Anticoagulation Control, Outcomes, and Associated Factors in Patients with Atrial Fibrillation Receiving Warfarin at Tertiary Care Hospital in Ethiopia

Abstract

Anticoagulation is the cornerstone in the prevention of stroke in atrial fibrillation. This study aimed at assessing the anticoagulation control and outcome and predictive factors in atrial fibrillation patients on warfarin therapy. A retrospective chart review was used to evaluate patients with atrial fibrillation who were on warfarin during two years follow up at the anticoagulation clinic of the hospital. The time in therapeutic range (TTR) was calculated using Rosendaal's method. Data were analyzed using SPSS software version 25. Univariable and multivariable analyses were computed to determine factors affecting TTR and bleeding events. We included 300 patients in this study. The mean percentage TTR was 42.03 ± 18.75. Only 38 (12.67%) patients achieved a TTR of above 65%. The average international normalized ratio (INR) testing frequency was 35 days (16.3-67.2 days). Taking 1 or 2 drugs along with warfarin was found to be better in achieving good TTR as compared to taking more than two drugs ( p = .014). Having heart failure was associated with a 2.45 times odds of poor anticoagulation control (TTR< 65%) ( p = .047). Male study participants were 2.53 times more likely of developing bleeding events than females ( p = .009). Bleeding events were observed in 62 (20.67%) patients. Study participants, who didn't have Diabetic Mellitus and those not receiving aspirin were at lower odds developing bleeding events (AOR = .196; C.I. = .060-.638; p−.007 and AOR = .099; CI. = .024-.416; p−.02), respectively. In summary, the time spent in the therapeutic range was minimal in this population of patients with AF on warfarin managed at a hospital run anticoagulation clinic in Ethiopia. Moreover, the number of co-prescribed medications, and having heart failure were associated with poor TTR. Bleeding events were high and affected by male sex, having DM comorbidity, and using aspirin.