Methods
Trial design and participants
For this explorative study, antidepressant users from the multicenter B-PROOF (B-Vitamins for the Prevention of Osteoporotic Fractures; ClinicalTrials.gov NCT00696514) study were included. A detailed description of the trial was published previously 14. In short, B-PROOF was a large multicenter, double-blind, placebo-controlled trial for which persons 65 years and older with mildly elevated homocysteine levels were recruited to participate between 2008 and 2011, for a follow-up period of 2-3 years. A total of 2,919 participants were included. The primary aim was to assess whether the addition of vitamin B12 and folic acid to vitamin D therapy prevented osteoporotic fractures. Because the intervention did not affect fall-related outcomes, data could be used for the current observational study 15. The Medical Ethics Committee of Wageningen University approved the study protocol of the B-PROOF study 14. Before entering the study, all participants gave their written informed consent. All experiments were conducted in accordance with the principles of the Declaration of Helsinki.