Anna-Marie Bloch Münster

Clinical and preclinical validation of the serum free light chain assay: identification of the critical difference for optimized clinical use

The use of the assay for the measurements of free light chains in serum (sFLCs) is increasing. However, there are technical limitations that potentially affect the use in serial measurements. We need further knowledge on the standards of analytical precision, the utility of conventional population‐based reference values and the critical difference (CD) between serial results required for significance. To answer these questions, the biological variation must be known.

Thrombophilia screening in the acute phase of deep venous thrombosis

Thrombophilia screening in the acute phase of deep venous thrombosis Anna-Marie Bloch Münster, Johannes Jakobsen Sidelmann & Jørgen Gram To cite this article: Anna-Marie Bloch Münster, Johannes Jakobsen Sidelmann & Jørgen Gram (2009) Thrombophilia screening in the acute phase of deep venous thrombosis, Scandinavian Journal of Clinical and Laboratory Investigation, 69:6, 633-635 To link to this article: http://dx.doi.org/10.3109/00365510903072012

Denaturing High-performance Liquid Chromatography mutation analysis in patients with reduced Protein S levels

BACKGROUNDnPatients with congenital Protein S deficiency have increased risk of venous thromboembolism. However, Protein S levels show large intra-individual variation and the biochemical assays have low accuracy and a high interlaboratory variability. Genetic analysis might aid in a more precise diagnosis and risk estimation. The aim was to design a high-throughput genetic analysis based on denaturing high-performance liquid chromatography to identify sequence variations in the gene coding for Protein S.nnnPATIENTSnIn total, 55 patients referred to the Section of Thrombosis and Haemostasis, Odense University Hospital, in the period 1998-2004 were included in the study.nnnRESULTSnMutations were found in ten of the 55 patients: Six different variants were identified, of which four were not previously reported: One were a nonsense mutation substituting a glutamine with a stopcodon (c.790C>T) and the rest were missense mutations (c.932T>G; c.1367A>G; c.1378T>C). Furthermore, four patients carried the same mutation (c.1045G>A), while two carried the Heerlen mutation (c.1378T>C).nnnCONCLUSIONSnThe reported method will be useful for rapidly detecting sequence variations in the gene coding for Protein S, giving a precise diagnosis and subsequently a better risk estimation.

Measurement of dabigatran: previously demonstrated Hemoclot® Thrombin Inhibitor assay reagent instability on Sysmex CS-2100i is no longer an issue

Abstract The Hemoclot® Thrombin Inhibitor (HTI) assay has been recommended for measurement of dabigatran concentrations in specific clinical situations. Traditionally, reagents for biochemical assays are prepared from instructions found in the package insert. For the HTI reagents the manufacturer recommends incubating the reagents much longer than indicated in the package insert. These recommendations are added to the application sheets designed for different analyzers. Many clinicians and laboratory personnel may be unaware of the discrepancy between the two instructions, resulting in incorrect handling of the reagents. The aim of this study was to investigate the effect of the two different preparation methods on reagent stability and test results. For the standard concentration range, reagent stability on Sysmex CS-2100i was only two hours instead of the eight hours indicated by the producer when following package insert instructions (incubation time: 15u2009min). Stability was increased to five hours when following the application sheet (incubation time: 60u2009min). Two years later, the study was repeated using samples of patients treated with dabigatran etexilate. This time, reagent stability was at least six hours. Since the reagent composition was unchanged, the increased stability could be due to changed logistics by the supplier, with stock and transfer closer by. Previously demonstrated HTI reagent instability is no longer an issue at our laboratory. The reliability of results of clinical studies in which the assay has been used is potentially compromised.

Data mining to assess variations in oral anticoagulant treatment

Variations in International Normalized Ratios (INR) are closely related to bleeding and thrombosis incidents in patients on oral anticoagulation treatment. This study investigates predictive factors that affect INR values. Data sampled with relatively high frequency allows for detection of local INR variations, and hence also allows detection and evaluation of predictive factors where time is taken into consideration. Univariate linear regression was applied and different models were reduced into a final predictive model. F-tests were utilized to test whether or not a model reduction would benefit INR predictions, in terms of decreasing observed variance. In addition to an INR submodel, the final model includes individual interaction from the last three days change in mean warfarin intake and three days change in mean vitamin K intake. Prediction residual error was mainly reduced by the INR submodel, while the warfarin model and the vitamin K submodel did not benefit predictions to same extend compared to the INR submodel. However, more studies on the temporal aspects of the effect of warfarin seem to be relevant.

