Alberto Tosetto

A quantitative analysis of bleeding symptoms in type 1 von Willebrand disease: results from a multicenter European study (MCMDM‐1 VWD)

Summary.  Background: A quantitative description of bleeding symptoms in type 1 von Willebrand disease (VWD) has never been reported. Objectives: The aim was to quantitatively evaluate the severity of bleeding symptoms in type 1 VWD and its correlation with clinical and laboratory features. Patients and methods: Bleeding symptoms were retrospectively recorded in a European cohort of VWD type 1 families, and for each subject a quantitative bleeding score (BS) was obtained together with phenotypic tests. Results: A total of 712 subjects belonging to 144 families and 195 controls were available for analysis. The BS was higher in index cases than in affected family members (BS 9 vs. 5, P < 0.0001) and in unaffected family members than in controls (BS 0 vs. −1, P < 0.0001). There was no effect of ABO blood group. BS showed a strong significant inverse relation with either von Willebrand ristocetin cofactor (VWF:RCo), von Willebrand antigen (VWF:Ag) or factor VIII procoagulant activity (FVIII:C) measured at time of enrollment, even after adjustment for age, sex and blood group (P < 0.001 for all the four upper quintiles of BS vs. the first quintile, for either VWF:RCo, VWF:Ag or FVIII:C). Higher BS was related with increasing likelihood of VWD, and a mucocutaneous BS (computed from spontaneous, mucocutaneous symptoms) was strongly associated with bleeding after surgery or tooth extraction. Conclusions: Quantitative analysis of bleeding symptoms is potentially useful for a more accurate diagnosis of type 1 VWD and to develop guidelines for its optimal treatment.

The discriminant power of bleeding history for the diagnosis of type 1 von Willebrand disease: an international, multicenter study

Summary.  Objective: The aim of this study was the validation of the criteria defining a significant mucocutaneous‐bleeding history in type 1 von Willebrand disease (VWD). Subjects and methods: To avoid selection bias, 42 obligatory carriers (OC) of type 1 VWD were identified from a panel of 42 families with type 1 VWD enrolled by 10 expert centers. OC were identified by the presence of an offspring and another first degree relative with type 1 VWD (affected subjects, AFF). A standardized questionnaire was administered to evaluate hemorrhagic symptoms at the time of first examination, using a bleeding score ranging from 0 (no symptom) to 3 (hospitalization, replacement therapy, blood transfusion). Sensitivity, specificity, diagnostic likelihood ratios, positive and negative predictive values for the diagnosis of type 1 VWD were calculated from the data collected in OC and in 215 controls. Results: Having at least three hemorrhagic symptoms or a bleeding score of 3 in males and 5 in females was very specific (98.6%) for the bleeding history of type 1 VWD, although less sensitive (69.1%). None of the misclassified OC had life‐threatening bleeding episodes after diagnosis. Conclusions: We suggest that the use of a standardized questionnaire and bleeding score may be useful for the identification of subjects requiring laboratory evaluation for VWD.

Predicting disease recurrence in patients with previous unprovoked venous thromboembolism: a proposed prediction score (DASH).

Summary.  Background:  In patients with unprovoked venous thromboembolism (VTE), the optimal duration of anticoagulation is anchored on estimating the risk of disease recurrence.

Activated Protein C Resistance and Factor V Leiden Mutation Are Independent Risk Factors for Venous Thromboembolism

