Evaluation of the analytical performance of endocrine analytes using sigma metrics

Background(a) To evaluate the clinical performance of endocrine analytes using the sigma metrics (σ) model. (b) To redesign quality control strategies for performance improvement.MethodsThe sigma values of the analytes were initially evaluated based on the allowable total error (TEa), bias, and coefficient of variation (CV) at QC materials level 1 and 2 in March 2018. And then, the normalized QC performance decision charts, personalized QC rules, quality goal index (QGI) analysis, and root causes analysis (RCA) were performed based on the sigma values of the analytes. Finally, the sigma values were re‐evaluated in September 2018 after a series of targeted corrective actions.ResultsBased on the initial sigma values, two analytes (FT3 and TSH) with σ > 6, only needed one QC rule (1_3S) with N2 and R500 for QC management. On the other hand, seven analytes (FT4, TT4, CROT, E2, PRL, TESTO, and INS) with σ < 4 at one QC material level or both needed multiple rules (1_3S/2_2S/R_4S/4_1S/10_X) with N6 and R10‐500 depending on different sigma values for QC management. Subsequently, detailed and comprehensive RCA and timely corrective actions were performed on all the analytes base on the QGI analysis. Compared with the initial sigma values, the re‐evaluated sigma metrics of all the analytes increased significantly.ConclusionsIt was demonstrated that the combination of sigma metrics, QGI analysis, and RCA provided a useful evaluation system for the analytical performance of endocrine analytes.     

尿清蛋白质控品的研制及室间质评的调查

目的制备尿清蛋白室内质控品,并进行室间质评调查。方法选取患者尿液样本,离心取上清液,加入乙二醇作为稳定剂,叠氮钠作为防腐剂,分装保存,观察稳定性和瓶间差,并进行室间质评调查。结果自制的尿清蛋白质控品除4℃保存的低值质控品外,CV均小于10%,有较好的稳定性,尤其在前3个月;此外,自制质控品的瓶间差较小,高值质控品瓶间差仅0.67%和0.81%,同时质控品的保存温度对瓶间差的影响很小。在全市的室间质评调查中低值质控品CV为63.3%(29.1%～70.3%);高值质控品CV为20.5%(15.9%～22.3%)。结论研制的尿清蛋白质控品的稳定性较好,易于制备,可应用于临床实验室的室内质控和室间质评。     

Methodological evaluation and comparison of five urinary albumin measurements

Background: Microalbuminuria is an indicator of kidney damage and a risk factor for the progression kidney disease, cardiovascular disease, and so on. Therefore, accurate and precise measurement of urinary albumin is critical. However, there are no reference measurement procedures and reference materials for urinary albumin. Methods: Nephelometry, turbidimetry, colloidal gold method, radioimmunoassay, and chemiluminescence immunoassay were performed for methodological evaluation, based on imprecision test, recovery rate, linearity, haemoglobin interference rate, and verified reference interval. Then we tested 40 urine samples from diabetic patients by each method, and compared the result between assays. Results: The results indicate that nephelometry is the method with best analytical performance among the five methods, with an average intraassay coefficient of variation (CV) of 2.6%, an average interassay CV of 1.7%, a mean recovery of 99.6%, a linearity of R=1.00 from 2 to 250 mg/l, and an interference rate of <10% at haemoglobin concentrations of <1.82 g/l. The correlation (r) between assays was from 0.701 to 0.982, and the Bland–Altman plots indicated each assay provided significantly different results from each other. Conclusion: Nephelometry is the clinical urinary albumin method with best analytical performance in our study. J. Clin. Lab. Anal. 25:324–329, 2011. © 2011 Wiley‐Liss, Inc.     

6σ理论在血液分析仪质量控制中的应用探索

目的通过对血液分析仪质量控制（QC）数据的σ值研究,探讨如何应用σ值来判断方法性能和选择QC规则。方法从我院2005至2006年Sysmex K-4500和Sysmex KX-21参加上海地区血液分析仪室内QC的数据中抽取12次,采用公式σ值=[允许总误差（TEa）-偏倚（bias）]/变异系数（CV）,按照美国临床实验室改进修正法案（CLIA′88）允许误差标准,得出各项的σ值。同时与仪器厂商、血液分析仪组和Sysmex组σ值比较。结果Sysmex K-4500白细胞（WBC）计数、红细胞（RBC）计数、血红蛋白（Hb）量、红细胞压积（Hct）和血小板（PLT）计数等项目σ均值分别为11.09、7.35、11.68、6.01和9.35,Sysmex KX-21分别为8.51、7.55、10.40、6.39和8.55,Sysmex组分别为4.37、3.81、5.63、2.18、5.33,与我院2台仪器比较σ值差异有统计学意义（P〈0.01）。结论本实验室Sysmex K-4500和Sysmex KX-21血液分析仪的σ值已达6.0以上,采用13.0s（n=2）QC规则就能满足质量要求,但应注意仪器校准和分析前、后质量问题。     

