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Nagler M.,Maastricht University | Nagler M.,Central Haematology Laboratory | Nagler M.,University of Bern | Bachmann L.M.,Medignition Inc. | And 2 more authors.
Blood | Year: 2016

Immunoassays are essential in the workup of patients with suspected heparin-induced thrombocytopenia. However, the diagnostic accuracy is uncertain with regard to different classes of assays, antibody specificities, thresholds, test variations, and manufacturers. We aimed to assess diagnostic accuracy measures of available immunoassays and to explore sources of heterogeneity. We performed comprehensive literature searches and applied strict inclusion criteria. Finally, 49 publications comprising 128 test evaluations in 15 199 patients were included in the analysis. Methodological quality according to the revised tool for quality assessment of diagnostic accuracy studies was moderate. Diagnostic accuracy measures were calculated with the unified model (comprising a bivariate random-effects model and a hierarchical summary receiver operating characteristics model). Important differences were observed between classes of immunoassays, type of antibody specificity, thresholds, application of confirmation step, and manufacturers. Combination of high sensitivity (>95%) and high specificity (>90%) was found in 5 tests only: polyspecific enzyme-linked immunosorbent assay (ELISA) with intermediate threshold (Genetic Testing Institute, Asserachrom), particle gel immunoassay, lateral flow immunoassay, polyspecific chemiluminescent immunoassay (CLIA) with a high threshold,andimmunoglobulinG(IgG)-specific CLIA with low threshold. Borderline results (sensitivity, 99.6%; specificity, 89.9%) were observed for IgG-specific Genetic Testing Institute-ELISA with low threshold. Diagnostic accuracy appears to be inadequate in tests with high thresholds (ELISA; IgG-specific CLIA), combination of IgG specificity and intermediate thresholds (ELISA, CLIA), high-dose heparin confirmation step (ELISA), and particle immunofiltration assay. When making treatment decisions, clinicians should be a aware of diagnostic characteristics of the tests used and it is recommended they estimate posttest probabilities according to likelihood ratios as well as pretest probabilities using clinical scoring tools. © 2016 by The American Society of Hematology.


Nagler M.,Central Haematology Laboratory | Nagler M.,Central University of Costa Rica | Bachmann L.M.,Medignition Inc. | Schmid P.,Central Haematology Laboratory | And 3 more authors.
PLoS ONE | Year: 2014

Patient self-management (PSM) of oral anticoagulation is under discussion, because evidence from real-life settings is missing. Using data from a nationwide, prospective cohort study in Switzerland, we assessed overall long-term efficacy and safety of PSM and examined subgroups. Data of 1140 patients (5818.9 patient-years) were analysed and no patient were lost to follow-up. Median follow-up was 4.3 years (range 0.2-12.8 years). Median age at the time of training was 54.2 years (range 18.2-85.2) and 34.6% were women. All-cause mortality was 1.4 per 100 patient-years (95% CI 1.1-1.7) with a higher rate in patients with atrial fibrillation (2.5; 1.6-3.7; p<0.001), patients>50 years of age (2.0; 1.6-2.6; p<0.001), and men (1.6; 1.2-2.1; p = 0.036). The rate of thromboembolic events was 0.4 (0.2-0.6) and independent from indications, sex and age. Major bleeding were observed in 1.1 (0.9-1.5) per 100 patient-years. Efficacy was comparable to standard care and new oral anticoagulants in a network meta-analysis. PSM of properly trained patients is effective and safe in a long-term real-life setting and robust across clinical subgroups. Adoption in various clinical settings, including those with limited access to medical care or rural areas is warranted. © 2014 Nagler et al.


Nagler M.,Central Haematology Laboratory | Nagler M.,University of Bern | Kathriner S.,Central Haematology Laboratory | Bachmann L.M.,Medignition Inc. | And 2 more authors.
Thrombosis Research | Year: 2013

Introduction To what extent haematocrit levels (Hct) and platelet counts (PLT) influence the measurement of parameters of thromboelastometry when assessed with the ROTEM® device is unclear. We investigated to what extent thromboelastometry measurements depend on Hct and PLT. Materials and Methods Whole blood samples were taken for in-vitro preparations of mixtures with three different levels of PLT and a varying Hct. Maximum clot firmness (MCF), clotting time (CT), clot formation time (CFT) and alpha angle (α) for INTEM, EXTEM, FIBTEM and APTEM was recorded. Results Measurements depended substantially on Hct and PLT. MCF readings were systematically lower with increasing Hct (0.2 vs. 0.4: - 7.8 (- 8.3 to - 7.2); p < 0.001, 0.2 vs. 0.55: - 14.5 (- 17.3 to - 14.3); p < 0.001) but higher with increasing PLT (50 vs. 125 × 109/l: 8.2 (4.2 to 12.3); p = 0.005, 50 vs. 250 × 109/l: 12.0 (7.2 to 16.8); p = 0.002). CT readings were systematically higher with increasing Hct (0.2 vs. 0.4: 9.2 (6.2 to 12.1); p = 0.001, 0.2 vs. 0.55: 38.2 (21.5 to 54.9); p = 0.003) while increasing PLT had no influence. CFT readings were also systematically higher with increasing Hct (0.2 vs. 0.4: 83.8 (40.2 to 127.6); p = 0.006, 0.2 vs. 0.55: 226.2 (110.7 to 341.7); p = 0.006) but systematically lower with increasing PLT (50 vs. 125 × 109/l: - 144.0 (- 272.3 to - 15.6); p = 0.036, 50 vs. 250 × 109/l: - 189.2 (- 330.4 to - 48.0); p = 0.02); readings of the alpha angle showed a similar pattern. Conclusions Our results suggest that readings of thromboelastometry parameters need to be adjusted by Hct and PLT to avoid potential confounding and miss-interpretations in clinical practice. © 2013 Elsevier Ltd.

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