Abstract
INTRODUCTION Vitamin D supplementation has been widely recommended to prevent falls. However, considerable controversy exists regarding the association of such supplementation and fall risk. Previous meta-analyses yielded inconsistent results because of differences in the baseline of 25-hydroxyvitamin D [25(OH)D] and dose of vitamin D and use of vitamin D or in combination with calcium in different studies. Furthermore, some studies published recently were not included in the previous meta-analyses. Therefore, an updated and comprehensive meta-analysis is warranted. METHODS We systematically searched several literature databases including PubMed and the Embase from inception to September 2020. The protocol for this meta-analysis was registered with PROSPERO (CRD42021226380). Randomized clinical trials (RCTs) reporting the effect of vitamin D supplementation alone or with calcium on fall incidence were selected from studies. Qualitative and quantitative information was extracted; the random-effects model was conducted to pool the data for fall; statistical heterogeneity was assessed using the I2 test and potential for publication bias was assessed qualitatively by a visual estimate of the funnel plot and quantitatively by calculation of the Begg's test and the Egger's test. RESULTS Of the citations retrieved, 31 eligible studies involving 57 867 participants met inclusion criteria, reporting 17 623 falls. A total of 21 RCTs of vitamin D alone and 10 RCTs of vitamin D plus calcium were included in the meta-analysis. The meta-analysis of 21 RCTs (51 984 participants) of vitamin D supplementation alone (daily or intermittent doses of 400-60 000 IU) did not show a reduced risk of falls (The risk ratio [RR] 1.00, 95% confidence intervals [CI] 0.95 to 1.05) compared to placebo or no treatment. Subgroup analyses showed that the baseline of serum 25(OH)D concentration less than 50 nmol/L resulted in a reduction of fall risk (RR 0.77, 95% CI 0.61 to 0.98). In contrast, the meta-analysis of 10 RCTs (5883 participants) of combined supplementation of vitamin D (daily doses of 700-1000 IU) and calcium (daily doses of 1000-1200 mg) showed a 12% reduction in the risk of fall (RR 0.88, 95% CI 0.80 to 0.97). CONCLUSIONS The combination of vitamin D and calcium have beneficial effects on prevention falls in old adults. Although vitamin D supplementation alone has no effect on fall risk in old adults with 25(OH)D levels higher than 50 nmol/L, vitamin D supplementation alone does have a benefit on prevention of falls in old adults with 25(OH)D levels lower than 50 nmol/L.