6σ理论在血液分析仪质量控制中的应用探索

目的通过对血液分析仪质量控制(QC)数据的σ值研究,探讨如何应用σ值来判断方法性能和选择QC规则。方法从我院2005至2006年Sysmex K-4500和Sysmex KX-21参加上海地区血液分析仪室内QC的数据中抽取12次,采用公式σ值=[允许总误差(TEa)-偏倚(bias)]/变异系数(CV),按照美国临床实验室改进修正法案(CLIA′88)允许误差标准,得出各项的σ值。同时与仪器厂商、血液分析仪组和Sysmex组σ值比较。结果Sysmex K-4500白细胞(WBC)计数、红细胞(RBC)计数、血红蛋白(Hb)量、红细胞压积(Hct)和血小板(PLT)计数等项目σ均值分别为11.09、7.35、11.68、6.01和9.35,Sysmex KX-21分别为8.51、7.55、10.40、6.39和8.55,Sysmex组分别为4.37、3.81、5.63、2.18、5.33,与我院2台仪器比较σ值差异有统计学意义(P<0.01)。结论本实验室Sysmex K-4500和Sysmex KX-21血液分析仪的σ值已达6.0以上,采用13.0s(n=2)QC规则就能满足质量要求,但应注意仪器校准和分析前、后质量问题。     

应用6σ质量管理方法评价c16000全自动生化分析系统检测质量水平

目的应用六西格玛(6σ)质量管理方法评价c16000全自动生化分析系统质量水平,以促进质量改进,提高检测质量。方法收集2018年海南省人民医院c16000全自动生化分析系统42项生化检测项目的室内质量控制(IQC)和室间质量评价(EQA)数据,通过IQC数据计算累计合成变异系数(CV),根据EQA数据评估偏移(Bias),依据我国卫生行业标准WS/T403-2012要求的允许总误差(TEa)计算各检测项目的西格玛σ水平及质量目标指数(QGI),分析导致性能不佳的主要原因。通过σ性能验证图评价各项目的分析性能及应采用的质控规则。结果 42项生化检测项目中有13项(31%)检测水平≥6σ,3项(7%)检测水平为5σ~6σ,7项(17%)检测水平为4σ~5σ,8项(19%)检测水平为3σ~4σ,7项(17%)检测水平为2σ~3σ,4项(9%)检测水平<2σ。在<6σ的检测项目中,2项需优先改进正确度,21项需优先改进精密度,6项正确度和精密度均需改进。结论 6σ质量管理方法是临床生化检验项目质量控制的有效管理方法,可提示生化检测项目需要改进的方向,促进临床实验室生化检验水平的提高。     

Laboratory quality control: using patient data to assess analytical performance.

Quality control plays a vital role helping to ensure the reliability of laboratory test results. The application of statistical quality control has been a component of laboratory medicine for approximately 50 years. Many of the control rules based on the early applications of statistical quality control have remained essentially unchanged since their initial introduction. Optimization of quality control rules can vary depending on the application for which a test is to be used. This review explores the various applications of laboratory quality control procedures and their role in identifying laboratory error. The ubiquitous use of computers in today's laboratories has enabled the development of more sophisticated means of assessing laboratory quality. The use of the Six Sigma technique and its adoption by the laboratory community is one example. Other examples include the use of patient-derived quality control procedures as a means of assessing laboratory performance. Early examples of these types of applications include use of Bull's algorithm, anion gap measurements, and delta checking. More recent applications include the correlation of laboratory test results, the average of normals procedure, and the Bhattacharya method.     

