A Higher Dose of Vitamin D Reduces the Risk of Falls in Nursing Home Residents: A Randomized, Multiple-Dose Study

Kerry E. Broe, MPH; Tai C. Chen, PhD; Janice Weinberg, ScD; Heike A. Bischoff-Ferrari, MD, MPH; Michael F. Holick, MD, PhD; Douglas P. Kiel, MD, MPH

Disclosures

J Am Geriatr Soc. 2007;55(2):234-239. 

In This Article

Discussion

During this 5-month nursing home study using data from a previously conducted randomized trial, participants in the group taking an 800 IU vitamin D supplement had fewer fallers, fell less, and had a 72% lower falls rate than the placebo group. From early descriptions of muscle weakness in rickets and osteomalacia,[25,26] the importance of vitamin D for muscle function has been recognized and characterized.[25,26,27,28] Higher serum 25(OH)D has been associated with better musculoskeletal function,[29,30] leading to a renewed focus on the potential contributions of vitamin D to the risk of falls in older persons.

The findings in the group taking 800 IU are consistent with fall reductions found in a Swiss randomized trial examining residents of long-stay geriatric care over 12 weeks[10] and a large Australian randomized trial examining residents of hostels and nursing homes over 2 years.[11] The Swiss trial found that in 122 elderly women (average age 85) those taking 800 IU of cholecalciferol and 1,200 mg of calcium for 12 weeks had 49% fewer falls than participants taking only 1,200 mg of calcium. The Australian trial found that, in a group of 625 male and female residents (average age 83), the incidence rate ratio for falls was 0.73 (95% CI=0.57-0.95) in the group supplemented with 10,000 IU of ergocalciferol weekly and 1,000 IU daily for 2 years compared with participants taking placebo. In contrast, a British clinical trial found no association between vitamin D and falls in 3,717 elderly care home residents randomized to 2.5 mg of ergocalciferol every 3 months or placebo for a median follow-up time of 10 months.[14] An overall healthier population in this study, indicated by a low number of overall falls, fractures, and higher baseline vitamin D concentrations, could be an explanation as to why no associations were observed.

No "dose response" trend of lower risk of falls with greater supplement dose was observed in this study. The only observed effects were in the group receiving 800 IU. Similar to other nursing home populations,[3,4,5] participants in this study had low baseline serum 25(OH)D concentrations, with 57% having serum concentrations of less than 20 ng/mL. Of the 78 participants taking a multivitamin at baseline, 54% had vitamin D concentrations less than 20 ng/mL. The standard 400 IU vitamin D supplement found in the HRCA multivitamin did not provide an adequate 25(OH)D concentration for more than half of those taking the multivitamin.

Recently, a panel of vitamin D experts concluded that a minimum serum concentration between 20 and 32 ng/mL would be optimal for bone health, and four of the five experts recommended a minimum concentration between 28 and 32 ng/mL.[18] Valid serum measures at the end of this study were not available for all participants. For the 17 participants in the group taking 800 IU with valid measures, the mean follow-up concentration of 29.95 ng/mL was well within the recommended optimal range, and none had serum measures below 20 ng/mL. Attaining serum concentrations within the recommended optimal range may have positive benefits on muscle function as well as bone health in this elderly nursing home population, and this may be the reason why significant reductions in falling were found only in the group taking 800 IU.

Falls in nursing homes are multifactorial.[31] Ensuring that residents are receiving adequate vitamin D supplementation represents one potential piece of falls intervention programs.

There were several limitations to this study. Multivitamin use was not discontinued for the trial, yet not everyone was taking a multivitamin. This made it difficult to estimate the precise supplement doses within each group. This relationship was further examined by creating quintiles of total vitamin D supplement intake, and it was found that those in the highest intake quintile (average 1,096 IU) had a 58% lower falls risk than those in the lowest intake quintile (111 IU). These results were similar to what was found in the analyses that focused on the randomized groups.

Generalizability of the findings is limited because of the small sample size, participants were all Caucasian, and although participants were on average 89 years old, they were healthier than the other HRCA residents. Because frailer residents may be at greater risk for falls and vitamin D deficiency, replication of these results in a frailer sample of nursing home residents is warranted. In addition, information was not available on how many residents were approached for the study and were excluded. This was a post hoc analysis of a study originally performed to assess serum vitamin D responses. Nevertheless, the randomized, placebo-controlled, multiple-dose study design with high compliance and a well-established computerized incident-report system for fall outcome assessment retained the strengths of the original study. There may have been underreporting of falls, because minor unwitnessed falls would not be reported, yet because of the randomized study design, significant differences in falls underreporting between the study groups would not be expected. Vitamin D intake from foods or vitamin D repletion through sun exposure was not assessed, but it is likely that both of these sources would be minimal given the diets and activities of most nursing home residents. Furthermore, for participants with information on follow-up serum levels available, the 25(OH)D serum measure reflected total vitamin D, both vitamin D2 and D3. Finally, the vitamin D tablet used was D2 not D3. Vitamin D3 potency exceeds that of D2.[32] Vitamin D2 was used in this study to be consistent with the type of vitamin D found in HRCA's multivitamin.

In this study cohort, elderly nursing home residents in the highest vitamin D supplement group (800 IU) had a lower rate of falling than those in placebo group or in the lower supplement groups. Ensuring that nursing home residents are receiving adequate daily supplemental vitamin D may reduce the number of falls in elderly nursing home residents and could potentially reduce the risk of fracture in this high-risk group.


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