Tachyphylaxis and reproducibility of desmopressin response in perioperative persons with nonsevere hemophilia A: implications for clinical practice.

Background: Desmopressin is frequently used perioperatively in persons with nonsevere hemophilia A. However, increase in factor (F)VIII:C after desmopressin use is interindividually highly variable. Tachyphylaxis has only been reported in test setting for persons with hemophilia A, with a remaining response of approximately 70% after a second dose compared with that after a first dose. Objectives: To study tachyphylaxis of FVIII:C response after multiple administration(s) of desmopressin in perioperative persons with nonsevere hemophilia A. Methods: We studied FVIII:C levels after desmopressin before (day 0 [D0]) and on days 1 (D1) and 2 (D2) after surgery in 26 patients of the DAVID and Little DAVID studies. We studied tachyphylaxis by comparing the responses at D1 and D2 with that at D0. We also assessed the reproducibility of the D0 response in comparison to an earlier performed desmopressin test. Results: The median absolute FVIII:C increase was 0.50 IU/mL (0.35-0.74; n = 23) at D0, 0.21 IU/mL (0.14-0.28; n = 17) at D1, and 0.23 IU/mL (0.16-0.30; n = 11) at D2. The median percentage of FVIII increase after the second administration (D1) compared with the first (D0) was 42.9% (29.2%-52.5%; n = 17) and that of the third (D2) compared with the first (D0) was 36.4% (23.7%-46.9%; n = 11). The FVIII:C desmopressin response at D0 was comparable with the desmopressin test response in 74% of the patients. Conclusion: Tachyphylaxis in the surgical setting was considerably more pronounced than previously reported, with FVIII:C at D1 and D2 of 36% to 43% of the initial response. Our results may have important implications for monitoring repeated desmopressin treatment when used perioperatively.

Clinical implications and cost-effectiveness analysis of rivaroxaban in patients with coronary artery disease or peripheral arterial disease in the Netherlands.

BACKGROUND: Patients with stable coronary artery disease (CAD) or peripheral artery disease (PAD) are at substantial risk of atherothrombotic events. The COMPASS trial showed that patients with stable CAD or PAD experienced significant benefits after treatment with rivaroxaban in combination with acetylsalicylic acid (ASA) compared with ASA alone. This paper aims to provide insight into the clinical and economic consequences of treatment with rivaroxaban from a Dutch societal perspective. METHODS: The clinical and economic implications of rivaroxaban in terms of the number of events prevented, costs, the incremental cost per life-years gained (LYG), and incremental cost per quality-adjusted life-years (QALYs) were determined based on a cost-effectiveness model for patients with stable CAD or PAD and in high-risk subgroups (i.e. patients with CAD and PAD, CAD and prior myocardial infarction and renal impairment, CAD and heart failure) using results from the Cardiovascular OutcoMes for People Using Anticoagulation Strategies (COMPASS) trial. RESULTS: Patients treated with rivaroxaban have an expected increased discounted life expectancy of 0.67 years. In high-risk groups discounted incremental life expectancy ranged from 1.33 to 1.90 years. The incremental cost-effectiveness ratio for the full COMPASS population was €9,760/LYG and €12,033/QALY, whereas, for high-risk subgroups of patients with underlying conditions, incremental cost-effectiveness ratios ranged from €2,966/LYG to €5,052/LYG and from €3,940/QALY to €6,815/QALY. Results from the sensitivity analyses revealed that the model results were robust to variations in single or multiple input parameters at once. CONCLUSIONS: The cost-effectiveness analysis showed that rivaroxaban in combination with ASA is a cost-effective treatment option in stable CAD or PAD patients. Rivaroxaban in combination with ASA is even more cost-effective in high-risk subgroups.

Perioperative bridging of anticoagulation: towards a more reserved approach.

