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Biomedical subjects

E Berntorp

Publications and source records attributed to E Berntorp.

At least 19 recordsLinked to original sources

Elective orthopedic surgery for hemophilia patients with inhibitors: New opportunities.

We report a series of 108 elective orthopedic surgical procedures in hemophilia patients with inhibitors, comprising 88 cases in which radiosynoviorthesis was performed and 20 cases in which major orthopedic procedures were carried out. Hemostatic cover was provided by recombinant factor VIIa (rFVIIa, NovoSeven(R), Novo Nordisk, Bagsvaerd, Denmark) in 17 cases, and by FVIII anti-inhibitor product (FEIBA, Baxter Corp, Toronto, Canada) in the remaining three procedures. A total of 51 patients from nine centers worldwide were included. The results of the procedures were characterized as good (82 procedures), fair (15), or poor (11). Postoperative bleeding complications requiring further surgical intervention occurred in three (15%) of the 20 major orthopedic procedures; all three procedures used rFVIIa as a hemostatic agent. Despite these complications, however, our study has shown that rFVIIa allows hemophilic patients with high inhibitor titers to undergo elective orthopedic surgery (EOS) with a greater expectation of success, leading to an improved quality of life. Thorough analysis of each case as part of a multidisciplinary team will help to identify further inhibitor patients in whom EOS can be performed both safely and effectively.

Blood Coagulation Factor Inhibitors↗

Experience with a new percutaneous port system, Percuseal, for intravenous injection in patients with haemophilia, von Willebrand disease and severe alpha1-antitrypsin deficiency.

We have implanted a new port system (Percuseal) in altogether 13 patients with haemophilia A, B, von Willebrand disease and alpha1-antitrypsin deficiency in order to facilitate venous access. The Percuseal system differs from subcutaneous ports, such as Port-a-Cath, in that the upper part of the device protrudes above the skin. In this way, the patient can easily puncture the port membrane under the guidance of his eyes without penetrating the skin. In the present study cohort, a number of complications occurred. These were mainly caused by repeated local infections (in five patients), which made it necessary to replace the ports in three of the patients and to permanently remove the ports as the first option in two of the patients. In one patient, the port was removed because of inconvenience when doing physical exercise. In one additional patient, a severe systemic infection occurred, causing spondylitis. Despite the high infection rate, most patients considered the device very convenient to use. Because of the side-effects seen in our study, the Percuseal port in its present form is not to be recommended for regular use. A reconstruction of the port, making it smaller and giving it an antibacteriostatic cap, may possibly make this kind of port system a feasible alternative to use in order to improve pharmacoeconomics in the prophylactic treatment of haemophilia and patients with alpha1-antitrypsin deficiency.

Adult↗

The pharmacokinetics of clotting factor therapy.

Clotting factor preparations are expensive and not readily available in all parts of the world. We are still facing shortages due to limited production. Thus, it is obvious that clotting factor therapy should be optimised as far as possible. The judicious use of pharmacokinetic principles should be one of the fundaments of dosing. There are several pitfalls in studies of clotting factor pharmacokinetics, such as discrepancies between assays, inadequate blood sampling protocols, problems to define the administered dose, uncertainty in the estimation of plasma volume for in vivo recovery calculation, and post-infusion activation of the clotting factor. Thus, while the pharmacokinetics of factor VIII is well characterised there are some discrepancies in the literature on factor IX. Recombinant factor VIIa is useful to treat haemorrhages in haemophilia complicated by inhibitors. The pharmacokinetics of VIIa has been investigated, however, the relationship between plasma level of VIIa and effect needs further exploration. Important applications of clotting factor pharmacokinetics include optimising the treatment and improving its cost-effectiveness during long-term prophylaxis as well as during bleeding episodes and surgery.

Blood Coagulation Factors↗

Impact of inhibitor epitope profile on the neutralizing effect against plasma-derived and recombinant factor VIII concentrates in vitro.

