A mathematical model to assess the influence of hematocrit on point of care glucose meter performance

ObjectivesTo develop and apply a mathematical model of the relationship between hematocrit, meter glucose and reference glucose concentrations as a tool for evaluation of whole blood glucose meters.Design and MethodsPatient blood gas specimens were used to compare the LifeScan SureStep Flexx and the Nova StatStrip glucose meters with reference results obtained from a Radiometer 725 blood gas analyzer. Linear regression analysis was conducted to determine the extent that patient hematocrit and reference glucose concentrations predicted the performance of the glucose meters.ResultsBland-Altman graphic analysis depicted that both glucose meters showed variance with the reference method. A mathematical model was derived from IFCC consensus equations that relate glucose meter results, hematocrit and plasma glucose values. Using the model, multivariate regression depicted that hematocrit affected the results of the SureStep Flexx meter in a manner dependent on the glucose concentration, whereas the StatStrip meter was not affected by hematocrit.ConclusionsLinear regression can be used to quantify the extent of hematocrit interference on the performance of glucose meters.     

21台床旁检验血糖仪与生化分析仪血糖检测结果比对

目的定期监测新疆医科大学第一附属医院21台床旁检验血糖仪（以下简称POCT血糖仪）检测结果与贝克曼生化分析仪血糖测定结果的一致性,全面了解医院血糖测定值之间的差异。方法挑选10例空腹血糖在3.76～19.84mmol/L（生化分析仪血糖检测结果）的患者,分别抽取乙二胺四乙酸（EDTA）抗凝全血和未抗凝血。EDTA抗凝血在POCT血糖仪测定血糖;不抗凝血在贝克曼DXC800生化分析仪测定血糖,每份标本测定3次,取均值。对合格的19台仪器按使用年限编号排序,随机抽样5台,用新疆维吾尔自治区临床检验中心POCT血糖室间质评物测定血糖,与靶值比对,计算偏倚。结果 POCT血糖仪测定结果与生化分析仪测定结果比对,19台偏倚在0.93%～11.49%范围,2台仪器测定值偏倚大于20%,19台POCT血糖仪测定值变异系数（CV%）为3.14%～10.82%。抽样的5台POCT血糖仪与新疆维吾尔自治区临床检验中心POCT血糖室间质评靶值（以下简称＂靶值＂）的偏倚为0%～6.87%。结论 21台POCT血糖仪中19台与生化分析仪血糖检测结果比对具有一致性,2台比对差异大。生化分析仪比POCT血糖仪检测结果偏高约0.94%～12.98%。抽样的5台POCT血糖仪与靶值之间的偏倚符合新疆维吾尔自治区临床检验中心质评判定标准。     

床旁检验血糖仪与生化分析仪血糖测定结果比对分析

目的对中山医院床旁检验（POCT）血糖仪与全自动生化分析仪血糖测定结果进行比对分析和偏倚评估,以保证血糖仪检测结果的一致性。方法参照《便携式葡萄糖仪血液葡萄糖测定指南》,采集肝素钠抗凝静脉血10份,血糖水平分布在3.20～25.81mmol/L。在POCT血糖仪和生化分析仪上重复测定3次,以生化仪为靶仪器,计算相对偏倚。结果 42台血糖仪中的38台与生化分析仪测定值相对偏倚在1%～13%,符合要求。结论通过对中山医院POCT血糖仪与生化分析仪血糖测定结果的比对和偏倚评估,评价血糖仪检测的准确性,以更好地规范医院床旁血糖仪的使用。     

床旁检测血糖和HbAlc的准确性及其应用价值

目的评价床旁检测（POCT）血糖和糖化血红蛋白（HbAlc）的准确性及其应用价值。方法对88例疑似糖尿病者行POCT方法测定HbAlc和实验室方法测定血浆血糖及HbAlc。将POCT方法测定毛细血管血糖及HbAlc的结果与相应静脉血的实验室测定结果作比较，评估POCT与实验室方法检测血糖和HbAlc的相关系数、平均偏差和一致性限度（LOA）等，进行横断面研究。结果两种方法测定值的相关系数为：血糖r=0．98，HbAlc r=0．95。血糖的平均偏差为0．36mmol／L（95％CI：0．13～0．62，LOA：-2．07～2．79mmol／L；P=0．007），HbAlc的平均偏差为0．02％（95％CI：-0．07％～0．09％；LOA：-0．66％～0．68％；P=0．95）。结论POCT检测HbAlc的结果准确可靠，方便实用，适于社区居民现场检测，以监测DM的疗效；而POCT检测血糖的结果尚需通过实验室血糖检测进行定期校正，不能直接用于DM诊断。     

