo de Protrombina (TP segundos) ETVBm 7,9%, ETVBd 5,3%, ET1 19%, ET2 13% ; Tempo parcial de tromboplastina ativada (APTT segundos): ETVBm 6,7%, ETVBd 4,5%, ET1 23%, ET2 11%; INR: ETVBm 7,9%, ETVBd 5,3%, ET1 20%, ET2 16%; Fibrinogênio: ETVBm 20.4%, ETVBd 13,6%, ET1 20%, ET2 16%; FVIII: ETVBm 13,3%, ETVBd 8,9%, ET1 30%, ET2 45%; FVII: ETVBm 16,1%, ETVBd 10,7%, ET1 31%, ET2 42%; Proteína C cromogênica (PCc): ETVBm 28% ETVBd 18,7%, ET1: 36%, ET2: 25%; Proteína S livre (PSl ): ETVBm: 31,1%, ETVBd 20,7%, ET1: 18%, ET2: 28%; Antitrombina cromogênica (ATc): ETVBm12,5%, ETVBd 8.9%, ET1 18%, ET2 28%. Os únicos analitos que atendem o requisito de qualidade de VBm ou VBd são: fibrinogênio, PC e PS. Embora cada laboratório possa decidir as especificações de qualidade que deseja aplicar, a questão a ser discutida é "qual é o requisito de qualidade desejável para a utilidade clínica destes testes?".

Utilidad del valor de referencia del cambio en la interpretación de resultados seriados en el monitoreo de pacientes oncológicos / Usefulness of the reference value of the change in the interpretation of results serially monitoring cancer patients

El valor de referencia del cambio (VRC) es el valor máximo que es permisible cambie el resultado de un analito entre dos mediciones sucesivas en un mismo paciente, sin que esta diferencia sea de relevancia clínica. Incluye critérios basados en la variabilidad biológica intraindividual (CVI) y la imprecisión analítica (CVA). La principal utilidad de los marcadores tumorales (MT) es el monitoreo de pacientes, resultando más apropiado informar el VRC que evaluar un resultado con su valor de referencia, como lo indica su bajo índice de individualidad. El objetivo fue evaluar la utilidad del VRC para detectar un cambio significativo entre resultados sucesivos en los principales MT. Se analizaron datos de sueros de controles de calidad de MT desde mayo de 2010 a febrero de 2014, se calculó el CVA%, y los datos de CVI % fueron obtenidos de bibliografía. Se calcularon los VRC para cada MT. Para los MT evaluados: AFP, CEA, CA125, CA15-3, CA19-9, PSA y tiroglobulina, los VRC fueron: 29.7, 32.3, 58.0, 16.3, 38.3, 42.7 y 34.2% respectivamente (p<0.05). Estos valores se compararon con datos bibliográficos. El VRC es un dato útil para el médico ya que colabora en la correcta interpretación de resultados seriados durante el seguimiento de pacientes, en la evaluación del tratamiento o en la estimación de recurrencias. Le permite saber si la diferencia encontrada entre dos valores consecutivos representa un cambio em el estado de salud del paciente. Nuestros VRC resultaron comparables con los de literatura

The reference change value (RCV) is the maximum allowable change between two consecutive results with no meaningful clinical relevance. It is analyzed within individual biological variability (CVI ) and analytical imprecision (CVA) criteria. For tumor markers (TM) monitoring is more appropriate to report RCV than reference interval due to their low individuality index. The aim of the study was to evaluate the usefulness of RCV to indicate a significant change between two consecutives TM results. Data from MT quality control serums (QC) were analyzed from May 2010 to February 2014, the imprecision was calculated as CVA% and CVI % data was obtained from literature. The RCV for each MT was calculated. The RCV for AFP, CEA, CA125, CA15-3, CA19-9, PSA and thyroglobulin were 29.7, 32.3, 58.0, 16.3, 38.3, 42.7 and 34.2% respectively (p < 0.05). These values were compared with literature data. The RCV is an appropriate tool for the clinicians and aids for the correct interpretation of results in the monitoring of patients, in treatment evaluation or estimation of recurrence. Physicians can determine whether the differences found between two successive values represent a change in the health status of the patient. The RCV calculated were comparable with those obtained in literature

Efecto del ayuno y hora de toma de muestras sobre las determinaciones en química clínica / Effect of the fasting and capture sample hour on clinical chemistry determinations

Las determinaciones realizadas en laboratorios clínicos deben considerar las variaciones propias de muestras biológicas sólo por ser parte de un sistema complejo. El presente trabajo estudió el efecto del ayuno y hora (h) de toma de muestra en determinaciones de glucosa, urea, creatinina, colesterol, triglicéridos, HDl-colesterol, LDL-colesterol, proteínas, albúmina y ácido úrico. Se conformó una muestra con 31 personas de Caracas con edades entre 18 y 54 años. A cada una se le tomó dos muestras de sangre: una a las 7am (ayuno 12H) y otra (diferente día) a la 1 pm (ayuno 6h, desayuno 7am estandarizado). Las mustras se procesaron en Konelab-20. Se comprobó la normalidad de las distribuciones y se compararon los grupos según el ayuno realizado, todo bajo técnicas de estadística inferencial en SPSS 12.0. Según los resultados no se encontraron diferencias significativas (p>0,05) en las muestras tomadas con ayuno de 12h y 6h en Glucosa, Proteínas totales, albúmina, ácido úrico, colesterol, triglicéridos, HDL-colesterol y LDL-colesterol, no así para el caso de creatinina y urea, donde se observaron diferencias significativas (p<0,05). No existen variaciones de los resultados en un mismo paciente, con dos muestras tomadas a diferentes horas, una en la mañana con 12h de ayuno y otra, en la tarde con 6h de ayuno para el colesterol, triglicéridos, fracciones lípidicas, proteínas, albúmina, acido úrico y glucosa. En el caso de urea y creatinina, existen diferencias significativas, por lo que se recomienda estableces intervalos de referencia biológicos para las determinaciones realizadas con 6h de ayuno.

