凝血酶原时间ISI/INR系统测定中的一些问题及改进意见

目的对凝血酶原时间(PT)测定ISI/INR系统出现的一些问题提出相应的改进建议。方法对上海市12家医院在用的仪器和匹配的PT试剂,对日常使用的正常血浆平均凝血酶原时间(MNPT)作调研实测,将结果进行分析;调查试剂的仪器特定(spec ific)国际敏感度指数(ISI)值与世界卫生组织(WHO)的手工法ISI定标值之间的差异;用2种已知国际标准化比值(INR)的异常参比血浆代替WHO的ISI系统作质控并行比较。结果12家中有4家日常使用的平均正常凝血酶原时间(MNPT)明显偏离实测值,分别为0.8、0.9、1.0和1.8 s。用WHO CRM149R参比,用手工法标定的凝血活酶和109 mmol枸橼酸钠抗凝的不同PT值血标本,在Sysm ex1500型、C.2000型仪器上测定试剂的仪器特定ISI,其结果比手工法分别减少4.1%和4.7%,但采用HEPES-枸橼酸钠抗凝剂标本时,2种型号仪器的特定ISI比手工法分别减少16.7%及7.7%。用已知INR异常参比血浆,国产品与进口品对照的结果良好。结论受调研12家中,有4家血凝分析仪器调研时实测的MNPT明显偏离日常使用值。有几家医院试剂的仪器特定ISI值也存在问题,建议纠正。用已知INR异常参比血浆代替WHO手工法标定凝血活酶ISI法作质控,使用简便,又不需MNPT参数,值得推广。     

凝血酶原时间-国际标准化比值的建立

目的 探讨在测定凝血酶原时间-国际标准化比值（PT-INR）实验过程中建立区域性国际敏感度指数（Local ISI）的方法.方法 在ACL TOP-700全自动血凝仪上使用ISI Calibrate血浆建立INR标准曲线,进行回归分析,计算Local ISI和区域性平均正常PT（Local MNPT）值,并用INRValidte血浆验证INR值.结果 A、B、C、D ISI Calibrate血浆PT值分别为11.75、30.80、43.55、77.55 s.实验所得INR标准曲线的回归方程为：Y= 1.258 4X＋2.412 7,Local ISI为0.79,Local MNPT为11.16,R2为0.999 5,斜率CV为0.6%.利用Local ISI和Local MNPT测定3种不同水平INRValidte血浆的PT-INR平均值分别为2.16、2.90、4.50.结论 利用Local ISI和Local MNPT值测定INRValidte血浆PT-INR具有可信性,是一种实用、可行的校正手段.     

口服抗凝治疗中凝血酶原时间测定标准化意义

目的:比较三种凝血活酶试剂对口服华法令抗凝治疗病人血标本测得的血浆凝血酶原时间(PTs),凝血酶原时间比率(PTR)和国际标准化比率(INR)间相关性及三种试剂的敏感性。方法:采用Quick一期法在凝血仪上测定50例华法令抗凝治疗病人的PT、PTR及INR值。结果:各组间PT和PTR均有显著性差异(均P<0.01),但各组间INR结果没有显著性差异(P>0.05);不同ISI凝血活酶所测定的INR变异系数不同,ISI的值越高,INR的CV值越大。结论:三种试剂均可用于口服抗凝剂治疗的PT监测,但必须用INR报告结果,便于室间质评。应选用JSI值低的组织凝血活酶试剂,以确保PT测定结果的准确性。     

血浆凝血酶原时间测定中建立仪器区域国际敏感指数的实验探讨

目的　探讨临床口服抗凝治疗时血浆凝血酶原时间 (PT)监测的标准化 ,为临床提供比较准确的PT 国际标准化比值 (PT INR)结果。方法　使用PT INR校准血浆建立PT测定试剂在不同仪器上的区域性国际敏感度指数 (LocalISI) ,以此对新鲜血浆进行PT测定。结果　未经LocalISI校准的PT试剂测定血浆的PT时 ,INR结果差异较大 (P <0 .0 1)。试剂经LocalISI校准后 ,测定血浆PT时 ,INR结果良好 (P >0 .0 5及Kap pa >0 .75 )。 结论　在PT测定时 ,只要建立仪器和测定试剂的LocalISI ,INR结果就具有较好的一致性。     

