Rituximab for treatment of inhibitors in haemophilia A. A Phase II study.

The development of antibodies against infused factor VIII (FVIII) in patients with haemophilia A is a serious complication leading to poorly controlled bleeding and increased morbidity. No treatment has been proven to reduce high titre antibodies in patients who fail immune tolerance induction or are not candidates for it. The Rituximab for the Treatment of Inhibitors in Congenital Hemophilia A (RICH) study was a phase II trial to assess whether rituximab can reduce anamnestic FVIII antibody (inhibitor) titres. Male subjects with severe congenital haemophilia A and an inhibitor titre ≥5 Bethesda Units/ml (BU) following a FVIII challenge infusion received rituximab 375 mg/m² weekly for weeks 1 through 4. Post-rituximab inhibitor titres were measured monthly from week 6 through week 22 to assess treatment response. Of 16 subjects who received at least one dose of rituximab, three (18.8%) met the criteria for a major response, defined as a fall in inhibitor titre to <5 BU, persisting after FVIII re-challenge. One subject had a minor response, defined as a fall in inhibitor titre to <5 BU, increasing to 5-10 BU after FVIII re-challenge, but <50% of the original peak inhibitor titre. Rituximab is useful in lowering inhibitor levels in patients, but its effect as a solo treatment strategy is modest. Future studies are indicated to determine the role of rituximab as an adjunctive therapy in immune tolerisation strategies.

Deep venous thrombosis screening in patients with inherited bleeding disorders and central venous catheters.

Children with inherited bleeding disorders often require central venous catheters (CVCs). Although CVCs are known to be complicated by deep venous thrombosis (DVT), little is known about the timeline of DVT development or risk of post-thrombotic syndrome (PTS). The aim of this study was to determine the timeline and confirm the incidence of thrombosis in patients with bleeding disorders who have CVCs. In 2002, we instituted a screening programme to monitor for CVC-related complications in children with haemophilia and von Willebrand disease. This is a retrospective review of this cohort. All children with CVC followed up between 1 January 2000 and 1 June 2009 were evaluated for DVT every 24 months with contrast venography and Doppler sonography. An institutional PTS severity scale was utilized at each visit. Thirty-six patients had 37 CVCs placed. Thirty patients had imaging studies, with DVT observed in 14 (47%). Most cases of DVT were diagnosed at the first venogram (median CVC duration 26 months). There were no abnormal ultrasound results. Sixteen patients (44%) had clinical findings consistent with PTS, including 10 (71%) with an abnormal venogram. Dilated chest wall veins appeared to be more strongly associated with underlying DVT (positive predictive value of 0.8) than arm circumference discrepancy. Successful transition to use of peripheral veins occurred at a median of 11 months after abnormal venograms. CVC-related DVT is common in children with inherited bleeding disorders and likely occurs earlier than previously thought. Clinical signs of PTS are also common, but long-term sequelae and severity of PTS are not known.

Implantable central venous access device procedures in haemophilia patients without an inhibitor: systematic review of the literature and institutional experience.

Elective surgical procedures involving central venous access devices (CVADs) in patients with haemophilia are often necessary for adequate factor delivery but there are few data regarding haemostatic coverage and acute complication rates accompanying these procedures. To describe experience with CVAD insertion, revision and removal in young haemophilia patients at our institution and in the literature and to assess acute complications following CVAD procedures. PubMed, Medline and Cochrane databases were searched for articles, which included a description of factor coverage during CVAD procedures. A retrospective review of our comprehensive haemophilia database identified patients undergoing CVAD placement, revision and removal between January 1993 and August 2005. Manual and electronic searches of the published literature yielded 14 articles, which met inclusion criteria. Peri-operative factor administration varied greatly among the reports. Mean acute infection and haematoma rates were 8% and 12.5% respectively. A retrospective review identified 49 CVAD placements, revisions, or removals meeting inclusion criteria. Most patients received outpatient bolus factor replacement to achieve a level of 100% preoperatively, immediately postoperatively and on postoperative days 1, 2, 3, 5 and 7. Thirty-six procedures were performed without hospitalization. Ten patients developed 11 (22%) minor haematomas postoperatively. Major haemorrhage, acute infection, or pneumothorax was not encountered. Few published data exist regarding haemostatic coverage and complications following CVAD procedures. Our institutional experience using a consistent management approach was favourable. Further studies are required to define optimal haemostatic coverage during minor surgical procedures in haemophilia.

Tissue plasminogen activator to prevent central venous access device infections: a systematic review of central venous access catheter thrombosis, infection and thromboprophylaxis.

