Continuous infusion therapy in haemophilia

Off-pump technique and replacement therapy for coronary artery bypass surgery in a patient with hemophilia B

Antithrombotic treatment and perioperative management in patients with hemophilia remains a challenge. As life expectancy in these patients is increasing, a concern about cardiovascular diseases is emerging. Herein we present the case of a 68 year-old patient with mild hemophilia B and multivessel coronary disease who underwent coronary artery bypass grafting (CABG) surgery. Off-pump surgery with continuous infusion FIX treatment was performed successfully with stable factor IX levels, and no bleeding or thrombotic complications. There is a paucity of cases reported regarding management of CABG in this population. To our knowledge, this is the first patient with mild hemophilia B that underwent CABG surgery with off-pump technique, that seems to be a secure and effective procedure.

Continuous infusion of recombinant activated factor VII: a review of data in congenital hemophilia with inhibitors and congenital factor VII deficiency

Introduction

Continuous infusion (CI) of clotting factors as a replacement therapy for perioperative hemostatic protection has been performed for many years, including with factors VIII and IX and recombinant activated factor VII (rFVIIa). This approach provides steady factor levels without requiring frequent administration of bolus doses.

Aim

To review safety, efficacy, and dosing data regarding CI of rFVIIa for hemostatic management of patients with congenital hemophilia with inhibitors (CHwI) or congenital factor VII deficiency (C7D).

Materials and methods

A literature review identified instances of CI of rFVIIa in patients with CHwI or C7D undergoing surgery or experiencing bleeding episodes. Data regarding safety, efficacy, and dosing were extracted.

Results

The safety and efficacy of 50 mcg/kg/h CI of rFVIIa following a 90 mcg/kg bolus injection, vs a standard bolus injection regimen, was reported for 24 patients with CHwI undergoing elective surgery in an open-label, randomized, Phase III trial. Efficacy was similar between CI and bolus injection groups at all postoperative time points assessed. Additionally, a postmarketing surveillance study reported effective (80%) and partially effective (20%) CI of rFVIIa in a Japanese cohort of ten patients with CHwI who underwent 15 surgical procedures. Finally, the safety and dosing of rFVIIa CI in 193 and 26 patients with CHwI and C7D, respectively, were reported in 11 prospective studies, 10 retrospective studies, and 30 case reports. No unexpected safety findings were reported.

Conclusion

rFVIIa CI has been performed safely and effectively in patients with CHwI and C7D undergoing surgery and during bleeding episodes in patients with CHwI.

Outcomes in Patients With Hemophilia and von Willebrand Disease Undergoing Invasive or Surgical Procedures

Adults with hemophilia A (HA), hemophilia B (HB), and von Willebrand disease (VWD) frequently require surgery and invasive procedures. However, there is variability in perioperative management guidelines. We describe our periprocedural outcomes in this setting. A retrospective chart review from January 2006 to December 2012 of patients with HA, HB, and VWD undergoing surgery or invasive procedures was conducted. Type of procedures, management including the use of continuous factor infusion, and administration of antifibrinolytics were reviewed. Adverse outcomes were defined as acute bleeding (<48 hours), delayed bleeding (≥48 hours), transfusion, inhibitor development, and thrombosis. We identified 59 patients with HA and HB. In all, 24 patients had severe hemophilia and 12 had mild/moderate hemophilia. Twelve patients had inhibitors. There were also 5 female carriers of HA and 6 patients with VWD. There were 34 major surgeries (26 orthopedic, 8 nonorthopedic) and 129 minor surgeries. Continuous infusion was used in 55.9% of major surgeries versus 8.5% of minor surgeries. Antifibrinolytics were administered in 14.7% of major surgeries versus 23.2% of minor surgeries. In all, 4 patients developed acute bleeding and 10 patients developed delayed bleeding. Delayed bleeding occurred in 28.6% of genitourinary procedures and in 16.1% of dental procedures. Five patients acquired an inhibitor and 2 had thrombosis. In conclusion, patients with HA, HB, or VWD had similar rates of adverse outcomes when undergoing minor surgeries or major surgeries. This finding underscores the importance of an interdisciplinary management and procedure-specific guidelines for patients with hemophilia and VWD prior to even minor invasive procedures.

