HLA-DRB1 and atrial fibrillation: Results of interaction analysis between HLA DRB1*15:01 and smoking revealed that approximately half of the AF due to smoking is independent of HLA DRB1*15:01 status (6.8%, 95%CI: 5.5 to 7.9) while the AF due to HLA independent of smoking was 23% (95%CI: 22.1 to 23.8).