| 1. |
- Berntorp, Erik
(författare)
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Prophylaxis in von Willebrand disease.
- 2008
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Ingår i: Haemophilia. - : Wiley. - 1351-8216 .- 1365-2516. ; 14 Suppl 5, s. 47-53
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews current issues regarding short-term (i.e. for surgery and invasive procedures) and long-term (i.e. regular infusions to prevent bleeding on a permanent or temporary basis) prophylaxis treatment using replacement concentrates for patients with von Willebrand disease (VWD) who do not respond satisfactorily to desmopressin. The standard treatment of these patients is with factor concentrates containing von Willebrand factor (VWF) and factor VIII (FVIII). When dosing these concentrates, the broad variations in content and quality of VWF as well as the FVIII content in the products should be considered. Peri-operative management strategies will depend on the VWD subtype, baseline VWF and FVIII levels, and size of procedure. FVIII level and VWF ristocetin cofactor activity may both be used to determine concentrate potency and to monitor treatment. Long-term prophylaxis, which has become a state-of-the-art approach in haemophilia, is not very common in VWD. However, more recent data suggest that a substantial number of VWD patients could benefit from prophylactic treatment with VWF-containing concentrates. For example, 35 Swedish VWD patients who required prophylaxis (mainly because of nose/mouth bleeds and joint bleeds) showed a substantial overall reduction in bleeding episodes and there were no signs of arthropathy in children who began prophylaxis before the age of 5 years since initiation of treatment with Haemate P/Humate-P. Studies of prophylaxis in VWD are urgently needed to develop evidence-based guidelines for this approach; the VWD International Prophylaxis study, for example, has commenced by the VWD Prophylaxis Network.
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| 2. |
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| 3. |
- Berntorp, Erik, et al.
(författare)
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Standardization and clinical utility of thrombin-generation assays.
- 2008
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Ingår i: Seminars in Thrombosis and Hemostasis. - : Georg Thieme Verlag KG. - 1098-9064 .- 0094-6176. ; 34:7, s. 670-682
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Tidskriftsartikel (refereegranskat)abstract
- Thrombin generation is a key process that determines the extent of a hemostatic plug or a thrombotic process. The ensuing thrombin burst is crucial for the formation of a stable fibrin clot. During its active life, thrombin exerts a multitude of highly regulated actions on the blood and the vessel wall, including the clotting of fibrinogen. The inappropriate generation of thrombin may lead to pathologic processes, foremost of which are hemorrhagic or thrombotic diseases. The coagulation system is usually investigated by means of two in vitro classic clotting tests, the activated partial thromboplastin time (APTT) and prothrombin time (PT), which assess only time to initiation of clot formation and do not entirely reflect global hemostatic balance. The APTT and PT permit identification of connectivity between the component activities identified as required for plasma coagulation and define the concept of intrinsic and extrinsic coagulation pathways, which converge at the point of formation of the prothrombinase complex. However, the mechanisms established by in vitro tests are not always mirrored in the human pathologies associated with bleeding or thrombosis. The recent development of newer tests based on the continuous registration of thrombin generation under in vitro conditions that mimic more closely what occurs in vivo prompt a reinvestigation of the balance between procoagulants and anticoagulants in patients with various hemostatic disorders. Thrombin-generation assays not only provide an overall assessment of hemostasis but also target potential extrahemostatic effects of the generated thrombin, a potent agonist of a multitude of cellular activation pathways. Moreover, estimation of an individual's thrombin-generation potential may correlate more closely with a hypercoagulable or hypocoagulable phenotype when compared with traditional coagulation tests. In this review, we discuss to what extent thrombin generation can be expected to reflect the clotting function of blood, the development and use of different thrombin-generation assay systems suitable for detecting changes in the kinetics of thrombin generation, and the clinical utility of thrombin generation.
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| 4. |
- Bolton-Maggs, P H B, et al.
(författare)
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von Willebrand disease update: diagnostic and treatment dilemmas
- 2008
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Ingår i: Haemophilia. - : Wiley. - 1351-8216 .- 1365-2516. ; 14:s3, s. 56-61
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Tidskriftsartikel (refereegranskat)abstract
- Although von Willebrand disease (VWD) is now well-described, many facets of diagnosis and management continue to be debated. The diagnosis of type 1 disease can be difficult but recent genetic analyses help to distinguish many factors which can influence von Willebrand factor (VWF) levels and bleeding phenotype. Type 2 disease (functional abnormalities) includes a particularly interesting group of disorders with faulty binding between VWF and FVIIIC (Normandy) where treatment methods need careful consideration. Type 3 VWD is the most severe form of VWD and a new international study is underway to examine the use of prophylaxis.
