Patient-relevant health outcomes for von Willebrand disease, platelet function disorders, and rare bleeding disorders:a Delphi study

Background: To assess patient value, it is essential to regularly measure health outcomes that matter to patients. It is currently unknown which health outcomes are important for patients with autosomal inherited bleeding disorders. Objectives: This study aimed to assess which health outcomes are important for patients with autosomal inherited bleeding disorders, consisting of von Willebrand disease, platelet function disorders, and rare bleeding disorders, as seen from the patients’, caregivers’, and healthcare professionals’ perspectives. Methods: Two panels, one consisting of patients and caregivers, and one consisting of healthcare professionals participated in a Delphi process. A list of 146 health outcomes was identified from the literature. During 3 rounds, both panels rated the importance of health outcomes on a 5-point Likert scale. A health outcome was considered important by a panel if it received a median score of 5 with an IQR of ≤1. Results: In total, 13 patients, 10 caregivers, and 19 healthcare professionals participated in the Delphi study. Both panels reached consensus on the importance of health outcomes related to bleeding episodes, life-threatening complications, and the intensity and impact of menstruation. Patients and caregivers additionally reached consensus on the importance of health outcomes related to menstruation and the impact of the bleeding disorder on their daily lives. Healthcare professionals reached consensus on the importance of health outcomes related to treatment, joint health, and pain. Conclusion: In this study, health outcomes were identified that should be considered when implementing value-based health care in the care of patients with autosomal inherited bleeding disorders.</p

Limited sampling strategies for individualized BAX 855 prophylaxis in severe hemophilia A:in silico evaluation

ObjectiveLimited sampling strategies (LSS) lower the burden of pharmacokinetic (PK)-guided dosing, but an extensive evaluation of LSS for BAX 855 (Adynovi) is currently lacking. This study aimed to develop a LSS for BAX 855 and combine this with a LSS of a standard half-life (SHL) factor VIII (FVIII) concentrate in a clinical setting.MethodsIndividual PK parameters of BAX 855 were estimated for 10 000 virtual patients with severe hemophilia A using Monte Carlo simulations. Several LSS consisting of 2-6 samples were examined based on patient burden, bias and accuracy of clearance, elimination half-life, volume of distribution and trough levels at 72 h (C72). Analyses were performed separately for adults and children &lt;12 years.ResultsThe preferred LSS for BAX 855 consisted of three sampling points at 15-30 min, 48 h and 72 h for both adults (mean accuracy C72: 14.0% vs. 10.8% using six samples) and children (mean accuracy C72: 14.9% vs. 11.4% using six samples). The best strategy with two samples (peak, 48 h) resulted in an adequate, but lower accuracy than strategies with ≥3 samples (mean accuracy C72: 22.3%). The optimal combination of the LSS of SHL FVIII and BAX 855 led to six samples during four clinical visits.ConclusionThis in silico study has identified that two to three samples are necessary to estimate the individual PK of BAX-855 adequately. These samples can be collected in one or two clinical visits. When combining PK profiling of SHL FVIII and BAX 855, six samples during four clinical visits are needed.</p

Reliability and validity of a novel haemophilia-specific self-efficacy scale

Higher self-efficacy in chronic disease patients is associated with higher development of self-management skills and increased quality-of-life. Quantification and monitoring of self-efficacy is therefore of importance. Self-efficacy in haemophilia patients has received little attention due to lack of standardized scales. To validate the novel Haemophilia-specific Self-Efficacy Scale (HSES) in haemophilia patients on prophylactic home treatment, haemophilia patients aged 1-18 years on prophylactic treatment ≥1 year were included from three Dutch Haemophilia Treatment Centres. The HSES consists of 12 items, relating to perceptions of the ability to function on a day-to-day basis with regard to patient's disease. Retest was performed in a subsample. Validity was proven by the General Self-Efficacy Scale and by the health-related quality-of-life assessment tool Haemo-QoL. Data were analysed from 53 children (response 75%), with a mean age of 9.8 years (SD 4.0). Mean total scale score of HSES was 55.5 (SD 4.7; range 38-60), with a ceiling effect of 17%. The HSES showed adequate internal consistency (Cronbach's alpha 0.72) and good test-retest reliability (Intra-Class-Correlation coefficient 0.75; P < 0.01; n = 37). The convergent validity was adequate as haemophilia-specific self-efficacy correlated significantly with general self-efficacy (r = 0.38; P < 0.01). High HSES scores correlated significantly with quality-of-life as measured by the Haemo-QoL (r = -0.42; P ≤ 0.01). The novel HSES is a reliable and valid tool to assess self-efficacy in paediatric haemophilia patients on prophylactic home treatment. High self-efficacy correlated with higher quality-of-life, further underlining the importance to standardly assess, monitor and improve self-efficacy

Does difference between label and actual potency of factor VIII concentrate affect pharmacokinetic-guided dosing of replacement therapy in haemophilia A?

