Laboratory assays of VWF activity and use of desmopressin trials in the diagnosis of VWD: a systematic review and meta-analysis.

Von Willebrand Disease (VWD) is associated with significant morbidity because of excessive bleeding. Early diagnosis and treatment is important to prevent and treat these symptoms. We systematically reviewed the accuracy of any VWF activity assay in the diagnosis and classification of patients for VWD. We searched Cochrane Central, MEDLINE, and EMBASE for eligible studies. Risk of bias was assessed using QUADAS-2 and certainty of evidence using the GRADE framework. We pooled estimates of sensitivity and specificity. The review included 77 studies that evaluated the use of newer tests of VWF platelet binding activity (VWF:GPIbR , VWF:GPIbM) and VWF:RCo for the diagnosis of VWD (13 studies), VWF propeptide to VWF:Ag ratio and desmopressin trial for the diagnosis of type 1C VWD (5 studies), VWF multimer analysis and VWF:CB/VWF:Ag ratio for the classification of type 2 VWD (11 studies), genetic testing and ristocetin-induced platelet aggregation to diagnose type 2B VWD (14 studies), genetic testing and FVIII:VWF binding to diagnose type 2N VWD (17 studies). Based on available diagnostic test accuracy, there appears to be comparable test accuracy results between newer tests of platelet binding activity of VWF function and VWF:RCo. The findings of these reviews support VWF multimer analysis or VWF:CB/VWF:Ag to diagnose type 2 VWD. The desmopressin trial test with 1- and 4-hour postinfusion blood work is the test of choice to confirm increased VWF clearance in patients with VWD suspected of type 1C. Additionally, genetic testing is most useful in diagnosing type 2B VWD and has a role in the diagnostic algorithm of suspected type 2N VWD

von Willebrand disease: proposing definitions for future research

von Willebrand disease (VWD) is a common bleeding disorder, which affects 1 in 100 individuals based on laboratory testing and at least 1 in 1000 individuals based on presence of abnormal bleeding symptoms.1,2 VWD was first described almost 100 years ago, and since the initial report, major advances in both diagnostic testing and treatment options have improved outcomes for patients living with VWD; however, many patients still experience significant complications and barriers to treatment. An underlying problem is the lack of consistent unified definitions. In recent work developing evidence-based guidelines for VWD,3,4 it was noted that studies on VWD often used varying definitions. For example, studies of von Willebrand factor (VWF) concentrates did not have consistent definitions for major bleeding, studies on VWF prophylaxis did not use consistent definitions of what constituted a prophylaxis regimen, and studies on desmopressin did not use consistent definitions of desmopressin responsiveness. In addition, common bleeding conditions, such as heavy menstrual bleeding (HMB) and postpartum hemorrhage are variably defined. Such inconsistencies in describing study regimens and endpoints hinder the ability to compare study outcomes and to advance treatment of patients with VWD. We propose definitions for future use in VWD research to facilitate comparison of treatment options. These definitions are based on the most common usage in the literature and endeavor to encompass the most common situations in VWD. The proposed definitions were derived from existing literature and discussed at the first in-person meetings of the guideline panels. Group members made amendments, and the consensus document was circulated to the group. All authors approved the final document