Background: Many observational studies have reported associations between low 25-hydroxyvitamin D (25[OH] vit D) levels and adverse cardiovascular (CV) outcomes. Recent randomized clinical trials have not found vitamin (vit) D 3 supplementation to reduce CV risk. However, these trials gave “blanket” doses regardless of 25[OH] vit D level, with none having "treated to target". We are performing the first study where subjects are prescribed vit D 3 supplementation based on individual 25[OH] vit D levels. Methods: The purpose of Target-D (NCT: 02996721) is to determine if achieving 25[OH] vit D levels >40 ng/mL among myocardial infarction (MI) patients will result in a reduction of adverse CV events. Subjects meeting study criteria from April 2017 to May 2023 were randomized to receive standard of care or clinical management of 25[OH] vit D levels. The treatment arm received targeted vit D 3 supplementation based on a dosing algorithm. Target-D is an event-driven trial that will conclude when 104 primary outcome events (composite of death, MI, heart failure hospitalization, and stroke) have occurred. Results: The study consort diagram is shown in Figure. Patient characteristics are shown in Table. Baseline 25[OH] vit D levels were 26.8±12.7 (median: 25) and were similar between arms (Table). Among those randomized to the treatment arm with a 25[OH] vit D levels < 40, 58.5% of patients began vit D 3 dosing at 5000 IU. Conclusions: Average baseline 25[OH] vit D levels were deficient in Target-D participants. The discrepancy in findings between observational and randomized trials of vit D may be due to the inability of vit D 3 supplementation doses to achieve therapeutic 25[OH] vit D thresholds. Target-D will evaluate if it is the level of serum 25[OH] vit D achieved that provides CV benefit and not necessarily the vit D 3 supplementation dose that is received. It is anticipated that the number of events needed for this event-driven trial will be achieved by May 2024.
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