In each case, beyond overall supplementation effects, temporal associations of the HR with duration of supplementation, and the agreement of patterns between clinical trial and observational study, are examined. Urinary tract stone occurrence analyses in the CT, by personal supplement use category, are also A-1155463 chemical structure presented to facilitate health benefit versus risk consideration. Methods Study populations and calcium and vitamin D supplementation selleck chemical A total of 36,282 postmenopausal women 50–79 years of age were randomized at 40 clinical sites to 1,000 mg calcium plus 400 IU vitamin D3 daily, given in two equal doses, versus placebo in the WHI

CaD trial during 1994–99. Concurrent calcium supplementation was permitted, as was vitamin D supplementation up to 600 IU daily (later increased to

Selleckchem ICG-001 1,000 IU daily). Details of the study design [24] and baseline characteristics [1, 2, 25] have been presented. All participating women provided written informed consent. No personal use of calcium or vitamin D supplements at baseline was reported by 42.2 % (15,302) of trial enrollees, whereas 43.5 % (15,796), 9.4 % (3,419), and 2.9 % (1,060) reported use of calcium plus vitamin D, calcium only, and vitamin D only, respectively, while baseline supplementation information was not available for 1.9 % (705) of women. Both single supplement and multivitamin/multimineral supplements were included in assessing personal use. The companion WHI prospective Observational Study (OS) enrolled 93,676 postmenopausal women 50–79 years of age from the same catchment population during 1994–98. Baseline characteristics have been presented [26]. To align with CT exclusionary criteria, we excluded 5,145 women with a baseline history of breast cancer, 15,511 women with no mammogram within 2 years prior to OS enrollment, 1,108 daily corticosteroid users, and 5,675 women who reported urinary tract stones at baseline, leaving 68,719 OS women. Of these, 34.3 % (23,561) reported no baseline supplementation with calcium or vitamin D, 49.9 % (34,257) reported use of both calcium and vitamin D, 12.5 % (8,576) reported

calcium only, and 3.4 % (2,325) reported vitamin D only. Among the 42,833 baseline calcium users, the 5th, 10th, Fossariinae 25th, 50th, 75th, 90th, and 95th percentiles for daily dosage (milligrams per day) were 57, 143, 200, 571, 1,000, 1,305, and 1,640, respectively. We defined baseline calcium users in the OS as those taking ≥500 mg/day and excluded those consuming a lower dosage from our analysis. This cutpoint gives a user group having average daily dose similar to the 1,000 mg/day used in the WHI trial. Similarly, the corresponding percentiles for vitamin D (IU/day) were 125, 171, 400, 400, 400, 600, and 800 with 58 % of users reporting 400 IU/day. We defined vitamin D users in the OS as those taking ≥400 IU/day and excluded those taking a lower dosage from analysis.