Massive bleeding episodes in patients with acquired haemophilia--case report

We present two cases with a history of acquired haemophilia with massive haemorrhage in the course of the disease. A 74-year-old man presented to the emergency room with an extensive, progressive swelling and haemorrhage in the region of left knee joint, both upper legs and forearms. Laboratory studies revealed the presence of the factor VIII inhibitor in the titer of 115 Bethesda U/mL, low level of factor VIII activity (19.2%) and severe anemia (Hb - 7.0 g%). The patient was treated with FFP transfusions and prednisone with cyclophosphamide to eradicate factor VIII inhibitor. The remission was achieved and lasts for a two years. A 52-year-old woman presented to the emergency room with an extensive subcutaneous haemorrhage in the region of right knee joint and right lower leg. Laboratory studies revealed the presence of the factor VIII inhibitor in the titer of 30 Bethesda U/mL. The factor VIII activity level was only 4%. The patient did not receive the FFP because the severity of the haemorrhage was low. She was treated with steroids. The factor VIII inhibitor disappeared after 2.5 months of therapy.     

High-resolution micro-computed tomography analyses of the abnormal trabecular bone structures in klotho gene mutant mice

Inactivation mutation of the recently discovered klotho gene in mice causes a syndrome resembling aging. Manifestations include short life span, atherosclerosis, gonadal atropy, skin atropy, emphysema, ataxia and ectopic calcification. These mice also exhibit abnormally high bone density in the epiphyses of their tibiae based on X-ray and histological analyses. However, micro-structures of the trabecular bones in arbitrary two-dimensional planes or three-dimensional regions are difficult to analyze by these techniques. Therefore, we applied high resolution micro-computed tomography (microCT) to characterize the micro-structural abnormality in the trabecular bone in long bones as well as in vertebrae of four- to six-week-old klotho mutant mice. Two-dimensional microCT analyses in the mid-sagittal plane as well as three-dimensional microCT analyses indicated that the trabecular bone volume fraction measured in the proximal metaphyses of the tibiae was increased more than twofold in klotho mutant mice compared with the wild-type mice. Similarly, the trabecular bone area fraction in the mid-sagittal plane of the lumbar vertebral bodies was also increased by about 80% at the proximal and distal ends. No significant difference was observed with regard to the cortical thickness in the mid-shaft of femora between klotho mutant and wild-type mice. Three-dimensional microCT analyses also indicated that the trabecular number and thickness of the proximal metaphyses of the tibiae were increased by about 80% and 300% respectively in the klotho mutant mice, while trabecular separation was 60% less in klotho mutant mice compared with the wild-type mice. These quantitative microCT analyses indicate that the inactivation of klotho gene expression results in an increase in three-dimensional bone volume fraction, number and thickness of the trabecular bones in these mice.     

Magnetic resonance imaging of normal and osteoarthritic trabecular bone structure in the human knee

OBJECTIVE: To use high-resolution magnetic resonance imaging (MRI) to evaluate the trabecular bone structure in the distal femur and the proximal tibia and its to correlate the findings with different stages of osteoarthritis (OA) of the human knee. METHODS: Axial images of the distal femur and proximal tibia were obtained at 1.5 T in patients without and with mild OA and with severe OA. The spatial resolution was 195 x 195 microm(2) with a 1-mm slice thickness. Apparent measures of trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular separation (Tb.Sp), and trabecular thickness (Tb.Th) were calculated. RESULTS: Significant differences existed in the trabecular bone structure of the femur and tibia. Differences in trabecular bone structure between the tibia and the femur decreased with the degree of OA. The apparent BV/TV, Tb.N, and Tb.Sp in the femoral condyles could be used to differentiate healthy patients or patients with mild OA from patients with severe OA (P < 0.05). Among individuals, the structural variation of the lateral and medial femoral condyle was indicative of the extent of the disease. CONCLUSION: High-resolution MRI of the knee joint can provide a noninvasive assessment of trabecular bone structure. Trabecular bone structure, determined by high-resolution MRI, shows significant variation in patients with varying degrees of OA. The impact of OA on trabecular bone is different in the tibia than in the femur, and this difference depends on the extent of the disease.     

