Comparison of medication adherence to different oral anticoagulants : population-based cohort study

Publisher Copyright: © Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.OBJECTIVE: Previous observational studies have yielded conflicting results on whether medication adherence differs between patients receiving warfarin and direct oral anticoagulants (DOACs). Importantly, no study has adequately accounted for warfarin dosing being continuously modified based on INR values while dosing of DOACs is fixed. We aimed to compare non-adherence between new users of apixaban, dabigatran, rivaroxaban and warfarin in a population-based cohort. METHODS: New users of apixaban, dabigatran, rivaroxaban and warfarin from 2014 to 2019 living in the Icelandic capital area were included. Non-adherence was defined as proportion of days covered below 80%. Inverse probability weighting was used to yield balanced study groups and non-adherence was compared using logistic regression. Factors associated with non-adherence were estimated using multivariable logistic regression. RESULTS: Overall, 1266 patients received apixaban, 247 dabigatran, 1566 rivaroxaban and 768 warfarin. The proportion of patients with non-adherence ranged from 10.5% to 16.7%. Dabigatran was associated with significantly higher odds of non-adherence compared with apixaban (OR 1.57, 95% CI 1.21 to 2.04, p<0.001), rivaroxaban (OR 1.45, 95% CI 1.12 to 1.89, p=0.005) and warfarin (OR 1.63, 95% CI 1.23 to 2.15, p<0.001). The odds of non-adherence were similar for apixaban, rivaroxaban and warfarin. Apart from the type of oral anticoagulants (OACs) used, female sex, hypertension, history of cerebrovascular accident and concomitant statin use were all independently associated with lower odds of non-adherence. CONCLUSION: Dabigatran was associated with higher odds of non-adherence compared with other OACs. Non-adherence was similar between apixaban, rivaroxaban and warfarin users. Female sex and higher comorbidity were associated with better medication adherence.Peer reviewe

Causes of gastrointestinal bleeding in oral anticoagulant users compared to non-users in a population-based study.

To access publisher's full text version of this article click on the hyperlink belowBackground/aims: Causes of gastrointestinal bleeding (GIB) in patients on oral anticoagulants (OACs) are not well established. The aims of the study were to compare the causes of GIB in patients on OACs and those not on OAC therapy. Methods: A nationwide study of all GIB events in patients on OACs in Iceland from 2014-2019 was conducted. Bleeding events were obtained through ICD-10 codes and review of endoscopy databases, confirmed by review of medical records. For comparison, patients not on OACs from previous Icelandic population-based studies were used. Results: Among 752 GIB events in 12,005 patients on OACs, 273 (1.9%) had verified upper and 391 (2.7%) had verified lower GIB. For lower GIB, multivariate analysis showed that OAC users were more likely to have colonic polyps (OR 6.6, 95% CI: 2.4 - 17.8, p < .001) or colorectal cancer (OR 3.7, 95% CI: 2.0 - 7.0, p < .001) but less likely to have ischemic colitis (OR 0.11, 95% CI: 0.04 - 0.26, p < .001). For upper GIB, bleeding from mucosal erosions (OR 4.0 95% CI: 2.5 - 7.9, p < .001) and angiodysplasia (OR 3.6, 95%CI: 1.5 - 8.6, p = .003) were more common in OAC users. Conclusions: A high proportion of GIB caused by colonic polyps and colorectal cancer among OAC patients indicates that OACs treatment may facilitate cancer diagnosis. The low proportion of ischemic colitis among those on OACs suggests that OACs provide a protective effect against ischemic colitis. OACs seem to increase the bleeding from angiodysplasia and mucosal erosive disease. Keywords: Gastrointestinal bleeding; anticoagulation; colon cancer; ischemic colitis.Eimskipasjodur University of Iceland Scientific grant of Landspital

Rivaroxaban Is Associated With Higher Rates of Gastrointestinal Bleeding Than Other Direct Oral Anticoagulants : A Nationwide Propensity Score-Weighted Study.

To access publisher's full text version of this article click on the hyperlink belowBackground: Gastrointestinal bleeding (GIB) rates for direct oral anticoagulants (DOACs) and warfarin have been extensively compared. However, population-based studies comparing GIB rates among different DOACs are limited. Objective: To compare rates of GIB among apixaban, dabigatran, and rivaroxaban. Design: Nationwide population-based cohort study. Setting: Landspítali-The National University Hospital of Iceland and the 4 regional hospitals in Iceland. Patients: New users of apixaban, dabigatran, and rivaroxaban from 2014 to 2019. Measurements: Rates of GIB were compared using inverse probability weighting, Kaplan-Meier survival estimates, and Cox regression. Results: In total, 2157 patients receiving apixaban, 494 patients receiving dabigatran, and 3217 patients receiving rivaroxaban were compared. For all patients, rivaroxaban had higher overall rates of GIB (3.2 vs. 2.5 events per 100 person-years; hazard ratio [HR], 1.42 [95% CI, 1.04 to 1.93]) and major GIB (1.9 vs. 1.4 events per 100 person-years; HR, 1.50 [CI, 1.00 to 2.24]) compared with apixaban. Rivaroxaban also had higher GIB rates than dabigatran, with similar point estimates, although the CIs were wider and included the possibility of a null effect. When only patients with atrial fibrillation were included, rivaroxaban was associated with higher rates of overall GIB than apixaban (HR, 1.40 [CI, 1.01 to 1.94]) or dabigatran (HR, 2.04 [CI, 1.17 to 3.55]). Dabigatran was associated with lower rates of upper GIB than rivaroxaban in both analyses. Limitations: Unmeasured confounding and small subgroup analyses. Conclusion: Rivaroxaban was associated with higher GIB rates than apixaban and dabigatran regardless of treatment indication.Icelandic Centre for Research Landspitali University Hospital Research Fun