Thawed cryoprecipitate stored for 6 h at room temperature: a potential alternative to factor VIII concentrate for continuous infusion

Continuous infusion (CI) of factor VIII concentrates has been demonstrated to be cost-effective method in maintaining stable levels of FVIII activity in haemophilia A patients with major bleeding or undergoing major surgery. Cryoprecipitates remain the major source of FVIII in developing countries-like the Philippines because of limited availability and high cost of concentrates. To support the use of cryoprecipitate as alternative to FVIII concentrate for CI in centres with no factor concentrates, FVIII levels in 37 bags of random cryoprecipitate were measured at 0, 2, 4 and 6 h after thawing, kept at room temperature with bacteriological culture studies performed on the sixth hour. The mean FVIII content at hour 0 was 108.10 U per bag. Type ORh+ blood had lower FVIII content (+/-78.91 U per bag) compared with blood types ARh+ (+/-121.64 U per bag) and BRh+ (+/-117.04 U per bag). The units stored <6 months had higher FVIII content (+/-117.74 U per bag) compared with those stored for over 6- but <12-months (+/-66.77 U per bag). The mean rate of decline of FVIII activity at 2, 4 and 6 h was statistically significant at 10.35% (P = 0.000), 21.49% (P = 0.000) and 29.41% (P = 0.000) from baseline, respectively, using the paired t-test. Similar finding was found across different blood types and storage duration. Only one of 37 bags grew Staphylococcus aureus on day 10 of incubation.

Management of haemophilia and its complications in developing countries

Eighty per cent of people with haemophilia live in developing countries, where technical expertise and health care facilities may be less than optimal. Haemophilia is a relatively rare disease and high-cost, technology-intensive therapy is not a high priority for the governments of developing countries. The rapid spread of transfusion-related viral infections in many developing countries presents further problems for haemophiliacs. However, it is possible to manage haemophiliacs patients with limited resources. Strategies for conserving factor concentrates, include education of doctors and patients, prenatal diagnosis, increasing the use of anti-fibrinolytic agents, physiotherapy, the use of fibrin glue, and simple orthotics and prosthetic measures. These approaches are helpful in the majority of these patients. Meanwhile, with the help of the World Federation of Haemophilia (WFH), all developing countries are gradually improving management skills for this relatively rare but disabling disease. The present review broadly describes the management of various aspects of severe haemophilia in developing countries.

Intensive exposure to factor VIII is a risk factor for inhibitor development in mild hemophilia A

BACKGROUND

Inhibitors are rare in boys with mild hemophilia A (MHA; factor (F)VIII:C > 5%) but may arise following intense FVIII exposure, e.g. continuous infusion (CI).

OBJECTIVES

To determine the impact of intense FVIII exposure in inhibitor formation in MHA at our institution and to compare this with previous reports.

PATIENTS AND METHODS

We reviewed FVIII exposure and inhibitor development in boys (ages 0-18 years) with MHA followed at our institution from 1996 to 2001 and conducted a Medline search (1966-2002) on the experience of inhibitor development following intensive/CI exposure to FVIII.

RESULTS

We identified 54 boys with MHA. Twenty-nine (54%) had been exposed to FVIII. Seven had received FVIII by CI. Four developed inhibitors; three high titer (at ages 10 years, 16 years and 17 years) and one low titer (at 1 month old). All four had received a CI of recombinant (r) FVIII of at least 6 days within 6 weeks of developing inhibitors. Baseline FVIII levels fell to < 1% in all cases and the three with high-titer inhibitors developed severe bleeding. Immune tolerance therapy (ITT) was attempted in two boys and was successful in one. Our literature search identified 35 cases (only four children) with MHA developing inhibitors following intense FVIII exposure often in the context of surgery.

