Accuracy and consistency of anti-Xa activity measurement for determination of rivaroxaban plasma levels.

Essentials Accurate determination of anticoagulant plasma concentration is important in clinical practice. We studied the accuracy and consistency of anti-Xa assays for rivaroxaban in a multicentre study. In a range between 50 and 200 µg L-1 , anti-Xa activity correlated well with plasma concentrations. The clinical value might be limited by overestimation and intra- and inter-individual variation. SUMMARY: Background Determining the plasma level of direct oral anticoagulants reliably is important in the work-up of complex clinical situations. Objectives To study the accuracy and consistency of anti-Xa assays for rivaroxaban plasma concentration in a prospective, multicenter evaluation study employing different reagents and analytical platforms. Methods Rivaroxaban 20 mg was administered once daily to 20 healthy volunteers and blood samples were taken at peak and trough levels (clinicaltrials.gov NCT01710267). Anti-Xa activity was determined in 10 major laboratories using different reagents and analyzers; corresponding rivaroxaban plasma concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Findings Overall Pearson's correlation coefficient of anti-Xa levels and HPLC-MS results was 0.99 for Biophen® Heparin (95% CI, 0.99, 0.99), Biophen® DiXaI (95% CI, 0.99, 0.99) and STA® anti-Xa liquid (95% CI, 0.99, 1.00). Correlation was lower in rivaroxaban concentrations below 50 µg L-1 and above 200 µg L-1 . The overall bias of the Bland-Altman difference plot was 14.7 µg L-1 for Biophen Heparin, 17.9 µg L-1 for Biophen DiXal and 19.0 µg L-1 for STA anti-Xa liquid. Agreement between laboratories was high at peak level but limited at trough level. Conclusions Anti-Xa activity correlated well with rivaroxaban plasma concentrations, especially in a range between 50 and 200 µg L-1 . However, anti-Xa assays systematically overestimated rivaroxaban concentration as compared with HPLC-MS, particularly at higher concentrations. This overestimation, coupled with an apparent interindividual variation, might affect the interpretation of results in some situations.

Mutational spectrum of the SERPING1 gene in Swiss patients with hereditary angioedema.

Hereditary angioedema with C1 inhibitor deficiency (C1-INH-HAE) is a rare autosomal dominant disease caused by mutations in the C1 inhibitor gene SERPING1. Phenotype and clinical features of the disease are extremely heterogeneous, varying even within the same family. Compared to HAE cohorts in other countries, the genetic background of the Swiss HAE patients has not yet been elucidated. In the present study we investigated the mutational spectrum of the SERPING1 gene in 19 patients of nine unrelated Swiss families. The families comprise a total of 111 HAE-affected subjects which corresponds to approximately 70% of all HAE-affected patients living in Switzerland. Three of the identified mutations are newly described. Members of family A with a nucleotide duplication as genetic background seem to have a more intense disease manifestation with a higher attack frequency compared to the other families. Newly designed genetic screening tests allow a fast and cost-efficient testing for HAE in other family members.

The Swiss National Registry for Primary Immunodeficiencies: report on the first 6 years' activity from 2008 to 2014.

The Swiss National Registry for Primary Immunodeficiency Disorders (PID) was established in 2008, constituting a nationwide network of paediatric and adult departments involved in the care of patients with PID at university medical centres, affiliated teaching hospitals and medical institutions. The registry collects anonymized clinical and genetic information on PID patients and is set up within the framework of the European database for PID, run by the European Society of Immunodeficiency Diseases. To date, a total of 348 patients are registered in Switzerland, indicating an estimated minimal prevalence of 4·2 patients per 100 000 inhabitants. Distribution of different PID categories, age and gender are similar to the European cohort of currently 19 091 registered patients: 'predominantly antibody disorders' are the most common diseases observed (n = 217/348, 62%), followed by 'phagocytic disorders' (n = 31/348, 9%). As expected, 'predominantly antibody disorders' are more prevalent in adults than in children (78 versus 31%). Within this category, 'common variable immunodeficiency disorder' (CVID) is the most prevalent PID (n = 98/217, 45%), followed by 'other hypogammaglobulinaemias' (i.e. a group of non-classified hypogammaglobulinaemias) (n = 54/217, 25%). Among 'phagocytic disorders', 'chronic granulomatous disease' is the most prevalent PID (n = 27/31, 87%). The diagnostic delay between onset of symptoms and diagnosis is high, with a median of 6 years for CVID and more than 3 years for 'other hypogammaglobulinaemias'.