凝血质的标定及凝血酶原时间标准化的临床应用

本文根据ＷＨＯ参比方法用已知国际敏感度指数的凝血质对两种未知ＩＳＩ的凝血质进行了标定，并以标准形式报告ＰＴ结果。     

凝血酶原时间测定的INR的若干问题

凝血酶原时间（PT）是当前监测口服抗凝药物的主要实验室指标。长期以来，PT的报告方式一直是多种多样的。例如，直接报告时间（秒）、百分活度、比率和PT指数等等。由于PT试验受试剂、组织来源不同、仪器和操作技术等多种因素的影响，其结果可发生很大的差异。为解决此问题，WHO于1979～1983年提出参比凝血活酶校正市售凝血活酶和国际标准化比率（internationalnormalizedratio，INR）作为标准化的PT报告方式。其公式为：INR-PTR”’式中，PTR是PT比率，即：被检测的PT（秒）／正常对照均值PT（秒）。（正常均值至少用20份正…     

凝血酶原时间国际标准化临床应用

凝血酶原时间(PT)是检测外源性凝血因子,以及临床口服抗凝剂治疗剂量控制的重要手段,也是手术前对外源性凝血因子筛选的常规实验.但由于不同的凝血质对结果影响很大,造成可比性很差,失去科学性.笔者根据WHO参比方法,用已知国际敏感度指数(ISI),通过国际标准化比值(INR)的计算,达到统一标准,具有可比性,应用于临床准确可靠.     

标准曲线法测定凝血酶原时间国际标准化比值

目的利用ＩＮＲ质控血浆，建立一种简便、易于临床实验室开展的凝血酶原时间国际标准化检测方法，并对其进行初步评价。方法用ＷＨＯ推荐的手工检测方法标定ＩＮＲ质控血浆ＩＮＲ值作为ＩＮＲ参比血浆，自动化凝血仪检测其ＰＴ凝固时间，建立ＩＮＲ标准曲线；利用标准曲线测定待检血浆的ＩＮＲ值。比较两种常用凝血活酶试剂并分别用ＩＮＲ公式计算法和本方法检测ＩＮＲ参比血浆的ＩＮＲ值，评价其线性、重复性以及不同试剂之间的重复性。用ＷＨＯ推荐的ＩＮＲ公式计算方法，分别用手工和仪器检测 ４７例临床标本 ＩＮＲ值，并与本方法进行比较。结果血浆 ＩＮＲ值与ＰＴ凝固时间有很好的线性关系（ｒ＝ ０．９９５）；单种试剂本方法检测ＩＮＲ参比血浆ＩＮＲ值，重复性良好（ＣＶ％＜２％）；两种不同试剂测定血浆ＩＮＲ值，结果显示本方法的重复性优于ＩＮＲ公式计算法；本方法测定结果与 ＷＨＯ推荐的手工法测定结果有很好的相关（ｒ＝０．９９），并比 ＩＮＲ 公式计算法检测的 ＩＮＲ值更接近手工检测值（ｔ检验Ｐ值：０．００３对０．０７３）。结论本方法能检测抗凝治疗患者血浆的ＩＮＲ值。用自动化仪器检测ＰＴ时，本方法较ＩＮＲ公式计算法简便易行，干扰因素少，其检测结果可能更接近血浆Ｉ     

凝血酶原时间测定标准化的几点探讨

目的 探讨不同试剂、报告方式对凝血酶原时间（PT）测定结果的影响。以及标本自身因素对仪器测定PT的影响。方法 采用两种不同国际敏感度指数（ISI）试剂、测定正常、异常两组标本,结果用秒数,凝血酶时间比值（PTR）、国际标准化比率（INR）表达, 对检测结果做统计学分析,另用梯度溶血、黄疸、脂血标本观察仪器测定PT的干扰情况。结果 两种试剂检测抗凝疗法病人血浆时,秒数和PTR差异显著（P＜0．05）,而用INR表达的结果则无显著差异（P＞0．05）。中度以上的溶血、黄疸、脂血标本干扰仪器测定。结论 监测抗凝药物治疗时,应用INR方式报告PT值,尽量采用ISI接近1．0的试剂、中度以上的溶血、黄疸、脂血标本最好用手工法测定。     

The effect of instruments for prothrombin time testing on the international normalized ratio

Prothrombin time (PT) testing is used for monitoring oral anticoagulant therapy, its result being usually expressed as international normalized ratio (INR). This is done using the international sensitivity index (ISI) specific of thromboplastin employed to carry out the test. In this way a good PT standardization may be achieved although the instruments used to calibrate the thromboplastins might influence the ISI value. Presented at the ‘2nd International Symposium on Standardization and Quality Control of Coagulation Tests: Implications for the Clinical Laboratory’, Rome, September 28–29, 1989.     

