The impact of frailty on coagulation and responses to warfarin in acute older hospitalised patients with atrial fibrillation: a pilot study.

BACKGROUND: The evidence on coagulation changes with frailty is not consistent and clinical studies suggest that frail older people may be at an increased risk of bleeding complications with anticoagulant therapy. AIMS: This study aims to assess the impact of frailty on coagulation function and on response to warfarin. METHODS: Inpatients aged over 65 years with atrial fibrillation (AF) were recruited. Frailty was determined using the Reported Edmonton Frail Scale. The Overall Haemostatic Potential (OHP) and Calibrated Automated Thrombogram (CAT) were used to globally assess coagulation function. RESULTS: Data of 95 participants were analysed, mean age 85.5 ± 6.2, 40% female, and 50.5% frail. Among participants not on anticoagulants (N = 36), there was an increased fibrin generation and decreased thrombin generation compared to the local established normal ranges in young healthy volunteers; the frail had significantly reduced fibrin generation compared to the non-frail. In the warfarin-treated group (N = 59), there was no difference on coagulation profiles between the frail and the non-frail from any of the coagulation tests. CONCLUSION: In this cohort of acute hospitalised patients with AF, the observed decreased fibrin generation in the frail may reflect decreased acute phase response as suggested with the lower plasma fibrinogen in that group. There was no difference in coagulation profiles between the frail and the non-frail amongst those taking warfarin. Compared to young healthy volunteers, older inpatients had increased fibrin generation and decreased thrombin generation. The findings reflect the complex interaction between age, frailty, acute illness, and coagulation.

Inherited macrothrombocytopenias.

Inherited macrothrombocytopenias are a clinically heterogeneous group of disorders, many of which cause moderate-to-severe bleeding tendencies in affected individuals, but which remain under-recognized and are frequently misdiagnosed as immune thrombocytopenia purpura. Diagnostic strategies to date have included a predominant phenotypic approach. The emergence of genetic testing and the implementation of next generation sequencing strategies in the investigation and diagnosis of these disorders have broadened our understanding of their pathogenesis, classification, and presentation. This review describes the increasingly expanding group of recognized inherited macrothrombocytopenias and highlights their pathophysiology and the role of phenotypic and genetic testing in their description and diagnosis.

Evaluating heparin-induced thrombocytopenia: the old and the new.

Heparin-induced thrombocytopenia (HIT) is a rare but potentially serious complication of heparin use. Prompt diagnosis is crucial and requires the integration of clinical assessment and laboratory testing. Pretest clinical scoring systems (i.e., 4 Ts) have been established. Immunoassays can detect the presence of antibodies directed toward heparin-platelet factor 4 (H-PF4) complexes, but provide no information about their ability to activate platelets. A low clinical score, when combined with a negative immunoassay result obviates the need for further testing. However, immunoassays and 4 Ts scores have only modest specificity. Functional testing (serotonin release assay or heparin-induced platelet activation) remain important in confirming the presence of pathogenic H-PF4 antibodies, but are technically demanding to perform and limited in guiding clinical decisions in the acute setting. This review evaluates current immuno- and functional assays available in the laboratory diagnosis of HIT, and describes recent attempts to improve the specificity of enzyme immunoassays, including adopting an immunoglobulin G-specific assay and raising the optical density value cutoff for a positive result. The importance of donor selection and newer functional assays, including flow cytometry-based assays, are also discussed. A current approach to integrating clinical scoring, immunoassays, and functional testing for HIT is also outlined.