Marion A. Koerper

Factor IX inhibitors and anaphylaxis in hemophilia B

PURPOSE We present clinical and laboratory data on 18 children from 12 hemophilia treatment centers in the United States, Canada, and Europe with the purpose of disseminating information regarding a recently recognized, potentially life-threatening complication of treatment in very young children with hemophilia B. PATIENTS AND METHODS Twelve hemophilia centers from the United States, Canada, and Europe provided clinical information and laboratory data concerning 18 children who had severe allergic reactions to infused factor (F) IX in close association with the development of an inhibitor to FIX. Laboratory testing for establishment of the diagnosis of hemophilia B and inhibitor to FIX was done locally at the centers treating these patients. FIX gene analysis was performed at one of six molecular genetics institutes. RESULTS All 18 children had severe hemophilia B, and in each an inhibitor antibody to FIX developed. The median age at the time of anaphylaxis (or anaphylactoid reaction) was 16 months, and the median number of exposure days to FIX was 11. The FIX inhibitor was detected almost simultaneously with the first occurrence of anaphylaxis in 12 of 18 patients. Maximum inhibitor titers were 4.5-600 Bethesda units (BU), with a median titer of 48 BU. FIX gene analysis, performed in 17 of 18 patients, demonstrated complete deletion of the FIX gene in 10 and major derangements in seven. Immune tolerance induction (ITI) regimens have been attempted in 12 patients, with generally poor responses. Two of the 12 experienced nephrotic syndrome while on ITI. Recombinant FVIIa has been successfully used to treat bleeding episodes in 11 of these children. CONCLUSION Physicians treating young children with hemophilia B should be aware of the potentially life-threatening complication of anaphylaxis. Children with complete gene deletions or major derangements of the FIX gene appear to be at greater risk. Those identified by genotype as being at greater risk may need to receive their first 10-20 treatments in a medical facility equipped for handling such emergencies. Recombinant FVIIa, although not licensed for use in the United States, appears to be the most suitable treatment option for bleeding episodes in such patients.

Factor V deficiency: a concise review.

Summary.  Factor V (FV; proaccelerin or labile factor) is the plasma cofactor for the prothrombinase complex that activates prothrombin to thrombin. FV deficiency can be caused by mutations in the FV gene or in genes encoding components of a putative cargo receptor that transports FV (and factor VIII) from the endoplasmic reticulum to the Golgi. Because FV is present in platelet α‐granules as well as in plasma, low FV levels are also seen in disorders of platelet granules. Additionally, acquired FV deficiencies can occur in the setting of rheumatologic disorders, malignancies, and antibiotic use and, most frequently, with the use of topical bovine thrombin. FV levels have limited correlation with the risk of bleeding, but overall, FV‐deficient patients appear to have a less severe phenotype than patients with haemophilia A or B. The most commonly reported symptoms are bleeding from mucosal surfaces and postoperative haemorrhage. However, haemarthroses and intramuscular and intracranial haemorrhages can also occur. Because no FV‐specific concentrate is available, fresh frozen plasma remains the mainstay of treatment. Antifibrinolytics can also provide benefit, especially for mucosal bleeding. In refractory cases, or for patients with inhibitors, prothrombin complex concentrates, recombinant activated FVIIa, and platelet transfusions have been successfully used. Some patients with inhibitors may also require immunosuppression.

Serum iron concentration and transferrin saturation in the diagnosis of iron deficiency in children: Normal developmental changes†

A group of 359 healthy children and 49 adults were studied for the purpose of estimating the normal limits for serum iron concentration and transferrin saturation. The 144 children and seven adults who has any other laboratory evidence of iron deficiency (abnormal values of serum ferritin, free erythrocyte protoporphyrin, hemoglobin concentration, or mean corpuscular volume) were excluded. In evaluating the 215 children and 42 adults who met the criteria to be considered normal we found that serum iron concentration and transferrin saturation were significantly lower in children between the ages of 0.5 and 12 years than in adults. We conclude that in children between the ages of 0.5 and 12 years, a transferrin saturation of less than 16% constitutes good evidence of iron deficiency only in conjuction with anemia and low mean corpuscular volume.

Utilization of care in haemophilia: a resource-based method for cost analysis from the Haemophilia Utilization Group Study (HUGS).