Translation, Cultural Adaptation, and Psychometric Properties of the Danish Version of the Anti-Clot Treatment Scale

Background u2003The Anti-Clot Treatment Scale (ACTS) is a 17-item, 2-factor (Burdens and Benefits), patient-reported outcome instrument to evaluate patient satisfaction with oral anticoagulant treatment. Objectives u2003This study aimed to translate and culturally adapt the English version of the ACTS into Danish and to subsequently validate the Danish version in a population of patients treated with dabigatran etexilate for atrial fibrillation. Methods u2003The ACTS was translated into Danish and culturally adapted. This prospective phase 4 study included 232 respondents who completed the Danish ACTS after 1u2009month of treatment with dabigatran etexilate for atrial fibrillation. Psychometric properties were evaluated. For test–retest reliability, the ACTS was measured twice, 2 weeks apart, in a subgroup of 50 stable patients. Results u2003Generally, a high level of treatment satisfaction was found. Confirmatory factor analysis showed a suboptimal fit for the two-factor model of the original version. Using modification indices of confirmatory factor analysis, a four-factor model had the best fit. Cronbachs α for internal consistency was acceptable at 0.78. There was good test–retest reliability with intraclass correlation at 0.80. Smallest detectable changes (SDCs) for individual patients were 5.89 points for the total ACTS, 5.57 for the reverse Burdens, and 3.34 for Benefits scores. Group SDCs were 0.39, 0.37, and 0.22 respectively. Substantial ceiling effects limit the ability to detect improvement at the high end of the scale. Conclusion u2003The Danish version of the ACTS has inadequate structural validity. Reliability was acceptable. Ceiling effects challenge detection of improvement of treatment satisfaction in clinical practice in this patient population.

Comprehensive characteristics of the anticoagulant activity of dabigatran in relation to its plasma concentration

BACKGROUNDnIssues with laboratory measurement of dabigatran include: 1. Do coagulation assays reflect dabigatran plasma concentrations? 2. Do samples from patients treated with dabigatran have the same coagulability as dabigatran-spiked samples from healthy volunteers? 3. What is the long-term stability of dabigatran after storage at -80u202f°C? This study aims to evaluate these questions.nnnMATERIALS AND METHODSnEcarin chromogenic assay (ECA), a laboratory-developed diluted thrombin time (LD-dTT), prothrombin time (PT) and activated partial thromboplastin time (APTT) and ROTEM® were used to measure dabigatran anticoagulant activity and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure dabigatran plasma concentrations. ROTEM® (EXTEM, INTEM, FIBTEM) was performed in whole blood and the other assays in platelet poor plasma (PPP), both in samples spiked with dabigatran (0, 25, 50, 100, 250, 500 and 1000u202fng/mL) from healthy donors and in ex vivo samples from patients treated with dabigatran etexilate. Citrated PPP samples were frozen and stored at -80u202f°C, 1, 3, 6 and 12u202fmonths until analysis.nnnRESULTSnEXTEM and FIBTEM clotting time (CT), ECA and LD-dTT correlate well with dabigatran plasma concentrations. With the exception of few ROTEM® parameters, there were no differences between spiked and patient samples. Samples were stable for at least 12u202fmonths at -80u202f°C.nnnCONCLUSIONSnEXTEM and FIBTEM CT, ECA and LD-dTT are suitable for measuring the effect of dabigatran in treated patients. In general, results from spiked plasma samples are similar to those of patient samples. Storage of dabigatran plasma samples for up to 12u202fmonths does not influence measured levels.

Analytical and between-subject variation of thrombin generation measured by calibrated automated thrombography on plasma samples

Abstract Background: The Calibrated Automated Thrombography (CAT) is an in vitro thrombin generation (TG) assay that holds promise as a valuable tool within clinical diagnostics. However, the technique has a considerable analytical variation, and we therefore, investigated the analytical and between-subject variation of CAT systematically. Moreover, we assess the application of an internal standard for normalization to diminish variation. Methods: 20 healthy volunteers donated one blood sample which was subsequently centrifuged, aliquoted and stored at −80u2009°C prior to analysis. The analytical variation was determined on eight runs, where plasma from the same seven volunteers was processed in triplicates, and for the between-subject variation, TG analysis was performed on plasma from all 20 volunteers. The trigger reagents used for the TG assays included both PPP reagent containing 5u2009pM tissue factor (TF) and PPPlow with 1u2009pM TF. Plasma, drawn from a single donor, was applied to all plates as an internal standard for each TG analysis, which subsequently was used for normalization. Results: The total analytical variation for TG analysis performed with PPPlow reagent is 3–14% and 9–13% for PPP reagent. This variation can be minimally reduced by using an internal standard but mainly for ETP (endogenous thrombin potential). The between-subject variation is higher when using PPPlow than PPP and this variation is considerable higher than the analytical variation. Conclusion: TG has a rather high inherent analytical variation but considerable lower than the between-subject variation when using PPPlow as reagent.

The role of M-components and immunoglobulins in patients with multiple myeloma: procoagulant and prognostic?

Reference EPFL-CONF-212539doi:10.1111/jth.12993View record in Web of Science Record created on 2015-09-28, modified on 2017-05-12