Gastrointestinal bleeding risk of non-vitamin K antagonist oral anticoagulants versus warfarin in general and after polypectomy: a population-based study with propensity score matching analysis

Background/Aims: Gastrointestinal bleeding (GIB) risk for non-vitamin K antagonist oral anticoagulants (NOACs) compared with warfarin is largely unknown. We aimed to determine the risk of overall and post-polypectomy GIB for NOACs and warfarin. Methods: Using the Korean National Health Insurance database, we created a cohort of patients who were newly prescribed NOACs or warfarin between July 2015 and December 2017 using propensity score matching (PSM). Kaplan-Meier analysis with log-rank test was performed to compare the risk of overall and post-polypectomy GIB between NOACs (apixaban, dabigatran, and rivaroxaban) and warfarin. Post-polypectomy GIB was defined as bleeding within 1 month after gastrointestinal endoscopic polypectomy. Results: Out of 234,206 patients taking anticoagulants (187,687 NOACs and 46,519 warfarin), we selected 39,764 pairs of NOACs and warfarin users after PSM. NOACs patients showed significantly lower risk of overall GIB than warfarin patients (log-rank P < 0.001, hazard ratio, 0.86; 95% confidence interval, 0.78-0.94; P=0.001). Among NOACs, apixaban showed the lowest risk of GIB. In the subgroup of 7,525 patients who underwent gastrointestinal polypectomy (lower gastrointestinal polypectomy 93.1%), 1,546 pairs were chosen for each group after PSM. The NOACs group showed a high risk of post-polypectomy GIB compared with the warfarin group (log-rank P= 0.001, hazard ratio, 1.97; 95% confidence interval, 1.16-3.33; P=0.012). Conclusions: This nationwide, population-based study demonstrates that risk of overall GIB is lower for NOACs than for warfarin, while risk of post-polypectomy GIB is higher for NOACs than for warfarin.