Development of national secondary reference materials of urea and creatinine in frozen human serum / 中华检验医学杂志

Objective:To develop a national secondary reference material of Urea and Creatinine in frozen human serum as a standard for metrological traceability.Methods:According to JJF1343-2012 "General and Statistical Principles for Characterization of Reference Materials" and JJF 1006-1994 " Technical Norm of Primary Reference Material ", the homogeneity, stability, and commutability were evaluated;Using the JCTLM recommended methods, the value of the reference materials was assigned through collaboration with 6 accredited reference laboratories from Guangdong Provincial Hospital of Chinese Medicine, Beijing Aerospace General Hospital, Shenzhen Mindray Bio-Medical Electronics, Maccura Biotechnology, Beijing Leadman Biochemistry, and Zhejiang MedicalSystem Biotechnology. Uncertainty components including inhomogeneity, stability and value assignment were evaluated.Results:The results of one-way analysis of variance of homogeneity for the reference materials showed P>0.05, and the stability evaluation was less than the critical value of the t-test. The measured values were in the 95% confidence interval in the four conventional detection systems for commutability, and the certified values and expanded uncertainties were urea:(14.7±0.3) mmol/L ( k=2),Cr:(313.9±14.5) μmol/L ( k=2). Conclusion:The prepared secondary reference materials of urea and creatinine had promising homogeneity, stability, and commutable, the values of urea and creatinine concentration in reference materials were accurate and reliable.

La trazabilidad en las mediciones del laboratorio clínico: impacto en la calidad y seguridad del paciente / Traceability in clinical laboratory measurements: impact on quality and patient safety

Las mediciones confiables, trazables metrológicamente y comparables proporcionan la base racional para la evaluación de la calidad de un resultado y el fortalecimiento de las redes de laboratorios clínicos, lo cual permite mejorar la calidad de atención y la seguridad del paciente. En este documento se revisan los principios básicos que deben seguirse para garantizar la trazabilidad de las mediciones del laboratorio clínico, las ventajas de utilizar métodos trazables, el impacto de no hacerlo, y se discuten las principales limitaciones para relacionar las mediciones con los estándares de medición de referencia apropiados

Reliable, metrologically traceable, and comparable measurements provide the rationale for evaluating the quality of a result and strengthening clinical laboratory networks, thereby improving quality of care and patient safety. This document reviews the basic principles that must be followed to ensure the traceability of clinical laboratory results, the advantages of using traceable methods, the impact of not doing so, and the main limitations in relating measurements to appropriate reference standards

Inductively Coupled Plasma Mass Spectrometry as a Reference Method to Evaluate Serum Calcium Measurement Bias and the Commutability of Processed Materials during Routine Measurements / 中华医学杂志(英文版)

<p><b>Background</b>Measuring total serum calcium is important for the diagnosis of diseases. Currently, results from commercial kits for calcium measurement are variable. Generally, the performance of serum calcium measurements is monitored by external quality assessment (EQA) or proficiency testing schemes. However, the commutability of the EQA samples and calibrators is often unknown, which limits the effectiveness of EQA schemes. The aim of this study was to evaluate the bias of serum calcium measurements and the commutability of processed materials.</p><p><b>Methods</b>Inductively coupled plasma mass spectrometry was applied as a comparative method, and 14 routine methods were chosen as test methods. Forty-eight serum samples from individual patients and 25 processed materials were quantified. A scatter plot was generated from patient samples, and 95% prediction intervals were calculated to evaluate the commutability of the processed materials and measurement bias at three concentration levels was used to determine the accuracy of routine assays.</p><p><b>Results</b>All assays showed high precision (total coefficient of variation [CV] <2.26%) and correlation coefficients (r > 0.99). For all assays, the mean bias for the 48 patient samples ranged from -0.13 mmol/L to 0.00 mmol/L (-5.61-0.01%), and the ranges for the three concentrations were -0.10-0.04 mmol/L (-5.71-2.35%), -0.14--0.01 mmol/L (-5.80--0.30%), and -0.19-0.04 mmol/L (-6.24-1.22%). The EQA samples, calibrators, and animal sera exhibited matrix effects in some assays; human serum pools were commutable in all assays; certificate reference materials were commutable in most assays, and only GBW09152 exhibited a matrix effect in one assay; and aqueous reference materials exhibited matrix effects in most assays.</p><p><b>Conclusions</b>Biases for most assays were within the acceptable range, although the accuracy of some assays needs improvement. Human serum pools prepared from patient samples were commutable, and the other tested materials exhibited a matrix effect.</p>

Interpretation of External Quality Assessment Results in Clinical Laboratories and Suggested Approach on Investigating Unacceptable Results / 现代检验医学杂志

Important objectives of external quality assessment (EQA) is to detect analytical errors and urge laboratories to take corresponding corrective actions.The paper described knowledge required to interpret EQA results and present a structured approach on how to handle unacceptable EQA results.The interpretation of EQA results depends on five key points:the control material,the target value,the number of replicates,the acceptance limits and between lot variations in reagents.When there are unacceptable EQA results,these factors may be the sources of errors.The ideal EQA sample has two important properties:having no matrix effects;having a target value established with a reference method.If either of these two criteria is not entirely fulfilled,results not related to the performance of the laboratory may arise.To help and guide the laboratories in handling an unacceptable EQA result,National Center for Clinical Laboratories has developed a preliminary investigation on the sources of errors and corrective actions for nonconforming EQA results in fifteen EQA schemes.Then a flow chart with additional comments was developed based on the investigation and the document of QMS24 to help laboratories improve quality by use of EQA results.

