Haemophilia and joint disease: pathophysiology, evaluation and management

In patients with haemophilia, regular replacement therapy with clotting factor concentrates (prophylaxis) is effective in preventing recurrent bleeding episodes into joints and muscles. However, despite this success, intra-articular and intramuscular bleeding is still a major clinical manifestation of the disease. Bleeding most commonly occurs in the knees, elbows, and ankles, and is often evident from early childhood. The pathogenesis of haemophilic arthropathy is multifactorial, with changes occurring in the synovium, bone, cartilage, and blood vessels. Recurrent joint bleeding causes synovial proliferation and inflammation (haemophilic synovitis) that contribute to end-stage degeneration (haemophilic arthropathy); with pain and limitation of motion severely affecting patients’ quality of life. If joint bleeding is not treated adequately, it tends to recur, resulting in a vicious cycle that must be broken to prevent the development of chronic synovitis and degenerative arthritis. Effective prevention and management of haemophilic arthropathy includes the use of early, aggressive prophylaxis with factor replacement therapies, as well as elective procedures, including restorative physical therapy, analgesia, aspiration, synovectomy, and orthopaedic surgery. Optimal treatment of patients with haemophilia requires a multidisciplinary team comprising a haematologist, physiotherapist, orthopaedic practitioner, rehabilitation physician, occupational therapist, psychologist, social workers, and nurses.Journal of Comorbidity 2011;1(1):51–59

Rao-Blackwellized Out-of-Sequence Processing for Mixed Linear/Nonlinear State-Space Models

We investigate the out-of-sequence measurements particle filtering problem for a set of conditionally linear Gaussian state-space models, known as mixed linear/nonlinear state-space models. Two different algorithms are proposed, which both exploit the conditionally linear substructure. The first approach is based on storing only a subset of the particles and their weights, which implies low memory and computation requirements. The second approach is based on a recently reported Rao-Blackwellized forward filter/backward simulator, adapted to the out-of-sequence filtering task with computational considerations for enabling online implementations. Simulation studies on two examples show that both approaches outperform recently reported particle filters, with the second approach being superior in terms of tracking performance

Rao-Blackwellized Particle Filters with Out-of-Sequence Measurement Processing

This paper addresses the out-of-sequence measurement (OOSM) problem for mixed linear/nonlinear state-space models, which is a class of nonlinear models with a tractable, conditionally linear substructure. We develop two novel algorithms that utilize the linear substructure. The first algorithm effectively employs the Rao-Blackwellized particle filtering framework for updating with the OOSMs, and is based on storing only a subset of the particles and their weights over an arbitrary, predefined interval. The second algorithm adapts a backward simulation approach to update with the delayed (out-of-sequence) measurements, resulting in superior tracking performance. Extensive simulation studies show the efficacy of our approaches in terms of computation time and tracking performance. Both algorithms yield estimation improvements when compared with recent particle filter algorithms for OOSM processing; in the considered examples they achieve up to 10% enhancements in estimation accuracy. In some cases the proposed algorithms even deliver accuracy that is similar to the lower performance bounds. Because the considered setup is common in various estimation scenarios, the developed algorithms enable improvements in different types of filtering applications

Mobile Manipulation with a Kinematically Redundant Manipulator for a Pick-and-Place Scenario

Mobile robots and robotic manipulators have traditionally been used separately performing different types of tasks. For example, industrial robots have typically been programmed to follow trajectories using position sensors. If combining the two types of robots and adding sensors new possibilities emerge. This enables new applications, but it also raises the question of how to combine the sensors and the added kinematic complexity. An omni-directional mobile robot together with a new type of kinematically redundant manipulator for future use as a service robot for grocery stores is proposed. The scenario is that of distributing groceries on refilling shelves, and a constraint- based task specification methodology to incorporate sensors and geometric uncertainties into the task is employed. Sensor fusion is used to estimate the pose of the mobile base online. Force sensors are utilized to resolve remaining uncertainties. The approach is verified with experiments

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 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

Economic evaluation: what are we looking for and how do we get there?

The interest in economic evaluation of alternative strategies for haemophilia treatment has increased through the years. Few studies have actually been undertaken, however, and most of them have been simple cost-minimization or cost-effectiveness analyses. From the perspective of the binational project 'Treatment strategies for severe haemophilia - prophylaxis vs. on-demand', the present paper discusses the pros and cons of different methods for economic evaluation and their data requirements. Severe haemophilia is a rare disease that requires lifelong treatment. In addition, treatment has both short- and long-term effects which are likely to differ between strategies. Accordingly, regardless of the chosen evaluation method, data requirements are non-trivial. Hence, the various problems connected to the generation of data, as well as how they may be addressed, are also discussed

Willingness to pay for on-demand and prophylactic treatment for severe haemophilia in Sweden.