两种抗凝血作为POCT血糖仪比对物的评价

[目的]探讨肝素和EDTA抗凝血POCT血糖仪血糖（Glu）检测结果是否存在差异。[方法]采集两种抗凝血,用八台POCT血糖仪（以下简称“仪器1—8”）和全自动干化学仪（以下简称“干化学仪”）检测血糖,以干化学仪检测值为目标“靶值”,将两种抗凝血POCT血糖仪检测结果与之比对,计算偏差,以体外诊断检验系统自测用血糖监测系统通用技术条件（简称“通用技术条件”,GB／T19634—2005）为依据,Glu〉4．2mmo]／L,相对偏差≤20％结果为合格。Glu≤4．2mmo]／L,绝对偏差〈0．83mmol／L为合格,本次比对以每台仪器I〉80％检测结果合格为该血糖仪合格判断标准。然后对每台POCT血糖仪肝素和ED—TA抗凝血检测结果作相关分析。[结果]Glu〉4．2mmol／L时,仪器1—8肝素抗凝血与“靶值”最小偏差0．9％,最大偏差28．6％。EDTA抗凝血与“靶值”最小偏差0．2％,最大偏差30．1％。Glu≤4．2mmol／L时,各台仪器两种抗凝剂检测值与目标“靶值”均小于0．83mmol／L。仪器1—8肝素抗凝静脉血（Y）和EDTA抗凝静脉血（x）相关系数T2〉0．95（P〈0．01）。[结论]本次结果提示,肝素和EDTA抗凝血POCT血糖仪检测血糖没有明显差异。两种抗凝血均可作为POCT血糖仪与强生干化学分析仪性能评价比对物。     

Interference of Accel wipes with LifeScan SureStep Flexx glucose meters

OBJECTIVES: To investigate the cause of a persistent test strip error code, error 2b, appearing on LifeScan SureStep Flexx glucose meters (Johnson and Johnson, Rochester, USA). DESIGN AND METHODS: SaniCloth Plus (The Dynarex Corporation, Orangeburg, USA), CaviWipes XL (Metrex, Orange, USA), and Accel (HANSA Med Ltd., Mississauga, Canada) sanitizing agents were tested in an attempt to reproduce the error. RESULTS: The error 2b code was encountered when the Accel was used as a cleaning agent, but not when SaniCloth Plus or CaviWipes XL were used. CONCLUSIONS: The hydrogen peroxide contained in Accel (HANSAmed, Ltd., Mississauga, Canada) interferes with the glucose oxidase reaction on the test strip, causing the error 2b code.     

POCT血糖仪比对试验及其质量管理的研究

目的定期监测番禺区中心医院POCT血糖仪的检测结果与生化分析仪血糖测定结果的一致性,了解血糖仪检测质量,规范血糖仪的管理。方法用新鲜乙二胺四乙酸(EDTA)抗凝全血对全院25台POCT血糖仪进行精密度试验,与生化分析仪作比对试验,并对结果进行分析。结果 23台血糖仪检测高、中值标本所得结果的变异系数(CV)在1.7～5.74之间,低值标本结果的标准差0.16～0.39mmol/L,符合国家对血糖检测系统的测量重复性要求;与生化分析仪测定结果比对,23台血糖仪检测5个标本的测定值均小于生化分析仪的测定值,测定值高于4.2mmol/L,其偏倚在-12～5.6之间,测定值低于4.2mmol/L,二者差异为0.11～0.79mmol/L,偏差均符合临床实和验室标准化协会对POCT血糖仪的准确度要求。结论 POCT血糖仪的精密度和准确度在可接受范围内,血糖仪的检测结果可信,人员培训与完善的质量管理是保证血糖仪检验质量的重要措施。     

床旁检验血糖仪与生化分析仪测定血糖的比对分析

目的 对床旁检验(POCT)血糖仪与生化分析仪血糖结果准确度进行比对分析.方法 每年2次分别用50份样品对中山市博爱医院血糖仪和生化分析仪同时检测血糖,进行准确度比对分析.结果 血糖仪的合格率明显逐年上升;血糖仪的不合格台数和不合格样品份数也明显逐年下降.结论 每年2次POCT血糖仪与生化分析仪血糖结果准确度比对对加强血糖仪的管理十分有效,可明显提高血糖仪的准确度,必须坚持开展.     