The inhibitory capacity of plasma samples from 24 patients with severe haemophilia A and high-responding inhibitors were evaluated in a concentrate-based assay using two plasma-derived (Haemate and Monoclate-P) and three recombinant (Helixate, Recombinate and ReFacto) factor VIII concentrates and correlated with the corresponding epitope profile. In most, but not all, inhibitor plasmas with a relatively low reactivity against the von Willebrand-containing product Haemate, the main epitopes were located in the FVIII light chain. The reactivities within the group of recombinant products varied in that the reactivity against the B-domain deleted ReFacto was in general higher than that against Recombinate and Helixate. This difference did not correlate with any particular epitope profile and indicates that the B-domain, type of formulation and/or purification procedures may have an impact on the inhibitor reactivity in vitro. The ratio between the inhibitor titres in the concentrate-based assay and the Bethesda assay was dependent on the inhibitor plasma and concentrate used. Taken together, our results show that the reactivity of inhibitor plasmas varies considerably between different FVIII concentrates and that it does not fully correlate with the epitope profile. Potential clinical implications of the observed differences in inhibitor reactivity are discussed.

Autoantibodies↗

Elective orthopaedic surgery for inhibitor patients.

We report on a series of 108 elective orthopaedic surgical procedures. It includes 88 radiosynoviortheses and 20 major orthopaedic procedures, performed on 51 patients at nine centres worldwide. The average age of patients was 28.5 years (range 5-40 years), and the average follow-up time was 2 years (range 1-5 years). There were 82 good results, 15 fair and 11 poor. In the synoviorthesis group (41 patients, 88 synoviortheses) the average age was 14.3 years (range 5-40 years) and the average follow-up was 6.5 years (range 1-10 years). There were 66 good results, 14 fair and eight poor. There were no complications. In the group of major orthopaedic procedures, the average age of the 10 patients was 32.5 years (range 27-40 years), and the average follow-up was 2.3 years (range 1-5 years). There were 16 good results, one fair and three poor. Postoperative bleeding complications occurred in three of the 20 major orthopaedic procedures performed (15% complications rate). They occurred in three patients treated with insufficient doses of recombinant activated factor VII. Despite such complications, the study has shown that haemophilic patients with inhibitors requiring elective orthopaedic surgery (EOS) can undergo such procedures with a high expectation of success. In other words, EOS is now possible in haemophilic patients with inhibitors, leading to an improved quality of life for these patients. Thorough analysis of each case as part of a multidisciplinary team will allow us to perform elective orthopaedic procedures in patients with inhibitors.

Adolescent↗

On-demand vs. prophylactic treatment for severe haemophilia in Norway and Sweden: differences in treatment characteristics and outcome.

Using an 11-year panel of 156 Norwegian and Swedish patients with severe haemophilia, and including retrospective case-book data from birth, we compared the differences in the haemophilia-related resource use between on-demand and prophylactic treatment. Patients treated on-demand had more surgery (arthrodeses, prostheses implantations and synovectomies) and more days lost from work. Median annual factor-concentrate consumption among adults (18+) was 211,000 IU [interquartile range (IQR) 154,000-268,000] or 3,024 IU kg-1 year(-1) for patients on prophylactic treatment and 55,000 IU (IQR 28,000-91,000) for on-demand patients (780 IU kg(-1) year(-1)). This was partly explained by the fact that the median dose per kg body weight was twice as great 28, (IQR 24-32) for prophylaxis compared with 14 (IQR 12-16) for on-demand. Prescribed dose per kg body weight was found to be an important factor explaining the variation in total annual factor-concentrate consumption per patient for both types of treatment. Other variables included in the panel-data regression analysis were the number of weeks on secondary prophylaxis for on-demand patients and age, body weight and type of haemophilia for children (0-17 years) on prophylaxis. Differences were consistently substantial and will affect both costs and benefits of the two treatment strategies.

Absenteeism↗

Consensus perspectives on prophylactic therapy for haemophilia: summary statement.

Participants in an international conference on prophylactic therapy for severe haemophilia developed a consensus summary of the findings and conclusions of the conference. In the consensus, participants agreed upon revised definitions for primary and secondary prophylaxis and also made recommendations concerning the need for an international system of pharmacovigilance. Considerations on starting prophylaxis, monitoring outcomes, and individualizing treatment regimens were discussed. Several research questions were identified as needing further investigation, including when to start and when to stop prophylaxis, optimal dosing and dose interval, and methods for assessment of long-term treatment effects. Such studies should include carefully defined cohorts, validated orthopaedic and quality-of-life assessment instruments, and cost-benefit analyses.