胆红素和血红蛋白对不同尿白蛋白检测方法结果干扰的研究

目的探讨尿中胆红素(Bil)和血红蛋白(Hb)在不同检测方法中对尿白蛋白检测结果的干扰。方法分别以Bil和Hb作为干扰物,对3种不同检测方法(免疫透射比浊法、免疫散射比浊法和免疫胶体金法)进行尿白蛋白检测的干扰试验。结果不同浓度的Bil和Hb对3种尿白蛋白检测方法的结果均会产生影响,且干扰率会随干扰物浓度的增高而增加。Hb对3种检测方法主要呈负干扰;Bil对免疫透射比浊法和免疫散射比浊法检测结果呈正干扰,而对免疫胶体金法检测结果呈负干扰。当尿液中Hb浓度相当于尿隐血"1+"时,Hb对3种检测方法的干扰率绝对值为6.72%～17.43%;当尿液中Bil浓度相当于Bil"1+"时,3种检测方法的干扰率绝对值为7.89%～22.94%。结论 Bil和Hb均会对尿白蛋白的检测结果造成干扰,在检测可能含有Bil和Hb患者尿液的尿白蛋白时,应考虑这些干扰因素对结果的影响。     

A model for setting analytical quality specifications and design of control for measurements on the ordinal scale.

A model for characterization of measurements on the ordinal scale is presented. It is based on transformation of the calculated fractions (fractiles) of positives from measurements on samples with known concentrations to a probit-natural log (probit-ln) scale. Such measurements could be made by other methods on ratio or difference scales but, for convenience (for example for speed or low cost), are measured on the ordinal scale by "simple" methods. The model is examined, and verified, using three examples from published data (haemoglobin, glucose, and leukocytes) and an external quality assessment survey on measurements of streptococcus. We show that it is possible to obtain reliable analytical quality specifications and to establish design of control systems for measurements on the ordinal scale. It is concluded that the presented probit-ln model for the ordinal scale is a tool which can improve and facilitate (i) characterizing methods with measurements on the ordinal scale, (ii) defining analytical quality specifications, (iii) designing external assessment as well as internal control schemes, (iv) validation of methods with measurements on the ordinal scale according to the analytical quality specifications, and further, (v) reduction of the number of samples required for method validation and the number of replicate measurements needed.     

Measurement of the albumin content of urinary protein using dipsticks.

An albumin selective urine strip based on bis (3',3'-diiodo-4', 4'-dihydroxy-5',5'-dinitrophenyl)-3,4,5,6-tetrabromo sulfonphthalein dye (DIDNTB) dye was examined in populations with clinical proteinuria. The relationship of albumin to the sum concentration of all protein in urine was found to vary widely even though the albumin concentration generally increased with the total protein concentration. The albumin reagent strips correlated well with immuno-nephrometric assays for albumin on specimens from hypertensives, diabetics, and renal disease which tended to have albumin contents of >/= 50.0%. High proteinuria concentrations of > 250 mg/l, with low albumin contents of 相似文献   

Application of a six sigma model to evaluate the analytical performance of urinary biochemical analytes and design a risk‐based statistical quality control strategy for these assays: A multicenter study

BackgroundThe six sigma model has been widely used in clinical laboratory quality management. In this study, we first applied the six sigma model to (a) evaluate the analytical performance of urinary biochemical analytes across five laboratories, (b) design risk‐based statistical quality control (SQC) strategies, and (c) formulate improvement measures for each of the analytes when needed.MethodsInternal quality control (IQC) and external quality assessment (EQA) data for urinary biochemical analytes were collected from five laboratories, and the sigma value of each analyte was calculated based on coefficients of variation, bias, and total allowable error (TEa). Normalized sigma method decision charts for these urinary biochemical analytes were then generated. Risk‐based SQC strategies and improvement measures were formulated for each laboratory according to the flowchart of Westgard sigma rules, including run sizes and the quality goal index (QGI).ResultsSigma values of urinary biochemical analytes were significantly different at different quality control levels. Although identical detection platforms with matching reagents were used, differences in these analytes were also observed between laboratories. Risk‐based SQC strategies for urinary biochemical analytes were formulated based on the flowchart of Westgard sigma rules, including run size and analytical performance. Appropriate improvement measures were implemented for urinary biochemical analytes with analytical performance lower than six sigma according to the QGI calculation.ConclusionsIn multilocation laboratory systems, a six sigma model is an excellent quality management tool and can quantitatively evaluate analytical performance and guide risk‐based SQC strategy development and improvement measure implementation.     

分析批长度Westgard西格玛规则在临床生化检测项目分析质量评价中的应用

目的 运用分析批长度Westgard西格玛规则对临床生化项目的质控策略进行分析.方法 收集实验室2019年室内质量控制数据,计算变异系数(CV);以室间质评(EQA)的结果计算偏倚(Bias);以美国临床实验室最新修正案(CLIA'2019)的允许总误差(TEA)及行业标准WS/T403-2012的TEA分别计算各生化...     