Venous thromboembolism affects about 1 of every 130 persons younger than 65 years of age (1, 2). The most common clotting abnormality associated with venous thromboembolism is a reduced inactivation of coagulation factor V by the physiologic inhibitor protein C (3, 4). A reduced prolongation of plasma clotting times after in vitro addition of activated protein C characterizes this condition, known as resistance to activated protein C (5). A single point mutation of the coagulation factor V gene, resulting in an R506Q substitution at the activated protein C cleavage site (the factor V Leiden mutation), has been found in almost all patients examined for venous thromboembolism who show resistance to activated protein C (6). The mutation has an allele prevalence of 1% to 7% in healthy white persons but is almost absent in other ethnic groups (7). Most of our knowledge about factor V Leiden genotype and resistance to activated protein C comes from selected cohorts of patients with venous thromboembolism (4, 6, 8-10). In a recent cross-sectional investigation of familial thrombophilia, the Vicenza Thrombophilia and Atherosclerosis Project (11), we determined both the phenotypic resistance to activated protein C and the factor V Leiden genotype in a large sample of participants 18 to 65 years of age. In the general population, about 2.3% of persons were carriers of the factor V Leiden genotype and 15% had a comparably reduced response to activated protein C even in the absence of the mutation (12). Thus, a substantial fraction of the population with a phenotype indistinguishable from that of carriers of the factor V Leiden mutation may also be at higher risk for thrombosis. In the present study, we evaluated the prevalence and the thrombotic risk associated with phenotype resistance to activated protein C or the genotype factor V Leiden in 15 109 participants. Methods Study Cohort We analyzed data from all 15 109 participants in the Vicenza Thrombophilia and Atherosclerosis Project. Participants were consecutively enrolled from May 1993 to June 1997. White persons 18 to 65 years of age who were born on an even date were randomly selected from the census list of the district of Vicenza, Italy. The area is served by two public hospitals that provide health services for every citizen and cover approximately 95% of the total hospitalizations in the area. Participants with a physical or mental disease that would hamper active participation were excluded. Sampling was delayed until resolution of symptoms in participants with concurrent minor illnesses (such as fever) or until delivery in pregnant participants. Details of the randomization and enrollment procedures are reported elsewhere (13). Discharge diagnoses from public hospitals were obtained from the local health authority database for patients 18 to 65 years of age. On the basis of the annual rate of hospital discharge for trauma or surgery (International Classification of Diseases, Ninth Revision, codes 805 to 828, 860 to 869, 890 to 897, and 928) and after stratifying by age and sex, we computed the expected number of traumas or surgeries in our cohort at time of observation. Only major surgical procedures (thoracic, abdominal, gynecologic, orthopedic, and neurologic surgery) were considered. Diagnosis of Past Episodes of Venous Thromboembolism By using a validated questionnaire (14), personal and familial history of venous thromboembolism was obtained from all participants before blood collection. Thus, both participants and researchers were blinded to activated protein C and factor V Leiden status. Doppler ultrasonography was performed in participants with symptoms of venous thromboembolism who were not currently receiving heparin or warfarin. In a previous study, we demonstrated that this approach had a sensitivity of 71.3% and a specificity of 98.9%; a higher sensitivity could be attained only at the expense of a specificity too low for epidemiologic purposes (14). Because participants were randomly selected from census lists and venous thromboembolism was ascertained in a blinded manner, the outcome misclassification resulting from imperfect sensitivity and specificity may be considered to be nondifferential for carriers and noncarriers of the factor V Leiden mutation. Given a specificity close to 100%, the bias resulting from nondifferential outcome misclassification in our study predictably yields lower, conservative estimates for relative risks and attributable fractions (15). Participants were considered positive for a family history of venous thromboembolism if they reported thromboembolic symptoms in at least two persons in the same family (16). Laboratory Studies Blood was obtained from fasting participants before 10:00 a.m. and was anticoagulated with sodium citrate (129 mmol/L; 1:9 vol:vol). Plasma was obtained by centrifugation at 2000 g for 20 minutes; it was then snap-frozen in liquid nitrogen and stored at 80 C within 2 hours. Leukocyte DNA was