Preparation of candidate reference materials for potassium in frozen human mixed serum / 中华检验医学杂志

Objective To prepare the candidate reference materials for frozen mixed serum potassium, in order to calibrate and evaluate the conventional methods to achieve mutual recognition of the results.Methods Fresh sera without hemolysis,lipemia and choloplania were collected.Serum pools were packed in the freezing tube in the 1 000 (1 ml/per).Use the Single Factor Analysis of Variance(ANOVA) to evaluate the homogeneity.The short-and long-term stability [(2 -8℃,room temperature,37 ℃) and long-term (-80 ℃ ) ] were investigatedby linear regression analysis.The value was assigned by transfer from NIST SRM-956c using reference method by ICP-MS and uncertain was calculated.We observed the commutability of 25 fresh patient serum samples and 3 levels candidate RMs between reference method and three analyzed systems.The candidate RMs( refernce materials) were then distributed to 33 laboratories in Beijing to apply in routine assay by using different detection systems.Results By statistical analysis of the SPSS 17 statistical software, the F value of homogeneity test of each level candidate RMs was 0.247, 0.117, 0.162.All of them were less than F0.05 (9,20) =2.39;Stability can be last at least 12 months,30 days, 12 days and 4 days at -80 ℃, 2-8℃, room temperature and 37℃respectively.The definited values of three levels candidate RMs for potassium were (2.349 ±0.028) mol/L,(3.845 ±0.024) mol/Land (5.831 ±0.042)mol/L;Coordinate dots of 3 levels candidate RMs are all within 95% confidence interval range of 25 serums regression line.They have the same speciality as serum.In correctness verification survey of 33 clinical laboratory of conventional methods,97%bias in results The biases of 97%RMs were within the range of ±2.5%( ±1/2 CLIA′88Tea).Conclusion The homogeneity, stability and commutability of 3 levels candidate RMs all meet the requirement and the target values are assigned accurately.

ISO 1 5 1 8 9:2 0 1 2 and External Quality Assessment / 现代检验医学杂志

External quality assessment (EQA)as an effective tool for quality control can help clinical laboratories to discover quality problems during testing process and prompt clinical laboratories to improve their testing quality.Samples used for traditional EQA frequently have matrix effects which assign the target value by grouping.Ideal samples for EQA are com-mutable which have the same numeric relationship between different measurement procedures as that expected for patients’ samples.And they can assess accuracy against a reference measurement procedure or a designated comparison method.When analyzing,robust statistical method can be used to reflect the variability of testing results between laboratories more truly. And the evaluation standards should be desirable.If unsatisfactory results appear,we should investigate every aspect of tes-ting process,find the root cause,and take corrective action.On condition that no official EQA scheme is launched for some analytes,it is necessary for us to evaluate the performance of analytes by alternative evaluation procedures.

Participating in the evaluation of combined value assignment of Cystatin-C as a national standard material candidate / 国际检验医学杂志

Objective As a collaborator of Beijing Institute of Medical Device Testing for value assignment of state standard ma-terial candidate Cystatin-C ,we have used the internationally accepted reference material to assign value for state standard material candidate Cystatin-C ,and help Beijing Institute of Medical Device Testing get Cystatin-C national standard material certificate . Methods According to the target value and operational procedure of international reference material ERM-DA471 ,We have tested 6 dilutions of standard material candidate Cystatin-C on calibrated Hitachi 7180 immunoassay system .Results The results demon-strate good repeatability and commutability ,and have been accepted in calculating the final value for the candidate standard materi-al ,our data has assisted Beijing Institute of Medical Device Testing in passing the criteria and obtaining Cystatin-C national standard material certificate .Conclusion Compared to the data from all participating collaborators ,our results hit right on the target value , and no significant matrix effects have been observed .

Harmonization: the Sample, the Measurement, and the Report

Harmonization of clinical laboratory results means that results are comparable irrespective of the measurement procedure used and where or when a measurement was made. Harmonization of test results includes consideration of pre-analytical, analytical, and post-analytical aspects. Progress has been made in each of these aspects, but there is currently poor coordination of the effort among different professional organizations in different countries. Pre-analytical considerations include terminology for the order, instructions for preparation of the patient, collection of the samples, and handling and transportation of the samples to the laboratory. Key analytical considerations include calibration traceability to a reference system, commutability of reference materials used in a traceability scheme, and specificity of the measurement of the biomolecule of interest. International organizations addressing harmonization include the International Federation for Clinical Chemistry and Laboratory Medicine, the World Health Organization, and the recently formed International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR). The ICHCLR will provide a prioritization process for measurands and a service to coordinate global harmonization activities to avoid duplication of effort. Post-analytical considerations include nomenclature, units, significant figures, and reference intervals or decision values for results. Harmonization in all of these areas is necessary for optimal laboratory service. This review summarizes the status of harmonization in each of these areas and describes activities underway to achieve the goal of fully harmonized clinical laboratory testing.

