Introduction: Vitamin D plays an essential role in supporting musculoskeletal health, and supplementation may lower the risk of falls. Vitamin D supplementation may be particularly beneficial in residential aged care (RAC) settings, given the high prevalence of Vitamin D deficiency within this population. However, past research on the effects of vitamin D supplementation on falls in RAC has reported inconclusive findings, partly due to study design limitations. We utilised a longitudinal study design to assess the association between the use of vitamin D and falls over 36 months in RAC.
Methods: A longitudinal cohort study was conducted using routinely collected electronic data extracted from 27 RAC facilities in Sydney, New South Wales, Australia. Study inclusion criteria were residents who: were permanent residents aged 65 years or older; admitted for the first time on or after the study start period of July 1, 2014, and were long-term residents (>30 days admission). We identified daily vitamin D usage over 36 months, and measured adherence using the Proportion of Days Covered (PDC) metric. PDC represents the proportion of days that residents were covered by vitamin D supplements with a value of ≥80% signifying optimal adherence. Primary outcomes were the number of all falls and injurious falls. We employed Generalized Estimating Equations (GEE) to investigate the longitudinal association between the use of vitamin D supplements and the subsequent risk of falls. This study was reviewed and approved by the Macquarie University Human Research Ethics Committee (ref: 52019614412614).
Results: A total of 4,520 participants were included, with over two-thirds of residents (67.8%; n=3,063) receiving vitamin D supplements during their stay. The median PDC was 74.8%, signifying that approximately half of the residents received daily vitamin D supplements for three-quarters of their total time spent in the RAC facilities. The proportion of residents achieving optimal adherence was 44.6% (n=1,365). Increasing age, osteoporosis or fracture history, and dementia were associated with a greater likelihood of achieving optimal adherence. After accounting for relevant demographics (e.g., age) and health conditions (e.g., dementia status), no significant relationship was observed between vitamin D supplement usage and fall outcomes: all falls (Incident Rate Ratio [IRR] 1.01; 95% CI 1.00-1.02; P=0.237) and injurious falls (IRR 1.01; 95% CI 1.00-1.02; P=0.091).
Conclusion: Vitamin D supplementation was prevalent in RAC settings; however, it did not demonstrate an association with a reduced risk of falls. This suggests that it may not be an effective standalone intervention for preventing falls in RAC. While clinicians should prioritise ensuring adequate vitamin D intake for residents' musculoskeletal health, other comprehensive measures may be necessary for falls prevention in RAC populations.