[New oral anticoagulants - influence on coagulation tests]. / Neue orale Antikoagulanzien - Einfluss auf Gerinnungstests.

The new oral anticoagulants (NOACs) represent alternative antithrombotic agents for prophylaxis and therapy of thromboembolic diseases. They act either by inhibition of the clotting factor Xa or IIa (thrombin). As a consequence, they influence several coagulation assays (for example prothrombin time, activated partial thromboplastin time). Because of the short half-life of these new agents, these changes show great variations in the course of 24 hours. Furthermore, there are significant differences of laboratory results depending on the used reagents. We explain the influence of apixaban, rivaroxaban (factor Xa inhibitors) and dabigatran (thrombin inhibitor) on the most commonly used coagulation assays. Besides we show that this influence depends on the way of action of the drug as well as on the principle of the coagulation assay. Being aware of this relationships helps to interpret the results of coagulation assays under influence of NOACs correctly.

Multicentre validation of the Geneva Risk Score for hospitalised medical patients at risk of venous thromboembolism. Explicit ASsessment of Thromboembolic RIsk and Prophylaxis for Medical PATients in SwitzErland (ESTIMATE).

There is a need to validate risk assessment tools for hospitalised medical patients at risk of venous thromboembolism (VTE). We investigated whether a predefined cut-off of the Geneva Risk Score, as compared to the Padua Prediction Score, accurately distinguishes low-risk from high-risk patients regardless of the use of thromboprophylaxis. In the multicentre, prospective Explicit ASsessment of Thromboembolic RIsk and Prophylaxis for Medical PATients in SwitzErland (ESTIMATE) cohort study, 1,478 hospitalised medical patients were enrolled of whom 637 (43%) did not receive thromboprophylaxis. The primary endpoint was symptomatic VTE or VTE-related death at 90 days. The study is registered at ClinicalTrials.gov, number NCT01277536. According to the Geneva Risk Score, the cumulative rate of the primary endpoint was 3.2% (95% confidence interval [CI] 2.2-4.6%) in 962 high-risk vs 0.6% (95% CI 0.2-1.9%) in 516 low-risk patients (p=0.002); among patients without prophylaxis, this rate was 3.5% vs 0.8% (p=0.029), respectively. In comparison, the Padua Prediction Score yielded a cumulative rate of the primary endpoint of 3.5% (95% CI 2.3-5.3%) in 714 high-risk vs 1.1% (95% CI 0.6-2.3%) in 764 low-risk patients (p=0.002); among patients without prophylaxis, this rate was 3.2% vs 1.5% (p=0.130), respectively. Negative likelihood ratio was 0.28 (95% CI 0.10-0.83) for the Geneva Risk Score and 0.51 (95% CI 0.28-0.93) for the Padua Prediction Score. In conclusion, among hospitalised medical patients, the Geneva Risk Score predicted VTE and VTE-related mortality and compared favourably with the Padua Prediction Score, particularly for its accuracy to identify low-risk patients who do not require thromboprophylaxis.

Relation of psychological distress to the international normalized ratio in patients with venous thromboembolism with and without oral anticoagulant therapy.

BACKGROUND: Psychological distress might affect the international normalized ratio (INR), but effects might vary depending on oral anticoagulant (OAC) therapy. OBJECTIVES: To investigate the association of psychological distress with INR and clotting factors of the extrinsic pathway in patients with and without OAC therapy. PATIENTS AND METHODS: We studied 190 patients with a previous venous thromboembolism (VTE); 148 had discontinued OAC therapy and 42 had ongoing OAC therapy. To assess psychological distress, all patients completed validated questionnaires to measure symptoms of depression, anxiety, worrying, anger and hostility. INR, fibrinogen, factor (F)II:C, FV:C, FVII:C and FX:C were measured as part of outpatient thrombophilia work-up. RESULTS: In VTE patients without OAC therapy, the odds of a reduced INR (< 1.00) were significantly increased from 1.5 to 1.8 times for an increase of 1 standard deviation (SD) in symptoms of depression, anxiety, worrying and anger, respectively, after adjusting for gender, age, body mass index, socioeconomic status, hematocrit and C-reactive protein. Worrying, anger and hostility also showed significant direct associations with FVII:C. In patients with OAC therapy, INR was unrelated to a negative affect; however, lower FVII:C related to anxiety and worrying as well as lower FX:C related to anger and hostility were observed in patients with OAC therapy compared with those without OAC therapy. CONCLUSIONS: Psychological distress was associated with a reduced INR in VTE patients without OAC therapy. The direction of the association between psychological distress and activity in some clotting factors of the extrinsic coagulation pathway might differ depending on whether VTE patients are under OAC therapy or not.

