Real-world experience: Effect of Apixaban on INR, More confusion to providers with inadvertent lab

Background: Factor X inhibition can cause the prolongation of PT by acting on the common pathway factors. Although, Expensive and less available “calibrated anti-FXa” predicts DOAC plasma level had better than prothrombin time (PT) and the international normalized ratio (INR). Consecutive reports raise more attention to (PT/INR) abnormalities in clinical scenarios for the minority of patients on DOACs. This study focuses on studying the magnitude of the Apixaban effect on INR elevation, which may be of clinical significance. Methods: This was a single-center, retrospective, observational analysis of adult patients who received at least 30 days of Apixaban. This study's primary outcome is to test the association between Apixaban use and significant INR elevation Results: Five hundred Fifty-two patients have screened in the study .194 patients meet our study aim criteria, Apixaban use was associated with a significant rise in INR levels after Apixaban (1.54 ± 2.59) compared to the previous values (1.03 ± 0.62) P <0.001. The mean rise was 0.58 (95% CI: 0.34-0.82, p<0.001). Multiple linear regression showed insignificance of all other tested variables, like Age, Polypharmacy, Use of CYP inhibitors, baseline INR, or renal function. Conclusion: Apixaban use is associated with a significant increase in INR in non-hospitalized patients, although the clinical outcomes of this observation are still understudied. Although routine monitoring of INR for Apixaban is generally unadvised, it is pivotal for practitioners to understand the magnitude of this phenomenon, more research is warranted to describe the clinical importance and guidance for those coagulation assays in daily practice.