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  • 11
    In: BMC Medicine, Springer Science and Business Media LLC, Vol. 18, No. 1 ( 2020-12)
    Kurzfassung: Silent cerebral infarcts (SCIs) are the most common neurological complication in children and adults with sickle cell disease (SCD). In this systematic review, we provide an overview of studies that have detected SCIs in patients with SCD by cerebral magnetic resonance imaging (MRI). We focus on the frequency of SCIs, the risk factors involved in their development and their clinical consequences. Methods The databases of Embase, MEDLINE ALL via Ovid, Web of Science Core Collection, Cochrane Central Register of Trials via Wiley and Google Scholar were searched from inception to June 1, 2019. Results The search yielded 651 results of which 69 studies met the eligibility criteria. The prevalence of SCIs in patients with SCD ranges from 5.6 to 80.6% with most studies reported in the 20 to 50% range. The pooled prevalence of SCIs in HbSS and HbSβ 0 SCD patients is 29.5%. SCIs occur more often in patients with the HbSS and HbSβ 0 genotype in comparison with other SCD genotypes, as SCIs are found in 9.2% of HbSC and HbSβ + patients. Control subjects showed a mean pooled prevalence of SCIs of 9.8%. Data from included studies showed a statistically significant association between increasing mean age of the study population and mean SCI prevalence. Thirty-three studies examined the risk factors for SCIs. The majority of the risk factors show no clear association with prevalence, since more or less equal numbers of studies give evidence for and against the causal association. Conclusions This systematic review and meta-analysis shows SCIs are common in patients with SCD. No clear risk factors for their development were identified. Larger, prospective and controlled clinical, neuropsychological and neuroimaging studies are needed to understand how SCD and SCIs affect cognition.
    Materialart: Online-Ressource
    ISSN: 1741-7015
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2020
    ZDB Id: 2131669-7
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  • 12
    In: Thrombosis and Haemostasis, Georg Thieme Verlag KG, Vol. 120, No. 05 ( 2020-05), p. 747-757
    Kurzfassung: Background The currently published population pharmacokinetic (PK) models used for PK-guided dosing in hemophilia patients are based on clinical trial data and usually not externally validated in clinical practice. The aim of this study was to validate a published model for recombinant factor VIII-Fc fusion protein (rFVIII-Fc) concentrate and to develop an enriched model using independently collected clinical data if required. Methods Clinical data from hemophilia A patients treated with rFVIII-Fc concentrate (Elocta) participating in the United Kingdom Extended Half-Life Outcomes Registry were collected. The predictive performance of the published model was assessed using mean percentage error (bias) and mean absolute percentage error (inaccuracy). An extended population PK model was developed using nonlinear mixed-effects modeling (NONMEM). Results A total of 43 hemophilia A patients (FVIII ≤ 2 IU/dL), aged 5 to 70 years, were included. The prior model was able to predict the collected 244 rFVIII-Fc levels without significant bias (–1.0%, 95% CI: –9.4 to 7.3%) and with acceptable accuracy (12.9%). However, clearance and central distribution volume were under predicted in patients 〈 12 years, which was expected as this age group was not represented in the previous model population. An enriched population PK model was constructed, which was able to successfully characterize PK profiles of younger children. Conclusion We concluded that the existing rFVIII-Fc population PK model is valid for patients ≥ 12 years. However, it is not reliable in younger patients. Our alternative model, constructed from real world patient data including children, allows for better description of patients ≥5 years.
    Materialart: Online-Ressource
    ISSN: 0340-6245 , 2567-689X
    Sprache: Englisch
    Verlag: Georg Thieme Verlag KG
    Publikationsdatum: 2020
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  • 13
    Online-Ressource
    Online-Ressource
    BMJ ; 2021
    In:  BMJ Case Reports Vol. 14, No. 4 ( 2021-04), p. e238036-
    In: BMJ Case Reports, BMJ, Vol. 14, No. 4 ( 2021-04), p. e238036-
    Kurzfassung: We explored the effects of extreme weight loss after gastric bypass surgery on factor VIII concentrate pharmacokinetic (PK) parameters in a patient with haemophilia A. We present a 32-year-old man with severe haemophilia A, with a body mass index (BMI) of 42.6 kg/m 2 who underwent laparoscopic sleeve gastrectomy. We showed that a population PK model with ideal body weight as morphometric variable instead of bodyweight led to an adequate description of the individual PKs in this patient with a variable BMI. Strikingly, no differences were observed in the individual PK parameters after extreme weight loss. Therefore, the resulting extreme weight loss after surgery did not lead to prophylactic dose changes in this patient with severe haemophilia. We carefully conclude that population PK–pharmacodynamic models are still obligatory to give more insight into functional effects of significant weight loss on the haemostatic balance.