Rivaroxaban: Quantification by anti-FXa assay and influence on coagulation tests: a study in 9 Swiss laboratories.

INTRODUCTION: Rivaroxaban (RXA) is licensed for prophylaxis of venous thromboembolism after major orthopaedic surgery of the lower limbs. Currently, no test to quantify RXA in plasma has been validated in an inter-laboratory setting. Our study had three aims: to assess i) the feasibility of RXA quantification with a commercial anti-FXa assay, ii) its accuracy and precision in an inter-laboratory setting, and iii) the influence of 10mg of RXA on routine coagulation tests. METHODS: The same chromogenic anti-FXa assay (Hyphen BioMed) was used in all participating laboratories. RXA calibrators and sets of blinded probes (aim ii.) were prepared in vitro by spiking normal plasma. The precise RXA content was assessed by high-pressure liquid chromatography-tandem mass spectrometry. For ex-vivo studies (aim iii), plasma samples from 20 healthy volunteers taken before and 2 - 3hours after ingestion of 10mg of RXA were analyzed by participating laboratories. RESULTS: RXA can be assayed chromogenically. Among the participating laboratories, the mean accuracy and the mean coefficient of variation for precision of RXA quantification were 7.0% and 8.8%, respectively. Mean RXA concentration was 114±43µg/L .RXA significantly altered prothrombin time, activated partial thromboplastin time, factor analysis for intrinsic and extrinsic factors. Determinations of thrombin time, fibrinogen, FXIII and D-Dimer levels were not affected. CONCLUSIONS: RXA plasma levels can be quantified accurately and precisely by a chromogenic anti-FXa assay on different coagulometers in different laboratories. Ingestion of 10mg RXA results in significant alterations of both PT- and aPTT-based coagulation assays.

Iron chelation with deferasirox in two patients with HFE hemochromatosis and chronic anemia.

We present 2 patients with hyperferritinemia, increased liver iron and hemochromatosis-associated HFE genotypes. At diagnosis, both patients had chronic anemia that prevented initiation of phlebotomy. Iron chelation with deferasirox proved to be a safe and effective means of substantially lowering ferritin levels.

Fatal outcome of a hepatitis B virus transfusion-transmitted infection.

BACKGROUND AND OBJECTIVES: In 2008, hepatitis B virus (HBV) DNA testing was not yet mandatory for the screening of blood donations in Switzerland. At that time, HBsAg was the only specific mandatory marker for HBV. The importance of high sensitivity for HBV NAT screening is shown. MATERIALS AND METHODS: Donor and recipient of a transfusion-transmitted HBV infection were followed up. Multiple samples were tested for HBV serological and molecular markers. RESULTS: At donation, the donor appeared healthy, HBsAg was negative and had a normal ALAT level. Ten weeks later, clinical symptoms suggested acute HBV infection as was confirmed with positive HBsAg, HBeAg, anti-HBc IgG, anti-HBc IgM and anti-HBe. The archived sample from the original donation was negative for anti-HBc, but positive for HBV DNA (17 IU/ml). A recipient transfused with the red cell concentrate was HBV DNA positive (3100 IU/ml) 3 months post-transfusion. After five months, HBsAg, HBeAg, anti-HBc and HBV DNA (1.1 x 10(11) IU/ml) were positive. Two weeks later, the patient died from complications associated with HBV infection and his underlying bone marrow disease. CONCLUSIONS: The present case illustrates the importance of introducing highly sensitive HBV NAT screening strategy to prevent possible HBV transfusion-transmitted infections from donors with low viral load.

Study of bioaccumulation of dalteparin at a therapeutic dose in patients with renal insufficiency.