BACKGROUND: To account for interindividual variability in the pharmacokinetics (PK) of factor concentrates, PK‐guided dosing is increasingly implemented in haemophilia patients. Calculations are based on provided label potency, but legislation allows a potency difference of ±20% between label and actual potency. It is unknown if these differences affect PK guidance. AIM: Explore the effects of potency differences on individual factor VIII (FVIII) PK parameters and the prediction of FVIII trough levels of dosing regimens. METHODS: We analyzed individual preoperative PK profiling data from severe and moderate haemophilia A patients included in the OPTI‐CLOT randomized controlled trial. Label and actual potency were compared, with data on potency provided by pharmaceutical companies. For both potencies, individual PK parameters were estimated and concentration‐time curves were constructed by nonlinear mixed‐effects modelling. Finally, we explored the effect of both the identified and the maximum legislated potency difference on predicted FVIII trough levels infused in a low and high dose regimen. RESULTS: In 45/50 included patients, actual potency was higher than its label potency. The median potency difference was 6.0% (range ‐9.2% to 18.4%) and resulted in varying individual PK parameter estimates but practically identical FVIII concentration‐time curves. As expected, predicted FVIII trough levels were linearly correlated to the actual dose. CONCLUSION: It is not necessary to take potency differences into account when applying PK guidance of FVIII concentrates in haemophilia A patients. However, when the patient is switched to another FVIII batch after PK‐guided dosing, trough levels may deviate ±20% from calculations based on label dose

Self-infusion of prophylaxis: Evaluating the quality of its performance and time needed

Prophylactic replacement therapy is the cornerstone of treatment in severe haemophilia. Regular infusions with clotting factor concentrate have been proven effective to prevent bleeding, subsequent (joint) damage, and positively affect the impact of haemophilia on daily life [1]. Patients or parents of younger patients learn to infuse clotting factor concentrate in a peripheral vein (i.v.) or a central venous access device (CVAD) [2]

Desmopressin to prevent and treat bleeding in pregnant women with an inherited bleeding disorder:a systematic literature review

Background: Although desmopressin (DDAVP) is an accessible and inexpensive hemostatic drug, its use in pregnancy is still debated due to safety uncertainties. Objectives: We aimed to review the safety and effectiveness of DDAVP in women with an inherited bleeding disorder during pregnancy and delivery. Methods: Databases were searched for articles up to July 25, 2022, reporting maternal and/or neonatal outcomes. PRISMA methodology for systematic reviews and meta-analyses was followed (PROSPERO CRD42022316490). Results: Fifty-three studies were included, comprising 273 pregnancies. Regarding maternal outcomes, DDAVP was administered in 73 women during pregnancy and in 232 during delivery. Safety outcome was reported in 245 pregnancies, with severe adverse events reported in 2 (1%, hyponatremia with neurologic symptoms). Overall, DDAVP was used as monotherapy in 234 pregnancies, with effectiveness reported in 153 pregnancies (82% effective; 18% ineffective). Regarding neonatal outcomes, out of 60 pregnancies with reported neonatal outcomes after DDAVP use during pregnancy, 2 children (3%) had a severe adverse event (preterm delivery n = 1; fetal growth restriction n = 1). Of the 232 deliveries, 169 neonates were exposed to DDAVP during delivery, and in 114 neonates, safety outcome was reported. Two children (2%) experienced a moderate adverse event (low Apgar score n = 1; transient hyperbilirubinemia not associated with DDAVP n = 1). Conclusion: DDAVP use during pregnancy and delivery seems safe for the mother, with special attention to the occurrence of hyponatremia and for the child, especially during delivery. However, due to poor study designs and limited documentation of outcomes, a well-designed prospective study is warranted.</p

Population pharmacokinetics of the von Willebrand factor-factor VIII interaction in patients with von Willebrand disease

Recent studies have reported that patients with von Willebrand disease treated perioperatively with a von Willebrand factor (VWF)/factor VIII (FVIII) concentrate with a ratio of 2.4:1 (Humate P/Haemate P) often present with VWF and/or FVIII levels outside of prespecified target levels necessary to prevent bleeding. Pharmacokinetic (PK)-guided dosing may resolve this problem. As clinical guidelines increasingly recommend aiming for certain target levels of both VWF and FVIII, application of an integrated population PK model describing both VWF activity (VWF:Act) and FVIII levels may improve dosing and quality of care. In total, 695 VWF:Act and 894 FVIII level measurements from 118 patients (174 surgeries) who were treated perioperatively with the VWF/FVIII concentrate were used to develop this population PK model using nonlinear mixed-effects modeling. VWF:Act and FVIII levels were analyzed simultaneously using a turnover model. The protective effect of VWF:Act on FVIII clearance was described with an inhibitory maximum effect function. An average perioperative VWF:Act level of 1.23 IU/mL decreased FVIII clearance from 460 mL/h to 264 mL/h, and increased FVIII half-life from 6.6 to 11.4 hours. Clearly, in the presence of VWF, FVIII clearance decreased with a concomitant increase of FVIII half-life, clarifying the higher FVIII levels observed after repetitive dosing with this concentrate. VWF:Act and FVIII levels during perioperative treatment were described adequately by this newly developed integrated population PK model. Clinical application of this model may facilitate more accurate targeting of VWF:Act and FVIII levels during perioperative treatment with this specific VWF/FVIII concentrate (Humate P/Haemate P).Thrombosis and Hemostasi