    Materialart: Online-Ressource
    ISSN: 1757-790X
    Sprache: Englisch
    Verlag: BMJ
    Publikationsdatum: 2021
    ZDB Id: 2467301-8
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  • 14
    In: Thrombosis and Haemostasis, Georg Thieme Verlag KG, Vol. 120, No. 07 ( 2020-07), p. 1056-1065
    Kurzfassung: Background von Willebrand factor (VWF) is crucial for optimal dosing of factor VIII (FVIII) concentrate in hemophilia A patients as it protects FVIII from premature clearance. To date, it is unknown how VWF behaves and what its impact is on FVIII clearance in the perioperative setting. Aim To investigate VWF kinetics (VWF antigen [VWF:Ag]), VWF glycoprotein Ib binding (VWF:GPIbM), and VWF propeptide (VWFpp) in severe and moderate perioperative hemophilia A patients included in the randomized controlled perioperative OPTI-CLOT trial. Methods Linear mixed effects modeling was applied to analyze VWF kinetics. One-way and two-way analyses of variance were used to investigate perioperative VWFpp/VWF:Ag ratios and associations with surgical bleeding. Results Fifty-nine patients with median age of 48.8 years (interquartile range: 34.8–60.0) were included. VWF:Ag and VWF:GPIbM increased significantly postoperatively. Blood type non-O or medium risk surgery were associated with higher VWF:Ag and VWF:GPIbM levels compared with blood type O and low risk surgery. VWFpp/VWF:Ag was significantly higher immediately after surgery than 32 to 57 hours after surgery (p  〈  0.001). Lowest VWF:Ag quartile (0.43–0.92 IU/mL) was associated with an increase of FVIII concentrate clearance of 26 mL/h (95% confidence interval: 2–50 mL/h) compared with highest VWF antigen quartile (1.70–3.84 IU/mL). VWF levels were not associated with perioperative bleeding F(4,227) = 0.54, p = 0.710. Conclusion VWF:Ag and VWF:GPIbM levels increase postoperatively, most significantly in patients with blood type non-O or medium risk surgery. Lower VWF antigen levels did not lead to clinically relevant higher FVIII clearance. VWF:Ag or VWF:GPIbM levels were not associated with perioperative hemorrhage.
    Materialart: Online-Ressource
    ISSN: 0340-6245 , 2567-689X
    Sprache: Englisch
    Verlag: Georg Thieme Verlag KG
    Publikationsdatum: 2020
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  • 15
    In: Thrombosis and Haemostasis, Georg Thieme Verlag KG, Vol. 121, No. 06 ( 2021-06), p. 731-740
    Kurzfassung: Background The pharmacokinetic (PK) properties of extended half-life (EHL) factor VIII (FVIII) concentrates differ, leading to variation in the optimal dosing regimen for the individual patient. The aim of this study was to establish these PK differences for various EHL FVIII concentrates by in silico simulations. Methods FVIII level over time profiles of rFVIII-SC, BAY 81–8973, rFVIII-Fc, BAX 855, BAY 94–9027, and standard half-life (SHL) rFVIII concentrates were simulated for 1,000 severe hemophilia A patients during steady-state dosing of 40 IU/kg every 72 hours or dosing as advised in the summary of product characteristics (SmPC). Results Although the elimination half-life values were comparable for rFVIII-FC, BAX 855, and BAY 94–9027, a higher area under the curve (AUC; 2,779 IU/h/dL) for BAY 94–9027 was obtained. During steady-state dosing of 40 IU/kg every 72 hours, 58.5% (rFVIII-SC), 69.3% (BAY 81–8972), 89.0% (rFVIII-Fc), 83.9% (BAX 855), and 93.7% (BAY 94–9027) of the patients maintained a trough level of 1 IU/dL, compared with 56.0% for SHL rFVIII. Following dosing schemes described in the SmPC, between 51.0 and 65.4% or 23.2 and 31.1% of the patients maintained a target trough level of 1 IU/dL or 3 IU/dL, respectively. Conclusion BAY 94–9027 showed the largest increase of AUC and best target attainment compared with SHL rFVIII, followed closely by BAX 855 and rFVIII-Fc. BAY 81–8973 and rFVIII-SC showed smaller PK improvements. Although our analyses increase insight into the PK of these FVIII concentrates, more studies evaluating the relation between factor levels and bleeding risk are needed.