New "plasma referenced" POCT glucose monitoring systems--are they suitable for glucose monitoring and diagnosis of diabetes?

BACKGROUND: Results from portable glucose meters should be reported as plasma values as recommended by IFCC. Three new "plasma calibrated" blood glucose meters (Abbott Precision Xcceed, Bayer Ascensia Contour and Roche Accu-Chek Aviva) were compared against laboratory venous plasma glucose measurements to determine their suitability for patient monitoring and diabetes diagnosis. METHODS: 115 capillary blood samples were analyzed on each of the three meters and compared to venous plasma measurements on the Dade Behring RXL analyzer (Hexokinase method). RESULTS: We found a significant positive bias of all meters compared to the laboratory reference method. Deviations of more than 10% were seen in more than a third of all glucose values in all three devices. 13%, 8.7% and 10.4%, respectively, of the values from the Abbott, Bayer and Roche devices fell in zone B or C of the Parkes' error grid. CONCLUSIONS: Neither glucose meter met the ADA or the NACB goals and should therefore not be used as screening tests to diagnose diabetes but are well suitable for patient monitoring.     

即时检验血糖仪检测指尖血及静脉全血的血糖结果比对分析

目的探讨指尖毛细血管血及抗凝静脉全血在即时检验(POCT)血糖仪检测结果的可行性。方法分别采取指尖血及静脉血22例,用POCT血糖仪检测血糖,同时在生化分析仪上检测血浆葡萄糖,对两部位血样检测结果与生化分析仪检测结果的偏倚程度进行比对。结果两部位血样POCT血糖仪检测结果与生化分析仪检测结果比对均为负偏倚,偏倚范围最低为-1.5%,最高为-13.9%,均未大于20%;静脉全血血糖偏倚比指尖血血糖偏倚程度高,两偏倚比较差异有统计学意义(P<0.01)。结论无论采用指尖血还是静脉全血,其POCT结果都可以接受,但采用指尖血样其检测结果更接近血浆葡萄糖。     

Evaluation of a glucose meter against analytical quality specifications for hospital use

BACKGROUND: The value of glucose meters in point of care testing (POCT) by medical professionals and self monitoring of blood glucose (SMBG) by patients is well established. We evaluated the SureSteppFlexx glucose meter against objective targets for imprecision and total error (TE). METHODS: The SureStepFlexx blood glucose system uses a reflectance-based glucose oxidase (GO) method and reports plasma-equivalent glucose values. The reference method was the Beckman LX20 Pro glucose oxidase/oxygen electrode method. Patient samples and commercial aqueous, quality control (QC) material were used to assess imprecision. To determine total error of the meters, results obtained on patient heparinized blood were compared against results obtained by the reference method using plasma. Analyses were carried out by an experienced nurse and technologist. RESULTS: Both operators achieved imprecision of < or =5% for all measurements. Overall, the percentage of results deviating from the total error targets were 0-21% and 4-13% for the nurse and technologist, respectively. Compared with earlier studies, the percentages of reported results outside the < or =10% and < or =5% American Diabetes Association (ADA) criteria are significantly lower. CONCLUSIONS: The SureSteppFlexx glucose meter meets analytical quality requirements and is suitable for POCT use in our hospital. We propose a tiered approach and suggest minimum, desirable and optimum total error targets for glucose meters of < or =5%, 7.9% and 13%, respectively.     

