Deviations from the 2021 ASH/ISTH/NHF/WFH guidelines
Our main deviation from the ISTH/ASH guidelines is the limit (below 35 IU/dL) of VWF activity for a definite VWD diagnosis. Mild bleeding symptoms are common in normal life, blood group O and some undiagnosed platelet defects or other acquired disorders (e.g. endocrinological diseases), and are thus often identified by the general practitioner, particularly in association with mucosal bleeding from dental procedures, epistaxis, or menorrhagia. The comprehensive questionnaire to distinguish normal from abnormal bleeding, together with the use of an appropriate bleeding assessment tool, is critical. Diagnosis of VWD, based on a higher limit of the VWF levels, can lead to increased patient morbidity and health care system burden as well as unnecessary intervention delay due to additionally confirmatory steps for patients who require urgent or elective surgery and can lead to unnecessary medical anxiety. Thus, it may hamper the use of antithrombotic medication when indicated [1]. A higher limit for VWF may also preclude another relevant diagnosis, such as enhanced fibrinolytic potential or platelet function disorder. Nevertheless, the clinical phenotype together with the laboratory phenotype establishes new VWD diagnoses, with the emphasis on the clinical phenotype.
A second deviation is our recommendation to use both VWF platelet-dependent and collagen-dependent activities. The reason for this is to avoid missing VWD type 2M variants that may have a selective reduced activity of only one of the activities i.e. type 2MGPIb and type 2MCB, respectively [2].
A third alteration refers to the assessment of clinical phenotype (BAT) by a clinician with special expertise on coagulation disorders. The personnel of primary care are not trained enough to perform BAT and they should refer the patients to a hematologist or a specialist working at the unit of coagulation disorders to order the relevant laboratory tests and management accordingly.