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| 5. |
- Donfield, S. M., et al.
(författare)
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Value added: increasing the power to assess treatment outcome in joint haemorrhages
- 2008
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Ingår i: Haemophilia. - : Wiley. - 1351-8216 .- 1365-2516. ; 14:2, s. 276-280
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Tidskriftsartikel (refereegranskat)abstract
- Subject reports of efficacy of treatment of haemophilia-related joint bleeding are by definition subjective, yet are often the primary outcome in studies comparing therapies. Verbal descriptors such as effective, partially effective, poorly effective, not effective are treated as dichotomous or categorical variables in analyses, lowering the statistical power relative to that which might be achieved with a continuous variable. The aims of this study were to examine reports of pain recorded on a 100-mm visual analogue scale (VAS) during the course of joint bleeding; determine whether pain varied by treatment period among pairs reporting discordant outcomes on a verbal scale (one product effective, the other not effective); test whether the two products under study were equivalent with respect to VAS scores; and evaluate their relationship to verbal reports of efficacy. Data from the international, prospective, randomized, crossover FEIBA NovoSeven Comparative study of two bypassing agents used for treatment of 96 bleeding episodes in 48 participants were examined. VAS scores were associated with verbal descriptors of efficacy at every time point, and were equivalent between treatment periods. There were differences in mean scores at time points at which participants rated one treatment effective, the other not effective. As a continuous variable, the VAS score may have more power than a dichotomous variable and when used with verbal descriptions of efficacy can improve the overall accuracy of assessment. This report highlights an important consideration in the selection of outcome measurement that can be generalized to other haemophilia treatment research.
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| 6. |
- Magnusson, Marie, et al.
(författare)
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Effects of pentoxifylline and its metabolites on platelet aggregation in whole blood from healthy humans
- 2008
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 0014-2999 .- 1879-0712. ; 581:3, s. 290-5
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Tidskriftsartikel (refereegranskat)abstract
- It is known that pentoxifylline inhibits platelet aggregation in vitro, but the effects from pentoxifylline and its main metabolites: 3,7-dimetyl-1(5 hydroxyhexyl)xanthine (R-M1 and S-M1), 3,7-dimetyl -1(4-carboxybutyl)xanthine (M4), 3,7-dimetyl -1(3-carboxypropyl)xanthine (M5), on platelet aggregation in whole blood in vitro and in vivo have not been studied. We found that pentoxifylline, rac-M1, R-M1, S-M1 and M4 significantly inhibit ADP induced platelet aggregation in whole blood in vitro in a concentration-dependent manner, R-M1 being the most potent followed by rac-M1, S-M1, pentoxifylline, and M4. In this series of experiments the effects on aggregation induced ATP-release were less pronounced and were only significant after treatment with pentoxifylline, rac-M1 and R-M1, but the potency order appears to be the same. Since the metabolites are not available for use in humans, and also since each substance would be extensively metabolised in vivo, we made an attempt to estimate the relative contribution of each substance to the total effect of pentoxifylline in vivo. Previously published concentrations of pentoxifylline and these metabolites in humans, after administration of pentoxifylline, were used in combination with the potency ratios from this study. The findings from these calculations were that the main effect in vivo comes from S-M1 followed by pentoxifylline, the other metabolites contribute less than 10% each. In conclusion: in the following potency order R-M1, rac-M1, pentoxifylline, S-M1 and M4 all have significant effects on platelet aggregation in whole blood in vitro. However, it appears that the main effects in vivo are caused by S-M1 and pentoxifylline.
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| 7. |
- Negrier, Claude, et al.
