Alexander KP, et al. - In this post-hoc subgroup analysis of the ARISTOTLE trial, researchers determined the prevalence of multi-morbidity among 16,800 older (age ≥ 55 years) patients with atrial fibrillation (AF) as well as its relation to clinical outcomes, and the efficacy and safety of apixaban vs warfarin. The number of comorbid conditions at baseline was used as the basis to categorize patients who were then followed-up for a median duration of 1.8 (1.3–2.3) years. Multi-morbidity was found to be prevalent in 64% (n = 10,713); 51% (n = 8491) had moderate multi-morbidity, 13% (n = 2222) had high multi-morbidity, and 36% (n = 6087) had no multi-morbidity. The features seen in the high multi-morbidity group vs no multi-morbidity group included being older, took twice as many medications, and had higher CHA₂DS₂-VASc scores. In association with multi-morbidity, increased adjusted rates per 100 patient-years were reported for stroke/systemic embolism, death, and major bleeding, with no interaction seen in relation to efficacy or safety of apixaban. This subgroup showed preserved efficacy and safety of apixaban.