An update on hip fracture risk associated with anticoagulant therapy: warfarin versus direct oral anticoagulants

Semi-empirical Anticoagulation Model (SAM): Dose prediction during warfarin therapy

Management of oral anticoagulant therapy is essential to ensure a good quality of life for patients. To assist clinicians, several computerized dosing algorithms were developed to determine optimal anticoagulant doses. However, these algorithms have several limitations that can lead to inaccuracies in dosing recommendations. To overcome some of these challenges, this paper proposes a warfarin dose prediction algorithm using individual patient sensitivity analysis. The proposed algorithm is designed to account for factors that influence an individual's response to warfarin, allowing it to more accurately adjust and optimize dosing. It is based on the Semi-empirical Anticoagulation Model (SAM), but has been extended to incorporate stochastic process analysis. This allows the algorithm to assess the probability of events that could change the relationship between the International Normalized Ratio (INR) and the therapy administered. To evaluate the effectiveness of the algorithm, a retrospective observational study of 1796 patients was conducted over one year. The study compared the doses of warfarin administered in clinical practice with those suggested by the algorithm. Percentage Bland-Altman Analysis was used to assess accuracy, which showed that the algorithm had an average accuracy of (3.24±25.80)%. When compared to other algorithms in the literature, which showed an accuracy of (5.73±60.9)%, the proposed algorithm showed significantly better accuracy. The improved accuracy of the proposed algorithm allows for more flexible and precise adjustments to therapy, resulting in an INR closer to the target range with less variability. This ultimately improves patient safety and the overall quality of life for those suffering from venous thromboembolism.

Comparative Risks of Fracture Among Direct Oral Anticoagulants and Warfarin: A Systematic Review and Network Meta-Analysis

Importance

Previous studies have shown the effectiveness and safety of direct oral anticoagulants (DOACs), including lower fracture risks, compared to warfarin. However, direct or indirect comparisons between different DOACs are scarce in the literature.

Objective

This study aims to compare fracture risks among different DOACs and warfarin, including apixaban, rivaroxaban, dabigatran, and edoxaban, in patients with non-valvular atrial fibrillation (NVAF) or venous thromboembolism (VTE).

Methods

We searched PubMed/MEDLINE, Embase, Cochrane CENTRAL, and Web of Science for randomized controlled trials and cohort studies comparing the fracture risks among patients who used warfarin or DOACs, up to March 2021. Two authors extracted data and appraised the risk of bias of included studies. The primary outcome was fracture risk. We performed pairwise meta-analyses to compare differences between medications and network meta-analyses using frequentist random-effects models to compare through indirect evidence. We used surface under the cumulative ranking curve (SUCRA) and mean ranks to determine the probability of a DOAC ranking best in terms of fracture risk.

Results

Thirty-one studies were included in the final analysis. Twenty-four randomized controlled trials and seven cohort studies with 455,343 patients were included in the systematic review and network meta-analysis. Compared to warfarin, the risk of any fractures was lowest with apixaban [relative risk (RR) = 0.59; 95% confidence interval (CI): 0.48-0.73], followed by rivaroxaban (RR: 0.72; 95% CI: 0.60-0.86), edoxaban (RR: 0.88; 95% CI: 0.62-1.23), and dabigatran (RR = 0.90; 95% CI: 0.75-1.07). No substantial inconsistency between direct and indirect evidence was detected for all outcomes.

Conclusions

All DOACs were safer than warfarin concerning the risk of fracture; however, apixaban had the lowest relative risk of fracture within the class of DOACs. Further head-to-head prospective studies should confirm the comparative safety profiles of DOACs regarding fractures.