BACKGROUND: Most invasive procedures require the interruption of oral anticoagulation. In 2015, an international randomised trial demonstrated that perioperative bridging caused more harm than benefit in most anticoagulated patients with atrial fibrillation, leading to a more restrictive Dutch national guideline in April 2016. The objective of the present study was to analyse the integration of the 2016 Dutch guideline for perioperative antithrombotic management from after publication until update of hospital protocols. METHODS: This is a retrospective cohort study of patients on vitamin K antagonists undergoing a surgical procedure between April 2016 and June 2017. RESULTS: The proportion of high-risk patients with venous thromboembolism or atrial fibrillation receiving bridging therapy decreased from 91% and 77%, respectively at the start of the study to 33% in both groups in the last months. In high-risk patients with a mechanical heart valve, the bridging rate remained stable at 70-80% for 12 months and increased to 100% in the last 3 months. Protocol adherence for high-risk patients decreased from 80% to below 43%. The 30-day incidence of major bleeding was 4.1% (15.2% in bridged patients and 0.7% in non-bridged patients) and 10.3% for clinically relevant non-major bleeding (23.9% in bridged patients and 6.0% in non-bridged patients). The incidence of thrombo-embolism was 0.5%. CONCLUSION: New evidence from the Dutch national guideline on perioperative bridging was adopted by physicians before the local hospital protocol was updated. Low incidence of thromboembolism in non-bridged patients and high incidence of bleeding in bridged patients support a more restrictive bridging policy.

Guidelines' risk assessment recommendations for venous thromboembolism prophylaxis: A comparison and implementability appraisal.

INTRODUCTION: Venous thromboembolism (VTE) prophylaxis guidelines for non-surgical patients recommend VTE- and bleeding risk assessment to guide prophylactic strategies. These recommendations differ between guidelines and implementation is suboptimal. Assessing a guideline's implementability characteristics helps predicting the ease of implementation and reveals barriers. OBJECTIVES: We aimed to compare guidelines' risk assessment recommendations and critically appraise the implementability characteristics. MATERIAL AND METHODS: Two guidelines, one from the American College of Chest Physicians and one from the National Institute for Health and Care Excellence were selected for comparison. Risk assessment methods and subsequent prophylactic recommendations were compared. Eight experts then appraised the guideline recommendations on intrinsic implementability characteristics using the GuideLine Implementability Appraisal (GLIA) instrument. GLIA identifies barriers and facilitators for guideline implementation in nine dimensions. RESULTS: Eleven out of 20 individual VTE-risk factors and 2 out of 19 individual bleeding-risk factors used, were present in both guidelines. Additionally, a high VTE- or bleeding risk was defined differently between the two guidelines. The GLIA appraisal identified implementation barriers within all recommendations analyzed. On content level, barriers were identified in recommendations addressing bleeding risk assessment, mechanical prophylaxis and critical care patients. On implementability level, barriers were identified in decidability, flexibility, effect on process of care and computability dimensions. CONCLUSION: Depending on the guideline used, VTE-prophylaxis will most likely be provided to different non-surgical patient populations, primarily due to discordance in bleeding risk assessment. Revising the recommendations, taking into account the most apparent implementation barriers, should be considered. However, insufficient evidence to support the recommendations currently complicates this.

Health-related quality of life, developmental milestones, and self-esteem in young adults with bleeding disorders.

BACKGROUND: The treatment of bleeding disorders improved in the last decades. However, the effect of growing up with bleeding disorders on developmental, emotional, and social aspects is understudied. Therefore, this study assesses HRQOL, developmental milestones, and self-esteem in Dutch young adults (YA) with bleeding disorders compared to peers. METHODS: Ninety-five YA (18-30 years) with bleeding disorders (78 men; mean 24.7 years, SD 3.5) and 17 women (mean 25.1 years, SD 3.8) participated and completed the Pediatric Quality of Life Inventory Young Adult version, the Course of Life Questionnaire, and the Rosenberg Self-Esteem Scale. Differences between patients with bleeding disorders and their peers, and between hemophilia severity groups, were tested using Mann-Whitney U tests. RESULTS: YA men with bleeding disorders report a slightly lower HRQOL on the total scale, physical functioning, and school/work functioning in comparison to healthy peers (small effect sizes). YA men with severe hemophilia report more problems on the physical functioning scale than non-severe hemophilia. YA men with bleeding disorders achieved more psychosexual developmental milestones than peers, but show a delay in 'paid jobs, during middle and/or high school.' A somewhat lower self-esteem was found in YA men with bleeding disorders in comparison to peers (small effect size). For YA women with bleeding disorders, no differences were found on any of the outcomes in comparison to peers. CONCLUSION: This study demonstrates some impairments in HRQOL and self-esteem in YA men with bleeding disorders. By monitoring HRQOL, problems can be identified early, especially with regard to their physical and professional/school functioning.

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis.

