Questioning vitamin D status of elderly fallers and nonfallers: a meta-analysis to address a 'forgotten step'.

BACKGROUND: Previous meta-analyses to determine the efficacy of vitamin D supplementation to prevent falls in the elderly have shown mixed results. Inconsistencies might depend on the dose of supplements, suggesting that serum 25-hydroxyvitamin D (25OHD) concentration could influence the risk of falling. Our objective was to systematically review and quantitatively analyse the relationship between serum 25OHD concentration and the occurrence of falls.

METHODS: A Medline search was conducted in December 2013, with no date limit, using the Medical Subject Heading terms 'Vitamin D' OR 'Ergocalciferols' OR 'Vitamin D deficiency' combined with 'Accidental Falls' OR 'Gait disorders, neurologic' OR 'Gait apraxia' OR 'Gait' OR 'Recurrent Falls' OR 'Falling'. Fixed and random-effects meta-analyses were performed to determine the following: (i) the effect size of the difference in 25OHD concentration between fallers and nonfallers and (ii) the risk of falling according to serum 25OHD concentration.

RESULTS: Of the 659 retrieved studies, 18 observational studies - including ten cross-sectional and eight cohort studies - met the selection criteria. All were of good quality. The number of participants ranged from 80 to 2957 (44-100% women); 11.0% to 69.3% were fallers. Serum 25OHD concentrations were 0.33 × SD lower in fallers compared to nonfallers [pooled effect size 0.33; 95% confidence interval (CI) 0.18-0.47]. The risk of falls was inversely associated with serum 25OHD concentration [summary odds ratio (OR) 0.97; 95% CI 0.96-0.99]. The association between falls and hypovitaminosis D varied according to the definition used; the summary OR for falls was 1.23 (95% CI 0.94-1.60) for 25OHD <10 ng mL(-1) , 1.44 (95% CI 1.17-1.76) for 25OHD <20 ng mL(-1) and 0.95 (95% CI 0.81-1.11) for 25OHD <30 ng mL(-1) .

CONCLUSIONS: Fallers have lower 25OHD concentrations, notably more often <20 ng mL(-1) , than nonfallers. These findings help to determine the profile of target populations that would most benefit from vitamin D supplements to prevent falls.