title: Calcium and vitamin D supplementation and incident rheumatoid arthritis: the Women's Health Initiative Calcium plus Vitamin D trial.
abstract: To determine whether calcium plus vitamin D supplementation (CaD) affects incidence of rheumatoid arthritis (RA). Participants enrolled in the Women's Health Initiative CaD trial (n = 36,282) were randomized to 1,000 mg calcium carbonate plus 400 IU of vitamin D(3) daily or to placebo. Incident RA cases were identified via self-report and validated rheumatic medication use. Cox proportional hazards models were used to compare RA incidence in the treatment versus placebo groups. The analysis included 32,435 women without the history of RA, of which 163 incident RA cases were identified over an average of 5.1 years. No significant differences in demographics, total personal vitamin D intake [P = 0.36], or solar irradiance [P = 0.68] were seen between the groups. In intention-to-treat analyses, no differences were observed in RA incidence [HR 1.04, 95% CI 0.76, 1.41]. No significant modifying effects were seen for stratum of age, solar irradiance, or total vitamin D intake, overall or when adjusted for adherence. Significant effect modifications were seen between CaD and total vitamin D intake and CaD and solar irradiance that suggest increased RA incidence with high vitamin D exposure. CaD supplementation did not demonstrate a significant effect on RA incidence in postmenopausal women. Modifying effects between CaD and both solar irradiance and dietary vitamin D intake are suggestive that multiple high vitamin D exposures may increase RA incidence. Further research is needed to fully explore the benefits and possible adverse effects of vitamin D supplementation on RA.
authors.affiliation: Washington Hospital Center, 110 Irving Street, Washington, DC 20010, USA.
authors.forename: Marius
authors.initials: M
authors.lastname: Racovan
authors.forename: Brian
authors.initials: B
authors.lastname: Walitt
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Collins
authors.forename: Mary
authors.initials: M
authors.lastname: Pettinger
authors.forename: Christine G
authors.initials: CG
authors.lastname: Parks
authors.forename: James M
authors.initials: JM
authors.lastname: Shikany
authors.forename: Jean
authors.initials: J
authors.lastname: Wactawski-Wende
authors.forename: Joann E
authors.initials: JE
authors.lastname: Manson
authors.forename: Larry
authors.initials: L
authors.lastname: Moreland
authors.forename: Nicole
authors.initials: N
authors.lastname: Wright
authors.forename: Rebecca
authors.initials: R
authors.lastname: Jackson
authors.forename: Barbara V
authors.initials: BV
authors.lastname: Howard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000453:epidemiology* / Q000517:prevention & control; D002119:Calcium Carbonate / Q000008:administration & dosage*; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D016896:Treatment Outcome; D014807:Vitamin D / Q000008:administration & dosage*; D016387:Women's Health
chemical_list: D014807:Vitamin D; D002119:Calcium Carbonate