Quality in Hemostasis and Thrombosis—Part I

Welcome to the latest issue of Seminars in Thrombosis & Hemostasis, this being devoted to the concept of “quality” within the field of thrombosis and hemostasis ([Fig. 1]). This is the first of an expected series of such issues, which will deal with both clinical and laboratory aspects of diagnosis, management, and testing in this field.

Figure 1 Focus on quality in coagulation and hemostasis testing.

The theme for this issue is nicely set with the leading two articles, which underscore the broad concept of “quality,”[1] both in general terms as well as by providing examples within the field of thrombosis and hemostasis. The first contribution is by Mario Plebani and colleagues, who overview the concept of quality testing within hemostasis as critical to ensuring patient safety and optimal clinical and therapeutic management.[2] These authors thoroughly discuss the concept of the brain-to-brain loop for laboratory diagnostics, first introduced by George Lundberg more than three decades ago.[3] According to this pioneering model, the first step in the loop involves the selection of laboratory tests in the brain of the physician caring for the patient, and the final step is the transmission of test results back to the ordering physician. However, there are several intermediary steps, some of which are preanalytical (e.g., identification of patient and blood samples, process of blood collection, and specimen handling); some are analytical, and relate to the actual performance of the test(s); whereas others are postanalytical and involve release of test results into the medical record and further steps such as the physician's reaction to laboratory information, their interpretation of these results, and subsequent appropriate clinical action. The authors propose that hemostasis testing should be viewed within such a paradigm, so that quality throughout the total testing process can be assured. For hemostasis testing, particular attention is required to ensure provision of appropriate test samples in the preanalytical phase.[4] Nevertheless, the timeliness of testing and an appropriate interpretation of test results are also paramount.[5] [6]

The second article by Olson and Harrison[7] is on “event management,” which is a key process to ensuring that laboratories learn from mistakes or failures.[8] Interestingly, the authors assert that currently, laboratories that systematically and effectively learn from failures that occur, especially from small mistakes and problems rather than from consequential adverse events, are rare. An effective event management program, such as that described by the authors, often requires a cultural sea change that emphasizes a process of detection and reporting of errors that is without reprisal. Steps of event management including engagement of the staff, the tools used, the steps of evaluation, the application to all elements of laboratory management, and the culture change necessary are discussed in this article.

The next two articles provide some recommendations on the key preanalytical steps involved in the collection and processing of blood samples destined for testing in hemostasis laboratories. The first article by Lippi et al[9] on sample collection provides a comprehensive guide to ensuring quality specimens for hemostasis testing. As explained by the authors, and also elsewhere,[4] [10] [11] [12] preanalytical activities, especially those directly connected to blood sample collection and handling, are the most vulnerable steps encountered in the testing process. Nevertheless, the receipt of unsuitable samples is commonplace in laboratory practice and represents a serious problem, given that the reliability of test results can be adversely compromised following analysis of these specimens. The article outlines the basic criteria for appropriate and safe venipuncture, including the use of correct technique, appropriate devices and needles, prevention of prolonged venous stasis, collection of nonhemolyzed specimens, the order of draw, and appropriate filling and mixing of primary collection tubes. The authors also summarize results from a recent investigation aimed to identify variation of several hemostasis test results due to underfilling of primary blood tubes, which is still a debated issue.[13]

Adcock-Funk and colleagues[14] then discuss preanalytical variables associated with sample processing, transportation, and storage. These variables include the temperature at which samples are transported and stored; the stability of samples once processed (whether maintained at room temperature, refrigerated, or frozen); methods of centrifugation; as well as the potential impact of using an automated line. Acknowledgment of these variables, as well as understanding their potential impact on assay results, is imperative to the reporting of high quality and accurate results. This article, a perfect companion to the former article, also presents the ideal conditions for sample handling. The article also provides an algorithm, as adapted from a previous publication by these authors,[15] which will permit the matrix identification of unknown specimens that are received as being appropriate (i.e., sodium citrate anticoagulant), but which may alternatively comprise serum, or heparin or EDTA anticoagulated samples.

