Table 2.
Effect of vitamin D supplementation on risk of falling and incidence of falls
| No./total no. (%) or incidence rate | |||
|---|---|---|---|
| Vitamin D | Placebo | OR/IRR (95% CI) a | |
| Annual survey data (n = 15 416) | n = 7729 | n = 7687 | |
| Any fall in previous month b | 2174/36 294 (6.0) | 2,106/36,007 (5.8) | 1.02 (0.95–1.10) |
| Diary data (N = 2093) c | n = 1045 | n = 1048 | |
| Any fall over 3 months | 159/1045 (15.2) | 153/1048 (14.6) | 1.07 (0.84–1.36) |
| Number of falls, IR per 1000 PYAR d | 820 | 728 | 1.13 (0.89–1.43) |
CI, confidence interval; IRR, incidence rate ratio; OR, odds ratio; PYAR, person‐years at risk.
Estimates compare vitamin D to placebo. ORs estimated using logistic regression; generalized estimating equations with an exchangeable correlation matrix used to account for participant clustering when analysing annual survey data. IRR estimated using negative binomial regression. All estimates adjusted for age, sex and state of residence. Analyses of diary data additionally adjusted for body mass index, physical activity and time outdoors at baseline.
Data analysed using a repeated measures approach to incorporate responses from all five annual surveys. Numerator is the total number of falls; denominator is the total number of surveys.
Results presented for people with complete data for all covariates included in the model. Minimally adjusted estimates (adjusted for age, sex and state) were not meaningfully different (see Table S10).
Goodness‐of‐fit chi‐squared test (based on the deviance) showed that the model was adequate.