Table 1.

Baseline Characteristics of Study Participants, by Atrial Fibrillation Status at Baseline, Women's Health Initiative Observational Study, 1994–1998

Characteristic	Atrial Fibrillation at Baseline (n = 4,376)			No Atrial Fibrillation at Baseline (n = 81,670)			P Value
	Mean (SD)	No.a	%	Mean	No.a	%
Age, years	66.9 (7.1)			63.2 (7.3)			<0.001
BMIb	27.4 (6.0)			27.2 (5.8)			0.04
Age at menopause, years	47.1 (7.1)			47.5 (6.6)			<0.01
Resting pulse (30 seconds)	34.1 (6.3)			34.7 (6.1)			<0.001
Ethnicity							<0.001
Non-Hispanic white		3,687	84.5		67,895	83.4
Black		393	9.0		6,658	8.2
Hispanic/Latino		115	2.6		3,195	3.9
Other		170	3.9		3,688	4.5
Educational level							<0.001
<College degree		2,852	65.6		46,448	57.3
≥College degree		1,498	34.4		34,552	42.7
Income							<0.001
<$20,000		949	23.6		11,687	15.4
$2,000–$49,999		1,867	46.4		32,580	43.0
$50,000–$74,999		658	16.4		15,564	20.6
≥$75,000		551	13.7		15,924	21.0
Marital status							<0.001
Never married		205	4.7		3,828	4.7
Divorced/separated		649	14.9		12,919	15.9
Widowed		1,027	23.6		13,667	16.8
Married/living such		2,476	56.8		50,858	62.6
Smoking status							0.19
Never smoker		2,224	51.7		41,135	51.0
Past smoker		1,837	42.7		34,417	42.7
Current smoker		244	5.7		5,116	6.3
Physical activity level							<0.001
No activity		690	16.0		10,813	13.4
Mild		1,795	41.7		30,858	38.1
Moderate		777	18.0		15,005	18.6
Strenuous		1,048	24.3		24,230	30.0
Age at menarche, years							0.02
≤10		296	6.8		5,322	6.5
11–13		2,991	68.6		57,656	70.8
14–15		886	20.3		15,205	18.7
≥16		188	4.6		3,282	4.0
Age at first birth, years							0.04
No term pregnancy		524	13.3		10,476	14.2
<20		538	13.7		9,121	12.4
20–29		2,516	64.0		47,758	64.9
≥30		352	9.0		6,278	8.5
Parity							<0.001
No term pregnancy		524	12.0		10,476	12.9
1		378	8.7		7,477	9.2
2–3		2,114	48.6		41,146	50.7
≥4		1,337	30.7		22,121	27.2
Hormone therapy use							<0.001
Never		1,755	40.1		33,167	40.7
Past		824	18.9		11,838	14.5
Current		1,793	41.0		36,590	44.8
Hysterectomy							<0.001
No		2,176	49.8		48,188	59.1
Yes		2,193	50.2		33,413	41.0
Hypertension							<0.001
Nonhypertensive		2,243	52.7		54,836	68.1
Untreated		441	10.4		6,183	7.7
Treated		1,570	36.9		19,533	24.3
Diabetes (treated)							<0.001
No		4,045	92.6		78,370	96.1
Yes		325	7.4		3,199	3.9
High cholesterol requiring medication
No		3,366	78.8		68,583	85.5
Yes		905	21.2		11,612	14.5
History of CVD							<0.001
No		3,029	69.2		75,065	91.9
Yes		1,347	30.8		6,605	8.1
History of CHF							<0.001
No		4,104	93.8		81,179	99.4
Yes		272	6.2		486	0.6
Warfarin use							<0.001
No		3,785	86.5		81,269	99.5
Yes		591	13.5		400	0.5
Anti-arrhythmic use							<0.001
No		4,091	93.5		81,594	99.9
Yes		285	6.5		75	0.1
Aspirin use							<0.001
No		2,923	66.8		63,358	77.6
Yes		1,453	33.2		18,311	22.4
Statin use							<0.01
No		3,859	88.2		75,212	92.1
Yes		517	11.8		6,457	7.9
β-blocker use							<0.001
No		3,335	76.2		75,567	92.5
Yes		1,041	23.8		6,103	7.5
Calcium channel blocker use
No		3,425	78.3		74,285	91.0
Yes		951	21.7		7,385	9.0
ACE inhibitor use							<0.001
No		3,804	86.9		75,468	92.4
Yes		572	13.1		6,202	7.6
Angiotensin II receptor blocker use							<0.001
No		4,314	98.6		81,090	99.3
Yes		62	1.4		580	0.7
Cardiac glycoside use							<0.001
No		3,137	71.7		81,175	99.4
Yes		1,239	28.3		494	0.6

Abbreviations: ACE, angiotensin-converting enzyme; BMI, body mass index; CHF, congestive heart failure; CVD, cardiovascular disease; SD, standard deviation.

^a Subgroup totals may not sum to the column total because of missing data.

^b Weight (kg)/height (m)².