Differential effects of IGF-1 deficiency during the life span on structural and biomechanical properties in the tibia of aged mice

Advanced aging is associated with the loss of structural and biomechanical properties in bones, which increases the risk for bone fracture. Aging is also associated with reductions in circulating levels of the anabolic signaling hormone, insulin-like growth factor (IGF)-1. While the role of IGF-1 in bone development has been well characterized, the impact of the age-related loss of IGF-1 on bone aging remains controversial. Here, we describe the effects of reducing IGF-1 at multiple time points in the mouse life span—early in postnatal development, early adulthood, or late adulthood on tibia bone aging in both male and female igf ^f/f mice. Bone structure was analyzed at 27 months of age using microCT. We find that age-related reductions in cortical bone fraction, cortical thickness, and tissue mineral density were more pronounced when IGF-1 was reduced early in life and not in late adulthood. Three-point bone bending assays revealed that IGF-1 deficiency early in life resulted in reduced maximum force, maximum bending moment, and bone stiffness in aged males and females. The effects of IGF-1 on bone aging are microenvironment specific, as early-life loss of IGF-1 resulted in decreased cortical bone structure and strength along the diaphysis while significantly increasing trabecular bone fraction and trabecular number at the proximal metaphysis. The increases in trabecular bone were limited to males, as early-life loss of IGF-1 did not alter bone fraction or number in females. Together, our data suggest that the age-related loss of IGF-1 influences tibia bone aging in a sex-specific, microenvironment-specific, and time-dependent manner.     

Transplacental transfer of postpartum inhibitors to factor VIII

Summary.  Acquired haemophilia due to antibodies directed against coagulation factor VIII is a well-recognized cause of severe haemorrhage in adults but an uncommon cause of bleeding in children. We present the cases of a mother with a life-threatening postpartum haemorrhage due to an autoantibody to factor VIII and her newborn who developed symptomatic bleeding after a minor surgical intervention as a result of transplacental transfer of the autoantibody. Both patients were treated with infusions of recombinant factor VIIa to control bleeding. The mother required immunosuppressive therapy to decrease inhibitor levels and the infant's levels decreased over time without specific treatment. We also provide a concise review of postpartum haemophilia and transplacental transmission of factor VIII autoantibodies to the neonate – a rare but potentially life-threatening complication of acquired haemophilia in women of childbearing age.     

Prevention of haemarthrosis in a murine model of acute joint bleeding

Summary.  Preservation of normal joint function in patients with haemophilia is a goal of modern therapy. Regular injections of anti-haemophilic factor concentrate reduce the risk of joint bleeding, the optimal regimen for which remains under investigation. The goals of the experiment described here are: (i) to assess the capacity of a murine model of severe haemophilic arthropathy to predict the likelihood of success of a test product to prevent joint bleeding and the complications that follow and (ii) to compare the effectiveness of recombinant human activated factor VII (rFVIIa) to recombinant human factor VIII (rFVIII) to prevent acute joint bleeding in the mouse model of haemarthrosis. Mice lacking expression of FVIII received a single intravenous injection of human rFVIII (280 U kg⁻¹), rFVIIa (10 mg kg⁻¹) or vehicle prior to blunt trauma injury to the knee joint. Mice receiving rFVIII and rFVIIa developed less injury-induced joint bleeding, swelling and loss of range of motion compared to mice pretreated with vehicle. Despite the reduction in clinical symptoms, synovial hyperplasia was evident in all groups after 7 days although less pronounced in mice receiving rFVIII and rFVIIa. The data under these experimental conditions demonstrate: (i) that this model can be used to evaluate novel therapies designed to prevent joint bleeding (prophylaxis) and (ii) both rFVIII and rFVIIa reduced acute haemarthrosis but did not completely prevent synovitis, the sequelae of blood induced joint injury.     

The biological efficacy profile of BAX 855, a PEGylated recombinant factor VIII molecule

Prophylaxis prevents joint and other bleeding episodes in patients with haemophilia A. Development of new factor concentrates with longer circulating half‐lives may encourage patients to start, continue or resume prophylaxis. The aim of this study was to compare the pharmacodynamic effect of a PEGylated full‐length recombinant factor VIII (rFVIII) concentrate with that of an unmodified rFVIII concentrate with respect to the duration of prophylactic efficacy in a murine model of haemophilic joint bleeding. Mice were pretreated with BAX 855 or unmodified rFVIII at specified times before right knee puncture to induce haemarthrosis; left knee joints served as controls. Joint bleeding was evaluated using a combination of visual and histological assessments. Administration of a single dose of unmodified rFVIII before joint puncture prevented haemarthrosis in mice up to 24 h, whereas pretreatment with BAX 855 protected the joint from bleeding up to 48 h. This pharmacodynamic study showed prolonged efficacy of BAX 855 compared to ADVATE in a haemophilia A mouse joint bleeding model. This finding supports the possibility of using BAX 855 to increase FVIII trough levels and/or extend the dosing interval in patients with haemophilia A on prophylaxis, which may potentially improve prophylactic efficacy and long‐term adherence.     