分析两种不同检测方式检测血糖结果的可比性

目的：对快速血糖仪与生化分析仪所测量的血糖值之间的准确性和相关性进行探讨和分析。方法收集该校附属医院2011年3月至2013年3月进行血糖检测的患者500例,根据血糖值分为3组,分别采用快速血糖仪与生化分析仪对患者的血糖值进行测量,并记录测量结果,分析快速血糖仪测量结果与生化分析仪测量结果的差异。结果根据美国临床实验室标准化委员会（NCCLS）2002年发布的葡萄糖 POCT 应用准则的要求,15台血糖仪中有4台血糖仪在高血糖浓度水平和1台血糖仪在低血糖浓度水平均超出要求范围。结论血糖仪能够很快提供患者的血糖值,但在血糖水平较高时,差异较大,临床上应该给予重视。     

血糖仪准确性评价方法探索

目的对宜宾市第二人民医院临床科室床旁检验(POCT)血糖仪精密度及准确度进行评价,探索一种既能保证检测结果的准确性,又能符合实际情况的质控方法。方法用厂家自带高、中、低值质控液对所有血糖仪做平行性试验;选高值质控CV最大的一台血糖仪测定高、中、低质控品20次,计算仪器的精密度;按美国临床实验室标准化委员会方法学评价文件(EP9)对POCT血糖仪测定的血糖与7600生化仪测定的血糖结果进行对比;按卫办医政发[2010]209号对POCT血糖仪测定的血糖与7600生化仪测定的血糖结果进行对比。结果 79台新投入仪器一致性良好;精密度均小于5%;POCT血糖仪与7600生化分析仪相关系数(r)=0.992 7,相关性好,但20%标本的偏差不满足EP9判断标准;根据卫办医政发[2010]209号质控准则79台仪器准确性良好。结论血糖质控标准建议使用卫办医政发[2010]209号,但多台血糖仪宜先做平行试验,再选出CV较大的仪器用该标准进行比对分析,便于更好地节约成本。     

Comparison of POCT and central laboratory blood glucose results using arterial, capillary, and venous samples from MICU patients on a tight glycemic protocol

BACKGROUND: Point of care (POC) glucose meters are routinely used to monitor glucose levels for patients on tight glycemic control therapy. We determined if glucose values were different for a POC glucose meter as compared to the main clinical laboratory for medical intensive care unit patients on a tight glycemic protocol and whether the site of blood sampling had a significant impact on glucose values. METHODS: Eighty-four patients (114 paired samples) who were on a tight glycemic protocol in the period November 2005 through August 2006 were enrolled. After simultaneous blood draws, we compared the glucose levels for the glucose meter (arterial/venous/capillary), blood gas (arterial/venous), and central clinical laboratory (serum/plasma from arterial/venous samples). RESULTS: The mean glucose levels of all arterial/venous/fingerstick samples using the glucose meter demonstrated a positive bias of 0.7-0.9 mmol/l (12.6-16.2 mg/dl) (p<0.001) relative to central laboratory venous plasma. There was also a smaller positive (0.1-0.3 mmol/l or 1.8-5.4 mg/dl, p<0.05) bias for arterial/venous blood gas samples and laboratory arterial serum/plasma glucose samples. Using Parkes error grid analysis we were able to show that the bias for arterial or venous POC glucose results would have not impacted clinical care. This was not the case, however, for fingerstick sampling where a high bias could have significantly impacted clinical care. Additionally, in 3 fingerstick samples a severe underestimation (<46% of the central laboratory plasma result) was found. CONCLUSION: Glucose meters using arterial/venous whole blood may be utilized in the MICU; however, due to the increased variability of results we do not recommend the routine use of capillary blood sampling for monitoring glucose levels in the MICU setting.     

Evaluation of Roche Accu-Chek Go and Medisense Optium blood glucose meters

BACKGROUND: We examined the analytical performance of two Roche Accu-Chek Go meters (reporting whole blood glucose) and two Medisense Optium meters (reporting plasma glucose) against laboratory plasma glucose measurement. METHODS: One hundred and twenty heparinized whole blood specimens were analyzed in duplicate on each of the four meters and compared to plasma glucose measurement on the Roche DP Modular system (glucose oxidase methodology). RESULTS: There was a significant difference in imprecision between the two Medisense meters (CV 3.7% and 4.9%), and between the Roche (CV 2.5% and 2.9%) and Medisense meters. The two Roche meters showed a consistent positive bias compared to the Modular, while the two Medisense meters over-read at low glucose concentrations and under-read at high glucose concentrations. Total error for the Roche meters averaged 10.8% and 8.9%, and for the Medisense meters averaged 12.5% and 15.6%, respectively. All results for all meters fell in error grid zones A and B. CONCLUSION: Neither meter met the ADA, CLIA or biological variation goals, although they came close to the NCCLS guideline. Neither meter reported plasma glucose equivalents. The Accu-Chek Go performed slightly better than the Optium meter, but the positive bias was puzzling and requires further explanation.     