BACKGROUND: Low-molecular-weight heparins (LMWH) are effective, safe and convenient for anticoagulation. Their use is limited in patients with renal insufficiency (RI) because of bioaccumulation. OBJECTIVES: Evaluate pharmacokinetic data of dalteparin at a therapeutic dose in patients with RI. PATIENTS AND METHODS: Prospective observational cohort study. Inpatients were included into three groups according to glomerular filtration rate (GFR): A > or = 60, B 30-59, C < 30 mL min(-1) 1.73 m(-2). Dalteparin was injected subcutaneously (s.c.) twice daily. Peak plasma anti-factor Xa activity (anti-Xa) was measured and adjusted to applied dose and body weight after the first dose, on day 2, and every 2nd day afterwards. Bioaccumulation factor R was calculated as quotient of the last and the first adjusted anti-Xa. Data are shown as median (interquartile range, IQR). RESULTS: Thirty-two patients (23 men) receiving dalteparin for > or = 2 days were analyzed. Follow-up was 6 days (IQR 4-10, range 2-22). Median dose was 90 (73-106) units kg(-1) per 12 h (P = 0.68). After the first dose, adjusted anti-Xa levels were 3.5 (2.6-5.0), 4.8 (3.3-5.5), 4.5 (3.7-7.5) x 10(-3) for the groups A, B, C; P = 0.26. On the last day, they were 6.1 (3.7-7.3), 7.1 (5.6-8.3), 10.2 (7.8-13.2) x 10(-3); A compared with C, P = 0.002. R was 1.46 (1.15-1.82), 1.36 (1.20-2.16) and 2.28 (1.53-2.93); A compared with C, P = 0.18. CONCLUSION: Therapeutically dosed dalteparin accumulates in patients with severe RI (group C). Dose adjustments according to anti-Xa are recommended for dalteparin if used in this patient population. However, no simple dosing scheme can be suggested yet because of wide inter-individual variation.

[Diagnosis and therapy of anemia in general practice]. / Diagnostik und Therapie der Anämie in der Praxis.

Anemia is a common problem in family medicine and therefore frequently investigated in general practice. Anemias are classified according to mean corpuscular volume (MCV) and reticulocyte count. An algorithm for the evaluation of the cause contains patients history and laboratory analysis including reticulocyte count, serum ferritin and CRP, serum vitamin B12, serum or erythrocyte folate and serum creatinine. Therewith most anemias in general practice can be explained. The most important types of anemia, e.g. iron deficiency anemia, are discussed as well as aspects of diagnosis and therapy. Iron deficiency anemia is often diagnosed together with other types of anemia, such as e.g. anemia of chronic disease. Particular aspects of anemia in the elderly as well as renal anemia are discussed.

Study of bioaccumulation of dalteparin at a prophylactic dose in patients with various degrees of impaired renal function.

BACKGROUND: Low-molecular-weight heparins (LMWH) have been shown to be effective and safe for prophylaxis of thromboembolic diseases. However, issues regarding safety and optimal use of LMWH arise in patients with renal insufficiency (RI). OBJECTIVES: To compare pharmacokinetic data of dalteparin for up to 3 weeks in patients with various degrees of RI. PATIENTS AND METHODS: Patients from general medical and surgical wards were included in this prospective cohort study and divided into three groups according to renal function: A=normal (GFR>or=60 mL min(-1)1.73 m(-2)), B=mild RI (GFR 30-59 mL min(-1)1.73 m(-2)), C=severe RI (GFR<30 mL min(-1)1.73 m(-2)). Dalteparin was injected s.c. once daily at a prophylactic dose. Peak anti-Xa activity levels (anti-Xa) were measured 4+/-1 h after injection on day 1 and every third day up to 3 weeks. Primary objectives were peak anti-Xa levels and adjusted anti-Xa levels, adjustment being carried out for dose and body weight. RESULTS: A total of 42 patients could be analyzed during a median of 10 days (interquartile range IQR 4-13, range 1-20). In all groups, adjusted peak anti-Xa levels were not different on day 10 compared with day 1. No bioaccumulation>30% could be found up to day 10 even in patients with severe RI. CONCLUSION: The use of dalteparin at a prophylactic dose was not associated with a bioaccumulation>30% even in patients with severe renal insufficiency during a median follow-up of 10 days (IQR 4-13, range 1-20).

[Prevalence and causes of anemia in a city general practice]. / Prävalenz und Ursachen von Anämien in einer städtischen Hausarztpraxis.

In 6% of 854 patients in a city general practice anemia was found. Anemia was defined by WHO criteria. An algorithm for the evaluation of the cause includes patient's history and laboratory investigations inclusive of reticulocyte count, serum ferritin with CRP, serum vitamin B12, serum or erythrocyte folate and serum creatinine, depending on clinical situation and mean corpuscular volume (MCV). Median age of the patients was 77 years. The most frequent underlying cause of anemia was chronic renal failure (in 21%). According to the high patient's age, iron deficiency, chronic disease and malignancy were frequent for anemia, too. 35% of patients had more than one cause of anemia. The results are compared with other sparse reports from general practices and are discussed regarding the particular situation in the elderly.

ADAMTS-13, von Willebrand factor and related parameters in severe sepsis and septic shock.

