Standardization, Quality Assurance, and Emerging Diagnostic Technologies in Hemostasis

This issue of Seminars in Thrombosis and Hemostasis reviews several aspects of the standardization and quality assurance in laboratory hemostasis as well as noting the emergence of several new diagnostic technologies in the field.

In the first contribution, Olson et al discuss the formation and initial work of External Quality Assurance in Thrombosis and Hemostasis (EQATH), an international collaboration of External Quality Assurance (EQA) programs with a common interest in improving the quality of hemostasis testing. Formed in 2005, the organization currently includes 11 EQA programs from 10 countries. EQATH has several goals, including the exchange of information and sharing of specimens to improve practice and standards, and to provide outreach and support to less developed countries without EQA. An initial cross-EQA survey of programs has revealed some variation in the structure, size, and complexity of the different programs. Of note, most EQA programs have deemed status from an accrediting or licensing agency, and successful participation satisfied requirements for accreditation for the participating laboratory. This type of benchmarking and cooperative activity among EQA programs should lead to improvement of EQA programs, and by natural progression, improvement of laboratory hemostasis practice in general.

Adams et al, representing the Australasian Society of Thrombosis and Haemostasis, provide some case examples to help review several emerging diagnostic technologies in hemostasis. Their informative article attempts to answer several important questions related to whether (1) new technologies can help predict the likelihood of thrombosis recurrence, (2) an understanding of the role of a disintegrin-like and metalloprotease with thrombospondin type 1 motifs (ADAMTS13) in microangiopathy has improved diagnostic methods for this disorder, and (3) thrombelastography has allowed better definition of bleeding risk than conventional hemostasis assays, especially in settings of acute hemostatic pathology. In terms of the first question, the relative merits of D-dimer testing, thrombin generation assays and the overall hemostatic potential are discussed. The second part of the article describes the history of ADAMTS13 from identification to current testing strategies. Assays that were initially time consuming and cumbersome are making way for rapid and automated tests, which are necessary for the timely confirmation and appropriate treatment of potentially catastrophic clinical disorders such as thrombotic thrombocytopenic purpura. A final section on the potential role of thrombelastography, particularly in acute care situations, completes the review.

Favaloro and Bonar review quality assurance in hemostasis from the perspective of the Royal College of Pathologists of Australasia (RCPA) Quality Assurance Program (QAP). This QAP deals with most of the current assays of hemostasis, and the contribution also notes several emerging diagnostic technologies that have arisen in the geographic area covered by the RCPA program. For von Willebrand disease (vWD) evaluations, nearly 50 plasma samples have been dispatched to survey participants over time, including representative samples from normal individuals plus all of the major vWD subtypes (i.e., types 1, 2A, 2B, 2M, 2N, and 3). Thrombophilia-associated tests assessed include activated protein C resistance, lupus anticoagulant (LA), and deficiencies of protein C, protein S, and antithrombin. Other tests include factor assays and inhibitors, D-dimer, heparin/anti-Xa assays, anticardiolipin antibody, and anti-beta₂-glycoprotein I antibody testing, and the genetic tests associated with thrombophilia such as factor (F) V Leiden and the prothrombin gene. The findings from this group have helped to identify several problems within laboratory diagnostics, including diagnostic errors; they also highlight how improvements in hemostasis testing can be achieved. One of the better examples from this QAP is that the addition of von Willebrand factor:collagen-binding activity assay testing in the vWD test panel workup leads to substantial reductions in the misidentification of vWD.

Jennings et al review quality assurance in hemostasis from the perspective of the United Kingdom National External Quality Assessment Scheme (NEQAS) program. In the United Kingdom, point-of-care (POC) testing for monitoring of anticoagulant therapy is quickly emerging as a particular challenge to the EQA program. Ensuring an accurate result from these POC instruments is just as important as ensuring accuracy in routine hemostasis laboratories; the result will still guide therapy, and an incorrect result may lead to inappropriate dosage with serious adverse consequences. Part of the challenge for any EQA program is to develop a process that ensures that assessment leads to precision by end users of POC instruments that is equal to that obtained by health care professionals. The NEQAS group members also share their experience with laboratory testing for FVIII, the clotting factor missing in people with hemophilia A. Different results can be obtained using the same sample depending on the methodology used (one-stage clotting versus two-stage clotting versus chromogenic), the plasma standard used, and whether a fresh or stored assay calibration curve is used. Such findings raise important implications not only in terms of test accuracy, but also subsequent clinical management (potential for undertreatment or overtreatment with factor replacement therapy), and particularly related to the newer recombinant factor replacement products. Additional information related to LA testing, genetic testing for thrombophilia, D-dimer testing, and emerging technologies such as thrombin generation, thromboelastography, and thromboelastometry, within the context of EQA, is also featured in this article.