不同类型标本及仪器对血糖检测结果的影响

目的探讨罗氏血糖仪与全自动生化分析仪检测不同类型标本血糖水平的差异。方法收集2017年2-5月于南京市栖霞区妇幼保健院就诊患者及体检者的末梢血及静脉血标本104例。比较罗氏血糖仪检测的末梢血(末梢血POCT组)、静脉全血(全血POCT组)、静脉血浆(血浆POCT组)、静脉血清(血清POCT组)和全自动生化分析仪检测的静脉血浆(血浆生化仪组)、静脉血清(血清生化仪组)的血糖水平;验证罗氏血糖仪的精密度及线性范围。结果3台罗氏血糖仪的批内CV和批间CV均小于7.5%,符合判定标准。罗氏血糖仪检测的静脉全血血糖水平在1.1~24.4 mmol/L呈线性,R 2>0.95;静脉血清血糖水平在0.6~25.3 mmol/L呈线性,R 2>0.95,均符合线性要求。血糖水平<6 mmol/L的检测结果中,全血POCT组血糖水平低于其余各组(P<0.05);血糖水平为6~10 mmol/L的检测结果中,全血POCT组血糖水平低于血浆POCT组、血清POCT组、血浆生化仪组及血清生化仪组(P<0.05)。各组检测的血糖水平两两之间均具有显著相关性(r>0.99,P<0.05)。结论罗氏血糖仪检测精密度高,具有良好的线性,末梢血、静脉血浆、静脉血清等标本在血糖仪上的检测结果与全自动生化分析仪检测结果具有较好的可比性;罗氏血糖仪检测静脉全血时需进行一定程度的校正以保证结果的准确性。     

Evaluation and quality assessment of glucose concentration measurement in blood by point-of-care testing devices.

BACKGROUND: In this study the analytical performance of eight glucose point-of-care testing (POCT) devices was evaluated. For this purpose, POCT measurement of glucose in heparinized blood collected from patients was paralleled by determination of the glucose concentration in the respective plasma by an analyzer (Hitachi 917) in the central laboratory, providing traceable results. METHODS: Trueness of POCT measurements was studied by comparing the plasma POCT values (mean of five measurements) with the results from the traceable measurement procedure (TMP). RESULTS: The percentage of POCT results within +/-6% of the TMP mean value ranged from 24% to 50%, depending on the POCT device. Within the reference interval of plasma glucose (4.4-6.0 mmol/L), up to 67% of the POCT values were lower than 4.4 mmol/L, leading to a false diagnosis of hypoglycemia. In the hypoglycemic range (<4.4 mmol/L) up to 29% of the POCT analyses were false normoglycemic. CONCLUSIONS: In conclusion, this study shows an insufficient trueness of glucose measurements by POCT devices in the normo- and hypoglycemic range. To improve quality assessment, sample splitting and simultaneous measurement of blood glucose concentration every 4 weeks by POCT devices and of plasma glucose concentration by a reliable TMP is recommended.     