pelleted after cell lysis with Triton X-100 (Sigma, St. Louis, Missouri) and was stored at 40 C (17). All measurements were subsequently performed within 2 weeks of collection (13). Resistance to activated protein C was measured as the activated protein C sensitivity ratio (clotting time with the buffer containing activated protein C divided by clotting time with buffer only) in an ACL300 coagulometer (Instrumentation Laboratory, Milan, Italy), as reported elsewhere (3, 12). The sensitivity ratio was then normalized to the ratio obtained with normal reference plasma. Because clotting times were measured up to 200 seconds, our test could reliably detect activated protein C sensitivity ratios up to 5.0 or normalized sensitivity ratios up to 2.2. Samples with a clotting time longer than 200 seconds were conservatively considered to have a normalized sensitivity ratio of 2.5. The test has been validated and was shown to have an interassay coefficient of variation of 4.6% for normal plasma in a series of 70 measurements (18). All participants with a normalized sensitivity ratio of 0.84 or less were screened for the factor V Leiden mutation. A previous study (12) showed that this cut-off identifies carriers of the factor V Leiden mutation with a theoretical sensitivity of 99.9%. In addition, screening was performed in all participants who had a past episode of venous thromboembolism or who were taking oral anticoagulants at time of sampling. A sample of 500 participants with a normalized sensitivity ratio above 0.84 were also screened as an internal control group. Five microliters of leukocyte DNA were amplified by polymerase chain reaction in a Perkin-Elmer 9600 thermocycler (Perkin-Elmer, Norwalk, Connecticut) followed by digestion with the Mnl I restriction enzyme (6). Screening for additional mutations of the factor V gene or clotting abnormalities that may cause phenotypic resistance to activated protein C was performed in participants with a personal history of venous thromboembolism, a normalized activated protein C sensitivity ratio of 0.84 or less, and no factor V R506Q mutation. These participants were screened for the presence of the factor V Cambridge (R306T) mutation or the factor V Hong Kong mutation (R306G) by polymerase chain reaction amplification of exon 7 of factor V and digestion with BstN I (19, 20). In addition, these participants were screened for lupus anticoagulant by using the dilute Russell viper venom test (21). Plasma factor VIII procoagulant activity was measured in participants with venous thromboembolism and in age- and sex-matched controls by using a one-stage clotting assay. Statistical Analysis We assumed that the factor V Leiden mutation has a marginal effect on overall survival (22, 23), thus allowing follow-up analysis of genetically identified participants (24). Incidence rates for venous thromboembolism were computed for carriers and noncarriers of the factor V Leiden mutation with a prospective approach that used Poisson regression to standardize rates for sex and age and to compute 95% CIs. To compute person-years at first exposure, we used age at first thromboembolic episode in participants with a previous episode of venous thromboembolism and age at study enrollment in healthy participants. Because the incidence of venous thromboembolism increases with age, we weighted the contribution of each participant in 10-year intervals within the regression model (25). The method of Kaplan and Meier was used to estimate thrombosis-free survival in carriers and noncarriers of the factor V mutation (26). Family clustering of venous thromboembolism could result in a biased overestimation of risk caused by the factor V Leiden mutation. Accordingly, the relative risk for venous thromboembolism in carriers of the mutation was also computed by considering only one randomly chosen family member when more of them were available. Using a cross-sectional approach, we subsequently evaluated the risk for venous thromboembolism as a function of phenotypic resistance to activated protein C and of presence of the factor V Leiden mutation. An unconditional logistic regression model was used to estimate the odds ratios associated with increasing levels of normalized activated protein C sensitivity ratio in both carriers and noncarriers of the factor V Leiden mutation by using age and sex as covariates (27). Participants taking oral anticoagulants were excluded from this analysis. Crude and age- and sex-adjusted odds ratios were computed in this model for participants with different levels of normalized sensitivity ratios: less than 0.50, corresponding to the phenotype of factor V Leiden homozygotes; 0.50 to 0.84, corresponding to the phenotype of factor V Leiden heterozygotes; 0.85 to 1.3, corresponding to the normal phenotype; and greater than 1.3, corresponding to the activated protein C hyperresponsive phenotype (12, 28). Confidence intervals for adjusted odds ratios were computed from logist

