Results of a randomized phase III/IV trial comparing intermittent bolus versus continuous infusion of antihaemophilic factor (recombinant) in adults with severe or moderately severe haemophilia A undergoing major orthopaedic surgery

In the era of primary prophylaxis in hemophilia, what types of orthopedic surgical interventions have been published in the 2020-2023 period and in which countries?

INTRODUCTION

Primary prophylaxis has significantly reduced the number of orthopedic surgical procedures performed on patients with hemophilia (PWH) worldwide. However, studies on orthopedic surgery in PWH are still being published in the medical literature.

AREAS COVERED

The aim of this article is to determine the types of orthopedic surgical interventions in PWH published between 2020 and 2023 and the countries in which they are published.

EXPERT OPINION

The following orthopedic surgical procedures are still performed on PWH: total knee, ankle, elbow and hip arthroplasty, ankle fusion, ankle distraction, and the surgical removal of hemophilic pseudotumors. The countries in which articles on orthopedic surgery in hemophilia have been published in the period 2000-2023 include China (14 articles); Republic of Korea and U.S.A. (3 articles each); Germany, Italy, Japan, Poland and Turkey (2 articles each); and 1 article each in the following countries: Austria, Belgium, Chile, France, Ireland, New Zealand, Russia, and The Netherlands. These data suggest that primary prophylaxis should be improved and extended to all patients globally.

Managing Relevant Clinical Conditions of Hemophilia A/B Patients

The Medical Directors of nine Italian Hemophilia Centers reviewed and discussed the key issues concerning the replacement therapy of hemophilia patients during a one-day consensus conference held in Rome one year ago. Particular attention was paid to the replacement therapy needed for surgery using continuous infusion (CI) versus bolus injection (BI) of standard and extended half-life Factor VIII (FVIII) concentrates in severe hemophilia A patients. Among the side effects, the risk of development of neutralizing antibodies (inhibitors) and thromboembolic complications was addressed. The specific needs of mild hemophilia A patients were described, as well as the usage of bypassing agents to treat patients with high-responding inhibitors. Young hemophilia A patients may take significant advantages from primary prophylaxis three times or twice weekly, even with standard half-life (SHL) rFVIII concentrates. Patients affected by severe hemophilia B probably have a less severe clinical phenotype than severe hemophilia A patients, and in about 30% of cases may undergo weekly prophylaxis with an rFIX SHL concentrate. The prevalence of missense mutations in 55% of severe hemophilia B patients allows the synthesis of a partially changed FIX molecule that can play some hemostatic role at the level of endothelial cells or the subendothelial matrix. The flow back of infused rFIX from the extravascular to the plasma compartment allows a very long half-life of about 30 h in some hemophilia B patients. Once weekly, prophylaxis can assure a superior quality of life in a large severe or moderate hemophilia B population. According to the Italian registry of surgery, hemophilia B patients undergo joint replacement by arthroplasty less frequently than hemophilia A patients. Finally, the relationships between FVIII/IX genotypes and the pharmacokinetics of clotting factor concentrates have been investigated.

Perioperative continuous infusions of factor VIII versus factor IX for patients with hemophilia A or B undergoing major surgery

Continuous factor VIII (FVIII) or factor IX (FIX) infusions are commonly used for patients with hemophilia A (HA) or B (HB) undergoing surgery to secure perioperative hemostasis. To describe differences between the initial recovery and subsequent FIX and FVIII levels, and describe clinical outcomes among HB and HA patients receiving perioperative continuous infusion (CI) of recombinant FVIII and FIX concentrates. Retrospective chart review was conducted on 8 consecutive patients with HB and 7 consecutive patients with HA who underwent major surgery between 2014 and 2018 and received continuous infusions of standard half-life factor concentrate. Median initial bolus dose per kilogram was higher for HB compared to HA patients [90.8 (IQR 78.0-98.7) vs. 52.1 (IQR 48.6-55.6) IU/kg], while initial CI dose-rates were similar [4.3 (IQR 3.8-4.6) vs. 4.2 (IQR 3.8-4.4) IU/kg/h]. Median post-bolus recovery was higher for FVIII compared to FIX [1.70 (IQR 1.23-1.75) vs. 0.88 (IQR 0.75-1.00) IU/mL]. Median factor levels also were higher for FVIII on post-operative days 1 to 3. HB patients had greater mean intraoperative estimated blood loss [285.7 (range 0-1000) vs. 142.8 (range 0-400) mL] and longer median length of hospital stay [9 (IQR 8-12) vs. 5 (IQR 4-6.5) days]. Our initial evidence suggests greater in vivo yield of rFVIII compared to rFIX in the perioperative setting. We identified poorer clinical outcomes in this small cohort of perioperative HB patients indicating that they may benefit from a higher CI rate for adequate surgical hemostatic coverage.

How do we optimally utilize factor concentrates in persons with hemophilia?

The current mainstay of therapy for hemophilia is to replace the deficient clotting factor with the intravenous administration of exogenous clotting factor concentrates. Prophylaxis factor replacement therapy is now considered the standard of care in both pediatric and adult patients with hemophilia with a severe phenotype to protect musculoskeletal health and improve quality of life. Heterogeneity in bleeding presentation among patients with hemophilia due to genetic, environmental, and treatment-related factors has been well described. Accordingly, the World Federation of Hemophilia recommends an individualized prophylaxis regimen that considers the factors mentioned above to meet the clinical needs of the patient, which can vary over time. This review focuses on the practical points of choosing the type of factor concentrate, dose, and interval while evaluating appropriate target trough factor levels and bleeding triggers such as level of physical activity and joint status. We also discuss the use of a pharmacokinetics assessment and its incorporation in the clinic for a tailored approach toward individualized management. Overall, adopting an individualized prophylaxis regimen leads to an optimal utilization of factor concentrates with maximum efficacy and minimum waste.