Performance of three blood glucose meters

OBJECTIVE: To evaluate the performance of three blood glucose meters. METHODS: The One Touch II (LifeScan, Milpitas, CA), Glucometer Elite (Bayer, Elkhart, IN), and Accu-Chek Advantage (Boehringer Mannheim, Indianapolis, IN) were compared with a reference laboratory method (Technicon Chem System, Tarrytown, NY). Blood glucose meters used in this study were validated by a clinically oriented approach known as the error grid analysis (EGA), for which the performance of the meters was compared to a laboratory standard, and by the criteria of the American Diabetes Association (ADA). Limits of agreement were evaluated using differences from the reference laboratory method and 95% Cls. Capillary blood was obtained from study participants in fasting state with the morning blood draw and tested on the three meters simultaneously. RESULTS: A total of 120 blood glucose meter readings were analyzed; values ranged from 62 to 396 mg/dL. For all three meters, at least 75% of the capillary blood glucose values fell into zone A (acceptable) of the EGA. The number of values falling into zone B (unacceptable) were 10, 8, and 6 for the Accu-Chek Advantage, the One Touch II, and the Glucometer Elite, respectively. Only 15-25% of the meter glucose readings met the ADA criteria of being within 5% of the laboratory standard. The mean difference from the reference values was least with the Glucometer Elite. CONCLUSIONS: The majority of blood glucose determinations obtained on the meters used in this study were within the acceptable limits using the EGA. The Glucometer Elite meter had the fewest values in the unacceptable range and had the least mean difference from reference laboratory values.     

Analytical performance of glucometers used for routine glucose self-monitoring of diabetic patients

BACKGROUND: Glucometry is an essential part of diabetes treatment, but so far, no standard quality control procedure verifying blood glucose meter results is available. In this study, we evaluated the analytical performance of eight glucose meters: GX and Esprit (Bayer Diagn.), MediSense Card Sensor, ExacTech (MediSense) with strips Selfcare (Cambridge Diagn), One Touch Basic, One Touch II, One Touch Profile (Lifescan) and Glucotrend (Boehringer Mannheim/Roche). METHODS: The evaluation included within-run imprecision, linearity, comparison with the laboratory method and calculation of differences between individual glucometers. RESULTS: Within-run imprecision ranged from 1.5% to 4.5%, linearity assessed as the correlation between measured and calculated glucose concentrations yielded r(2) values from 0.97 to 0.981. Analytical bias of glucose concentration values obtained by the glucometry amounted from 0.14% to 16.9% of values measured by the laboratory method. Bias higher than 5% was found for One Touch Basic, II and Profile meters (however, glucose concentrations in plasma obtained by the laboratory method One Touch meters showed analytical bias from 3.0% to 8.8%). The regression analysis yielded slope values from 0.77 to 1.09 and r(2) values from 0.86 to 0.98. The best correlations with the laboratory method were found for One Touch Basic, II Profile, Glucotrend and Esprit meters. The calculated differences between the individual glucose meters can constitute 0.02-1.49 mmol/l (0.96-26.9%) at glucose concentration 5.55 mmol/l, and 0.16-4.16 mmol/l (0.96-24.96%) at glucose concentration 16.67 mmol/l. Error grid analyses have shown that Glucometers One Touch Basic and One Touch Profile yielded all results in zone A (acceptable). The remaining glucometers yielded 1-7% of results in zones B (insignificant errors), C or D (lack of detection and treatment). CONCLUSIONS: All studied glucometers had both small deviation from laboratory reference values (<10%) and high concurrence with results obtained by the laboratory method.     

POCT血糖仪与全自动生化分析仪检测血葡萄糖结果对比分析

目的 探讨POCT快速血糖仪与自动生化分析仪检测血糖结果的相关性及差异性,为临床提供参考.方法 用5个浓度的质控品和患者标本在POCT血糖仪上进行检测,连续测试5 d,计算变异系数(CV).用POCT快速血糖仪和全自动生化分析仪对54例患者的末梢血和静脉血浆进行血糖检测,测得的数据用SPSS统计学软件进行分析,评价POCT血糖仪与全自动生化仪与测定结果的相关性.结果 5个浓度的质控品和患者标本在POCT血糖仪上所测结果的CV在2.6%～4.2%,低于厂家的声明,也符合国家对血糖检测系统的测量重复性要求(CV不超过7.5%).雅培Optium Xceed血糖仪与全自动生化仪所测结果的相关系数(r)=0.974,相关性较好.结论 雅培Optium Xceed血糖仪在精密度和准确度等方面均符合临床要求,其检测结果接近血浆葡萄糖检测结果.但是POCT血糖仪仅可用于患者空腹血糖的监测或血糖过筛实验,不能代替实验室血糖的检测结果作为确诊实验.