Post-analytical Issues in Hemostasis and Thrombosis Testing

A novel von Willebrand factor multimer ratio as marker of disease activity in thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP), an autoantibody-mediated severe ADAMTS13 deficiency, is caused by insufficient proteolytic processing of von Willebrand factor (VWF) multimers (MMs) and microvascular thrombi. Recurrence of acute iTTP is associated with persistence or reappearance of ADAMTS13 deficiency. Some patients remain in remission despite recurring or persisting severe ADAMTS13 deficiency. In a prospective 2-year observational study, we investigated VWF MM patterns and ADAMTS13 in patients with iTTP in remission and at acute episodes. Of the 83 patients with iTTP, 16 suffered 22 acute episodes whereas 67 remained in clinical remission during follow-up, including 13 with ADAMTS13 <10% and 54 with ADAMTS13 ≥10%. High -molecular weight to low-molecular weight VWF MM ratio based on sodium dodecyl sulfate-agarose gel electrophoresis was compared with ADAMTS13 activity. VWF MM ratio was significantly higher in patients in remission with <10% compared with ≥10% ADAMTS13 activity. Fourteen samples obtained from 13 to 50 days (interquartile range; median, 39) before acute iTTP onset (ADAMTS13 <10% in 9 patients and 10%-26% in 5) showed VWF MM ratios significantly higher than those from 13 patients remaining in remission with ADAMTS13 <10%. At acute iTTP onset, VWF MM ratio decreased significantly and was low in all patients despite <10% ADAMTS13. The VWF MM ratio does not depend exclusively on ADAMTS13 activity. The disappearance of high molecular weight VWF MMs resulting in low VWF MM ratio at iTTP onset may be explained by consumption of larger VWF MMs in the microcirculation. The very high VWF MM ratio preceding acute iTTP recurrence suggests that VWF processing is hampered more than in patients remaining in remission.

Computer-assisted diagnostics

Healthcare is at the edge of a profound renovation or collapse due to the rapid inflow of machine learning protocols and procedures able to optimize several processes. Clinical trials are key for the progress of science and the correct interpretation of data. Rickard et al., in this journal, report that data on misidentification rates in medical trials are scarce. In five trials involving more than 800 blood or histology specimens examined, data clarification forms (DCFs) were issued for 21% of instances, and 67% were related to sample identification. The authors suggest that a suitable number of de- recognized data points is critical. Moreover, a formalized process involving the specimen accession employed in routine care is key to mitigate recognition errors and their potential profound impact on clinical research and outcome. We fully agree with the authors and their report is highly relevant today that we face transformation in healthcare. We suggest that 3D barcoding may mitigate several issues on misidentification.

Hemostasis and Thrombosis: An Overview Focusing on Associated Laboratory Testing to Diagnose and Help Manage Related Disorders

Hemostasis is a complex but balanced process that permit normal blood flow, without adverse events. Disruption of the balance may lead to bleeding or thrombotic events, and clinical interventions may be required. Hemostasis laboratories typically offer an array of tests, including routine coagulation and specialized hemostasis assays used to guide clinicians for diagnosing and managing patients. Routine assays may be used to screen patients for hemostasis-related disturbances but may also be used for drug monitoring, measuring efficacy of replacement or adjunctive therapy, and other indications, which may then be used to guide further patient management. Similarly, "specialized" assays are used for diagnostic purposes or may be used to monitor or measure efficacy of a given therapy. This chapter provides an overview of hemostasis and thrombosis, with a focus on laboratory testing that may be used to diagnose and help manage patients suspected of hemostasis- and thrombosis-related disorders.

Post-analytical Issues in Hemostasis and Thrombosis Testing: An Update

There are typically three phases identified as contributing to the total testing process. The preanalytical phase starts with the clinician and the patient, when laboratory testing is being considered. This phase also includes decisions about which tests to order (or not), patient identification, blood collection, blood transport, sample processing, and storage to name a few. There are many potential failures that may occur in this preanalytical phase, and these are the topic of another chapter in this book. The second phase, the analytical phase, represents the performance of the test, which is essentially covered in various protocols in this book and the previous edition. The third is the post-analytical phase, which is what occurs after sample testing, and is the topic of the current chapter. Post-analytical issues are generally related to reporting and interpretation of test results. This chapter provides a brief description of these events, as well as guidance for preventing or minimizing post-analytical issues. In particular, there are several strategies for improved post-analytical reporting of hemostasis assays, with this providing the final opportunity to prevent serious clinical errors in patient diagnosis or management.

Sources and solutions for spurious test results in coagulation

In the coagulation laboratory, much emphasis has been placed on rapid and accurate testing; however, spurious results that are inaccurate and do not reflect the actual status of the patient can potentially lead to an incorrect diagnosis and altered intervention. Errors in coagulation results and interpretation can occur at any point of the process from obtaining the specimen to interpretation and use of the result by the clinician. The main sources of error include the patient's biological and preanalytical variation, analytical testing, and postanalytical use of the reported result(s). This article reviews various sources of error leading to spurious results, providing methods to recognize these aberrant results and presenting solutions for minimizing their occurrence.

Promptly reporting of critical laboratory values in pediatrics: A work in progress

In the 21^st century, the determination of alert thresholds remains the most challenging and controversial issue in clinical pediatrics. Pre-analytical, analytical, and post-analytical matters will consolidate or undermine the fate of any laboratory process. Pre-analytical issues need to be cleared off before the laboratory physician can dispatch the result to the pediatrician in charge. Once it is cleared off, the classification of essential laboratory results is paramount. It is more than an academic exercise and may be subdivided in the order of priority we handle it to inform promptly and safely the primary physicians. Currently, we are applying new modes of making sure relevant information is transmitted without interrupting the standard workflow of the primary physicians in charge for the child, who eventually need a fast line of action for results that may be life-threatening.

Postanalytical considerations that may improve the diagnosis or exclusion of haemophilia and von Willebrand disease

von Willebrand disease (VWD) and haemophilia represent the most common inherited or acquired bleeding disorders. However, many laboratories and clinicians may be challenged by their accurate diagnosis or exclusion. Difficulties in diagnosis/exclusion may include analytical issues, where assays occasionally generate an incorrect result (ie representing an analytical error) or have limitations in their measurement range of and/or low analytical sensitivity. Also increasingly recognized is the influence of preanalytical issues on the diagnosis of VWD or haemophilia. Unfortunately, postanalytical considerations are often not well considered in the diagnostic process. Therefore, this narrative review aims to provide an overview of some important postanalytical considerations that may help improve the diagnosis of VWD and haemophilia. This review primarily discusses aspects around reporting of test results. However, we also discuss other less well-recognized postanalytical considerations, including the use of assay ratios to help identify differential diagnoses and then guide further investigation.