An efficient approach to improve the catalytic activity of titanosilicates is introduced. The Doehlert matrix (DM) statistical model was utilized to probe the synthetic parameters of mesoporous titanosilicate microspheres (MTSM), in order to increase their catalytic activity with a minimal number of experiments. Synthesis optimization was carried out by varying two parameters simultaneously: homogenizing temperature and surfactant weight. Thirteen different MTSM samples were synthesized in two sequential 'matrices' according to Doehlert conditions and were used to catalyse the epoxidation of cyclohexene with tert-butyl hydroperoxide. The samples (and the corresponding synthesis conditions) with superior catalytic activity in terms of product yield and selectivity were identified. In addition, this approach revealed the limiting values of each synthesis parameter, beyond which the material becomes catalytically ineffective. This study demonstrates that the DM approach can be broadly used as a powerful and time-efficient tool for investigating the optimal synthesis conditions of heterogeneous catalysts.

Preference for direct oral anticoagulants in patients treated with vitamin K antagonists for venous thromboembolism.

BACKGROUND: Direct oral anticoagulants (DOACs) are an alternative for vitamin K antagonists (VKA) in the treatment and prevention of venous thromboembolism (VTE). Patient preferences for treatment options have not been extensively explored. METHODS: A random sample of 200 patients was obtained from those treated with VKA for deep vein thrombosis, pulmonary embolism or both at the Thrombosis Service Amsterdam. Preference for DOACs relative to VKA was assessed using a treatment trade-off technique administered as a questionnaire sent to all patients. The trade-off consisted of four consecutive scenarios: 1 (no need for laboratory control), 2 (decreased bleeding risk), 3 (less interactions with food and other drugs), 4 (higher efficacy). RESULTS: The response rate was 68%. In scenario 1, 36% of patients would switch to a DOAC. This proportion rises to 57% (odds ratio [OR] 2.3; 95% confidence interval [CI] 1.6-3.3) for scenario 2. Scenario 3 resulted in 64% of patients preferring a DOAC (OR 3.2; 95%CI 2.2-4.6). The advantage of greater efficacy did not result in a noteworthy change in the preference. Patients who were less satisfied with their current treatment, who were younger and those with higher education were more likely to prefer a DOAC over a VKA. The variables gender, treatment duration, and type of VKA were not significantly associated with DOAC preference. CONCLUSION: Almost two-thirds of patients preferred DOACs over VKA. Patients considered the lack of regular laboratory monitoring, the lower risk of serious bleeding and less interactions with food and other drugs the most important arguments to switch to a DOAC.

Determination of the median effective dose (ED50 ) of spinal chloroprocaine in labour analgesia.

The primary goal of this study was to determine the median effective dose (ED50 ) of spinal chloroprocaine for labour analgesia. Thirty-eight parturients requesting neuraxial analgesia were enrolled. Doses of 1% chloroprocaine were determined by the technique of up-down sequential allocation, with an initial dose of 20 mg and steps of 2 mg. The chloroprocaine spinal dose was given as the spinal component of a combined spinal-epidural, which was then supplemented with an epidural dose of 7.5 µg sufentanil in 7 ml saline. Effective analgesia was defined as a score ≤ 10 mm within 15 min on a 100-mm visual analogue pain scale. Using the isotonic regression estimator method, the ED50 of chloroprocaine for the spinal component of a combined spinal-epidural for labour was calculated to be median (95%CI) 12.0 (9.3-17.0) mg.

Home parenteral nutrition-associated thromboembolic and bleeding events: results of a cohort study of 236 individuals.