Armando Tripodi[16] then provides an overview of problems and solutions for testing hemostasis assays while patients are on anticoagulant therapy. Anticoagulant drugs affect several coagulation parameters, either directly or indirectly. These agents include heparins (unfractionated and low molecular weight), vitamin K antagonists such as warfarin and other coumarins, and the new oral anticoagulants such as dabigatran (Pradaxa®, Boehringer Ingelheim, Ingelheim, Germany), rivaroxaban (Xarelto®, Bayer, Leverkusen, Germany), and apixaban (Eliquis®, Pfizer, NY).[17] [18] [19] [20] [21] [22] [23] In general, postponing the performance of laboratory investigation upon discontinuation of the drug, preferably 2 days or more depending on the drug's half-life, is always the preferred option. If this strategy is unfeasible and patients remain on treatment, results of testing will likely be affected and result interpretation then requires great caution and knowledge of the peculiar and differential mechanism of action of the relevant anticoagulant drug being used.

Adam Cuker[24] then continues the discussion of anticoagulant therapy, focusing on unfractionated heparin. This agent remains a widely used anticoagulant for the treatment of venous thromboembolism (VTE) and several other thrombotic and prothrombotic conditions nearly 100 years after its initial discovery. Decades of experience and investigation have contributed to our knowledge of this agent,[25] but crucial questions regarding its optimal use in clinical practice remain unanswered. The aims of this review are to critically examine the evidence for dosing and laboratory monitoring of unfractionated heparin in the management of VTE and highlight areas of uncertainty and future research.

This issue of Seminars in Thrombosis & Hemostasis then changes track slightly to focus on quality issues related to molecular biology testing for inherited thrombophilia disorders. Cooper and colleagues[26] provide a state-of-the-art discussion on this topic, emphasizing that as the understanding of the genetic basis of the inherited thrombophilias has increased over recent years, so too has their routine diagnostic genetic analysis. This review considers methods used to test for the factor V (F5) Leiden mutation and prothrombin 20210A (F2 c.*97G > A) allele, and analysis of the SERPINC1, PROC, and PROS1 genes in cases of antithrombin, protein C, and protein S deficiency, respectively. Issues relating to quality are explored, highlighting where analytical and sample-handling errors may occur. Detection of the FV Leiden mutation and the prothrombin c.*97G > A allele are best performed using real-time-polymerase chain reaction analysis as this relatively simple technique allows their discrimination from rare variants of neighboring nucleotides, not possible using the more time-consuming restriction digestion assays. With the advent of low-cost and high-throughput sequence analysis, direct sequencing has become the first-line method to provide a definitive diagnosis of the inherited deficiencies of natural inhibitors. Large cohort studies have shown that antithrombin and protein C mutations are identified in between 61 and 87% of patients, whereas the detection rate in protein S deficiency is substantially lower, at around 40% of patients. Best practice guidelines are discussed covering a wide variety of the issues and all laboratories are encouraged to participate in appropriate external quality assessment or assurance (EQA) schemes to ensure they continue to offer a high quality service.

Thrombophilia investigations represent the current most often sought diagnostic evaluation for specialized hemostasis centers, and the test requests are often inappropriate (requested on the wrong patients or on the right patients at the wrong time point). This can best be evidenced by audits of diagnostic practice,[27] [28] [29] and to some extent also relates to the previous article by Tripodi[16] on the timing of investigations while patients are on anticoagulant therapy. Several clinically and patient underrecognized benefits of EQA participation for molecular testing exist, namely the monitoring of laboratory activity, the capture of inappropriate test results, and corrective actions to improve future testing, aspects that may be missing from “direct-to-consumer” testing.[30]

