title: Predictors of von Willebrand disease diagnosis in individuals with borderline von Willebrand factor plasma levels.
abstract: BACKGROUND
  In individuals with borderline von Willebrand factor (VWF) plasma levels, second-level tests are required to confirm or exclude von Willebrand disease (VWD). These tests are time-consuming and expensive.
  
  
  OBJECTIVE
  To assess which parameters can predict VWD diagnosis in individuals with borderline VWF levels (30-60 IU dL(-1) ).
  
  
  METHODS
  Nine hundred and fifty individuals with bleeding episodes or abnormal coagulation test results were investigated with first-level tests (blood count, prothrombin time, activated partial thromboplastin time, blood clotting factor VIII, VWF ristocetin cofactor activity [VWF:RCo], and VWF antigen), and 93 (62 females and 31 males; median age, 28 years; interquartile range 15-44) had borderline VWF:RCo levels. All underwent second-level investigations to confirm or exclude VWD. A multivariable logistic regression model was fitted with sex, age, bleeding score, family history, VWF:RCo and ABO blood group as predictors, and used to predict VWD diagnosis.
  
  
  RESULTS
  Forty-five of the 93 individuals (48%) had VWD (84% type 1). A negative linear relationship between VWF:RCo levels and risk of VWD diagnosis was present, and was particularly evident with blood group non-O [adjusted odds ratio 7.00 (95% confidence interval [CI] 1.48-33.11) for every 5 IU dL(-1) decrease in VWF:RCo]. The other variable clearly associated with VWD diagnosis was female sex (adjusted odds ratio 5.76 [95% CI 1.47-22.53]). The area under the receiver operating characteristic curve of the full logistic model was 0.89 (95% CI 0.82-0.95).
  
  
  CONCLUSIONS
  In individuals with borderline VWF, the two strongest predictors of VWD diagnosis are low VWF:RCo levels (particularly in those with blood group non-O) and female sex. This predictive model has a promising discriminative ability to identify patients with borderline VWF levels who are likely to have VWD.
authors.affiliation: Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and University of Milan, Milan, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Bucciarelli
authors.forename: S M
authors.initials: SM
authors.lastname: Siboni
authors.forename: F
authors.initials: F
authors.lastname: Stufano
authors.forename: E
authors.initials: E
authors.lastname: Biguzzi
authors.forename: M T
authors.initials: MT
authors.lastname: Canciani
authors.forename: L
authors.initials: L
authors.lastname: Baronciani
authors.forename: M T
authors.initials: MT
authors.lastname: Pagliari
authors.forename: S
authors.initials: S
authors.lastname: La Marca
authors.forename: C
authors.initials: C
authors.lastname: Mistretta
authors.forename: F R
authors.initials: FR
authors.lastname: Rosendaal
authors.forename: F
authors.initials: F
authors.lastname: Peyvandi
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001772:Blood Cell Count; D001777:Blood Coagulation; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D010314:Partial Thromboplastin Time; D011237:Predictive Value of Tests; D011517:Prothrombin Time; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult; D014842:von Willebrand Diseases / Q000097:blood / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000032:analysis*
chemical_list: D015415:Biomarkers; C029417:Von Willebrand antigen; D014841:von Willebrand Factor
keywords: ABO blood group system; Bayesian prediction; blood coagulation; von Willebrand disease; von Willebrand factor