Human coagulation factor FVIIa (recombinant) in the management of limb-threatening bleeds unresponsive to alternative therapies: results from the NovoSeven emergency-use programme in patients with severe haemophilia or with acquired inhibitors.

This open-label, emergency-use study evaluated the efficacy and safety of activated human coagulation factor VIIa (recombinant) (rFVIIa) (NovoSeven; Novo Nordisk Pharmaceuticals, Inc., New Jersey, USA) in treating limb-threatening joint or muscle bleeds in 17 patients with haemophilia A or B and six patients with acquired inhibitors to factor VIII or factor IX. All patients had previously failed on one or more alternative therapies. rFVIIa administration was effective or partially effective in controlling joint or muscle bleeds in 34 out of 35 (97%) bleeding episodes; in 23 patients, 14 of 17 (82%) muscle bleeds and 16 of 18 (89%) joint bleeds were effectively controlled. These findings suggest that rFVIIa is an effective and well-tolerated therapeutic option in the management of joint or muscle haemorrhage in patients with haemophilia and in patients with acquired inhibitors.     

A 2 yr longitudinal radiographic study examining the effect of a bisphosphonate (risedronate) upon subchondral bone loss in osteoarthritic knee patients

OBJECTIVES: To determine whether risedronate (RIS) slows down trabecular bone loss in the medial compartment of the proximal tibia, a characteristic of patients with progressive knee osteoarthritis (OA). METHODS: Initially, 100 patients were randomly selected from each treatment group (each N approximately 300) comprising placebo and RIS 5 mg/day, 15 mg/day and 50 mg/week from a double blind, multi-centre, placebo-controlled, 2 yr investigation of OA knee patients in North America. Using fluoroscopic semi-flexed standard radiography, baseline and exit knee radiographs were digitized by laser scanner. Following computerized measurement of minimum medial compartment joint space width, each group was subdivided into joint space narrowing (JSN) non-progressor or JSN-progressor (JSN >or=0.6 mm measured at any point post-baseline). Computerized method of fractal signature analysis (FSA) quantified longitudinal changes separately in horizontal and vertical trabeculae in region of interest (three-fourth width of tibial compartment x 6 mm height) in the medial compartment. Following the initial study, all JSN-progressor knees within the entire patient cohort (N = 1232) were similarly analysed. RESULTS: OA knees in JSN non-progressor group had a slight decrease in FSA for vertical and horizontal trabeculae and showed no drug effect. In JSN-progressor knees, bone loss was greater in both placebo and RIS 5 mg/day groups compared with those in RIS 15 mg/day group in which trabeculae were retained, and in the RIS 50 mg/week group in which the vertical trabecular number increased significantly (P < 0.05). CONCLUSION: This preliminary study showed that patients with marked cartilage loss (JSN>or=0.6 mm) receiving RIS 15 mg/day retained vertical trabecular structure, and those receiving RIS 50 mg/week increased vertical trabecular number, thereby preserving the structural integrity of subchondral bone in knee OA.     

Persistent factor VIII inhibitors and orthopaedic complications in children with severe haemophilia A

Summary. Persistence of inhibitors against factor VIII (FVIII) may be a risk factor that increases physical disability in haemophilia A (HA) patients. This study aimed to evaluate prevalence of FVIII inhibitors in previously treated children with severe HA and the impact of persistent inhibitors on knee joint status and lumbar bone mineral density (BMD). Fifty children with severe HA, FVIII <1%; aged 5–16 years were enrolled in this study; they received plasma‐derived FVIII on‐demand treatment for 50–250 exposure days (EDs). Inhibitors were checked at basal visit and were followed up for 1 year, using Bethesda assay. Cross‐sectional clinical scoring and radiological evaluation of the knee joint (by Arnold‐Hilgartner staging and Pettersson score), along with lumbar BMD by Dual Energy X‐ray Absorptiometry (DEXA) were performed. Patients with persistent inhibitors for 1 to 5 years, median 2.5 years, were 10 (20%). Six had high titre and none of them had completely normal knees, seven had advanced knee arthropathy and six had low lumbar BMD in comparison to 2 and 8 of the 40 patients without inhibitors respectively (P < 0.05). Persistence of inhibitors for more than 2 years without immuno‐prophylaxis was a risk factor for joint damage. Low lumbar BMD was found in 88.9% of patients with stages four and five knee arthropathy and in 66.7% of patients with positive hepatitis C. Severe HA children in this Egyptian study had a relatively low prevalence of persistent FVIII inhibitors, which, if not treated, may increase the risk of knee arthropathy and lumbar osteopenia.     

