Adherence to prophylaxis and bleeding outcome in haemophilia: a multicentre study.

Prevention of bleeding and joint damage in severe haemophilia is dependent on adherence to prophylactic replacement therapy. The aim of this study was to assess adherence to prophylaxis, including associations with age, bleeding and clotting factor consumption (CFC). In three Dutch haemophilia centres, semi-structured interviews about adherence to prophylaxis in the previous 2 weeks were conducted with patients or parents of a child with haemophilia. Patients were classified, according to pre-specified definitions, as adherent, sub-optimally adherent or non-adherent based on missing, timing, and dose of infusions. Association of annual bleeding rates, mean CFC, person performing the infusion (parents verus patients) with adherence categories were analysed. Overall, 241 patients with haemophilia using prophylaxis were studied. Parents were more adherent (66%; n = 48/73) than patients (43%; n = 72/168). Sub-optimal adherence occurred in 29% of parents and 37% of patients and was characterized by changes in timing of infusion (mostly from morning to evening), while missing <6% of infusions. Non-adherence occurred less often: in 5% of parents and 20% of patients. Reduced adherence was associated with lower CFC, but not with joint bleeding. In conclusion, non-adherence in haemophilia was relatively rare, yet 1/3 of patients struggled to administer prophylaxis at the appropriate time of day.

A population pharmacokinetic model for perioperative dosing of factor VIII in hemophilia A patients.

The role of pharmacokinetic-guided dosing of factor concentrates in hemophilia is currently a subject of debate and focuses on long-term prophylactic treatment. Few data are available on its impact in the perioperative period. In this study, a population pharmacokinetic model for currently registered factor VIII concentrates was developed for severe and moderate adult and pediatric hemophilia A patients (FVIII levels <0.05 IUmL-1) undergoing elective, minor or major surgery. Retrospective data were collected on FVIII treatment, including timing and dosing, time point of FVIII sampling and all FVIII plasma concentrations achieved (trough, peak and steady state), brand of concentrate, as well as patients' and surgical characteristics. Population pharmacokinetic modeling was performed using non-linear mixed-effects modeling. Population pharmacokinetic parameters were estimated in 75 adults undergoing 140 surgeries (median age: 48 years; median weight: 80 kg) and 44 children undergoing 58 surgeries (median age: 4.3 years; median weight: 18.5 kg). Pharmacokinetic profiles were best described by a two-compartment model. Typical values for clearance, intercompartment clearance, central and peripheral volume were 0.15 L/h/68 kg, 0.16 L/h/68 kg, 2.81 L/68 kg and 1.90 L/68 kg. Interpatient variability in clearance and central volume was 37% and 27%. Clearance decreased with increasing age (P<0.01) and increased in cases with blood group O (26%; P<0.01). In addition, a minor decrease in clearance was observed when a major surgical procedure was performed (7%; P<0.01). The developed population model describes the perioperative pharmacokinetics of various FVIII concentrates, allowing individualization of perioperative FVIII therapy for severe and moderate hemophilia A patients by Bayesian adaptive dosing.

Achieving self-management of prophylactic treatment in adolescents: The case of haemophilia.

OBJECTIVE: Adolescents with a chronic disorder, such as haemophilia, need to attain responsibility for their disease. The aim was to gain insight into how adolescents achieve self-management of prophylactic treatment. METHODS: In three Dutch Haemophilia Treatment Centres, adolescents (10-25 years) received structured questions on treatment responsibility and self-management (pre-specified definitions) during routine nursing consultation. RESULTS: In total, 155 interviews were performed in 100 patients (median age 14.4 years). Self-infusion was initiated at a median age of 12.3 years (IQR 11.5-13.0) and self-management was achieved 9.6 years later, at a median age of 22.6 years. This process included three phases coinciding with known stages of adolescence. In early adolescence, patients acquired the technique of self-infusion (12.3 years) leading to independent self-infusion in middle adolescence (17.2 years). In late adolescence, patients demonstrated an increase in more complex skills, such as bleeding management and communication with the haemophilia physician (19.9-22.6 years). CONCLUSION: Although, the first steps in self-management with regard to self-infusion are taken in early adolescence, complete self-management was achieved in late adolescence after almost 10 years. PRACTICE IMPLICATIONS: Insight in this transitional process helps to provide individualized support and emphasizes the need for continued education with regard to self-management skills.

[Haemophilia]. / Hemofilie.

Haemophilia is an X-linked inherited clotting disorder with a prevalence of 1 per 5000 men. A deficiency of clotting factor VIII (FVIII; haemophilia A) or IX (FIX; haemophilia B) causes haemophilia patients to suffer from spontaneous bleeding and excessive blood-loss following surgery or trauma. Prophylactic administration of a factor VIII- or factor IX-concentrate is the standard treatment for children with severe haemophilia. Women who are carriers of the F8 or F9 gene mutation can have a lowered plasma concentration of factor VIII or IX, and thus suffer from a mild form of haemophilia. Drugs that have a negative influence on blood clotting, such as NSAIDs, can lead to life-threatening bleeding in haemophilia patients. One of the main complications of haemophilia treatment is the formation of inhibiting antibodies that inactivate FVIII or FIX. Haemophilia patients should be treated by a multidisciplinary team in a hospital with a haemophilia treatment centre.