CONCLUSIONS

The incidence of inhibitors in our MHA population was 7.4%. If expressed according to exposure the incidence was significantly higher: 14% (4/29) for any exposure to FVIII and 57% (4/7) for exposure by CI. A prospective study to address whether CI is associated with an increased incidence of inhibitor development in MHA is warranted.

Pharmacological strategies to decrease transfusion requirements in patients undergoing surgery

Surgical procedures are inevitably associated with bleeding. The amount of blood loss may vary widely between different surgical procedures and depends on surgical as well as non-surgical factors. Whereas adequate surgical haemostasis may suffice in most patients, pro-haemostatic pharmacological agents may be of additional benefit in patients with (diffuse) surgical bleeding or in patients with a specific underlying haemostatic defect. In general, surgical haemostasis and pharmacological therapies can be complementary in controlling blood loss. The use of pharmacological therapies to reduce blood loss and blood transfusions in surgery has historically been restricted to a few drugs. Antifibrinolytic agents (aprotinin, tranexamic acid and aminocaproic acid) have the best evidence supporting their use, especially in cardiac surgery, liver transplantation and some orthopaedic surgical procedures. Meta-analyses of randomised, controlled trials in cardiac patients have suggested a slight benefit of aprotinin, compared with the other antifibrinolytics. Desmopressin is the treatment of choice in patients with mild haemophilia A and von Willebrand disease. It has also been shown to be effective in patients undergoing cardiac surgery who received aspirin up to the time of operation. However, overall evidence does not support a beneficial effect of desmopressin in patients without pre-existing coagulopathy undergoing elective surgical procedures. Topical agents, such as fibrin sealants have been successfully used in a variety of surgical procedures. However, only very few controlled clinical trials have been performed and scientific evidence supporting their use is still limited. Novel drugs, like recombinant factor VIIa (eptacog alfa), are currently under clinical investigation. Recombinant factor VIIa has been introduced for the treatment of haemophilia patients with inhibitors, either in surgical or non-surgical situations. Preliminary data indicate that it may also be effective in surgical patients without pre-existing coagulation abnormalities. More clinical trials are warranted before definitive conclusions can be drawn about the safety and the exact role of this new drug in surgical patients. Only adequately powered and properly designed randomised, clinical trials will allow us to define the most effective and the safest pharmacological therapies for reducing blood loss and transfusion requirements in surgical patients. Future trials should also consider cost-effectiveness because of considerable differences in the costs of the available pro-haemostatic pharmacological agents.

Acquired hemophilia: a single-center survey with emphasis on immunotherapy and treatment-related side-effects

OBJECTIVES

Acquired hemophilia is a rare disease caused by the development of autoantibodies against factor VIII. Since 1981 we have observed 17 patients with this disorder in our institution. The objective of this survey was to assess the epidemiological features, clinical course, and mortality rate of these patients, with special emphasis on therapy-related side-effects. Also, we present our results with an immunosuppressive approach based on the severity of bleeding episodes.

METHODS

Clinical records of all patients with acquired hemophilia due to factor VIII inhibitor admitted or referred to our hospital between 1981 and 2001 were reviewed retrospectively. We collected each patient's sex, age, medical history, presenting symptoms, activated partial thromboplastin time, factor VIII activity, and inhibitor titre. Patient's clinical courses, including their bleeding episodes, response to therapy, and therapy-related side-effects, were also recorded.

RESULTS

Complete and partial responses were achieved in 14 and one patient, respectively (overall response rate 88%) after a median time to complete response of 3.5 months (range 30 d - 25 months). The inhibitor-related and overall mortality rates were 12% and 29%, respectively. Side-effects were frequent: two patients had blood-borne infections, three patients had thrombotic complications, and nine patients had immunosuppressive therapy-related side-effects. In five patients, discontinuation of cyclophosphamide or prednisone was required.

