Comparative Effectiveness of Direct Oral Anticoagulants versus Warfarin Among Nursing Home Residents with Atrial Fibrillation

Background: Residents of nursing homes are rarely included in clinical trials, including for conditions highly prevalent in this population as is non valvular atrial fibrillation (NVAF).

Objectives: We conducted a real-world comparative effectiveness study to assess the safety and effectiveness of DOAC vs. warfarin among nursing home residents with NVAF.

Methods: This retrospective cohort study used Minimum Data Set linked to Medicare claims from 2011 to 2018 and included residents of nursing homes with diagnoses of NVAF who newly initiated DOAC or warfarin. We evaluated three outcomes: time to stroke or systemic embolism, time to major bleeding, and time to all-cause death. In addition, we used time to pneumonia as a negative control outcome to evaluate the role of unmeasured confounding. We used sociodemographic factors, CHA₂DS₂-VASc score, HAS-BLED score, comorbidities, co-medications, cognitive status, activities of daily living and other psychosocial measures to calculate inverse probability of treatment weights (IPTW). We used IPTW weighted competing risk regression for stroke/systemic embolism, major bleeding, and pneumonia. We used IPTW weighted Cox proportional hazard regression for all-cause death.

Results: Among 38,983 residents included in the study, 19,366 (49.7%) initiated DOACs and 19,617 (50.3%) warfarin. In the IPTW analysis, compared to warfarin, DOAC use was associated with less stroke/systemic embolism (4.50 vs. 4.71 events per 100 person-years; adjusted hazard ratio [aHR] 0.89, 95% confidence intervals [CI] 0.81-0.99). We found no significant difference between DOAC and warfarin for major bleeding (12.6 vs. 12.4 events per 100 person-years; aHR 0.98, CI 0.92-1.04) and all-cause death (48.1 vs. 49.0 events per 100 person-years; IPTW analysis aHR 0.98, CI 0.95-1.01). There was no significant difference between DOAC and warfarin for the risk of pneumonia (aHR 0.96, CI 0.91-1.01), indicating little or no unmeasured confounding.

Conclusions: Among nursing home residents with NVAF, the use of DOAC was associated with a reduced risk of ischemic stroke or systemic embolism without an increased risk of major bleeding or all-cause death. DOACs may be superior alternatives to warfarin among nursing home residents with NVAF.