Table 1. Baseline characteristics of the study subjects.

Variables	n	EC	Follow-up person-year	ID	p-value
				(‰/yr)
Total	718,409	682	6,052,634	0.11
Gender					<0.001
Female	350,943	53	2,939,167	0.02
Male	367,466	629	3,113,467	0.20
Age at baseline (yr)					<0.001
20–44	435,539	166	3,620,914	0.05
45–64	185,837	338	1,515,365	0.22
≥65	97,033	178	916,355	0.19
Periodontal disease					<0.001
No PD	208,578	358	2,272,009	0.16
Dental prophylaxis	343,332	156	2,813,676	0.06
Intensive treatment	121,324	134	795,327	0.17
PD without treatment	45,175	34	171,622	0.20
Co-morbidity
Esophageal ulcer	4,563	36	37,190	0.97	<0.001
Alcohol abuse	805	5	6,472	0.77	0.001
Esophageal reflux	4,812	10	37,951	0.26	0.029
Diabetes mellitus	82,916	94	683,140	0.14	0.067
Hypertension	176,236	206	1,452,366	0.14	<0.001
Hyperlipidemia	115,745	93	922,864	0.10	0.079