Avaliando a comutatividade: importante requisito da qualidade para laboratórios clínicos / Understanding commutability: important quality requirement for clinical laboratories

INTRODUÇÃO: Poucos laboratórios no Brasil realizam a avaliação da comutatividade dos resultados de exames, provavelmente por desconhecimento dos procedimentos para sua realização e também pela pouca importância dada a essa avaliação. OBJETIVO: Avaliar a comutatividade dos resultados de exames hematológicos realizados em três analisadores automatizados em um laboratório de um hospital público universitário, em Belo Horizonte, MG, Brasil, propondo procedimento prático, de baixa complexidade, factível de ser utilizado em laboratórios clínicos. MATERIAL E MÉTODOS: As amostras foram selecionadas visando obter valores nos níveis de decisão terapêutica. Foram processadas seis amostras por dia, durante quatro dias, em duplicata em três analisadores, totalizando 48 replicatas em cada instrumento. Foi avaliada a correlação entre os resultados de 10 dos principais parâmetros hematológicos obtidos nos instrumentos-teste e aqueles obtidos com o instrumento-referência. Foram estimados os erros sistemáticos e totais, considerando as especificações da variação biológica como limite máximo aceitável. RESULTADOS: O coeficiente de correlação (r) entre os equipamentos para os parâmetros investigados foi > 0,975. Os erros sistemático (médio) e total, obtidos para os parâmetros analisados, quando se comparam os equipamentos de teste com o de referência, atenderam às especificações da qualidade definidos. Discussão: A comutatividade é um importante processo da gestão da qualidade do laboratório clínico e visa garantir a comparabilidade de resultados de exames realizados por diferentes sistemas. CONCLUSÃO: Utilizando procedimento padronizado internacionalmente, prático e de baixa complexidade, demonstrou-se que os exames realizados nos equipamentos avaliados são equivalentes, podendo ser usados indistintamente no acompanhamento de pacientes.

INTRODUCTION: Few Brazilian laboratories evaluate the commutability of test results, probably due to the lack of procedure expertise as well as the neglected importance of its assessment. OBJECTIVE: The aim of this study was to evaluate the commutability of hematological test results performed with three automated analyzers at the laboratory of a public university hospital in Belo Horizonte, MG, Brazil, proposing a practical, simple, and feasible procedure to be applied in clinical laboratories. MATERIAL AND METHODS: Samples were selected in order to obtain hematologic values for therapeutic decision levels. Six samples were processed in duplicate in three analyzers daily during a four-day period amounting to a total of 48 replicates in each instrument. The correlation between the results of 10 hematologic parameters obtained with test instruments and the reference instrument was assessed. Systematic and total errors were estimated and criteria for acceptable performance were based on the biological variation specifications. RESULTS: The correlation coefficient (r) between test instruments and reference instrument results was > 0.975. Systematic (mean) and total errors met the required quality specifications when compared with reference instruments. Discussion: Commutability is an important process of quality management in clinical laboratories and it ensures the comparability of test results carried out with different procedures. CONCLUSION: Through a practical, simple, and internationally standardized procedure, this study showed that test results from the evaluated instruments were equivalent, which allows their use in patient monitoring.

Primary study on stability and commutability of recombinant human muscle creatine kinase isozyme in different matrix / 临床检验杂志

Objective To investigate the stability and comparability of recombinant human muscle creatine kinase isozyme(CK-MM)in different matrix,and to find out a suitable matrix as a reference material for application of CK measurement system.Methods The stability of the recombinant CK-MM was observed by measuring its catalytic activity in self-made matrix,anti-freeze additive matrix,the certified reference material(CRM)matrix and human serum matrix respectively.For understanding the commutability among different measurement system total CK catalytic activity in various concentration of human serum and the catalytic activity of recombinant CK-MM in different matrix specimen were measured with IFCC recommended reference method and routine reagent produced by Roche and Zhongsheng Diagnostic Company respectively.Results The recombinant CK-MM was stable for 25 days in the self-made matrix,23 days in CRM matrix and at least 240 days in antifreeze additive matrix stored at-20 ℃.The recombinant enzyme protein in self-made matrix and CRM matrix was commutable.Low concentrations of recombinant CK-MM in human serum and in anti-freeze additive matrix were also commutable.Conclusion The recombinant CK-MM had good stability and commutability in either self-made matrix or CRM matrix.It might be used as a candidate reference material for the determination of total creatine kinase in serum.