Vitamin D Supplementation Does Not Improve Functional Outcomes in Postmenopausal Women with Vitamin D Deficiency

EBM Focus - Volume 10, Issue 33

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Reference - JAMA Intern Med 2015 Aug 3 early online (level 1 [likely reliable] evidence)

Vitamin D deficiency is associated with musculoskeletal complications including pain and weakness, osteomalacia, osteoporosis, and secondary hyperparathyroidism (J Clin Endocrinol Metab 2011 Jul;96(7):1911, Postgrad Med 2006 Jun-Jul;119(1):25). Vitamin D deficiency is especially prevalent in postmenopausal women who are already at an increased risk of osteoporosis and osteoporosis-related fractures (QJM 2005 Sep;98(9):667). Evidence supporting the use of vitamin D supplements for the treatment and prevention of osteoporosis is limited, and recommendations from current guidelines are inconsistent on the use of vitamin D for these purposes (National Osteoporosis Foundation 2013 PDF, Ann Intern Med 2013 May 7;158(9):691). Recent data has suggested that vitamin D supplementation may also reduce the risk of falls in patients with low vitamin D levels (Cochrane Database Syst Rev 2012 Sep 12;(9):CD007146). This data has led the American Geriatrics Society and British Geriatrics Society to recommend at least 800 units/day of vitamin D supplements to older persons with proven vitamin D deficiency, and to consider supplementation for all older adults at increased risk of falls (J Am Geriatr Soc 2011 Jan;59(1):148). A recent randomized trial compared high-dose vitamin D3 vs. low-dose vitamin D3 vs. placebo for 1 year in 230 postmenopausal women with vitamin D insufficiency (25-hydroxyvitamin D levels 14-27 ng/mL). The primary outcome was change in calcium absorption, but rate of falls was one of the secondary outcomes investigated.

The high-dose regimen included 50,000 units of vitamin D3 twice monthly plus placebo daily, and the low-dose regimen consisted of 800 units of vitamin D3 daily plus placebo twice monthly. The placebo group received both daily and twice monthly placebos to maintain blinding. All women were also counseled to consume 600-1,400 mg calcium daily by diet or supplemental calcium, if needed. Women with evidence of osteoporosis, taking bisphosphonates or other bone active medications in the preceding 6 months, or with certain comorbidities were excluded. From days 30-365, the mean 25-hydroxyvitamin D level increased to 56 ng/mL with high-dose vitamin D3 and 28 ng/mL with low-dose vitamin D3 compared to 19 ng/mL with placebo (p< 0.001 across groups). The change in total fractional calcium absorption at 1 year was significantly increased in the high-dose vitamin D3 group compared to the low-dose vitamin D3 and placebo groups (+1% vs. -2% vs. -1.3%, respectively). This difference did not correlate with any clinical outcomes. There were no significant differences in the number of falls or percent of fallers across groups, with 35 falls in 29.7% of women in the high-dose vitamin D3 group vs. 36 falls in 32.9% of women in the low-dose vitamin D 3 group vs. 33 falls in 30.3% of women in the placebo group. There were also no significant differences in other clinical or bone health outcomes including fracture, Timed Up and Go Test, Five Sit-to-Stand Test, functional status measures, or physical activity.

This study contrasts with 2 previous systematic reviews (Cochrane Database Syst Rev 2012 Sep 12;(9):CD007146, JAMA 2004 Apr 28;291(16):1999) that found a decrease in the risk of falls with vitamin D supplementation. This discrepancy may in part be explained by the included populations, with the systematic reviews including older adults in general compared to the specific population of postmenopausal women with vitamin D deficiency included in this trial. Also, the mean age of the patients analyzed in the systematic reviews was about 10 years older than the women included in this trial. This study suggests that supplemental vitamin D does not reduce risk of falls. Finally, although there were no differences seen in bone health or functional status, the trial may have been too short to adequately assess these outcomes.

For more information, see the Vitamin D intake and supplementation and Calcium and vitamin D for treatment and prevention of osteoporosis topics in DynaMed Plus. DynaMed users click here and here.