Congenital absence of the inferior vena cava : a rare risk factor for idiopathic deep-vein thrombosis

Congenital absence of the inferior vena cava (AIVC) is a rare vascular defect, commonly reported as a fortuitous finding. The presence of AIVC in patients with DVT is underestimated because AIVC cannot be detected by compression B-mode ultrasonography. By use of computed tomography, we diagnosed four cases of AIVC in young patients with idiopathic DVT over a 5 year period. Based on the occurrence of DVT in patients below 30 years in our area during the same period, we estimate that AIVC is present in about 5% of cases of DVT in young patients. Computed tomography or angiography should be used for the diagnosis of idiopathic DVT in young patients.

Questions and answers on the use of dabigatran and perpectives on the use of other new oral anticoagulants in patients with atrial fibrillation: A consensus document of the Italian Federation of Thrombosis Centers (FCSA)

Dabigatran and other new oral anticoagulants (OAC) represent a step forward in stroke prevention in patients with atrial fibrillation (AF). They indeed have been shown to be an alternative to vitamin K antagonists (VKAs) without the burden of laboratory control. However, these new drugs compete with an effective and well-established therapy, thus bringing about a series of questions and doubts. In this report members of the board of the Italian Federation of Thrombosis Centers (FCSA) answer some questions every clinician might be confronted with.

Risk of recurrence after venous thromboembolism in men and women: patient level meta-analysis

Objective To determine the effect of sex on the risk of recurrent venous thromboembolism in all patients and in patients with venous thromboembolism that was unprovoked or provoked (by non-hormonal factors). Data source Comprehensive search of electronic databases (Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials) until July 2010, supplemented by review of conference abstracts and contact with content experts. Study selection Seven prospective studies investigating an association between D-dimer, measured after anticoagulation was stopped, and disease recurrence in patients with venous thromboembolism. Data extraction Patient level databases were obtained, transferred to a central database, checked, and completed with further information provided by authors. Data synthesis 2554 patients with a first venous thromboembolism had follow-up for a mean of 27.1 (SD 19.6) months. The one year incidence of recurrent venous thromboembolism was 5.3% (95% confidence interval 4.1% to 6.7%) in women and 9.5% (7.9% to 11.4%) in men, and the three year incidence of recurrence was 9.1% (7.3% to 11.3%) in women and 19.7% (16.5% to 23.4%) in men. Among patients with unprovoked venous thromboembolism, men had a higher risk of recurrence than did women (hazard ratio 2.2, 95% confidence interval 1.7 to 2.8). After adjustment for women with hormone associated initial venous thromboembolism, the risk of recurrence remained higher in men (hazard ratio 1.8, 1.4 to 2.5). In patients with provoked venous thromboembolism, occurring after exposure to a major risk factor, recurrence of disease did not differ between men and women (hazard ratio 1.2, 0.6 to 2.4). In women with hormone associated venous thromboembolism and no other risk factors, recurrence was lower than that in women with unprovoked venous thromboembolism and no previous hormone use (hazard ratio 0.5, 0.3 to 0.8). Conclusion In patients with a first unprovoked venous thromboembolism, men have a 2.2-fold higher risk of recurrent venous thromboembolism than do women, which remained 1.8-fold higher in men after adjustment for previous hormone associated venous thromboembolism in women. In patients with a first provoked venous thromboembolism, risk of recurrence does not differ between men and women with or without hormone associated venous thromboembolism. Indefinite anticoagulation may be given greater consideration in men than in women after a first venous thromboembolism.

Does the clinical presentation and extent of venous thrombosis predict likelihood and type of recurrence? A patient-level meta-analysis

