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Introduction Oral contraceptive (OC) use increases the risk of venous thromboembolism (VTE), but the effect of duration of use remains to be elucidated. Patients and methods This case-control study was aimed to investigate the duration of OC use on the risk of VTE according to women age, periods of use, prevalence of other risk factors and the role of thrombophilia abnormalities. Seven-hundred patients and 209 controls who used OC were stratified into short users (≤ 1 year), long users (1 to 5 years), and very long users (> 5 years). Results and conclusions Compared to non-users, the odds ratio (OR) for VTE was 9.0 (95% CI 6.9–12.2) in short, 6.5 (95% CI 4.8–83.7) in long and 5.9 (95% CI 4.4–8.1) in very long users. The risk of VTE in short users was highest in women ≤ 30 years and in the first year of use (OR 13.1, 95% CI 7.7–22.4) and decreased afterward (OR 7.7, 95% CI 5.0–11.9). This trend was not observed in women > 30 years. Compared to non-carriers and non-users, a joint effect of thrombophilia abnormalities and OC use on VTE risk was observed particularly in short users (OR 62.2, 95% CI 29.8–129.6), but also afterward (OR 25.4, 95% CI 16.5–39.2). Other transient risk factors for VTE were present in 25% of very long and 16% of short users. In conclusion, the risk of VTE in OC users decreases over time only before 30 years and in first users. Thrombophilia abnormalities strongly interact with the duration of OC use in determining VTE.

Background An association between high red cell distribution width (RDW) and venous thromboembolism (VTE) has been observed. However, it is not known whether this association differs within various manifestations of VTE, nor if there is an interaction between RDW and thrombophilia abnormalities on the risk of VTE. Aims To investigate whether RDW is a marker of the risk of VTE; to identify subgroups of patients in which the association between RDW and VTE is stronger; to investigate a possible interaction between RDW and thrombophilia abnormalities. Methods Case–control study on 730 patients with a first objectively-confirmed VTE episode (300 unprovoked and 430 provoked) consecutively referred to our Center between 2007 and 2013, and 352 healthy controls. Blood was taken for a thrombophilia work-up and a complete blood count, including RDW, at least three months after VTE. Results Individuals with RDW above the 90 th percentile (> 14.6%) had a 2.5-fold increased risk of VTE compared to those with RDW ≤ 90 th percentile, independently of age, sex, body mass index, other hematological variables and renal function (adjusted odds ratio: 2.52 [95%CI:1.42-4.47]). The risk was similar for unprovoked and provoked VTE, and slightly higher in patients with pulmonary embolism (adjusted odds ratio 3.19 [95%CI:1.68-6.09]) than in those with deep vein thrombosis alone (2.29 [95%CI:1.22-4.30]). No interaction between high RDW and thrombophilia abnormalities on the risk of VTE was observed. Conclusion Our findings confirm RDW as an independent and easily available marker for stratification of the risk of VTE.

Background Sudden sensorineural hearing loss (ISSHL) is idiopathic in 85% of cases and cochlear micro-thrombosis has been hypothesized as pathogenic mechanism. The role of thrombophilia and cardiovascular risk factors in ISSHL is controversial and whether these risk factors influence the clinical outcome of ISSHL is unknown. Methods and patients To investigate the role of thrombophilia and cardiovascular risk factors in ISSHL and to evaluate their influence on clinical outcome of the disease, 118 patients with a first episode of ISSHL and 415 healthy controls were investigated. Thrombophilia screening included measurements of antithrombin, protein C, protein S, factor V Leiden, prothrombin G20210A, antiphospholipid antibodies, fibrinogen, factor VIII and homocysteine. Results Deficiencies of antithrombin, protein C or S taken together, high factor VIII and hyperhomocysteinemia were significantly associated with ISSHL (OR [95%CI]: 7.55 [1.05-54.47], 2.91 [1.31-6.44] and 2.69 [1.09-6.62], respectively), whereas no association was found with the remaining thrombophilia markers. A 2-fold increased risk of poor clinical outcome was observed for every 5 μmol/L increase of fasting homocysteine levels (adjusted OR [95%CI]) 2.13 [1.02-4.44]) until levels of approximately 15 μmol/L, then the risk increased slowly. Cardiovascular risk factors (arterial hypertension, hyperlipidemia, diabetes and smoking) were associated with an increased risk of ISSHL (OR [95%CI] 1.88 [1.17-3.03]) and with a poor clinical outcome (OR [95%CI] 2.22 [0.93-5.26]). Conclusions Hyperhomocysteinemia, high factor VIII and, with more uncertainty, deficiencies of antithrombin, protein C or S and cardiovascular risk factors increase the risk of ISSHL. Hyperhomocysteinemia and cardiovascular risk factors are associated with a poor clinical outcome of ISSHL.