The recent unequivocal demonstration that prophylaxis, three to four weekly factor infusions, is effective in preventing joint disease in children with haemophilia, has provided impetus to initiate prophylaxis early in such children. Yet, nearly a quarter (22%) of the 83% who required central venous access devices for factor infusion developed central venous access catheter (CVAD)-related infection. This limitation of CVAD use prevents many families from initiating prophylaxis. The frequent occurrence of local thrombosis accompanying CVAD-related infection in surgical patients and autopsy cases, the thrombogenic plastic CVAD surfaces, and local clot formation at the insertion site, suggest the potential role of thrombolytic agents in preventing these infections. Yet, correlation between CVAD-related infection and local thrombosis in children with haemophilia are lacking, and thromboprophylaxis to prevent CVAD-related infection is controversial. Tissue plasminogen activator (t-PA), a recombinant serine protease glycoprotein that lyses plasmin-bound fibrin and is safe and effective in the treatment of occluded catheters, has not been evaluated in the prevention of these infections. We performed a literature review of CVAD-related infection, CVAD-related thrombosis, and thromboprophylaxis studies to evaluate the role of t-PA in the prevention of these infections in children with haemophilia. Metanalysis of published thromboprophylaxis trials demonstrate current prophylaxis regimens do not prevent CVAD infection, and further, that thrombosis and infection do not necessarily occur simultaneously. Pilot data demonstrate CVAD infection reduction in haemophilic children by monthly t-PA in 18 haemophilic children, suggesting the potential role of t-PA in CVAD infection prevention. Clinical trials to evaluate t-PA in CVAD infection prevention are justified.

Fatal central venous catheter-related infection in haemophilia.

Central venous catheters (CVC) are frequently used in children with haemophilia to deliver factor infusions for the treatment or prophylaxis of bleeding. Complications of CVCs in patients with haemophilia include thrombosis and infection. We report a young boy with severe haemophilia A and an inhibitor who developed disseminated Staphylococcus aureus infection most likely related to a CVC. To our knowledge, this is the first reported case of fatal sepsis secondary to a CVC in a patient with haemophilia.

Consensus recommendations for use of central venous access devices in haemophilia.

Venous access is essential for delivery of haemophilia factor concentrate. Wherever possible, peripheral veins remain the route of choice, and the use of central venous access devices (CVADs) should be limited to cases of clear need in patients with caregivers able to exercise diligence in CVAD care and should continue no longer than necessary. CVADs are of recognized value for repeated administration of coagulation factors in haemophilia, particularly for prophylaxis and immune tolerance therapy and in young children. Evidence to guide best practices has been fragmentary, and standardized methods for CVAD usage have yet to be established. We have developed management recommendations based upon available published evidence as well as extensive clinical experience. These recommendations address patient and CVAD selection; CVAD placement, care and removal; caregiver/patient guidance; and complications, including infection and thrombosis. In the absence of inhibitors, ports are recommended, primarily because of fewer associated infections than with external catheters. For patients with inhibitors, ports also appear to be associated with fewer infections. Infection is the most frequent complication, and recommendations to prevent and treat infections are supported by extensive clinical data and experience. Strict adherence to handwashing and aseptic technique are essential elements of catheter care. Evidence-based data regarding the detection and treatment of CVAD-related thrombotic complications are limited. Caregiver education is an integral part of CVAD use and the procedural practices of users should be regularly re-assessed. These recommendations provide a basis for sound current CVAD practice and are expected to undergo further refinements as new evidence is compiled and clinical experience is gained.

Catheter-related deep venous thrombosis in children with hemophilia.

Central venous catheters (CVCs) are a common adjunct to hemophilia therapy, but the risk of CVC-related deep venous thrombosis (DVT) in hemophiliacs is not well defined. In a previous study, 13 patients with CVCs had no radiographic evidence of DVT. However, recent abstracts and case studies demonstrate that DVT does occur. Therefore, this study sought to determine the frequency of DVT in children with hemophilia and long-term CVCs and to correlate venographic findings with clinical features. All hemophilia patients with tunneled subclavian CVCs in place for 12 months or more were candidates for evaluation. Patients were examined for physical signs of DVT and questioned about catheter dysfunction. Contrast venograms were obtained to identify DVT. Fifteen boys with severe hemophilia were evaluated, including 9 from the initially studied group of 13. Eight patients had evidence of DVT, 5 of whom previously had normal venograms. Five of 15 patients had clinical problems related to the CVC, all of whom had DVT. Four of 15 patients had suggestive physical signs; 3 had DVT. The mean duration of catheter placement for all patients was 57.5 months (range, 12-102 months). For patients with DVT, the mean duration was 66.6 +/- 7.5 months, compared to 49.5 +/- 7.2 months for patients without DVT (P =.06). No patient whose CVC was in place fewer than 48 months had an abnormal venogram. Many hemophilia patients with CVCs develop DVT of the upper venous system, and the risk increases with duration of catheter placement.