Predicting the Absolute Risk of Ischemic Stroke in Asian Patients with Atrial Fibrillation: Comparing the COOL-AF Risk Score with CARS/mCARS Models for Absolute Risk and the CHA2DS2-VASc Score

Background: The aims of this study were (1) to validate the CARS and mCARS methods in an Asian population with atrial fibrillation (AF) and (2) to compare the CARS and mCARS models for absolute risk using the COOL-AF method and CHA(2)DS(2)VASc scores for the prediction of ischemic stroke or systemic embolism (SSE). Methods: We analyzed the results from a prospective nationwide multicenter AF registry. Follow-up data were collected for 3 years. The main outcomes were SSE. Predictive models of the 3-year SSE of the COOL-AF model, the CHA(2)DS(2)VASc score, the CARS for the no-OAC group, and the mCARS for the OAC group were developed and evaluated by C-statistics, and calibration plots were created for the whole group, as well as for oral anticoagulant (OAC) users and no-OAC patients. Results: We studied 3405 patients (mean age: 67.8 years; 58.2% male, 75.4% OAC). The incidence rates of SSE were 1.51 (1.26–1.78), 1.93 (1.39–2.60), and 1.37 (1.10–1.68) for all patients, no-OAC patients, and OAC patients, respectively. For the whole population, the COOL-AF score had a C-statistic of 0.697 (0.682–0.713), which was superior to the CHA(2)DS(2)-VASc [0.655 (0.639–0.671)]. For the no-OAC group, the CARS predicted SSE with a C-statistic of 0.685 (0.652–0.716), which was similar to the CHA(2)DS(2)-VASc [0.684 (0.651–0.7150] and COOL-AF models [0.692 (0.659–0.723)]. For the OAC group, the mCARS had a C-statistic of 0.687 (0.669–0.705) that was similar to the COOL-AF [0.704 (0.686–0.721)] and better than the CHA(2)DS(2)-VASc score [0.655 (0.637–0.674)]. Conclusions: The calculation of the individual absolute risks using the CARS and mCARS models can predict SSE in an Asian population. Small differences were evident between the COOL-AF and CHA(2)DS(2)-VASc scores.