BACKGROUND: Insufficient control of von Willebrand factor (VWF) multimer size as a result of severely deficient ADAMTS-13 activity results in thrombotic thrombocytopenic purpura associated with microvascluar thrombosis and platelet consumption, features not seldom seen in severe sepsis and septic shock. METHODS: ADAMTS-13 activity and VWF parameters of 40 patients with severe sepsis or septic shock were compared with those of 40 healthy controls of the same age and gender and correlated with clinical findings and sepsis outcome. RESULTS: ADAMTS-13 activity was significantly lower in patients than in healthy controls [median 60% (range 27-160%) vs. 110% (range 63-200%); P < 0.001]. VWF parameters behaved reciprocally and both VWF ristocetin cofactor activity (RCo) and VWF antigen (VWF:Ag) were significantly (P < 0.001) higher in patients compared with controls. Neither ADAMTS-13 activity nor VWF parameters correlated with disease severity, organ dysfunction or outcome. However, a contribution of acute endothelial dysfunction to renal impairment in sepsis is suggested by the significantly higher VWF propeptide and soluble thrombomodulin levels in patients with increased creatinine values as well as by their strong positive correlations (creatinine and VWF propeptide r(s) = 0.484, P < 0.001; creatinine and soluble thrombomodulin r(s) = 0.596, P < 0.001). CONCLUSIONS: VWF parameters are reciprocally correlated with ADAMTS-13 activity in severe sepsis and septic shock but have no prognostic value regarding outcome.

[Iron-deficiency anemia and gastrointestinal bleeding]. / Eisenmangelanamie bei gastrointestinalen Blutungen.

The physiology of iron homeostasis, clinical presentation, diagnosis, differential diagnosis and therapeutic options in iron-deficiency anemia are discussed. Iron deficiency is the most common haematological disorder encountered in general practice and iron-deficiency anemia is the most frequently occurring anemia throughout the world. Blood loss is a major cause of iron-deficiency anemia. Gastrointestinal bleeding is the most common cause of iron deficiency in adult men and is second only to menstrual blood loss as a cause in women. Iron-deficiency anemia is not a disease itself but a manifestation of an underlying disease, searching for the latter is therefore crucial and may be of far greater importance to the ultimate well-being of the patient than repleting iron stores. The symptoms and signs of iron deficiency are partially explained by the presence of anemia. However, there also appears to be a direct effect of iron deficiency on the central nervous system. The most important screening investigations for iron deficiency in clinical practice are the haemoglobin, the haematocrit and the mean corpuscular volume (MCV). The single most important measure of iron status is the serum ferritin, values below the lower limit of normal being specific for iron deficiency. In inflammation, hepatopathy and haemolysis serum ferritin is also released leading to falsely elevated values, therefore an analysis of the C-reactive protein (CRP) should always accompany the analysis of serum ferritin. Repleting iron stores is usually done with oral iron therapy, the available preparations are comparable with respect to efficacy, side effects and costs. The main indications for parenteral iron therapy are intolerance to oral iron, intestinal malabsorption and poor compliance to an oral regimen. The iron sucrose preparation should bepreferentially used for that purpose, the total dose is calculated from the amount of iron needed to restore the haemoglobin deficit plus an additional amount to replenish iron stores.

Venous thromboembolism prophylaxis in acutely ill medical patients: definite need for improvement.

AIM OF THE STUDY: To examine the frequency and adequacy of thromboprophylaxis in acutely ill medical patients hospitalized in eight Swiss medical hospitals. METHODS: A cross-sectional study of 1372 patients from eight Swiss hospitals was carried out. After exclusion of patients (275) given therapeutic anticoagulation, 1097 patients were audited. The adequacy of thromboprophylaxis was assessed by comparison with predefined explicit criteria. RESULTS: Of 1097 patients, 542 (49.4%) received thromboprophylaxis. According to the explicit criteria, 644 (58.7%) should have been on prophylaxis (P < 0.001, when compared with the rate observed). The rate of prevention differed widely between hospitals (from 29.4 to 88.6%) with no difference between teaching and nonteaching hospitals. According to the explicit criteria, a substantial proportion (44.9%) of the patients who should have been treated were not. Conversely, 41.3% of the patients were unnecessarily treated. CONCLUSIONS: Even though the appropriateness of the explicit criteria used could be challenged, our data suggest that the current practice is associated with important uncertainty leading to both overuse and underuse of thromboprophylaxis in patients hospitalized in medical wards. More efforts are urgently needed to develop new or endorse existing explicit, evidence-based criteria and guidelines for thromboprophylaxis in this population of patients.