The last three articles in this issue reflect original studies related to the quality theme. In the first, Dardikh and colleagues[31] focus on acquired functional coagulation inhibitors by reviewing their epidemiology, and the results of a wet workshop on their laboratory detection, and underscoring the implications for the quality of inhibitor diagnosis. In brief, the accurate detection and quantification of coagulation inhibitors remains a challenging problem for most diagnostic laboratories.[32] Prolonged screening assays and abnormal results of mixing tests with normal plasma may indicate the presence of such inhibitors. However, discrimination of functional coagulation inhibitors from lupus anticoagulant, heparin, or other therapeutically active antithrombotic drugs is required. The aim of the External Quality Control for Assays and Test Foundation workshop was to investigate, within groups of experts from dispersed professional laboratories, the quality of inhibitor detection and the difficulties encountered during the analytical process. In this article, the authors included 8 samples representing varying milieu that were tested by 10 groups of participants from 20 different countries. Workshop participants were asked to report results of all investigations performed, and to provide a likely diagnosis and/or a conclusion of the hemostasis abnormality represented by the test samples. Generally, the sensitivity of inhibitor detection was high but the differential diagnosis was unsatisfactory, as many false-positive and false-negative results were observed. One remarkable observation was the lack of a clear step-by step analysis of the nature of an inhibitor once a positive mixing test had been detected. The possible consequences of these observations for the appropriate diagnosis and clinical management of patients are discussed, and a diagnostic algorithm for the differential diagnosis and confirmation of acquired coagulation inhibitors is presented.

Hayward et al[33] then focus on EQA of platelet disorder investigations, and specifically the results of international surveys on diagnostic tests for dense granule deficiency and platelet aggregometry interpretation. Notably, the quality of platelet aggregation and dense granule-deficiency testing is important for diagnosing platelet function disorders. Indeed, platelet function-related testing remains one of the most difficult activities undertaken by laboratories, both in terms of sample processing and testing.[12] [14] [34] After a successful pilot exercise on diagnosing platelet dense-granule deficiency by electron microscopy (EM), the North American Specialized Coagulation Laboratory Association (NASCOLA) launched regular EQA for dense granule EM, as well as for the interpretation of platelet aggregation findings. For EMEQA, between 2009 and 2011, there was excellent performance in distinguishing normal from dense granule-deficient samples and good agreement (>70%) on classifying most electron dense structures in platelets. For aggregation EQA, some normal variants were misclassified and overall case interpretations were more acceptable for rare disorders than for common findings. The authors conclude that there is a need to improve the quality of platelet disorder evaluations, and that deficits in performance could be addressed by translating guideline recommendations into practice. This article adds to the growing list of recent initiatives related to EQA in platelet function testing.[35] [36]

The final article in this issue of Seminars in Thrombosis & Hemostasis is by Bonar and colleagues,[37] and on the topic of EQA for heparin monitoring. Although there is considerable debate regarding the usefulness of laboratory heparin monitoring, as partly discussed by Cuker[24] in this issue, this activity remains a substantial aspect of most hemostasis laboratories' activity. Accordingly, EQA of test processes remains an essential component of such testing, thereby ensuring that laboratories provide the best available service to clinicians for patient management. This report provides an overview of recent and past EQA related to heparin monitoring using data from the Royal College of Pathologists of Australasia (RCPA) Haematology Quality Assurance Program (QAP), and heparin containing plasma samples with concentrations ranging from 0 to 1.4 U/mL. Laboratory tests evaluated comprised activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen, and anti-Xa assays. In brief, results for APTT and TT testing were as expected, with prolongation with increasing concentrations of unfractionated heparin. Fibrinogen assays were generally unaffected by the presence of therapeutic heparin levels. Importantly, although cross-laboratory median values for the anti-Xa assay were close to target values, substantial interlaboratory variation in results, expressed as coefficient of variation (CV), was observed in all exercises conducted over an 8-year period (5 to 28% for low-molecular weight heparin and 19 to 37% for unfractionated heparin). Duplicate samples sent in consecutive surveys resulted in similar median values. Interestingly, for potential reasons explored in this article, the use of a survey-provided standard for use as assay calibrant improved interlaboratory CVs in earlier surveys, but not in the most recent survey.

We would like, as always, to thank all the authors to this issue of Seminars in Thrombosis & Hemostasis for their original and comprehensive contributions, and hope that our readership finds the content of considerable interest.

• References

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