Coagulometer international sensitivity index (ISI) derivation,a rapid method using the prothrombin time/international normalized ratio (PT/INR) Line: a multicenter study

Summary. Background: The original WHO procedure for prothrombin time (PT) standardization has been almost entirely abandoned because of the universal use of PT coagulometers. These often give different international normalized ratio (INR) results from the manual method, between individual makes of instruments and with instruments from the same manufacture. Method A simple procedure is required to derive local INR with coagulometers. The PT/INR Line method has recently been developed using five European Concerted Action on Anticoagulation (ECAA) certified plasmas to derive local INR. This procedure has been modified to derive a coagulometer PT/INR Line providing International Sensitivity Index (ISI) and mean normal PT (MNPT) for coagulometers and give local INR. Results have been compared with conventional ISI calibrations at the same laboratories. Results: With human thromboplastins, mean ISI by local calibration was 0.93 (range: 0.77–1.16). With the PT/INR Line, mean coagulometer ISI was higher, for example 0.99 (0.84–1.23) but using the PT/INR Line derived MNPT there was no difference in local INR. Between‐centre INR variation of a certified validation plasma was reduced with human and bovine reagents after correction with local ISI calibrations and the PT/INR Line. Conclusion: The PT/INR Line–ISI with its derived MNPT is shown to provide reliable local INR with the 13 different reagent/coagulometer combinations at the 28 centres in this international study.     

Importance of device evaluation for point-of-care prothrombin time international normalized ratio testing programs

OBJECTIVE: To determine the accuracy of 2 commercially available point-of-care devices relative to plasma international normalized ratio (INR) values. PATIENTS AND METHODS: Point-of-care INR testing was performed with the CoaguChek and ProTime 3 devices in consecutive patients attending an anticoagulation clinic between June 18, 2003, and August 6, 2003. Results were compared with plasma INRs using a sensitive thromboplastin (International Sensitivity Index, 1.0). RESULTS: Ninety-four patients agreed to participate in the study. Relative to the plasma INR, values were in agreement +/-0.4 INR unit 82% and 39% of the time for the CoaguChek and ProTime 3 devices, respectively. The mean +/- SD CoaguChek INRs were 0.2+/-0.31 unit lower, whereas ProTime 3 INRs were 0.8+/-0.68 unit higher than plasma INR values. Treatment decisions based on these data would have resulted in inappropriate dose adjustments 10% and 22% of the time for these 2 respective devices. Correlation with plasma was greater for the CoaguChek (r2=0.90) compared with the ProTime 3 device (r2=0.73). CONCLUSIONS: Optimal warfarin treatment requires accurate measurement of the INR. The choice of a point-of-care device for INR management depends on the reliability of INR data generated by the device.     

Poor agreement among prothrombin time international normalized ratio methods: comparison of seven commercial reagents

BACKGROUND: Prothrombin time (PT) has long been the most popular test for monitoring oral anticoagulation therapy. The International Normalized Ratio (INR) was introduced to overcome the problem of marked variation in PT results among laboratories and the various recommendations for patient care. According to this principle, all reagents should be calibrated to give identical results and the same patient care globally. This is necessary for monitoring of single patients and for application of the results of anticoagulation trials and guidelines to clinical practice. METHODS: We took blood samples from 150 patients for whom oral anticoagulation had been prescribed. Plasmas were separated and PTs determined by use of seven commercial reagents and four calibrator sets. The differences in results were assessed by plotting, for each possible pair of methods, the differences in INR values for each sample against the mean INR value (Bland-Altman difference plots). RESULTS: Mean results differed significantly (P <0.001) for 17 of 21 possible paired comparisons of methods. Only two pairs of methods produced very similar results when assessed for problems of substantial differences in INR values; a significant, systematic increase in the difference with INR; and a significant systematic increase in the variation in difference with increasing INR values. CONCLUSIONS: The agreement among several (and perhaps most) commercial INR methods is poor. The failure of current calibration strategies may severely compromise both the monitoring of individual patients and the application of oral anticoagulation guidelines and trial results to clinical practice.     

血浆凝血酶原时间测定中建立仪器区域国际敏感指数的实验探讨

目的探讨临床口服抗凝治疗时血浆凝血酶原时间(PT)监测的标准化,为临床提供比较准确的PT-国际标准化比值(PT-INR)结果.方法使用PT-INR校准血浆建立PT测定试剂在不同仪器上的区域性国际敏感度指数(Local ISI),以此对新鲜血浆进行PT测定.结果未经Local ISI校准的PT试剂测定血浆的PT时,INR结果差异较大(P<0.01).试剂经Local ISI校准后,测定血浆PT时,INR结果良好(P>0.05及Kappa>0.75).结论在PT测定时,只要建立仪器和测定试剂的Local ISI, INR结果就具有较好的一致性.