The estimated annual incidence of cerebral vein thrombosis (CVT) is 3 to 4 cases per million in adults and 7 cases per million in neonates. Among the commonest risk factors there are oral contraceptive use, pregnancy and puerperium that make CVT more frequent in women than in men. Cerebral tumors, infections and traumas are less encountered local risk factors. In 15-20% of patients CVT remains unprovoked. Coagulation abnormalities causing thrombophilia, as well as hyperhomocysteinemia, are worthy to be investigated in patients with CVT. Rarely CVT can be the first clinical manifestation of a myeloproliferative neoplasm. The recurrence rate of CVT is low, but venous thromboembolism in the common sites (lower-limb deep vein thrombosis or pulmonary embolism) can recur, particularly in patients with a first idiopathic CVT. Early diagnosis and anticoagulant treatment reduce morbidity of CVT and improve survival, although the optimal duration of anticoagulant treatment is not well established.

Background The risk of venous thromboembolism (VTE) is increased by an excess of procoagulant or by a defect of anticoagulant proteins, with circumstantial risk factors playing a significant contribution. These conditions are directly linked to or are compatible with increased thrombin generation. Assuming that the more thrombin is generated the higher is the risk of VTE, an overall coagulation test monitoring ex vivo thrombin generation and reflecting the interaction of pro- and anticoagulant proteins would be useful to determine the risk of VTE. Patients and methods This hypothesis was tested by measuring the endogenous thrombin potential (ETP) without or with thrombomodulin (TM) in plasmas from 403 individuals stratified according to their relative risk of VTE (no, low, intermediate, or high risk) according to whether or not they had congenital and/or circumstantial risk factors. Odds ratio (OR) and 95% confidence interval (CI), taken as a measure of the relative risk of having high levels of ETP, were calculated for the different categories relatively to the no-risk category. Results When the ETP was measured with TM, ORs (95% CI) were 2.10 (1.23–3.60); 4.03 (2.18–7.45) and 4.96 (2.40–10.23) for the low-, intermediate and high-risk category. When ETP was measured without TM there was no gradient of OR values as function of the risk category. Conclusions ETP measured with TM may help to distinguish individuals with different risk of VTE, however, the practical utility of measuring ETP in clinical practice remains to be evaluated in prospective studies.

Among the so called antiphospholipid (aPL) antibodies Lupus Anticoagulant (LAC) is considered the strongest risk factor for thromboembolic events. In individuals without a previous thromboembolic event (carriers), LAC is a risk factor when associated with the presence of anticardiolipin (aCL) and aβ2-Glycoprotein I (aβ2GPI) antibodies. On the other hand, data on carriers of isolated LAC positivity are sparse and inconclusive. The aim of this study was to prospectively determine the incidence of thrombosis in a cohort of carriers of isolated LAC positivity. One-hundred seventy-nine carriers of LAC confirmed twelve weeks apart and in a reference laboratory were studied. During a total follow up of 552 person-years, there were seven thromboembolic events (1.3% person-y). All the seven patients had at least one adjunctive major risk factor for thrombosis. The cumulative incidence of thromboembolic events was 3.1% (95% CI 0.6-5.6) after 2years, and 5.9% (95% CI 1.2-10.6) after 5 and 10years. On a multivariate regression analysis considering age, sex, autoimmune disease, risk factors for arterial and venous thrombosis, use of aspirin, only age was found to be an independent predictor of thromboembolic events (HR=1.1, 95% CI 1.0-1.2, p=0.02). These data might be relevant in clinical practice and underline the importance of differentiating LAC carriers in terms of isolated positivity or positivity associated with the presence of antibodies to aCL and β2-glycoprotein I.