UNLABELLED: Essentials Sparse or outdated studies focus on thrombotic and bleeding risk in home parenteral nutrition (HPN). 236 HPN patients followed at a single center for a total of 684 patient-years were evaluated. Rates of venous thrombosis and major bleeding, and prevalence of vena cava syndrome are provided. Anticoagulants might reduce thrombosis risk, but population-specific safety concerns remain. SUMMARY: Background Home parenteral nutrition (HPN) is necessary for patients with intestinal failure. Recurrent catheter-related thrombosis (CRT) is common, leading to infectious complications, pulmonary embolism, vascular access loss and intestinal transplantation. The efficacy and safety of anticoagulants are unknown in this setting and based on sparse and low-quality observational data. Objectives Our aim was to estimate the incidence of thromboembolic, bleeding and anticoagulant-related complications in HPN patients, and evaluate risk factors for first venous thrombosis (VT). Methods This retrospective cohort study included all adult patients followed for long-term HPN at our center between 1986 and 2014. Primary outcomes were symptomatic objectively diagnosed VT, encompassing CRT and venous thromboembolism, and major bleeding. Secondary outcomes were vena cava syndrome and heparin-induced thrombocytopenia or hypersensitivity. Results A total of 236 patients were included (median HPN duration, 17 months) and 136 received anticoagulants at HPN onset (57.6%). Overall, the annual incidence of first VT was 11.4% (95% confidence interval [95% CI], 8.6-14.7%); VT was associated with a personal history of thrombosis (adjusted hazard ratio, 2.22; 95% CI, 1.06-4.64), whereas anticoagulation seemed to account only for a mild protection (adjusted hazard ratio, 0.72; 95% CI, 0.36-1.44). The annual incidence of major bleeding was 4.3% for patients on anticoagulants vs. 1.8% for those off anticoagulants. Vena cava syndrome developed in 20.7% of patients with VT. One patient had isolated heparin-induced thrombocytopenia (0.6%) and four had heparin hypersensitivity (2.5%). Conclusions Patients on HPN have a significant risk of venous thrombosis, major bleeding and vena cava syndrome. Anticoagulants might reduce thrombosis risk, but population-specific safety concerns remain.

Direct factor Xa inhibitor edoxaban: from bench to clinical practice.

Edoxaban is a direct factor Xa inhibitor and has become the fourth direct oral anticoagulant (DOAC) approved for stroke prevention in atrial fibrillation (AF) and for treatment and secondary prevention of venous thromboembolism (VTE). This review provides an overview of the key characteristics of edoxaban and clinical evaluation program leading to regulatory approval. Approval for AF and VTE treatment was based on large phase III randomized controlled trials that showed that edoxaban reduces the risk of bleeding compared with warfarin and provides similar protection against thromboembolism. Edoxaban is the second once-daily DOAC, is tested in a reduced dose for patients with a moderate renal impairment, body weight of ≤60 kg or concomitant use of p-glycoprotein inhibitors and thereby is a valuable addition to the therapeutic arsenal of modern anticoagulation. For AF regulatory approval in the USA is limited to patients with a creatinine clearance of 15-95 ml/min. Another limitation is the need for initial parenteral anticoagulation with heparin in treatment of acute VTE.

In vivo increase in thrombin generation by four-factor prothrombin complex concentrate in apixaban-treated healthy volunteers.

BACKGROUND: Four-factor prothrombin complex concentrate (PCC) (Cofact; Sanquin Blood Supply) 50 IU kg(-1) increased thrombin generation beyond baseline values in healthy, rivaroxaban-treated subjects. OBJECTIVE: To assess whether infusion with doses of 37.5 IU kg(-1) and 25 IU kg(-1) PCC reverses the anticoagulant effect of high-dose apixaban, another oral direct factor Xa inhibitor. METHODS: In a randomized, double-blind, placebo-controlled, crossover study, six healthy subjects received twice-daily apixaban 10 mg for 3.5 days followed by a single bolus of 37.5 IU kg(-1) PCC, 25 IU kg(-1) PCC, or placebo. The primary outcome was the effect of PCC 15 min after infusion on thrombin generation (endogenous thrombin potential [ETP]); secondary outcomes were the immediate effect of PCC on prothrombin time (PT) and the effect of PCC as compared with placebo over a period of 24 h on ETP and PT. RESULTS: Fifteen minutes after infusion of 37.5 IU kg(-1) and 25 IU kg(-1) PCC, ETP increased from 41% ± 11% to 56% ± 23% (P = 0.06) and from 44% ± 12% to 51% ± 15% (P = 0.03), respectively. ETP significantly differed over time between 37.5 IU kg(-1) PCC and placebo during 24 h after infusion (P < 0.01). Both PCC doses restored apixaban-induced PT prolongation after 15 min (P < 0.01), and this was sustained over a period of 24 h. CONCLUSION: Both 37.5 IU kg(-1) PCC and 25 IU/kg PCC improved coagulation parameters in healthy subjects, suggesting partial reversal of the anticoagulant effect of apixaban. This implies that PCC might be considered in patients with apixaban-associated bleeding. However, ETP was not immediately restored to pre-apixaban levels, suggesting that these doses are too low to instantly and fully restore hemostasis at peak apixaban levels.

Decreased plasma levels of activated factor VII in patients with deep vein thrombosis.

