Appendix Table A1.

Baseline Characteristics of Calcium and Vitamin D Trial Participants by Extension Study Participation Status

	Nonextension participant		Extension participant
	(N=6420)		(N=29,862)
	N	%	N	%	p-value
Age group at screening, years					<0.0001
50–59	2091	32.6	11,331	37.9
60–69	2712	42.2	13,807	46.2
70–79	1617	25.2	4724	15.8
Race/ethnicity					<0.0001
White	4813	75.0	25,342	84.9
Black	815	12.7	2500	8.4
Hispanic	476	7.4	1026	3.4
American Indian	43	0.7	106	0.4
Asian/Pacific Islander	152	2.4	569	1.9
Unknown	121	1.9	319	1.1
Education					<0.0001
None to some high school	594	9.3	1309	4.4
High school diploma or equivalent	1235	19.4	5438	18.3
School after high school	2717	42.6	11,656	39.3
College degree or higher	1826	28.7	11,276	38.0
Gail 5-year risk of breast cancer					<0.0001
<1.25	2417	37.6	10,241	34.3
1.25–1.74	1912	29.8	9958	33.3
≥1.75	2091	32.6	9663	32.4
Medical history
Kidney stones	74	1.3	269	1.0	0.04
Stroke	109	1.7	239	0.8	<0.0001
Myocardial infarction	205	3.2	449	1.5	<0.0001
Fracture	2177	38.3	10,362	38.2	0.99
Colorectal cancer	12	0.2	39	0.1	0.27
Breast cancer	13	0.2	44	0.1	<0.0001
Prior hormone usea					<0.0001
None	2219	34.6	9277	31.1
Past	1141	17.8	4802	16.1
Current estrogen-alone	1592	24.8	7532	25.2
Current estrogen+progestin	1468	22.9	8251	27.6
Body mass index, kg/m2					<0.0001
<25	1549	24.2	8030	27.0
25–<30	2167	33.9	10,796	36.3
≥30	2682	41.9	10,880	36.6
Physical activity, MET h/wk					<0.0001
None	1285	22.4	5039	18.5
0.5–4.125	1261	21.9	5645	20.7
>4.125–9.5	1113	19.4	5472	20.1
>9.5–17.75	1028	17.9	5557	20.4
≥17.75	1060	18.4	5534	20.3
Alcohol intake					<0.0001
Nondrinker	766	12.1	2988	10.1
Past drinker	1448	22.8	4953	16.7
<1 drink per month	907	14.3	4141	14.0
<1 drink per week	1253	19.7	6361	21.5
1–<7 drinks per week	1383	21.8	7997	27.0
≥7 drinks per week	596	9.4	3212	10.8
Smoking					<0.0001
Never	3138	49.5	15,615	52.8
Past	2517	39.7	11,871	40.2
Current	682	10.8	2079	7.0
Total vitamin D (supplements+diet), IU/db					<0.0001
<200	2612	41.9	10,886	37.1
200–<400	1207	19.4	5595	19.1
400–<600	1418	22.8	7065	24.1
≥600	991	15.9	5800	19.8
Vitamin D supplement useb	2741	42.7	14,426	48.3	<0.0001
Geographic region at randomization by latitude					<0.0001
Southern, <35°N	2563	39.9	8310	27.8
Middle, 35–40°N	1550	24.1	8493	28.4
Northern, ≥40°N	2307	35.9	13,059	43.7
Total calcium intake (supplements+diet+medications), mg/db					<0.0001
<800	2527	40.6	9580	32.6
800–<1200	1632	26.2	7738	26.4
≥1200	2069	33.2	12,028	41.0
Calcium and/or vitamin D supplement useb	3275	51.0	17,340	58.1	<0.0001
Hormone therapy trial participant	3173	49.4	12,916	43.3	<0.0001
Diet modification trial participant	4200	65.4	21,010	70.4	<0.0001
CaD trial randomization assignment
Intervention	3151	49.1	15,025	50.3
Control	3269	50.9	14,837	49.7

^aValues incorporate hormone therapy use during year 1 of the clinical trial, including exposure to the Hormone Therapy trials.

^bVitamin D and calcium variables incorporate intake reported at year 1 of the clinical trial.

MET, metabolic equivalents; CaD, calcium and vitamin D.