Cunningham et al review quality assurance in hemostasis from the perspective of the College of American Pathologists (CAP) program based in the United States. This QAP has evaluated the performance characteristics of a variety of hemostasis tests over a long period of time (since 1963 for some tests). These include routine tests such as the prothrombin time and activated partial thromboplastin time, plus various coagulation factor activity assays, vWF assays, unfractionated heparin monitoring, LA testing, and most recently, platelet function. There are major benefits to EQA, including enhanced patient care and safety through improved laboratory testing, characterization of test accuracy and precision across multiple methods, identification of poor performance in clinical laboratories for targeted improvement, and satisfaction of accreditation and regulatory requirements. Test precision for factor assays is still seen as a cause of concern by CAP, as are some specific methodologies in other assay systems. This is the first QAP organization to initiate EQA for platelet function (for the PFA-100 test system). This has been achieved using a novel approach of supplying specimen tubes without samples, one containing no additives and the other containing platelet glycoprotein IIb/IIIa inhibitor, for use with on-site collected blood.

Spannagl et al review quality assurance in hemostasis in Germany via the EQA program INSTAND (Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien e.v.), with a particular focus on government regulation and patient outcome. Unlike the NEQAS program, this QAP has decided against EQA for POC instruments for monitoring of anticoagulant therapy. Of additional interest, the prothrombin time and activated partial thromboplastin time tests are under special mandatory regulation in terms of acceptability criteria, with results, respectively, within 23% and 21% deviation from the mean values acceptable. Additional comments regarding other tests assessed by this QAP complete the article.

Mammen, Nair, and Srivastava share their experience with the establishment of an EQA program in India. This fledgling QAP has had an interesting journey over the last few years, beginning in the year 2000 with 25 laboratories associated with the chapters of the Hemophilia Federation (India), and with samples and analysis of results supported by United Kingdom NEQAS. This was converted to a national program in 2003, in association with the Indian Society of Haematology and Transfusion Medicine, and currently more than 100 laboratories are registered in the program. The program has helped identify many causes for unacceptable performance. The challenges ahead are to increase participation, improve reporting of results, and provide individualized support to laboratories to improve performance when necessary. Unlike the situation in developed countries, there is no mandatory requirement for laboratories within India to participate in an EQA program. It is pleasing to acknowledge the assistance of NEQAS in the development of this program, and it is hoped that other developed EQA programs would similarly incorporate such aims, perhaps through the activities of EQATH, as mentioned.

Hayward and Eikelboom provide a state-of-the-art contribution on quality assurance in platelet function, related both to classical aggregation procedures and to a large range of newly emerging technologies. These tests are used widely by hemostasis laboratories but are not currently subjected to any EQA, due to the complexity of the tests involved and the difficulties in providing appropriate material for quality assurance and multilaboratory testing purposes. Platelet function testing also lacks specific and appropriate guidelines, and is poorly standardized among laboratories. Thus, despite common laboratory usage and ongoing clinical requests, the clinical utility of much platelet function data will remain uncertain, particularly when applied to the question of monitoring antiplatelet drug therapy, until appropriate standardization and EQA is available.

Hubbard provides a current synopsis of the availability and impact of international biological standards for coagulation factors and inhibitors through the National Institute for Biological Standards and Control (NIBSC). The use of such standards has proved extremely successful in promoting global harmonization of estimates between laboratories and methods. Most plasma coagulation factors and inhibitors are calibrated in International Units (IU), which are defined as the amount of analyte in 1 mL of normal pooled plasma. Adoption of the IU has provided clarity in the definition of normal and abnormal states, and has facilitated dose calculation for replacement therapy. Plasma standards are currently available for the following: FII, FV, FVII, FVIII, FIX, FX, FXI, FXIII, fibrinogen, von Willebrand factor, antithrombin, protein C, and protein S. Concentrate standards are currently available for the following: FII, FVII, FVIIa, FVIII, FIX, FIXa, FX, fibrinogen, von Willebrand factor, antithrombin, and thrombin. The initial experience of NIBSC may also prove valuable in the future as we move to deal with the challenges of standardization associated with products of bioengineering.

Finally, Favaloro provides a commentary on standardization, regulation, quality assurance, and emerging technologies within hemostasis. The benefits of these processes are substantial, and more often than not, generally are obvious. In contrast, there are some problems and issues related to the processes, which often tend to be less evident. Part of the problem relates to clinical pressures to perform testing in routine diagnostics that is still under clinical evaluation or of uncertain benefit. Regulatory pressures, intended to provide standardization benefits, can also have adverse effects, including reduction of technologies to inferior test systems, or extended delays to the introduction of new technologies.

I thank all of the authors for their excellent contributions in this issue. The subject of quality assurance is poorly understood by many of my clinical colleagues, who seem to take for granted that the test result they obtain on their patient from their testing laboratory is unquestionably accurate. The simple fact is that this would not be so without the external peer review we scientists undertake in the EQA process. Any laboratory that can test for a particular analyte can provide a clinician with a number. However, unless that laboratory also successfully participates in continued proficiency testing or EQA, we should be advised that that number may not necessarily be the right number.