BACKGROUND: The initiating trigger in the development of deep vein thrombosis (DVT) remains unidentified. It has been suggested that tissue factor (TF)-bearing microparticles play a key role, which indicates a role for the TF pathway in the initiation of DVT. OBJECTIVE: To assess the role of the TF pathway in the initiation of venous thrombosis, we measured plasma levels of factor VII and VIIa in patients with acute DVT and in controls. METHODS: We included 148 patients diagnosed with acute DVT and 179 controls in this study. Antigen levels of FVII and FVIIa were measured by using assays recently developed in our laboratory. RESULTS: Median FVII levels in patients were 109.8% (interquartile range [IQR] 86.0-153.2) compared with 102.2% (IQR 76.1-141.7) in controls. Individuals with FVII levels in the upper quartile had a 1.6-fold increased risk for the presence of a DVT (odds ratio 1.6, 95% confidence interval 0.8-3.1). Median FVIIa levels in patients were 50.2 ng mL(-1) (IQR 25.2-86.1) compared with 96.6 ng mL(-1) (69.9-168.9) in controls. Individuals with FVIIa levels in the lowest quartile had a > 5-fold increased risk for the presence of a DVT (odds ratio 5.5, 95% confidence interval 2.8-10.6). Both risks did not change substantially after adjustment for potential confounders. CONCLUSION: Decreased plasma levels of FVIIa in patients with deep vein thrombosis may indicate ongoing consumption of FVIIa and suggest a contributory role for TF in venous thrombus formation.

von Willebrand factor propeptide and the phenotypic classification of von Willebrand disease.

The ratios between von Willebrand factor propeptide (VWFpp) or factor VIII activity ( FVIII: C) and VWF antigen (VWF:Ag) reflect synthesis, secretion, and clearance of VWF. We aimed to define the pathophysiology of 658 patients with type 1, 2, or 3 von Willebrand disease (VWD) with VWF levels ≤30 U/dL from the Willebrand in The Netherlands (WiN) study using the VWFpp/VWF:Ag and FVIII: C/VWF:Ag ratios. We evaluated the use of VWFpp in the classification and diagnosis of VWD. On the basis of the ratios, reduced VWF synthesis was observed in 18% of type 1 and only 2% of type 2 patients. A significant proportion of type 3 patients had detectable VWFpp (41%). These patients had a lower bleeding score than type 3 patients who had a complete absence of VWF:Ag and VWFpp (14.0 vs 19.5; P = .025). The majority of these patients had missense mutations with rapid VWF clearance, whereas type 3 patients with no VWFpp were homozygous for null alleles. In conclusion, VWFpp identified severe type 1 VWD with very low VWF levels in patients who had previously been classified as type 3 VWD. This study underlines the clinical significance of the VWFpp assay in the diagnosis and classification of VWD.

Real-world variability in dabigatran levels in patients with atrial fibrillation.

BACKGROUND: In clinical practice, physicians are given the choice of selecting one of two dabigatran doses based on patient characteristics, with the lower dose typically used in patients at a higher risk of bleeding. OBJECTIVES: The objectives of the study were to (i) estimate the inter- and intra-patient variability in dabigatran levels with 110 mg (DE110) and 150 mg (DE150) doses, (ii) examine the effect of physicians' dose selection on levels in DE110 and DE150 subgroups, and (iii) explore whether a single trough measurement identifies patients with extreme levels on subsequent visits. METHODS: In this prospective observational study of 100 patients with atrial fibrillation (AF), peak and trough levels of dabigatran were measured with the Hemoclot(®) assay at baseline and every 2 months thereafter (maximum four visits). RESULTS: Inter-patient variability in dabigatran levels (geometric coefficient of variation [gCV], 51-64%) was greater than intra-patient variability (gCV, 32-40%). Similar medians and distributions of levels were observed in DE110 and DE150 subgroups. Patients receiving DE110 were older, had lower renal function and weighed less than those receiving DE150. Up to 40% of patients whose trough levels were in the upper extremes, and up to 80% of patients whose trough levels were in the lower extremes at baseline, showed subsequent levels that fell in the middle quartiles. CONCLUSIONS: Our data support the practice of selecting the dabigatran dose based upon clinical characteristics because it results in similar levels of drug exposure in patients given DE110 or DE150. They do not support the concept that a single Hemoclot(®) measurement reliably identifies patients with consistently high or low values.