Summary.  The Haemophilia Utilization Group Study (HUGS) was created 10 years ago to examine the annual utilization and cost of haemophilia‐related healthcare services. Retrospective chart reviews for 336 patients with haemophilia A receiving treatment in one of five comprehensive haemophilia treatment centres (HTCs) during 1995 were completed through interview of the provider. This method provided adequate collection of data from patient charts without the abstractor having direct access to patient health information. Utilization data were used to impute the costs of different components of care (e.g. physician visits, factor VIII concentrate, emergency room, hospitalization). The total annual cost of care was

Clinical perspectives of emerging pathogens in bleeding disorders

139 102 (SD

Quality of life in haemophilia A: Hemophilia Utilization Group Study Va (HUGS‐Va)

304 033). Factor VIII concentrate costs comprised the largest proportion of these costs; mean factor VIII concentrate use was 128 517 units per patient per year. Unbilled physician utilization accounted for 7.8% of the mean total physician costs per annum, while mean allied healthcare costs accounted for 33.5% of the total annual allied healthcare costs per patient. In the ordinary least‐squares regression model, higher costs were associated with severe factor VIII deficiency, arthropathy, more comorbid conditions, an inhibitor to factor VIII concentrate, infusing through a port and prophylaxis. Although factor VIII concentrate is the most costly component, the treatment of haemophilia uses many healthcare resources. HUGS has demonstrated that patient clinical characteristics and physician practices predominantly drive the costs of haemophilia care. Specifically, patients with more severe arthropathy had greater healthcare costs. As future funding decisions are made, it is important to provide for all components of care.

Low CD4+ Counts in a Study of Transfusion Safety

Summary As a result of immunological and nucleic-acid screening of plasma donations for transfusion-transmissible viruses, and the incorporation of viral reduction processes during plasma fractionation, coagulation-factor concentrates (CFC) are now judged safe in terms of many known infectious agents, including hepatitis B and C viruses, HIV, and human T-cell lymphotropic virus. However, emerging pathogens could pose future threats, particularly those with blood-borne stages that are resistant to viral-inactivation steps in the manufacturing process, such as non-lipid-coated viruses. As outlined in this Review, better understanding of infectious diseases allows challenges from newly described agents of potential concern in the future to be anticipated, but the processes of zoonotic transmission and genetic selection or modification ensure that plasma-derived products will continue to be subject to infectious concerns. Manufacturers of plasma-derived CFC have addressed the issue of emerging infectious agents by developing recombinant products that limit the need for human plasma during production. Such recombinant products have extended the safety profile of their predecessors by ensuring that all reagents used for cell culture, purification steps, and stabilisation and storage buffers are completely independent of human plasma.

Physiologic changes in vascular birthmarks during early infancy: Mechanisms and clinical implications

Summary.  This study describes health‐related quality of life (HRQoL) of persons with haemophilia A in the United States (US) and determines associations between self‐reported joint pain, motion limitation and clinically evaluated joint range of motion (ROM), and between HRQoL and ROM. As part of a 2‐year cohort study, we collected baseline HRQoL using the SF‐12 (adults) and PedsQL (children), along with self‐ratings of joint pain and motion limitation, in persons with factor VIII deficiency recruited from six Haemophilia Treatment Centres (HTCs) in geographically diverse regions of the US. Clinically measured joint ROM measurements were collected from medical charts of a subset of participants. Adults (N = 156, mean age: 33.5 ± 12.6 years) had mean physical and mental component scores of 43.4 ± 10.7 and 50.9 ± 10.1, respectively. Children (N = 164, mean age: 9.7 ± 4.5 years) had mean total PedsQL, physical functioning, and psychosocial health scores of 85.9 ± 13.8, 89.5 ± 15.2, and 84.1 ± 15.3, respectively. Persons with more severe haemophilia and higher self‐reported joint pain and motion limitation had poorer scores, particularly in the physical aspects of HRQoL. In adults, significant correlations (P < 0.01) were found between ROM measures and both self‐reported measures. Except among those with severe disease, children and adults with haemophilia have HRQoL scores comparable with those of the healthy US population. The physical aspects of HRQoL in both adults and children with haemophilia A in the US decrease with increasing severity of illness. However, scores for mental aspects of HRQoL do not differ between severity groups. These findings are comparable with those from studies in European and Canadian haemophilia populations.

Immunologic abnormalities in patients with hemophilia A.

To the Editor: Laurence and coworkers,1 as well as others,2,3 have reported that the depletion of CD4+ T lymphocytes may be associated with AIDS-defining or other severe illnesses in persons withou...

Formation of prostacyclin (PGI2) by the ductus arteriosus of fetal lambs at different stages of gestation.

Vascular birthmarks are the most common birthmarks encountered in newborns. Many dermatologists are unfamiliar with the normal physiologic changes that affect and alter their appearance during early infancy. In this article we discuss normal newborn hemodynamic/neurovascular physiology and the associated clinical findings in neonatal skin. The physiologic anemia of infancy and its resultant effects on skin color and the appearance of vascular birthmarks are detailed. Finally, the pitfalls and obstacles to early diagnosis of vascular birthmarks and the subtle differences between them are reviewed, as are the challenges in assessing response to early pulsed dye laser treatment in the context of the changing vascular physiology.