Consensus Statements as Topic↗

Prophylactic therapy for haemophilia: early experience.

During the 1960s, it was reported from Sweden that haemophiliacs with factor levels above 1% rarely develop arthropathy. This observation suggested that severe haemophilia could be converted to a milder form by regular infusions with factor concentrate. After several earlier publications, a report was published in 1992 that detailed 25 years' experience with prophylaxis in 60 patients from the Malmö centre. The results showed that starting prophylaxis early in life with a dose regimen that would prevent factor VIII or IX plasma levels from falling below 1% could prevent the development of haemophilic arthropathy. Also, older age groups who had received less intensive treatment, and who started prophylaxis later in life, were still in a much better condition than historic controls. In the 1970s several small but well-controlled studies from the USA, Germany and Italy clearly showed the benefit of prophylaxis in reducing bleeding frequency. Early experience from the Netherlands was published in 1971. Since these early studies, the results have been corroborated from many countries and in a large multinational study. Although the benefits of prophylaxis seem unquestionable, several research questions remain to be better elucidated, such as when to start and when to stop, dosing and dose interval, and how to assess the long-term treatment effects. These issues are of great economic importance, and the need for health economical studies is obvious.

Adolescent↗

Risk of haemorrhagic stroke in patients with oral anticoagulation compared with the general population.

OBJECTIVES: To compare the incidence of haemorrhagic stroke (HS), and the risk of fatal outcome after HS in patients with oral anticoagulation (OA) treatment and in the general population. DESIGN: Five-year cohort study. SETTING: The Anticoagulation Clinic, Malmö University Hospital, Lund, Sweden. SUBJECTS: A total of 4434 patients treated with OA (6693 treatment years) from 1 Oct 1993 to 30 Sept 1998. The population-based Stroke Register of Malmö, Lund, Sweden (STROMA). RESULTS: Forty-eight patients had HS according to ICD 9 code 430 and 431. HS occurred at a higher age in women compared with men (mean age 79.5 years vs. 74.7 years, P=0.009). The age-adjusted relative risk of HS during OA treatment was 10.9 (CI 6.7-17.6) for men and 9.3 (CI 5.7-15.0) for women, as compared with the untreated general population. Number needed to harm (NNH) (person-years) was 103 for men and 188 for women. Adjusted for age and sex, OA treatment was significantly associated with fatal outcome in patients with HS (OR=2.6, CI 1.4-4.8). CONCLUSIONS: Patients with OA treatment had approximately 10 times higher risk of HS as compared with the general population, and the risk increased markedly with age. OA treatment is associated with an increased case fatality in patients with HS.

Age Distribution↗

Monitoring the bioavailability of FEIBA with a thrombin generation assay.

BACKGROUND: Hemophilia A patients with inhibitors are generally treated with preparations containing activated coagulation factors to achieve hemostasis by bypassing factor (F)VIII. OBJECTIVES: We developed an assay for monitoring the kinetic of thrombin generation in human FVIII inhibitor plasma reconstituted in vitro with activated prothrombin complex concentrate, FEIBA, and in plasma samples from hemophilia A patients taken after FEIBA treatment. PATIENTS AND METHODS: For pharmacokinetic studies three patients with severe hemophilia A and with a high-titer inhibitor received a single dose of FEIBA. Repeated FEIBA treatment was monitored in one patient with acquired hemophilia A. Coagulation was triggered in citrated plasma by adding a low concentration of tissue factor/phospholipid complex and CaCl2 in the presence of a fluorogenic thrombin substrate. The intensity of the fluorescence signal (FU) was continuously monitored, and the rate of increase in the fluorescence signal for every time point, which reflects the actual thrombin concentrations, was calculated. RESULTS: The maximum rate of substrate conversion, which indicates the highest thrombin concentration, was approximately 1900 FU min(-1) in a normal plasma pool. Practically no thrombin generation was observed in the FVIII inhibitor plasma, but when it was spiked with FEIBA, the rate and the peak of thrombin generation increased dose-dependently to close to normal. Plasma samples from FVIII inhibitor patients treated with a single dose of FEIBA had an improved thrombin maximum within an hour after treatment, which gradually returned to baseline values with a half-life of 4-7 h. Changes in the characteristic parameters of thrombin generation coincided with the repeated administration of FEIBA in a patient with acquired hemophilia A. CONCLUSIONS: This assay enables the pharmacodynamic and pharmacokinetic properties of bypassing therapies to be monitored, thus helping to optimize treatment.