Introduction Antithrombin (AT), protein C (PC) and protein S (PS) deficiencies are risk factors for venous thromboembolism. Overlapping values between heterozygous carriers and normal individuals often make a correct classification of a deficiency difficult. The aim of this study was to investigate the effect of sex, age, menopause and hormone therapy on natural anticoagulant plasma levels in a large group of healthy individuals, and to evaluate the need of separate reference ranges. Materials and Methods AT and PC were measured with a chromogenic assay, antigenic free PS with an ELISA test. To evaluate the effect of sex, age, oral contraception, hormonal status (and their interaction) on AT, PC and PS levels, linear regression models were used. Biological relevance and the value of the normal deviate z were chosen as rules to decide for separate reference ranges. Results The study population consisted of 1837 healthy adult individuals (741 men, 1096 women), aged 18-85years (median age: 44years). In men AT levels decreased after the age of 50years. Men had higher levels of PS than women, particularly at young ages. In women, after correction for menopause, only PC levels increased with age. Menopause affected AT and PS, but not PC levels. Oral contraceptive intake was associated with a decrease of AT and PS, and an increase of PC levels. Conclusions For AT, PC and PS, sex- and age-specific normal reference ranges can be useful, in order to better discriminate true carriers of a natural anticoagulant deficiency.

Abstract 3987 Poster Board III-923 Background Microparticles (MPs) are circulating, submicroscopic fragments ( Aim of the study To investigate the association between high plasma levels of MPs and risk of VTE Patients and Methods In a case-control study, 186 patients with a first episode of VTE (deep venous thrombosis and/or pulmonary embolism) and 418 healthy controls were included. MPs were analyzed by flow cytometry with a gate defined by a 1 μm beads and using APC-Annexin V together with FITC anti-CD41 or FITC anti-CD142 antibodies in order to identify platelet MPs (MP-Plts) and MPs exposing tissue factor (MP-TF), respectively. MPs levels were expressed as number/μL. Results Patients had significantly higher median plasma levels of both MPs-Plts and MPs-TF than controls [1942 vs 1519 (p95th percentile of the control group (3633/μL for MPs-Plts and 1113/μL for MPs-TF) than in those with MPs levels ≤95th percentile [for MPs-Plts: OR=2.59 (95%CI 1.23 – 5.45); for MPs-TF: OR=2.38 (1.15 – 4.92)]. The risk increased in a dose-dependent manner for both MPs-Plts and MPs-TF, particularly above the 75th percentile of the distribution in controls. The exclusion of patients whose MPs levels were measured within 6 months from VTE (in order to avoid the possible effect of the acute phase on MPs measurements), did not change the results [adjusted OR: 2.63 (1.18 – 5.89) for MPs-Plts and 2.36 (1.10 – 5.19) for MPs-TF]. The Table shows the relative risks of VTE associated with the presence or absence of high MPs levels and thrombophilia. Individuals with MPs >95th percentile or thrombophilia alone had a 2 to 3-fold increased risk of VTE, whereas those with both MPs-Plts >95th percentile and thrombophilia had a 9-fold increased risk of VTE. This synergistic effect was confirmed also for MPs-TF and remained after the exclusion of patients whose blood sample was collected within 6 months from VTE [OR 7.72 (1.68-35.4) for MP-Plts and 8.14 (2.08-31.8) for MP-TF]. Conclusions Plasma levels of MPs are significantly higher in patients with VTE than in healthy controls. MPs levels >95th percentile are associated with a 2.5-fold increased risk of VTE. There is a synergistic interaction between high levels of MPs and thrombophilia on VTE risk. Disclosures: No relevant conflicts of interest to declare.

Vitamin K-antagonists (VKA) decreases vitamin K coagulation factors. To counterbalance this effect, it has been postulated that non-vitamin K proteins increase during VKA treatment. To investigate if VKA affect FVIII, a cohort of 1772 patients referred from Jan 1997 to Oct 2008 to our Thrombosis Center for a thrombophilia screening after at least 3 months from diagnosis of first venous thrombosis was studied. At the time of blood sampling, 1303 patients had discontinued VKA for at least one month, whereas the remaining 469 were still taking VKA. FVIII was significantly higher in patients on VKA than in those who had discontinued VKA (mean±SD: 144 ± 41 IU/dL and 134 ± 40 IU/dL, respectively, p < 0.0001), also after adjustment for sex, age, body mass index, thrombophilia and time elapsed from thrombosis in a multiple linear regression analysis. In order to avoid overestimation of FVIII levels, patients should be preferentially tested after VKA discontinuation.

The Publisher regrets that this article is an accidental duplication of an article that has already been published in a supplement entitled '3rd International Symposium on Women's Health Issues in Thrombosis and Haemostasis'. The duplicate article has therefore been withdrawn.