    Materialart: Online-Ressource
    ISSN: 0340-6245 , 2567-689X
    Sprache: Englisch
    Verlag: Georg Thieme Verlag KG
    Publikationsdatum: 2021
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  • 16
    In: Thrombosis and Haemostasis, Georg Thieme Verlag KG, Vol. 120, No. 10 ( 2020-10), p. 1407-1416
    Kurzfassung: Objective Most von Willebrand disease (VWD) patients can be treated with desmopressin during bleeding or surgery. Large interpatient variability is observed in von Willebrand factor (VWF) activity levels after desmopressin administration. The aim of this study was to develop a pharmacokinetic (PK) model to describe, quantify, and explain this variability. Methods Patients with either VWD or low VWF, receiving an intravenous desmopressin test dose of 0.3 µg kg−1, were included. A PK model was derived on the basis of the individual time profiles of VWF activity. Since no VWF was administered, the VWF dose was arbitrarily set to unity. Interpatient variability in bioavailability (F), volume of distribution (V), and clearance (Cl) was estimated. Results The PK model was developed using 951 VWF activity level measurements from 207 patients diagnosed with a VWD type. Median age was 28 years (range: 5–76), median predose VWF activity was 0.37 IU/mL (range: 0.06–1.13), and median VWF activity response at peak level was 0.64 IU/mL (range: 0.04–4.04). The observed PK profiles were best described using a one-compartment model with allometric scaling. While F increased with age, Cl was dependent on VWD type and sex. Inclusion resulted in a drop in interpatient variability in F and Cl of 81.7 to 60.5% and 92.8 to 76.5%, respectively. Conclusion A PK model was developed, describing VWF activity versus time profile after desmopressin administration in patients with VWD or low VWF. Interpatient variability in response was quantified and partially explained. This model is a starting point toward more accurate prediction of desmopressin dosing effects in VWD.
    Materialart: Online-Ressource
    ISSN: 0340-6245 , 2567-689X
    Sprache: Englisch
    Verlag: Georg Thieme Verlag KG
    Publikationsdatum: 2020
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  • 17
    Online-Ressource
    Online-Ressource
    Georg Thieme Verlag KG ; 2023
    In:  Thrombosis and Haemostasis Vol. 123, No. 03 ( 2023-03), p. 317-325
    In: Thrombosis and Haemostasis, Georg Thieme Verlag KG, Vol. 123, No. 03 ( 2023-03), p. 317-325
    Kurzfassung: Background Little is known on how sports participation affects bleeding risk in hemophilia. This study aimed to examine associations between sports participation, factor VIII (FVIII) levels and bleeding in persons with hemophilia A. Methods In this observational, prospective, single-center study, persons with hemophilia A who regularly participated in sports were followed for 12 months. The associations of patient characteristics, FVIII levels, and type/frequency of sports participation with bleeding were analyzed by repeated time-to-event modelling. Results One hundred and twelve persons (median age: 24 years [interquartile range:16–34], 49% severe, 49% on prophylaxis) were included. During follow-up, 70 bleeds of which 20 sports-induced were observed. FVIII levels were inversely correlated with the bleeding hazard; a 50% reduction of the baseline bleeding hazard was observed at FVIII levels of 3.1 and a 90% reduction at 28.0 IU/dL. The bleeding hazard did not correlate with sports participation. In addition, severe hemophilia, prestudy annual bleeding rate, and presence of arthropathy showed a positive association with the bleeding hazard. Conclusion This analysis showed that FVIII levels were an important determinant of the bleeding hazard, but sports participation was not. This observation most likely reflects the presence of adequate FVIII levels during sports participation in our study. Persons with severe hemophilia A exhibited a higher bleeding hazard at a similar FVIII levels than nonsevere, suggesting that the time spent at lower FVIII levels impacts overall bleeding hazard. These data may be used to counsel persons with hemophilia regarding sports participation and the necessity of adequate prophylaxis.