The objective of the present paper was to provide an estimate of the benefits of on-demand and prophylaxis treatment strategies for severe haemophilia in monetary terms. Using the contingent-valuation method, which simulates a missing market by asking people about their willingness to pay (WTP), we asked a representative sample (n = 609) of the Swedish population if they would be willing to pay a specific amount (bid) so that patients with severe haemophilia could receive on-demand treatment and another bid for prophylactic treatment. Different respondents were offered different bids and the bid vector ranged from 71 Euro cents to EUR 130. The order of the bid questions was randomized so that half of the respondents were asked first about their WTP for on-demand treatment, and then about their WTP for prophylaxis, while the order was reversed for the other half of the respondents. The mean estimated WTP (year 2002) was EUR 39 (95% CI 31-47) for on-demand and EUR 65 (95% CI 55-73) for prophylaxis. Our sensitivity analysis showed that the ranking of the two treatment alternatives was robust in that the WTP was greater for prophylaxis in all possible subsets. The point estimates of WTP varied somewhat in subsets defined by individual characteristics, but confidence intervals always overlapped that of the main results. The WTP for on-demand and prophylaxis exceeded the calculated cost of treatment per taxpayer of providing on-demand and prophylactic treatment, respectively, based on our previous result

The Malmo International Brother Study (MIBS). Genetic defects and inhibitor development in siblings with severe hemophilia A

BACKGROUND AND OBJECTIVES: The strongest risk factor identified for inhibitor development in people with severe hemophilia A is the type of factor VIII gene mutation. The objective of this study was to evaluate the mutation type dependent concordance rate of inhibitor formation in siblings. DESIGN AND METHODS: The gene defect, treatment and inhibitor history were evaluated in 113 families in which two or more siblings had severe hemophilia A. RESULTS: Seventy-nine of the families (69.9%) were concordant in that either all or none of the siblings had a history of inhibitors. The concordance in 59 families with inhibitors was 42.4%. The corresponding figures for the 74 families with intron 22 inversion were 63.5% and 40.0%, respectively, and the overall concordance within 14 families with nonsense mutations was 78.6%. The siblings in two families with large gene deletions had no inhibitor history. A small proportion of the families with missense mutations, small deletions/insertions and splice site mutations developed inhibitors, but in four of the families two or more siblings developed high-responding inhibitors. In 18 of the 25 concordant families (72.0%) with inhibitors, the inhibitor was also of the same type (high-responding). INTERPRETATION AND CONCLUSIONS: This is the first study of the association between inhibitor formation and the causative factor VIII gene mutation in siblings. The data show that the type of mutation provides, to some extent, the basis for this relationship, but the mutation itself is not enough to predict the risk for therapy-induced inhibitor formation

Bleeding phenotype of patients with moderate haemophilia A and B assessed by thromboelastometry and thrombin generation

Introduction Predicting the bleeding phenotype is crucial for the management of patients with moderate haemophilia. Global coagulation assays evaluate haemostasis more comprehensively than conventional methods. Aim To explore global coagulation assays and the bleeding phenotype of patients with moderate haemophilia A (MHA) and B (MHB). Methods The MoHem study is a cross-sectional, multicentre study covering Nordic patients with MHA and MHB. Thromboelastometry in whole blood and thrombin generation (TG) in platelet-poor plasma (1, 2.5 and 5 pM tissue factor (TF)) were compared with joint health (Haemophilia Joint Health Score (HJHS)) and treatment modality. Results We report on 61 patients from Oslo and Helsinki: 24 MHA and 37 MHB. By TG (2.5 pM TF), patients who had been without replacement therapy during the previous 12 months depicted higher endogenous thrombin potential (P = .03). In contrast, those who had low ETP (< median) captured higher HJHS (P = .02). Patients who had undergone orthopaedic surgery generated least thrombin (P = .02). By thromboelastometry, those without the need of factor consumption had short clotting times, and quick times to maximum velocity (< median values) (P = .03). Factor VIII/factor IX activity (FVIII/FIX:C) did not align with the bleeding phenotype, but FIX:C Conclusion TG differentiated patients with moderate haemophilia according to HJHS, annual factor consumption, and whether orthopaedic surgery had been performed. Thromboelastometry differentiated according to factor consumption only. Global coagulation assays may assist predicting the bleeding phenotype in moderate haemophilia.Peer reviewe

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