Immunogenetics of factor VIII inhibitor development

Objective: Progressive destruction of joints resulting from recurrent intra-articular haemorrhage represents the major morbidity resulting from haemophilia A or B. In addition to systemic clotting factor replacement, therapies localized to haemophilic joints may provide adjunctive protection. In a factor VIII^-/- mice model, we investigated if extra-vascular delivery of recombinant human clotting factor VIII (rhFVIII) via intra-articular (IA) injection can prevent bleeding-induced joint damage, and also examined the possibility that IA delivery of FVIII carries greater risk of developing anti-rhFVIII inhibitor antibody. Methods: FVIII^-/- mice received rhFVIII by inserting a 30.5 G needle into the left knee joint, along with a range doses of FVIII(100, 25 and 5 IU kg⁻¹) in 5 μL, normal saline as the control. Comparison group received the same needle injury and intravenous (IV) rhFVIII (100, 25 and 5 IU kg⁻¹). 14 days after injury, both knee joints were collected for histological examination. To exclude the possibility that IA clotting factor was entering into circulation, mice received 100 IU kg⁻¹ rhFVIII IA, and FVIII activity was measured by aPTT. To see if IA rhFVIII delivery can carry greater risk of developing anti-FVIII antibody, mice were treated with a total dose of 300 IU kg⁻¹ rhFVIII over 10 days, either by IA or IV. 14 days after exposure, anti-FVIII was detected. After induction of anti-FVIII antibody by IV rhFVIII, mice were subjected either to needle puncture under coverage of bypassing agent (FEIBA) 100 IU kg⁻¹ or 100 IU kg⁻¹ IV rhFVIII, or needle puncture with 25 IU kg⁻¹ rhFVIII. Control mice received needle puncture with normal saline. Two weeks later, knee joints were collected for histological examination. Summary: Mice receiving only saline at the time of needle puncture developed synovitis (mean score 5.0 ± 0.5). Mice treated with 25 IU kg⁻¹ IA rhFVIII developed better protection than mice treated with 100 IU kg⁻¹ IV rhFVIII (lower pathology score for IA, 0.733 ± 0.278 vs. IV 2.57 ± 1.70) and even better protection was achieved by the dose of 100IU IU kg⁻¹ IA (Pathology score of 0.25 ± 0.31). IA injection of 100 IU kg⁻¹ rhFVIII did not lead to increased circulating FVIII activity at any time point up to 48 h. In IV-treated mice, 100% of mice developed anti-FVIII antibody (8.06BU), while only 50% of mice developed anti-FVIII inhibitor at the lowest detection limit (0.61BU). In the presence of inhibitory antibody, only 46% of mice receiving IV FVIII survived the needle injury, 58% with FEIBA and 100% of mice survived with 25 IU kg⁻¹ FVIII IA injection. In the saline-injected control mice, needle injury led to a mean pathology score of 6.8. Neither IV FVIII nor FEIBA provided effective protection, with pathology scores of 6.3 and 5.4, respectively. Surprisingly, 25 IU kg⁻¹ IA rhFVIII produced a pathology score of only 1.7. Conclusion: Extravascular rhFVIII in the joint space can contribute protection against bleeding-induced joint damage. Intra-articular rhFVIII delivery did not induce greater risk of inhibitory antibody formation in FVIII knockout mice than circulating factor VIIII challenge; in fact, a lower incidence was observed. In the presence of anti-FVIII inhibitory antibodies, IA delivery of FVIII still can offer protection from bleeding-induced joint damage.     