Summary.  Aim: To determine if the mode of presentation of venous thromboembolism (VTE), as deep vein thrombosis (DVT) or pulmonary embolism (PE), predicts the likelihood and type of recurrence. Methods: We carried out a patient‐level meta‐analysis of seven prospective studies in patients with a first VTE who were followed after anticoagulation was stopped. We used Kaplan‐Meier analysis to determine the cumulative incidence of recurrent VTE according to mode of presentation, and multivariable Cox regression to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for mode of and extent of DVT as potential risk factors for recurrence. Results: The 5‐year cumulative rate of recurrent VTE in 2554 patients was 22.6%. In 869 (36.1%) patients with PE, the 5‐year rate of any recurrence (DVT or PE) was 22.0%, and recurrence as PE was 10.6%. In 1365 patients with proximal DVT, the 5‐year recurrence rate was 26.4%, and recurrence with PE was 3.6%. The risk of recurrence as PE was 3.1‐fold greater in patients presenting with symptomatic PE than in patients with proximal DVT (HR, 3.1; 95% CI, 1.9–5.1). Patients with proximal DVT had a 4.8‐fold higher cumulative recurrence rate than those with distal DVT (HR, 4.8; 95% CI, 2.1–11.0). Conclusion: Whilst DVT and PE are manifestations of the same disease, the phenotypic expression is predetermined. Patients presenting with PE are three times more likely to suffer recurrence as PE than patients presenting with DVT. Patients presenting with calf DVT are at low risk of recurrence and at low risk of recurrence as PE.

No treatment for low-risk thrombocythaemia : results from a prospective study

Essential thrombocythaemia (ET) is a chronic myeloproliferative disorder characterized by the occurrence of thromboembolic episodes, particularly in patients aged > 60 years or with a previous history of thrombosis, and/or by haemorrhages in patients with an exceedingly high platelet count. In these subgroups of patients the use of cytoreductive therapy is beneficial in terms of risk/benefit ratio. Only limited anecdotal data are available on the thrombotic or haemorrhagic risk and survival in young asymptomatic ET patients with a platelet count < 1500 × 109/l. Therefore the optimal management of these patients is unknown.

Patient-Level Meta-analysis: Effect of Measurement Timing, Threshold, and Patient Age on Ability of d-Dimer Testing to Assess Recurrence Risk After Unprovoked Venous Thromboembolism

BACKGROUND In patients with a first unprovoked venous thromboembolism (VTE), an elevated d-dimer level after anticoagulation is stopped is a risk factor for recurrent VTE. However, questions remain about the utility of measuring d-dimer in clinical practice. PURPOSE To determine whether the timing of testing, patient age, and the cut point used to define a positive or negative result affect the ability of d-dimer testing to distinguish risk for recurrent disease. DATA SOURCES Comprehensive search of electronic databases (MEDLINE, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials) until July 2010, supplemented by reviewing conference abstracts and contacting content experts. STUDY SELECTION 7 prospective studies that investigated an association between d-dimer, measured after stopping anticoagulation, and disease recurrence in patients with a first unprovoked VTE (proximal deep venous thrombosis, pulmonary embolism, or both). DATA EXTRACTION Patient-level databases were obtained, transferred to a central database, checked, completed with further information provided by study investigators, and pooled into a single database. DATA SYNTHESIS 1818 patients with a first unprovoked VTE were followed for a mean of 26.9 months (SD, 19.1). A study-stratified multivariate Cox regression model, which included patient age, sex, hormone therapy use at the time of the index event, body mass index, timing of postanticoagulation d-dimer testing, and inherited thrombophilia as possible confounders, indicated that the hazard ratio for d-dimer status (positive vs. negative) was 2.59 (95% CI, 1.90 to 3.52). Only male sex had a significant effect on risk for recurrent VTE independent of d-dimer status. The Cox regression model and the log-rank test confirmed that the risk for recurrent VTE was higher in patients with a positive d-dimer result than in those with a negative result, regardless of the timing of postanticoagulation d-dimer testing or patient age. No study- or assay-specific d-dimer effect was found, and reassessing the analysis after recoding data according to specific quantitative d-dimer cut points (500 µg/L and 250 µg/L) did not change the results. LIMITATIONS Unmeasured variables could have affected the risk for recurrent VTE. The study population was predominantly white. CONCLUSION In patients with a first unprovoked VTE who have their d-dimer level measured after stopping anticoagulation, the timing of d-dimer testing, patient age, and the assay cut point used do not affect the ability of d-dimer to distinguish patients with a higher or lower risk for recurrent VTE.