Mechanisms of action and clinical use of specific reversal agents for non-vitamin K antagonist oral anticoagulants

A Combination of Ex Vivo and In Vivo Strategies for Evaluating How Much New Oral Anticoagulants Exacerbate Experimental Intracerebral Bleeding

Background  Intracerebral hemorrhage is the most serious complication of anticoagulant therapy but the effects of different types of oral anticoagulants on the expansion of these hemorrhages are still unclear. Clinical studies have revealed controversial results; more robust and long-term clinical evaluations are necessary to define their outcomes. An alternative is to test the effect of these drugs in experimental models of intracerebral bleeding induced in animals. Aims  To test new oral anticoagulants (dabigatran etexilate, rivaroxaban, and apixaban) in an experimental model of intracerebral hemorrhage induced by collagenase injection into the brain striatum of rats. Warfarin was used for comparison. Methods  Ex vivo anticoagulant assays and an experimental model of venous thrombosis were employed to determine the doses and periods of time required for the anticoagulants to achieve their maximum effects. Subsequently, volumes of brain hematoma were evaluated after administration of the anticoagulants, using these same parameters. Volumes of brain hematoma were evaluated by magnetic resonance imaging, H&E (hematoxylin and eosin) staining, and Evans blue extravasation. Neuromotor function was assessed by the elevated body swing test. Results and Conclusions  The new oral anticoagulants did not increase intracranial bleeding compared with control animals, while warfarin markedly favored expansion of the hematomas, as revealed by magnetic resonance imaging and H&E staining. Dabigatran etexilate caused a modest but statistically significant increase in Evans blue extravasation. We did not observe significant differences in elevated body swing tests among the experimental groups. The new oral anticoagulants may provide a better control over a brain hemorrhage than warfarin.

SMASH-U classification: a tool for aetiology-oriented management of patients with acute haemorrhagic stroke

Intracerebral haemorrhage (ICH) is responsible for disproportionately high morbidity and mortality rates. The most used ICH classification system is based on the anatomical site. We used SMASH-U, an aetiological based classification system for ICH by predefined criteria: structural vascular lesions (S), medication (M), amyloid angiopathy (A), systemic disease (S), hypertension (H), or undetermined (U). We aimed to correlate SMASH-U classification of our patients to the intra-hospital mortality rates. We performed a single centre retrospective study at the Santa Maria Della Misericordia Hospital, Perugia (Italy) including consecutive patients between January 2009 and July 2017 assigned with 431 ICD-9 (International Classification of Diseases-9). We classified the included patients using SMASH-U criteria, and we analysed the association between SMASH-U aetiology and ICH risk factors to the outcome defined as intra-hospital mortality, using multivariable logistic regression analysis. The higher intra-hospital mortality rate was detected in the systemic disease (36.1%), medication (31.5%), and undetermined (29.4%) groups. At multivariable analysis, medication and systemic disease groups resulted associated with the outcome (odds ratio 3.47; 95% CI 1.15-10.46; P = 0.02 and 3.64; 95% CI 1.47-9.01; P = 0.005, respectively). Furthermore, age and high NIHSS at admission resulted significantly associated with intra-hospital mortality (odds ratio 1.01; 95% CI 1-1.03; P = 0.04 and 1.12; 95% CI 1.03-1.22; P = 0.008, respectively). In our retrospective study, the aetiology-oriented classification system SMASH-U showed to be potentially predictive of intra-hospital mortality of acute haemorrhagic stroke patients and it may support clinicians in the acute ICH management.

Cost-effectiveness analysis of apixaban compared to other direct oral anticoagulants for prevention of stroke in Austrian atrial fibrillation patients

OBJECTIVES

Several direct oral anticoagulants (DOACs) have been approved by the European Medicines Agency since 2008. The aim of the present cost-effectiveness-analysis was to analyze apixaban compared to other DOACs and vitamin K antagonists (warfarin) in Austria.

METHODS

A cost-utility-model was developed to simulate lifetime-costs and quality-adjusted-life-years of DOACs and warfarin, based on a published Markov-Model and 23 randomized trials with 94,656 atrial-fibrillation (AF) patients. Each year, a patient has a probability of suffering a clinically relevant (extracranial) bleed, an intracranial hemorrhage (ICH), an ischemic stroke or a myocardial infarction (MI), remaining healthy, or deceasing. Direct-costs (2018€) were derived from published sources from the payer's perspective.

RESULTS

In the base-case, warfarin had the lowest cost of 12,968 € (95%-CI±593 €) followed by apixaban (15,269 €±661 €), edoxaban (15,534 €±641 €), dabigatran (15,687 €±667 €), and rivaroxaban (17,522 €±764 €). Apixaban had the highest quality-adjusted-life-years estimate at 5.45 (SD, 0.06). In a Monte-Carlo probabilistic sensitivity analysis, apixaban was cost-effective vs. edoxaban, dabigatran, warfarin, and rivaroxaban in 85.6%, 79.0%, 76.4%, and 61.2% of the simulations, respectively.

CONCLUSION

In patients with AF and an increased risk of stroke, prophylaxis with apixaban was highly cost-effective from the perspective of the Austrian health-care system.