Platelet function analyzer (PFA)‐100® closure time in the evaluation of platelet disorders and platelet function

Abstract

Summary. Background: Closure time (CT), measured by platelet function analyzer (PFA‐100®) device, is now available to the clinical laboratory as a possible alternative or supplement to the bleeding time test. Aim: On behalf of the Platelet Physiology Subcommittee of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis (ISTH‐SSC), a working Group was formed to review and make recommendations on the use of the PFA‐100 CT in the evaluation of platelet function within the clinical laboratory. Methods: The Medline database was searched to review the published information on the PFA‐100 CT in the evaluation of platelet disorders and platelet function. This information, and expert opinion, was used to prepare a report and generate consensus recommendations. Results: Although the PFA‐100 CT is abnormal in some forms of platelet disorders, the test does not have sufficient sensitivity or specificity to be used as a screening tool for platelet disorders. A role of the PFA‐100 CT in therapeutic monitoring of platelet function remains to be established. Conclusions: The PFA‐100 closure time should be considered optional in the evaluation of platelet disorders and function, and its use in therapeutic monitoring of platelet function is currently best restricted to research studies and prospective clinical trials.

New developments in laboratory diagnosis and monitoring

“…Presently, the most common type of diagnostic assay used to investigate a known or suspected platelet function disorder is an assessment of platelet aggregation function, often by LTA [12,16,17]. Although some laboratories perform Ôscreening testsÕ [such as the bleeding time and Platelet Function Analyzer-100 Ò (Siemens/Dade-behing, Marburg, Germany) closure time] [19], neither the bleeding time nor the closure time has sufficient sensitivity to rule out common platelet function disorders [23,25]. LTA has considerable diagnostic utility when performed by rigorously standardized procedures [25,26] with validated reference intervals [27] on samples from individuals referred for bleeding problems.…”

“…Recent surveys, including the largest worldwide survey of clinical laboratories by the International Society on Thrombosis and Haemostasis [16], have been helpful to identify which aspects of commonly performed platelet function tests, such as light transmission aggregation (LTA), show the greatest deviation in practice [17][18][19]. The lack of standardization in testing has led a number of organizations to develop guidelines and recommendations, using expert opinion and/or systematic reviews of the literature [12,[20][21][22][23]. Presently, many diagnostic laboratories need to update their practices in order to meet these new recommendations [22].…”

Anti-platelet Therapy Resistance – Concept, Mechanisms and Platelet Function Tests in Intensive Care Facilities

“…The PFA -100 and the updated version Innovance PFA-200 (Siemens, Marburg, Germany), were developed for platelet dysfunction screening as a standardised alternative to the bleeding time [78,79]. Using appropriate cartridges, platelet function analyser simulates primary haemostasis.…”

Platelet function analyzer (PFA)‐100® closure time in the evaluation of platelet disorders and platelet function: reply to a rebuttal

“…We agree that there is an urgent need to establish if laboratory tests are useful in individualizing patient therapy for improved clinical outcomes with antiplatelet agents in different clinical settings. We also agree that data obtained for PFA-100 Ò closure times are influenced by test procedures, as outlined in our review [2], and that like other laboratory tests, the test requires adequately trained staff.…”

“…We would like to clarify our recommendation that currently the PFA-100 Ò closure time is best restricted to prospective clinical trials referred to the use of the test in therapeutic monitoring [2]. We acknowledge that this recommendation may need to be updated in the future as more evidence emerges from clinical studies.…”