Higher circulating standardized 25(OH)D is not associated with increased falls risk

Introduction:Falls are the second leading cause of unintentional injury. In the U.S., 1 in 4 older adults fall annually and ∼20% of falls cause serious injury, e.g., fracture. It has been reported that higher vitamin D status is associated with increased falls risk. The purpose of this analysis was to evaluate the association of retrospectively standardized 25(OH)D with falls in postmenopausal women. This is a secondary analysis of data from a 4‐year randomized controlled trial evaluating the effect of vitamin D3and calcium supplementation on cancer. Methods:Subjects were a population‐based sample of 2,303 healthy postmenopausal women age 55+ in rural Nebraska. Excluding missing data (n=194) 2,109 participants were followed. The treatment group received vitamin D32000 IU/daily. Circulating 25(OH)D was measured using the Diasorin Liaison assay on sera collected at baseline and annually (V1, V3, V5 & V9). Subsequently, retrospectively standardized 25(OH)D results were obtained using stored sera analyzed by HPLC following the Vitamin D Standardization Program protocol. Falls (#, date and type) were captured every 6 mo by subject interview and self‐reported falls diary. The visit date at which a fall was reported was used as the date of fall. Association between standardized 25(OH)D and falls risk was assessed in a multivariable logistic model adjusted for baseline age and total calcium intake. For this analysis, standardized 25(OH)D was divided into 6 levels: 50 ng/mL. The dependent variable was any reported fall during the study vs. no reported falls.Results:Mean baseline age was 65 yr (range 55‐91). Mean (range) standardized baseline 25(OH)D was 33 ng/mL (10‐77) with no difference between treatment and control groups. At year 4 mean 25(OH)D was 40 ng/mL (13‐75) in the treatment group and 31 ng/mL (12‐66) in placebo. At least 1 fall was reported in 1,461 participants (69%); the occurrence rate was the same in both groups. In the treatment group, 727 of 1,051 reported falling 1 or more times compared to 734 of 1,058 in the placebo group. At no level of 25(OH)D was there an increased risk of falls after adjusting for baseline age and mean total calcium intake. Conclusion:In this cohort of postmenopausal women, vitamin D supplementation did not increase falls risk. Higher 25(OH)D concentration using retrospectively standardized data was not associated with greater falls risk.