Relationships among bone mineral densities, static alignment and dynamic load in patients with medial compartment knee osteoarthritis

OBJECTIVE: To investigate the relationships among bone mineral density (BMD), static alignment and the adduction moment of the knee in patients with tibiofemoral osteoarthritis (OA). METHODS: Sixty-nine patients with medial compartment knee OA underwent radiographic evaluation, gait analysis and BMD measurements at the proximal tibia and lumbar spine. RESULTS: The bone mineral distribution of the medial to lateral part of the proximal tibia correlated significantly with the peak knee adduction moment and the mechanical axis. Furthermore, the adduction moment correlated significantly with the mechanical axis. However, the BMD of the lumbar spine and the bone mineral distribution of the posterior to anterior part of the proximal tibia did not correlate with any other measurement. CONCLUSIONS: Our results suggest that the bone mineral distribution of the proximal tibia is directly affected but lumbar BMD is not influenced by the local mechanical stress around the knee with medial compartment OA.     

Acquired factor VIII inhibitor presenting as macular haemorrhage

We report a rare case of idiopathic acquired factor VIII inhibitor in an 80-year old Chinese man presented as sudden onset of monocular blindness because of macular haemorrhage. This was complicated by painful glaucoma that did not respond to medical treatment. The patient died of cerebral haemorrhage shortly afterwards. Most cases of reported intraocular bleeding in acquired haemophiliacs are iatrogenic because of intraocular operations in undiagnosed cases, and spontaneous intraocular haemorrhage has never been reported. The literature reports of intraocular bleeding in hereditary and acquired haemophilia cases are summarized.     

Acute intestinal obstruction due to intramural haemorrhage in small intestine in a patient with severe haemophilia A and inhibitor

Patients with severe haemophilia A usually present with joint, gastrointestinal and urinary tract haemorrhage. Bleeding elsewhere is often precipitated by pre-existing pathology or trauma. We report a patient with severe haemophilia A, who presented with symptoms of acute intestinal obstruction. He has a factor VIII inhibitor and receives recombinant factor VIIa on demand at home. The CT scan of abdomen showed dilated small intestine with fluid filled loops and a long segment in the jejunum with marked transmural thickening. There was no other pathology in the small intestine. These appearances were consistent with intramural haemorrhage in the small intestine as the cause of acute obstruction. He was managed conservatively with recombinant factor VIIa and this resulted in resolution of his symptoms. This case highlights an unusual presentation of bleeding in a haemophilia patient. Intestinal obstruction due to haemorrhage in the small intestinal wall is extremely rare and only previously reported in a few haemophilia patients. It also highlights the effectiveness of conservative management with recombinant factor VIIa as opposed to immediate exploratory surgery.     

Disease modifying effects of N-butyryl glucosamine in a streptococcal cell wall induced arthritis model in rats

OBJECTIVE: To evaluate the effect of different doses of N-butyryl glucosamine (GlcNBu) on joint preservation and subchondral bone density and quality in a streptococcal cell wall (SCW) induced arthritis model in Lewis rats. METHODS: Chronic arthritis was induced in 36 female Lewis rats by a single intraperitoneal injection of SCW antigen. The 4 groups studied were: (1) no arthritis, no drug treatment; (2) arthritis, no drug treatment; (3) arthritis, oral GlcNBu 20 mg/kg/day; and (4) arthritis, oral GlcNBu 200 mg/kg/day. Inflammation (ankle swelling) was quantified throughout the clinical course; bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry on dissected distal femurs and proximal tibiae, in user defined regions of interest. Qualitative and quantitative 3-D bone architecture changes were determined using microcomputerized tomography on the left tibiae. Subchondral plate thickness and trabecular bone connectivity were studied on the proximal tibia epiphyses from the central coronal sections of each scanned tibia. RESULTS: GlcNBu inhibited inflammatory ankle swelling at both 20 and 200 mg/kg/day, the latter being statistically significant, with an average reduction of 33%. GlcNBu preserved or enhanced BMD and bone connectivity and prevented further bone loss at both the high and the low dose. Comparisons of the isosurfaces and the architectural measures in the different groups showed that GlcNBu effectively protected the joint surfaces from further erosion in this model of chronic inflammatory arthritis. For some of the bone measurements, increasing doses of GlcNBu showed increasing protective effects, while for other measurements, effects were maximal at the lower dose. CONCLUSION: These data indicate that GlcNBu provides antiinflammatory and antierosive effects by preserving BMD, joint integrity, and bone architecture in involved joints of the SCW model.     