CONCLUSIONS

Although our response rates were remarkable, this survey showed that treatment-related morbidity could also be very important. Therefore, it is pertinent to bear in mind these potential side-effects in order to decide the most appropriate therapy for each particular patient.

MonoFIX-VF, a new mono-component factor IX concentrate: a single-centre continuous-infusion study

MonoFIX-VF, a monocomponent factor IX concentrate, has replaced the use of Prothrombinex-HT as the treatment of choice for patients with factor IX deficiency in Australia. The haemostatic effect of MonoFIX-VF, administered by continuous infusion, was assessed in four subjects being treated for 10 bleeding episodes including five surgical procedures. MonoFIX-VF was found to be a safe and effective treatment for patients with haemophilia B.

Perioperative pharmacokinetics of factor VII concentrate during liver surgery in a patient with congenital factor VII deficiency: an individual mathematical model

A patient with congenital factor VII deficiency (baseline activity, 7%) underwent surgery for hepatocellular carcinoma. No literature reference was found concerning the management of this coagulation defect in patients requiring liver surgery. We report one such case, with special reference to the peri-operative management of factor VII replacement therapy and the pharmacokinetic behavior of factor VII. As a result of accidental suprahepatic vein lesion, a bleeding episode occurred. This was associated with an increase in factor VII clearance and volume of distribution values from 1.30 to 3.85 l/h, and from 6.51 to 13.2 l, respectively. After surgery, the patient continued to receive the concentrate every 8 h during the first nine post-operative days. No post-operative bleeding or thrombotic event was observed. The patient was discharged in good condition.

Continuous infusion of coagulation factor products

OBJECTIVE

To review clinical information related to the use of continuous infusion factor products in patients with hemophilia. Specifically, case reports and open-label trials are summarized involving the use of factor VIII and recombinant factor VIIa for a variety of indications including surgical prophylaxis, acute bleeding, primary prevention, and management of inhibitors. In addition, issues surrounding the use of continuous infusion of factor products such as pharmacokinetic rationale, stability/sterility, and cost are reviewed.

DATA SOURCES

Primary and review articles were identified through a MEDLINE search (1990-June 2001) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated, and all information deemed relevant was included in this review.

DATA SYNTHESIS

Data concerning the administration of factor products are primarily detailed in open-label trials and case reports. Comparisons between intermittent bolus injections and continuous infusion of factor products are limited and primarily compare continuous infusion regimens with historical controls. The rationale behind the continuous-infusion approach is linked to the pharmacokinetics of factor products administered via this route. Pharmacokinetic data reveal that, with continuous infusion of factor products, a reduction in clearance and a maintenance of factor serum concentrations are noted.

CONCLUSIONS

Administration of factor products (factor VIII and recombinant factor VIIa) via continuous infusion has produced favorable hemostatic effects compared with intermittent bolus injections. The advantages of continuous infusion include maintenance of a constant factor concentration, thereby reducing risk of bleeding from excessively low trough concentrations, and a decrease in factor consumption related to a reduction in factor clearance with constant infusion. Manufacturers recommend using reconstituted factor products either immediately or within 1-3 hours after reconstitution; however, several studies have found the products to be stable and sterile for longer periods.

Cost-utility analysis of primary prophylaxis versus treatment on-demand for individuals with severe haemophilia

OBJECTIVE

To assess the cost effectiveness of primary prophylaxis with clotting factor instead of treatment following a bleed (on-demand) for individuals with severe haemophilia.

DESIGN

Different data sources on the clinical effects and costs of treatments were combined using a Markov model.

SETTING

English treatment centres.

PERSPECTIVE

UK societal.

PARTICIPANTS

Hypothetical cohorts of 100 individuals with severe haemophilia A or B or severe von Willebrands disease.

INTERVENTIONS

Primary prophylaxis treatment on-demand with clotting factor.

OUTCOME MEASURES

Costs, quality-adjusted life-years (QALYs) and incremental cost per QALY in UK pounds ( pound, 1999/2000 values).

