Table 1.

Population description

		Training (n = 29 884)	Validation (n = 6036)	Internal test (n = 9993)	External test (n = 5808)
	Atrial fibrillation, n (%)	3307 (11.1%)	228 (3.8%)	361.0 (3.6%)	218.0 (3.8%)
Age, n (%)	<65 years	14 758 (49.4%)	3334 (55.2%)	5518 (55.2%)	2951 (50.8%)
	≥65 years	11 483 (38.4%)	2702 (44.8%)	4475 (44.8%)	2857 (49.2%)
	Missing	3643 (12.2%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Sex, n (%)	Male	10 196 (34.1%)	2265 (37.5%)	3841 (38.4%)	2179 (37.5%)
	Female	16 428 (55.0%)	3771 (62.5%)	6152 (61.6%)	3629 (62.5%)
	Missing	3260 (10.9%)	0 (0.0%)	0 (0.0%)	0 (0.0%)