Adult↗

Factor VIII inhibitor-bypassing agents act by inducing thrombin generation and can be monitored by a thrombin generation assay.

Factor VIII (FVIII)-bypassing agents have complex modes of action but all control bleeding in inhibitor patients by triggering the generation of thrombin. No routine test is available for monitoring this therapy in patients with inhibitors against FVIII. We present an assay that records FEIBA- or FVIIa-mediated changes in thrombin generation (TG) in FVIII inhibitor plasma samples. In plasma samples spiked with FEIBA TG was normalized above 0.4 U/ml, while for recombinant FVIIa (rFVIIa) more than 12.5 microg/ml were required to induce TG in the absence of tissue factor (TF). Addition of TF increased the TG potential of rFVIIa in vitro. This assay seems suitable for monitoring the pharmacokinetics of inhibitor bypassing agents during treatment and possibly for predicting responses to treatment.

Autoantibodies↗

The prognostic value of global haemostatic tests in the intensive care unit setting.

BACKGROUND: Global haemostatic tests are often abnormal in critically ill patients, secondary to activation or consumption of coagulation factors or inhibitors. Methods for analysing plasma levels of these factors are, however, not widely available, and the predictive value of global tests is not known. We examined the clinical applicability to predict the outcome of the global haemostatic tests used at most hospitals. METHODS: Blood was collected from patients within 6 h of admission to an intensive care unit (ICU) and tested regarding platelet count, International Normalized Ratio (INR), and activated partial thromboplastin time (APTT). Ninety-two patients with platelet counts <100 x 10(9) l(-1), INR > 1.36 and/or APTT >45 s were included in a study group, and an additional 92 patients with a comparable age and sex distribution, but not fulfilling these laboratory criteria, constituted a control group. The following data were recorded for each patient: number of days in the ICU and hospital; alive or deceased when released from the ICU and hospital; survival at 30 days and 180 days. RESULTS: Survival upon discharge from the ICU and hospital was significantly reduced in the study group. This was especially pronounced in patients with medical disorders, whereas the survival rate was slightly higher in surgery patients. Expressing the survival predicting ability of the screening tests as odds ratios for all patients (study and control groups together) indicated that prolonged APTT in particular foretold a lower survival rate at studied time-points after admission to the ICU. CONCLUSIONS: The global haemostatic tests INR and APTT can predict survival in critically ill patients, and prolonged APTT in particular seems to be associated with a negative prognosis.

Aged↗

Clinical outcomes and resource utilization associated with haemophilia care in Europe.

We conducted a multicentre, cross- sectional study of 1042 haemophilia subjects across Europe to compare various health outcomes associated with on-demand vs. prophylactic factor-substitution therapy. Demographic, medical history, and healthcare resource utilization data were analysed along with the number of bleeding events over the past 6 months. Treatment-cost data were also examined to provide preliminary information for future economic studies. A logistic regression analysis, controlling for other statistically significant covariates, showed that patients treated on demand were 3.4 times more likely to have had a joint bleed over the previous 6 months than those treated with prophylaxis. Multiple regression analyses further confirmed these findings, because on-demand subjects had, on average, 5.15 more joint bleeds over the reporting period than patients treated with prophylaxis. Notably, these findings were even more dramatic for younger haemophilia patients when our study sample was stratified by age. Due to the high cost of factor replacement, healthcare costs were significantly higher for subjects treated prophylactically. While hospital costs for prophylaxis subjects were, on average, lower, statistically significant cost savings for prophylactic subjects were not noted. These results suggest that clinicians and health policy decision-makers should consider the advantages of prophylactic therapy for haemophilia patients in formulating treatment protocols and allocating health resources.