Cross-reactivity to porcine factor VIII of factor VIII inhibitors in patients with haemophilia in Australia and New Zealand

Abstract Background: Inhibitory antibodies which neutralise factor VIII develop in 10–20% of individuals with inherited haemophilia A and rarely as autoantibodies in normal individuals to cause acquired haemophilia. The antibodies are directed against human factor VIII but cross-react to varying degrees with porcine factor VIII. Porcine factor VIII can be used for treatment in individuals with low cross-reactivity.
Aims: To determine the cross-reactivity of factor VIII inhibitors between human factor VIII and porcine factor VIII, in a population of patients with inherited and acquired haemophilia A. Also, to determine whether patients with inherited haemophilia and inhibitors have a higher incidence of factor VIII gene inversion in intron 22.
Methods: Samples and data sheets from 43 patients with inherited and ten with acquired haemophilia were submitted from hospitals in Australia and New Zealand. Inhibitor levels to human and porcine factor VIII were measured by the Bethesda method in 39 with inherited and nine with acquired haemophilia A.
Results: Of 39 patients with inherited haemophilia A, cross-reactivity was 0% in 17 patients,1–19% in six, 20–39% in 11 and 40–80% in five. In six of nine patients with acquired haemophilia cross-reactivity was 7%. In inherited severe haemophilia A, the frequency of the intron 22 inversion was not greater in 37 study patients than in 28 patients without an inhibitor.
Conclusions: Many patients in Australia and New Zealand with inhibitors to human factor VIII presently show a low or absent level of cross-reactivity to porcine factor VIII. These may respond to treatment with this concentrate at least in the short term. There remains a group of patients with high cross-reactivity who will respond only to recombinant factor Vila or prothrombin complex concentrates.     

Development of a factor VIII inhibitor in a newborn haemophiliac

A major problem in the treatment of haemophilia A is the development of inhibitors (antibodies) against factor VIII. We report the case of a newborn male with no family history of haemophilia who developed an intracerebral haemorrhage. On day 10 post-delivery severe haemophilia A was diagnosed and treatment with recombinant FVIII (rFVIII) concentrate was started. Seventy-two hours later the presence of inhibitors was suspected because high doses of rFVIII were required to maintain therapeutic FVIII plasma levels. Days after, the inhibitor was detected. The quick detection of the inhibitor in this newborn haemophiliac allowed us to start the immunotolerance early, without interruption in the administration of rFVIII.     

Disarticulation of a knee joint in a haemophiliac with high inhibitor titre

Summary. Disarticulation of a knee joint in an 8-year-old haemophilia A patient with high inhibitor of 3450 Bethesda units (BU) is described. He had an infected compound fracture of the tibia and fibula. Surgery was successfully performed after extensive plasma exchange; administration of immunosuppressive agents such as cyclophosphamide, methylprednisolone, intravenous immunoglobulin and cyclosporine were combined with a loading dose of 100 units kg^-1 of factor VIII concentrate, followed by continuous infusion of 16 units kg^-1 h^-1 of factor VIII in the form of factor VIII concentrate and cryoprecipitate for 7 days and decreased to 8 units kg^-1 h^-1 in the form of cryoprecipitate for 19 more days. During the 1st to 7th post-operative days, the lowest factor VIII inhibitor was 18 BU and the factor VIII level ranged from < 1–2.1 IU dL^-1. On the 9th and 13th post-operative day, although the inhibitor rose to 330 and 2700 BU, respectively, there was no serious bleeding. The suture was removed on the 21st post-operative day. The inhibitor spontaneously decreased to 550, 232 and 14 BU at 1, 7 and 10 months, respectively.     

Home therapy with continuous infusion of factor VIII after minor surgery or serious haemorrhage

Summary. Administration of factor VIII (F VIII) concentrates by continuous infusion is now routinely used at several haemophilia centers but almost exclusively for hospitalized patients. We evaluated various aspects of home therapy with continuous infusion of an immunoaffinity purified F VIII concentrate (Monoclate P®, Armour) in patients who would normally have been treated with high doses in bolus injections or with continuous infusion as in-patients. Twenty haemophilia A patients, eight after minor surgery and 12 for serious haemorrhage, received continuous infusion with undiluted F VIII by a minipump for a mean of 0.9 days in the hospital, followed by 3.3 days at home. Infusion bags were exchanged every 2.5 days. No haemorrhagic complications occurred, and five haemorrhages that had been resistant to treatment with bolus injections responded promptly to the continuous infusion. There were no technical problems and patient compliance and acceptance was good. We find this mode of therapy safe, efficacious and convenient for the patients as well as for the staff.