RESULTS

The baseline results showed that treating individuals with severe haemophilia A/severe von Willebrands disease or severe haemophilia B with primary prophylaxis instead of treatment on-demand cost an additional pound 46500 and pound 8600 per QALY gained, respectively. However, the results were extremely sensitive to a number of factors including the clotting factor unit cost, the time between prophylactic doses and the discount rate.

CONCLUSIONS

Despite the high costs of treatment, primary prophylaxis was cost effective compared with treatment on-demand in some scenarios. Primary prophylaxis is more likely to be cost effective for individuals with severe haemophilia B compared with individuals with severe haemophilia A/severe von Willebrands disease. Further research is required to assess the relationship between methods of clotting factor infusion and health-related quality-of-life.

Recombinant factor IX (BeneFix) by adjusted continuous infusion: a study of stability, sterility and clinical experience

The safety and efficacy of adjusted continuous infusion (CI) of recombinant factor IX (FIX; BeneFix) was assessed in vitro and in a clinical study. BeneFix was reconstituted at 100 IU mL-1 with or without unfractionated heparin (4 U mL-1) and stored at either 4 degrees C or room temperature. Reconstituted BeneFix retained at least 90% activity over 14 days if stored at 4 degrees C but stability was reduced at room temperature. BeneFix reconstituted in a sterile pharmacy was free of bacterial contamination. Six patients with haemophilia B received seven CIs of BeneFix to cover routine surgery and severe bleeding episodes. The CIs lasted between 3 and 10 days. In all cases, haemostasis was excellent and the desired therapeutic FIX level was easily maintained. No thrombotic episodes or inhibitor development occurred but two patients developed thrombophlebitis at the infusion site when heparin was not added to the infusion. BeneFix is not currently licensed for CI and we suggest that studies to enable licensing should be established as soon as possible.

Stability and sterility of a recombinant factor VIII concentrate prepared for continuous infusion administration

Minipumps may facilitate cost-effective and convenient continuous infusion (CI) therapy for severe hemophilia A. This study evaluated the in vitro sterility, ability to support bacterial growth, and specific activity stability of a recombinant factor VIII (FVIII; Bioclate, Centeon) delivered by simulated CI at a variety of temperatures and after the addition of heparin or antibiotic. Closed system CIs of Bioclate (89.5 IU/ml) with and without heparin were sampled and cultured over a 6 day period. Bioclate (53.7 IU/ml) with and without heparin or vancomycin was inoculated with 102-105 CFU/ml of S. aureus, S. epidermidis, Escherichia coli, E. cloacae, or Y. enterocolitica and assessed by quantitative culture after 1 and 3 days. The stability of Bioclate (50, 100, and 250 IU/ml) at three temperatures (21 degrees C, 37 degrees C, and 39 degrees C) with and without heparin or vancomycin was tested over a period of 28 days. FVIII activity was measured in triplicate by a chromogenic assay (Coamatic Factor VIII, Chromogenix) and purity evaluated by Western blot. No bacterial growth was detected during CI of FVIII for up to 6 days. Following bacterial inoculation, there was rapid growth (>3 log increase) of all tested bacterial species except S. aureus which only displayed a 1 log expansion at 3 days. The addition of heparin containing 9.45 microg/U benzyl alcohol had no effect on bacterial growth. The addition of vancomycin caused a modest suppression of S. aureus growth but not of E. coli. Diluent alone did not support bacterial growth. Neither concentration, increased temperature, nor the addition of heparin or vancomycin had a significant effect on FVIII activity stability. Samples retained >75% baseline activity for between 3 and 7 days, except the infusion of Bioclate 50 IU/ml plus heparin maintained at 21 degrees C which remained stable for 28 days. Western blot analysis supported the activity assay findings. Standard and concentrated preparations of Bioclate are suitable for CI when delivered by the MiniMed 404-SP minipump. Because of the observed nutritive capability of this FVIII concentrate for sustaining bacterial growth, any contamination could result in systemic infection.