Real-World Impact of Setting a Narrow International Normalized Ratio Target Range in the Management of Older Adult Patients on Warfarin

Abstract

Introduction: Elderly patients intrinsically have higher bleeding risks, deterring clinicians from prescribing them oral anticoagulants. Setting a narrow international normalized ratio (INR) target range might potentially mitigate some of these risks. This study sought to compare the outcomes of elderly patients who were assigned to either a narrow INR target range or the conventional INR target range in a real-world environment. Methods: This was a retrospective cohort study with the primary and secondary outcomes being the mean percentage time above INR 3.0 and the mean percentage time below INR 2.0 and the incidents of bleeding and thromboembolism associated with oral anticoagulant therapy, respectively. Patients and health care workers managing them had no prior knowledge of this study. Results: Data of 150 patients with a narrow INR target range (2.0-2.5) and 164 patients with a conventional INR target range (2.0-3.0) were collected and analyzed. The narrow INR group had significantly higher underlying risks of bleeding than the conventional INR group. Patients in the narrow INR group had a significantly lower percentage time above INR 3.0 but no significant difference in the percentage time below INR 2.0. Adjusted incidence rate ratio (IRR) for bleeding events was significantly lower for the narrow INR group, while the adjusted IRR for thromboembolic events between both groups was similar. Conclusion: Patients assigned to a narrow INR target range in real-world practice spent a significantly lower amount of time below an INR of 3.0 compared to conventional INR target range with lower incidents of bleeding complications and no increase in subtherapeutic INRs.