    Materialart: Online-Ressource
    ISSN: 0340-6245 , 2567-689X
    Sprache: Englisch
    Verlag: Georg Thieme Verlag KG
    Publikationsdatum: 2023
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  • 18
    In: Haemophilia, Wiley, Vol. 27, No. 6 ( 2021-11), p. 974-983
    Kurzfassung: Haemophilia A patients require perioperative clotting factor replacement to limit excessive bleeding. Weight‐based dosing of Factor VIII (FVIII) does not account for inter‐individual pharmacokinetic (PK) variability, and may lead to suboptimal FVIII exposure. Aim To perform an external validation of a previously developed population PK (popPK) model of perioperative FVIII in haemophilia A patients. Methods A retrospective chart review identified perioperative haemophilia A patients at the University of North Carolina (UNC) between April 2014 and November 2019. Patient data was used to externally validate a previously published popPK model proposed by Hazendonk. Based on these validation results, a modified popPK model was developed to characterize FVIII PK in our patients. Dosing simulations were performed using this model to compare FVIII target attainment between intermittent bolus (IB) and continuous infusion (CI) administration methods. Results A total of 521 FVIII concentrations, drawn from 34 patients, were analysed. Validation analyses revealed that the Hazendonk model did not fully capture FVIII PK in the UNC cohort. Therefore, a modified one‐compartment model, with weight and age as covariates on clearance (CL), was developed. Dosing simulations revealed that CI resulted in improved target attainment by 16%, with reduced overall FVIII usage by 58 IU/kg, compared to IB. Conclusion External validation revealed a previously published popPK model of FVIII did not adequately characterize UNC patients, likely due to differences in patient populations. Future prospective studies are needed to evaluate our model prior to implementation into clinical practice.
    Materialart: Online-Ressource
    ISSN: 1351-8216 , 1365-2516
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2021
    ZDB Id: 2006344-1
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  • 19
    In: British Journal of Clinical Pharmacology, Wiley
    Kurzfassung: Recombinant factor IX Fc fusion protein (rFIX‐Fc) is an extended half‐life factor concentrate administered to haemophilia B patients. So far, a population pharmacokinetic (PK) model has only been published for patients aged ≥12 years. The aim was to externally evaluate the predictive performance of the published rFIX‐Fc population PK model for patients of all ages and develop a model that describes rFIX‐Fc PK using real‐world data. Methods We collected prospective and retrospective data from patients with haemophilia B treated with rFIX‐Fc and included in the OPTI‐CLOT TARGET study (NTR7523) or United Kindom (UK)‐EHL Outcomes Registry (NCT02938156). Predictive performance was assessed by comparing predicted with observed FIX activity levels. A new population PK model was constructed using nonlinear mixed‐effects modelling. Results Real‐world data were obtained from 37 patients (median age: 16 years, range 2–71) of whom 14 were aged 〈 12 years. Observed FIX activity levels were significantly higher than levels predicted using the published model, with a median prediction error of −48.8%. The new model showed a lower median prediction error (3.4%) and better described rFIX‐Fc PK, especially for children aged 〈 12 years. In the new model, an increase in age was correlated with a decrease in clearance ( P   〈  .01). Conclusions The published population PK model significantly underpredicted FIX activity levels. The new model better describes rFIX‐Fc PK, especially for children aged 〈 12 years. This study underlines the necessity to strive for representative population PK models, thereby avoiding extrapolation outside the studied population.
    Materialart: Online-Ressource
    ISSN: 0306-5251 , 1365-2125
    RVK:
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2023
    ZDB Id: 1498142-7
    SSG: 15,3
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  • 20
    In: Haemophilia, Wiley, Vol. 26, No. 3 ( 2020-05)
    Kurzfassung: Diagnostic evaluation of patients with a bleeding tendency remains challenging, as no disorder is identified in approximately 50% of patients. An impaired interplay of several haemostatic factors might explain bleeding phenotype in these patients. Objective To investigate whether global haemostasis assays are able to identify haemostatic abnormalities in patients with a bleeding tendency unexplained by current diagnostic laboratory tests. Materials and methods Patients of ≥12 years with a bleeding tendency were included from a tertiary outpatient clinic. Bleeding phenotype was assessed with the ISTH‐BAT. Patients were classified as having bleeding of unknown cause (BUC) or a mild bleeding disorder (MBD) based on abnormalities assessed by routine haemostatic tests. Global haemostasis tests (rotational thromboelastometry (ROTEM), thrombin generation test (TG) and plasma clot lysis time (CLT)) were measured in all patients. The results were compared with 76 controls. Results One hundred and eighty‐one patients were included, and 60% (109/181) was classified as having BUC. BUC patients demonstrated a significantly prolonged lag time in TG (median 7.7 minutes, IQR 6.7‐8.7) and a significantly prolonged CLT (median 60.5 minutes, IQR 54.7‐66.1) compared to controls. No differences in ROTEM variables were found. Patients with MBD showed an impaired thrombin generation with a significantly decreased ETP (median 1024 nmol/L*min, IQR 776‐1355) and peak height (median 95 nmol/L, IQR 76‐138), compared to BUC patients and controls. Conclusion No major differences were found in ROTEM and TG variables in BUC patients compared to controls. BUC patients did have a significantly prolonged clot lysis time. The underlying mechanism for this finding is unknown.
    Materialart: Online-Ressource
    ISSN: 1351-8216 , 1365-2516
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2020
    ZDB Id: 2006344-1
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