The determination realized in clinical laboratories must considerer the individual variations of biological samples, only for being a part of a complex system. The present work studied the effect the fasting and hour (h) of capture of samples in determinations of glucose, urea, creatinina, cholesterol, triglicéridos, HDl-cholesterol, LDL-cholesterol, proteins, albumen and uric acid. We studied a sample of 31 persons from Caracas with ages between 18 and 54 years. To each one was drawn two samples of blood: one at 7am (12h fasting) and the other a different day at 1pm (6h fastinf, post standarized breakfast at 7am). The samples were tested in a Konelab-20. The normality of the distributions was verified and the groups and were compared according to the fasting under test of statics inferencial in SPSS 12.0. No significant differences found (p>0,05) in the samples taken with fasting of 12h and 6h in HDL, Glucose, Total Proteins, albumen, uric acid, cholesterol, triglicéridos, cholesterol and LDL-cholesterol, this was not the case for creatinina and urea, where significant differences were observed (p<0,05). Variation of the results does not exist in the same patient, with two samples taken at different hours, one in the morning with 12 h of fasting and other one, in the evening with 6h of fasting for the cholesterol, triglicéridos, lipidic fractions, proteins, albumen, uric and glucose. In case of urea and creatinina, significant difference exist, so we recommend establishing reference biological intervals for the determinations of these components realized with 6h of fasting.

Long-term biological variability of serum lipids in Chinese / 中华检验医学杂志

Objective To investigate long-term biological variability of serum lipids in Chinese. Methods Serum lipids in a Chinese population with relatively stable life styles were monitored with standardized measurements for 1 year (specimens were taken bimonthly) (23 subjects) or 10～15 years (yearly) (100 subjects). Results The total intra-individual variability (analytical and biological variations combined) of total cholesterol, triglycerides, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol averaged 10%, 28%, 16% and 18%, respectively. Conclusion Biological intra-individual variability is a major source of inaccuracy of cardiovascular risk assessments based on lipid measurements. Measures need to be taken to minimize biological variation when medical decisions are to be made in the treatment of lipid disorders.

A Comparative Study of Biological and Analytical Variabilities in Automated Blood Cell Analysis / 대한임상병리학회지

BACKGROUND: The National Committee for Clinical Laboratory Standards (NCCLS) recommends that the analytical variability must not exceed 25% of the biological variability in automated blood cell analysis. This study was conducted to determine whether routine automated blood cell analysis by Coulter STKS (Coulter Corp., Miami, FL, U.S.A) comforms with the NCCLS's recommendations. METHODS: Routine CBC analysis with STKS was performed on 22 healthy volunteers. The tests included calculating WBC, RBC, hemoglobin, MCV, platelet, MPV, and percentages of the granulocytes, lymphocytes, and monocytes. Blood samples were collected twice in one week interval to study the total variability. For the analytical variability, blood samples from 12 subjects were tested twice immediately after venipuncture for within-run variability, and samples from 10 subjects were tested immediately and 6 hours after venipuncture for within-day variability. The analytical variability was calculated as the sum of within-run and within-day variabilities. The biological variability was calculated by subtracting the analytical variability from total variability. The ratios of analytical and biological variabilities were calculated by dividing the analytical variability by the biological variability. RESULTS: Ratios of analytical and biological variabilities were as follows: 0.22 for WBC, 0.20 for RBC, 0.21 for hemoglobin, 0.39 for platelet, 1.98 for MPV, 0.07 for %granulocyte, 0.11 for %lymphocyte, and 1.81 for %monocyte. The ratio for MCV was not obtained because the analytical variability exceeded total variability. CONCLUSIONS: The analytical variability did not exceed 25% of the biological variability in all test categories except platelet, MPV and the percentage of monocyte. Thus, it is recommended that the analytic variability of all test categories be reduced so as to be in conformity with the NCCLS' recommendations.

A Comparative Study of Biological and Analytical Variability of Automated Clinical Chemistry Tests / 대한임상병리학회지

BACKGROUND: Results of automated clinical chemistry tests are affected by many factors including analytical variability. In 1976, the College of American Pathologists (CAP) Conference on the analytical goals in clinical chemistry recommended that analytical variability should be less than 1/4 of the appropriate biological variability to improve distinction between normal and diseased populations. This study is conducted to evaluate whether automated clinical chemisty analyses performed in our laboratory is in conformance with the CAP's recommendation. METHODS: Routine chemistry and electrolyte tests were performed using Hitachi 747 automatic analyzer on 22 healthy volunteers. Blood samples were obtained from the volunteers' same vein twice in one week interval to study the total variability. Serum samples from 12 subjects were tested in duplicate immediately after blood collection for within-run analytical variability; and samples from another 10 subjects were repeated after 6 hours for within-day analytical variability. Within-run analytical variability plus within-day analytical variability make total analytical variability. Biological variability was defined as the difference between total variability and the analytical variability. Finally, ratios of analytical and biological variabilities were calculated. RESULTS: The ratios of analytical and biological variabilities of uric acid, glucose, and K were less than 0.25. But ratios of BUN, PO4, alkaline phosphatase, total bilirubin, AST, cholesterol, ALT, Cl, and protein exceeded 0.25. The ratios of Na, Ca, albumin, CO2, and creatinine could not be calculated. CONCLUSIONS: It is suggested that the analytical processes of the automated clinical chemistry tests be improved so as to be in conformity with the CAP's recommendation.