(författare)
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Surgical evaluation of a recombinant factorVIII prepared using a plasma/albumin-free method: Efficacy and safety of Advate in previously treated patients
- 2008
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 100:2, s. 217-223
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of factor F(V)III replacement in patients with haemophilia A undergoing surgery is critical for FVIII concentrates, yet large scale, multi-center prospective studies, particularly using continuous infusion, are generally lacking for new products. This study evaluated efficacy and safety of a newly developed recombinant FVIII (rAHF-PFM) administered by bolus or continuous infusion in haemophilia A patients undergoing surgery. Subjects >= 5 years of age with baseline FVIII:C <= 2%, and >= 150 prior FVIII exposure days were included in this prospective, international, open-label, uncontrolled clinical trial. rAHF-PFM was administered perioperatively by bolus infusion (BI) or continuous infusion (CI) according to the standard use at the center to prevent bleeding complication. Both the surgeon and haematologist rated efficacy during hospitalization. Fifty-eight subjects underwent 65 surgical procedures (22 major haemorrhagic risk; 35 minor, 8 dental procedures). Bolus infusion was used exclusively in 47 procedures and continuous infusion, with or without supplemental bolus infusions, in 18. Haemostatic efficacy was assessed as excellent or good for 100% of intraoperative ratings (17 CI, 44 BI, 61 total procedures), and 100% of postoperative ratings performed at time of discharge (18 CI, 44 BI, 62 total procedures). Median total consumption of rAHF-PFM during hospitalization was 822 IU/kg/surgery with CI and 910 IU/kg/surgery with BI. Overall rAHF-PFM was well tolerated, and FVIII inhibitors were not detected. In conclusion, rAHF-PFM administered via continuous infusion or bolus injections is safe, non-immunogenic, and effective for perioperative hemostatic management in previously treated haemophilia A patients.
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| 8. |
- Rask, Olof, et al.
(författare)
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Oestrogen treatment of constitutional tall stature in girls: is there a risk of thrombosis or bleeding?
- 2008
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Ingår i: Acta Pædiatrica. - : Wiley. - 1651-2227 .- 0803-5253. ; 97:3, s. 342-347
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To evaluate haemostatic effects and clinical outcome of oestrogen treatment of constitutionally tall stature in girls. Methods: We conducted a single-centre cohort study, 63 girls referred over a period of 15 years were investigated. The girls were given oestrogen treatment for constitutional tall stature at a median initial dose of 300 ug ethinyl estradiol/day and were consecutively examined for changes in coagulation. Medical records were retrospectively reviewed, additional data were collected at follow-up by blood sampling and interviews. Results: After 1 year of treatment, levels of antithrombin and von Willebrand factor (VWF) were significantly decreased (p < 0.001 and p = 0.015, respectively), whereas there was no significant change in levels of plasminogen inhibitor type 1. No venous thromboembolism (VTE) or major side effects were observed. Genetic risk factors for thrombosis were present, as was expected. The mean height reduction was 5.5 cm. The height-reducing effect was inversely correlated with chronological age (r =-0.44, p < 0.01) and bone age (r =-0.61, p < 0.01). Conclusions: Changes in coagulation parameters occurred both towards pro- and anticoagulation. Treatment with high-dose ethinyl estradiol can successfully limit final height, and it is most effective when started at a younger bone age.
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| 9. |
- Steen Carlsson, Katarina, et al.
(författare)
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Cost and outcome: comparisons of two alternative bypassing agents for persons with haemophilia A complicated by an inhibitor.
- 2008
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 99:6, s. 1060-1067
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Tidskriftsartikel (refereegranskat)abstract
- The development of inhibitory antibodies to factor VIII is a serious complication of haemophilia. Two haemostatic agents with different bypassing mechanisms have been used in the treatment of patients with inhibitors: activated prothrombin complex concentrate (aPCC) and recombinant factor VIIa (rFVIIa). The objective was to compare cost and outcome of aPCC and rFVIIa in the treatment of joint bleeds. The analyses were based on the FENOC (FEIBA NovoSeven Comparative Study) crossover study where 48 patients used aPCC and rFVIIa to treat two joint bleeds. Incremental cost-effectiveness ratios were calculated for three outcome measures and the variation in cost was analyzed using two alternative regression methods. Results were subjected to sensitivity analyses. Key determinants of cost were prescribed dose, bodyweight and treatment in addition to protocol. The cost of aPCC was on average lower than rFVIIa. At all but one time point, patients rated slightly higher (but not statistically significantly) percentages of treatment efficacy and stopping of the bleed by aPCC. The reported reduction in pain from start of treatment up to 48 hours varied considerably among individuals. The different relative prices in the US, Turkey and Sweden mattered, but did not reverse the main results. In conclusion, the cost per episode was significantly lower for aPCC. The large individual-level variation in reduction of pain supports decisions that consider the individual patient's experience and that accept trade-offs between cost and reduction in pain rather than focusing on cost only.
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