A Novel Body Mass Index-Based Thromboembolic Risk Score for Overweight Patients with Nonvalvular Atrial Fibrillation

Background: A novel risk prediction model appears to be urgently required to improve the assessment of thrombotic risk in overweight patients with nonvalvular atrial fibrillation (NVAF). We developed a novel body mass index (BMI)-based thromboembolic risk score (namely AB(2)S score) for these patients. Methods: A total of 952 overweight patients with NVAF were retrospectively enrolled in this study with a 12 -month follow-up. The primary endpoint was 1 -year systemic thromboembolism and the time to thrombosis (TTT). The candidate risk variables identified by logistic regression analysis were included in the final nomogram model to construct AB(2)S score. The measures of model fit were evaluated using area under the curve (AUC), C -statistic, and calibration curve. The performance comparison of the AB2S score to the CHADS2 and CHA(2)DS(2)-VASc score was performed in terms of the AUC and decision analysis curve (DAC). Results: The AB(2)S score was constructed using 7 candidate risk variables, including a 3 -category BMI (25 to 30, 30 to 34, or >= 35 kg/m(2)). It yielded a c -index of 0.885 (95% CI, 0.814-0.954) and an AUC of 0.885 (95% CI, 0.815-0.955) for predicting 1 -year systemic thromboembolism in patients with NVAF. Compared to the CHADS(2) score and CHA(2)DS(2)-VASc score, the AB(2)S score had greater AUC and DAC values in predicting the thromboembolic risk and better risk stratification in TTT (P < .0001, P = .082, respectively). Conclusion: Our results highlighted the importance of a BMI-based AB(2)S score in determining systemic thromboembolism risk in overweight patients with NVAF, which may aid in decision -making for these patients to balance the effectiveness of anticoagulation from the underlying thrombotic risk.