Table 1.

Characteristics of Participants in the Women’s Health Initiative (WHI) Calcium and Vitamin D Trial at the Time of WHI Screening (i.e., Year 0), by Supplementation Group, 1995–2000

Characteristic	Supplementation Group		Placebo Group		P Value
	No.	%a	No.	%a
Age, years					>0.99
50–59	6,726	37.0	6,696	37.0
60–69	8,276	45.5	8,243	45.5
70–79	3,174	17.5	3,167	17.5
Race/ethnicity					0.45
White	15,051	82.8	15,104	83.4
Black	1,680	9.2	1,635	9.0
Hispanic	785	4.3	717	4.0
American Indian	77	0.4	72	0.4
Asian/Pacific Islander	370	2.0	351	1.9
Annual income, dollars					0.68
<20,000	2,942	16.2	2,876	15.9
20,000–49,999	8,122	44.7	8,092	44.7
≥50,000	6,205	34.1	6,192	34.2
Marital status					0.96
Never married	725	4.0	712	3.9
Divorced/separated	2,850	15.7	2,875	15.9
Widowed	3,004	16.5	3,008	16.6
Married/living as married	11,522	63.4	11,442	63.2
Regional solar irradiance, Langleys					>0.99
475–500	3,861	21.2	3,852	21.3
400–430	3,016	16.6	3,012	16.7
75–380	2,009	11.1	2,009	11.1
350	3,924	21.6	3,879	21.4
300–325	5,366	29.5	5,354	29.6
Smoking status					0.50
Never smoker	9,325	51.3	9,428	52.1
Past smoker	7,255	39.9	7,133	39.4
Current smoker	1,405	7.7	1,356	7.5
Alcohol intake, drinks/day					0.63
0	5,055	27.8	5,100	28.2
>0–<1	11,065	60.9	10,977	60.6
≥1	1,908	10.5	1,900	10.5
Hormone useb					0.24
Never use	5,810	32.0	5,685	31.4
Past use	3,007	16.5	2,937	16.2
Current use	9,359	51.5	9,484	52.4
Body mass indexc					0.17
<25	4,745	26.1	4,834	26.7
25–<30	6,476	35.6	6,487	35.8
≥30	6,870	37.8	6,692	37.0
Physical activity, MET-hours/week					0.60
<3.00	5,405	29.7	5,340	29.5
3.00–9.99	4,642	25.5	4,648	25.7
10.00–19.99	3,647	20.1	3,569	19.7
≥20.00	2,852	15.7	2,891	16.0
Total vitamin D intake, IU/day					0.32
<100	2,750	15.1	2,653	14.7
100–<200	4,092	22.5	4,025	22.2
200–<400	3,373	18.6	3,419	18.9
400–<600	4,180	23.0	4,293	23.7
≥600	3,426	18.8	3,363	18.6
Dietary vitamin D intake, IU/day					0.47
<100	4,893	26.9	4,747	26.2
100–<200	7,434	40.9	7,496	41.4
200–<400	4,651	25.6	4,651	25.7
≥400	843	4.6	859	4.7
Supplemental vitamin D intake, IU/day					0.41
None	9,639	53.0	9,507	52.5
<400	1,795	9.9	1,780	9.8
400–<800	6,339	34.9	6,401	35.4
≥800	403	2.2	418	2.3
Meeting IOM guidelines for vitamin D intaked					0.99
No	15,379	84.6	15,430	85.2
Yes	2,374	13.1	2,391	13.2
Total calcium intake, mg/day					0.44
<400	1,318	7.3	1,273	7.0
400–<800	4,790	26.4	4,732	26.1
800–<1,000	2,514	13.8	2,459	13.6
1,000–<1,200	2,198	12.1	2,195	12.1
≥1,200	7,001	38.5	7,094	39.2
Dietary calcium intake, IU/day					0.52
<400	2,406	13.2	2,378	13.1
400–<800	7,629	42.0	7,603	42.0
800–<1,000	2,906	16.0	2,878	15.9
1,000–<1,200	1,868	10.3	1,853	10.2
≥1,200	3,012	16.6	3,041	16.8
Supplemental calcium intake, IU/day					0.55
None	8,027	44.2	7,885	43.5
<400	4,289	23.6	4,295	23.7
400–<800	3,358	18.5	3,406	18.8
≥800	2,502	13.8	2,520	13.9
Total saturated fat intake, g/day					0.79
<15.1	4,469	24.6	4,415	24.4
15.1–21.4	4,463	24.6	4,479	24.7
21.5–29.7	4,505	24.8	4,367	24.1
≥29.8	4,384	24.1	4,492	24.8
Use of antidepressant medicationb					0.03
No	16,992	93.5	16,820	92.9
Yes	1,184	6.5	1,286	7.1
Burnam depression scale (37) scoreb					0.25
<0.06	16,401	90.2	16,244	89.7
≥0.06	1,708	9.4	1,790	9.9
WHI Hormone Trial assignment					0.74
Not randomized	10,122	55.7	10,071	55.6
Active	4,039	22.2	4,078	22.5
Placebo	4,015	22.1	3,957	21.9
WHI Dietary Modification Trial assignment					0.30
Not randomized	5,582	30.7	5,490	30.3
Intervention	4,767	26.2	4,878	26.9
Comparison	7,827	43.1	7,738	42.7

Abbreviations: IOM, Institute of Medicine; MET, metabolic equivalent task; WHI, Women’s Health Initiative.

^aPercentages may not sum to 100 because of missing data.

^bMeasured at year 1.

^cWeight (kg)/height (m)².

^dThe IOM guidelines for vitamin D intake are ≥600 IU/day for women aged 50–70 years and ≥800 IU/day for women aged ≥70 years (42).