应用西格玛度量和稳健算法评价不同检测系统糖化血红蛋白检测结果的可比性

目的分析和评价浙江省糖化血红蛋白(HbA1c)项目的检测质量及不同系统检测结果的可比性。方法收集2018年浙江省HbA1c室间质量评价(EQA)数据,按照检测系统分组。以采用稳健算法计算的5个标本均值为靶值,并计算各组的稳健均值和实验室间的稳健变异系数(CV)。计算每个标本各分组的西格玛水平及加权西格玛水平。结果将268家实验室中纳入统计分析的实验室按检测系统分为4个组:A组(44家)、B组(87家)、C组(50家)、D组(26家)。5个标本的总体稳健CV依次为2.58%、1.85%、5.05%、2.70%和4.77%。A、B、C、D组的实验室间稳健CV分别为1.80%~3.16%、1.72%~2.64%、1.32%~1.81%、1.67%~3.38%,各组对应的西格玛平均值分别为1.19(-0.35~2.39)、2.42(1.66~3.25)、2.95(2.2~3.44)、0.26(-2.76~2.92)。仅C组有3个标本和B组有1个标本的西格玛水平>3。5个标本的加权西格玛水平分别为2.48、3.00、0.87、2.41和1.30,平均值为2。结论西格玛度量和稳健统计方法可更深入和客观地分析EQA结果中反馈的HBA1c检测质量水平。浙江省HbA1c检测质量水平尚不理想,需进一步采取质量管理措施,以实现检验结果互认的目标,满足临床诊断糖尿病的需求。     

通过过程计划和质量控制来保证分析质量的研究

目的　探讨利用质量控制和室间质量评价来证实常规检验符合规定性能准则的方法。方法　室间质量评价准则是分析的“总误差”要求 ,需要将其转化为提供规定分析质量保证水平所必须的允许不精密度、允许不准确度和质量控制 (质控规则和质控测定值个数 )的操作过程规范。结果通过把具有规定概率的统计质量控制应用于检测过程 ,常规检验将取得期望的质量要求。结论　分析质量保证检验的这种应用是通过过程计划和质量控制来保证检验质量的一种定量方法。     

Westgard西格玛规则在血站质控实验室的应用

目的 旨在帮助血站质量控制实验室利用Westgard西格玛规则选取适合的室内质控规则.方法 血站质量控制实验室的测量不精密度可以使用室内质控累积计算出的变异系数,把2020年室间质评(EQA)结果回报的偏倚值作为偏倚(Bias),允许总误差(TEa)采用我国卫生行业标准WS/T406-2012的评价指标,计算实验室血液...     

Application of Sigma metrics in the quality control strategies of immunology and protein analytes

BackgroundSix Sigma (6σ) is an efficient laboratory management method. We aimed to analyze the performance of immunology and protein analytes in terms of Six Sigma.MethodsAssays were evaluated for these 10 immunology and protein analytes: Immunoglobulin G (IgG), Immunoglobulin A (IgA), Immunoglobulin M (IgM), Complement 3 (C3), Complement 4 (C4), Prealbumin (PA), Rheumatoid factor (RF), Anti streptolysin O (ASO), C‐reactive protein (CRP), and Cystatin C (Cys C). The Sigma values were evaluated based on bias, four different allowable total error (TEa) and coefficient of variation (CV) at QC materials levels 1 and 2 in 2020. Sigma Method Decision Charts were established. Improvement measures of analytes with poor performance were recommended according to the quality goal index (QGI), and appropriate quality control rules were given according to the Sigma values.ResultsWhile using the TEa_NCCL, 90% analytes had a world‐class performance with σ>6, Cys C showed marginal performance with σ<4. While using minimum, desirable, and optimal biological variation of TEa, only three (IgG, IgM, and CRP), one (CRP), and one (CRP) analytes reached 6σ level, respectively. Based on σ_NCCL that is calculated from TEa_NCCL, Sigma Method Decision Charts were constructed. For Cys C, five multi‐rules (1_3s/2_2s/R_4s/4_1s/6_X, N = 6, R = 1, Batch length: 45) were adopted for QC management. The remaining analytes required only one QC rule (1_3s, N = 2, R = 1, Batch length: 1000). Cys C need to improve precision (QGI = 0.12).ConclusionsThe laboratories should choose appropriate TEa goals and make judicious use of Sigma metrics as a quality improvement tool.