Battle of the Blood Thinners: Unveiling the Impact of Apixaban and Warfarin on GI Bleeding in Advanced Kidney Disease Patients When Used for Management of VTE
Authors: Ali Asgar Juzer , Benchakroun Amal , Hassani Samar , Sass Nicholas , Steadman Azin , Perez Anthony , Duchow Mariel , Asad Omar , Jones Can , Ostos Catherine , Alvarado Francisco , Chait Robert 
Published: December 2024

Background:
The advent of Direct Oral Anticoagulants (DOACs), particularly direct Xa inhibitors such as apixaban, has revolutionized the management of thromboembolic disorders. Their advantages include a simplified dosing regimen, elimination of the need for INR (International Normalized Ratio) monitoring, and oral administration. However, comprehensive analyses comparing the risk profiles of patients on DOACs versus Vitamin K Antagonists (VKAs) like Warfarin, using a large multinational database, are scarce. This study aims to fill this gap by evaluating patient encounters and admissions for Venous Thromboembolic Events (VTE) where the use of DOAC or VKA was indicated, considering various comorbidities, including different stages of chronic kidney disease (CKD).
Methods:
Utilizing a comprehensive, multi-institutional national database, we evaluated admission encounters. These encounters were identified using the International Classification of Diseases (ICD) codes for a range of endpoints, including gastrointestinal bleeding and both ischemic and hemorrhagic strokes. These evaluations were conducted specifically for patients who were administered either Apixaban or Warfarin. In addition to the primary endpoints, we also incorporated demographic information of the patients into our analysis. This included age, gender, race, Body Mass Index (BMI), and the presence of any comorbidities. This comprehensive approach allowed us to account for a wide range of variables that could potentially influence the outcomes of interest.
Results:
In the Bivariate Analysis, the chi-square procedure was used to test for an association between two categorical variables. With a sample size of 8504, there was not a significant overall association between the medication group and gastrointestinal bleeding at the 95% confidence limit. In the Multivariate Analysis used Logistic Regression to model the probability of gastrointestinal bleeding. The analysis found that the odds of having a GI Bleed varied significantly depending on the BMI Group and the presence of ESRD, when all other variables were held constant. For instance, patients with an underweight BMI were 2.33 times as likely to have a GI Bleed compared to patients with a healthy-weight BMI.
Discussion:
The study conducted a comprehensive analysis of the outcomes of gastrointestinal bleeding in patients with advanced chronic kidney disease (CKD) who were administered either Apixaban or Warfarin for therapeutic anticoagulation for Venous Thromboembolic Events (VTE). The analysis was conducted using a multi-institutional national database, incorporating a wide range of variables including age, gender, race, Body Mass Index (BMI), and the presence of any comorbidities. The results of the study indicated no significant overall association between the medication group and the occurrence of GI bleeding. However, certain factors were found to influence the likelihood of GI bleeding. For instance, patients with an underweight BMI were found to be 2.333 times as likely to experience GI bleeding compared to patients with a healthy-weight BMI. Similarly, patients with End-Stage Renal Disease (ESRD) were 1.519 times as likely to experience GI bleeding compared to patients without ESRD.
Conclusion:
These findings suggest that while the type of anticoagulant may not significantly influence the risk of GI bleeding, patient-specific factors such as BMI and the presence of ESRD can significantly impact the likelihood of this outcome. Therefore, these factors should be taken into consideration when prescribing anticoagulant therapy for patients with advanced CKD. Further research is needed to explore these associations and to develop strategies to mitigate the risk of GI bleeding in this patient population.