Age Factors↗

Quality-of-life differences between prophylactic and on-demand factor replacement therapy in European haemophilia patients.

The European Study on the Clinical Outcomes and Resource Utilization associated with Haemophilia Care was designed to compare various health outcomes associated with on-demand and prophylactic factor substitution methods in European haemophilia patients. While the primary objective of this research is to conduct an economic analysis, an important component of this study is to evaluate quality-of-life differences that may exist between patients who utilize these two styles of therapy. Quality-of-life research has emerged as a primary measure of health outcomes because it allows the augmentation of traditional clinical indicators of health with data gathered from the patient's perspective. A total of 1033 haemophilia patients from 16 European haemophilia treatment centres were enrolled in this study. The SF-36, a multidimensional quality-of-life instrument, was administered to all participants. This instrument measures eight health-related quality-of-life dimensions: physical functioning, physical role limitations, bodily pain, general health, vitality, social functioning, emotional role limitations, and mental health. All haemophilia subjects enrolled in the study scored significantly lower than the population normative means in the three physical dimensions and in the general health dimension. HIV-negative haemophiliac subjects differed significantly by factor substitution type in a multivariate analysis examining all eight health dimensions. Univariate analyses testing each dimension separately indicated that patients treated prophylactically reported significantly less bodily pain, better general health, and scored significantly higher in the physical functioning, mental health, and social functioning dimensions. While these results suggest that health-related quality-of-life may be better for haemophilia patients treated prophylactically, future prospective studies that gather periodic quality-of-life data over time should be conducted.

Acquired Immunodeficiency Syndrome↗

Progress in haemophilic care: ethical issues.

Care of haemophilic patients has dramatically improved during the past 40-50 years. Clotting factor concentrates have become much safer. Expensive treatments such as prophylaxis, immune-tolerance induction, the use of bypassing agents in inhibitor patients, and the replacement of joints have become available. However, there is still a shortage of factor concentrate, and we are yet to discover the most cost-effective treatment for patients. There is also a wide gap in the availability of these treatments between developing and developed countries, and a risk that patients are treated in unnecessarily expensive ways in some parts of the world compared with those who suffer from a lack of treatment in other parts, thus creating the ethical dilemma of whether less safe but more affordable concentrates should be used in developing countries. Other issues that raise ethical problems are the use of molecular genetics and gene therapy. It is proposed that international working groups, preferably under the auspices of the World Health Organisation and the World Federation of Hemophilia, take responsibility to solve the ethical issues in haemophilic care, the basis of which should be to promote the education of modern care and to set up clinical studies, including studies on health economics, so that treatment and care are cost-effective and based on sound evidence.

Cost-Benefit Analysis↗

Prophylactic treatment for severe haemophilia: comparison of an intermediate-dose to a high-dose regimen.

A multicentre study was performed in Sweden and the Netherlands, comparing effects of two prophylactic regimens in 128 patients with severe haemophilia, born 1970-90. 42 Swedish patients (high-dose prophylaxis), were compared with 86 Dutch patients (intermediate-dose prophylaxis). Patients were evaluated at the date of their last radiological score according to Pettersson. Annual clotting factor consumption and bleeding frequency were registered for a period of three years before evaluation. Patients in the high-dose group were younger at evaluation (median 15.2 vs. 17.9 years), started prophylaxis earlier (median 2 vs. 5 years), and used 2.19 times more clotting factor kg-1 year-1. Patients treated with high-dose prophylaxis had fewer joint bleeds (median 0.3 year-1 vs. 3.3 year-1) and the proportion of patients without arthropathy as measured by the Pettersson score was higher (69% vs. 32%), however, the age-adjusted difference in scores (median 0 points vs. 4 points) was small and at present not statistically significant. Clinical scores and quality of life were similar. These findings suggest that, compared with intermediate-dose prophylaxis, high-dose prophylaxis significantly increases treatment costs and reduces joint bleeds over a period of 3 years, but only slightly reduces arthropathy after 17 years of follow-up.

Adolescent↗