Table 1. Baseline^* (1987–89) characteristics of Atherosclerosis Risk in Communities participants enrolled in Medicare fee-for-service, overall and by source of incident atrial fibrillation diagnosis.

	Total	No Incident AF Diagnosis	ARIC Only AF Diagnosis	CMS Only AF Diagnosis	ARIC and CMS AF Diagnosis
	(n = 10,134)	(n = 9015)	(n = 93)	(n = 288)	(n = 738)	p-value
Age, years	66.4±1.5	66.4±1.5	66.7±1.9	66.5±1.6	66.6±1.6	0.01
Women, %	57.0	58.5	46.2	42.4	45.4	<0.0001
Black, %	26.0	27.2	32.3	13.2	15.3	<0.0001
High school graduate, %	76.8	77.4	62.4	76.4	71.5	<0.0001
Current smoker, %	23.2	22.6	30.1	22.2	29.3	0.0002
Current drinker, %	55.3	55.3	46.7	57.6	55.0	0.34
BMI (kg/m2)	27.7±5.2	27.6±5.2	28.8±5.6	28.1±5.1	28.6±5.4	<0.0001
Hypertension, %	34.2	32.8	39.8	40.0	49.0	<0.0001
Antihypertensive medication, %	25.0	23.8	25.0	31.9	37.1	<0.0001
Diabetes mellitus, %	10.6	10.0	18.3	12.9	16.4	<0.0001
Total cholesterol, mg/dL	216.6±41.7	216.3±41.6	220.8±49.6	217.2±45.4	219.3±39.5	0.20
LDL-c, mg/dL	139.0±39.2	138.5±39.2	143.6±47.4	141.8±44.0	142.8±35.6	0.01
HDL-c, mg/dL	52.1±17.0	52.5±17.1	49.1±14.5	49.4±16.4	47.7±15.6	<0.0001
Triglycerides, mg/dL	130.7±85.3	129.0±84.1	140.5±71.5	136.2±100.9	147.8±92.0	<0.0001
Left ventricular hypertrophy, %	1.8	1.6	2.2	2.9	3.7	0.0002
Previous myocardial infarction, %	3.4	2.8	3.2	6.6	9.5	<0.0001
Heart failure, %	4.1	3.7	4.4	4.3	8.5	<0.0001
Coronary heart disease, %	4.1	3.4	3.3	9.1	11.4	<0.0001

*Baseline age is age upon meeting enrollment criteria for the present analysis. All other characteristics are from the initial ARIC study exam (1987–1989).

ARIC =  Atherosclerosis Risk in Communities.

CMS =  Centers for Medicare and Medicaid Services.

Continuous variables presented as mean ± standard deviation (SD).

P-values from testing the null hypothesis of independence from chi-square (categorical) and F-test (continuous).