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Vitamin D and falls in the elderly

Meta-analysis
Results
Comment

We know that falls are common amongst elderly people, causing considerable morbidity and mortality. With an ageing population the medical problems of falls (Bandolier 25), and the costs to society, can only increase. Previous studies have shown a moderate effect of vitamin D supplements on fracture risk, which has been attributed to changes in bone mineral density (Bandolier 37).

But fracture incidence reduction occurs within two to three months, and is consistent with a beneficial effect of vitamin D on muscle strength, leading to a reduction in falls and hence fractures. A recent meta-analysis has investigated the effect of vitamin D supplements on falls in the elderly.

Meta-analysis

The review identified double-blind, randomised controlled trials of vitamin D in elderly populations that reported on falls [1]. The study population were community dwelling or institutionalised, with a mean age of at least 60 years, and in a stable state of health, so excluded, for example, those with recent acute hospitalisation or alcohol problems.

Falls were the result of low trauma, ideally involving 'unintentionally coming to rest on the ground, floor or other low level', so excluded falls against a wall or furniture, or falls from a ladder (high trauma). The method of ascertainment and definition of the fall had to be clearly defined. The search strategy was comprehensive and not restricted by language.

Results

Five trials, with 1,237 participants, satisfied the inclusion criteria. The mean age ranged from 71 to 85 years, and only two trials included any men (total 239, 19%). Two trials gave vitamin D 800IU/day together with 1200 mg/day calcium; two trials gave an active vitamin D analogue and no calcium supplement; one trial gave vitamin D 400 IU/day with no calcium supplement, but reported dietary intake of 800-1000 mg/day. The duration of treatment was two months to three years.

There were consistently fewer falls in participants given vitamin D (Figure 1), but the result was statistically significant in only one trial. Combining the five trials, 37% of people had a fall with control, compared with 30% with vitamin D. The relative risk was 0.81 (0.69 to 0.94) with a number needed to treat of 14 (8 to 51) to prevent one fall.



Figure 1. Falls in elderly people with and without vitamin D supplements





Five other trials, with an additional 8764 participants, did not satisfy the inclusion criteria because the clinical characteristics of the participants (eg unstable health states) or outcome measures used (eg included only falls leading to medical attention) and would be expected to dilute any effect of vitamin D. When these trials were included in the analysis, the reduction in falls was only 13% compared with about 20% using the five high-quality trials. Despite this expected reduction in effect, the benefit remained (just) statistically significant.

Although sample sizes limited statistical significance, there was no evidence of a difference in effect for men and women, or for studies with longer or shorter duration. There were insufficient data to determine the most effective dose (although in the trials 400 IU/day was probably insufficient, while 800 IU/day produced an effect) or formulation of vitamin D, or the role of calcium.

Comment

One striking thought is how common falls were in these studies, ranging from 16% to 63% in all ten treatment and control groups in the five included trials. This makes fall prevention of real and growing importance. The authors discuss the possible physiological mechanism by which vitamin D may affect muscle function, so this result does not come out of the blue. There is a legitimate reason why use of vitamin D may help prevent falls in the elderly. Whether it is fall prevention, or increased bone strength, or both, reduced falls and fractures means less risk of devastating outcomes in older people.

While further studies could help to define the most effective dose and formulation, and the cost-effectiveness of targeted supplementation based on baseline vitamin D, the authors suggest that the economic and social costs of falls justify consideration of vitamin D supplementation based on the results of their meta-analysis.

Vitamin D is not without problems, though, perhaps most in the more frail older old. Some sensible guidelines would be useful, and perhaps exist.

Reference:

  1. HA Bischoff-Ferrari et al. Effect of vitamin D on falls: a meta-analysis. JAMA 2004 291: 1999-2006.

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