Abstract 14841: Higher Than Daily RDA Recommended Vitamin D 3 Dosing and Multiple Titrations Are Required to Achieve >40 ng/mL 25-hydroxy Vitamin D Levels in Acute Coronary Syndrome (ACS) Participants Enrolled and Randomized to Targeted Vitamin D Treatment: The Target D Trial

Abstract

Background: Low vitamin (vit) D serum levels in observational data are associated with increased cardiovascular (CV) events. Prevalence of vit D deficiency (≤20 ng/mL) in the USA is estimated at 40%. Meanwhile, doses for USA recommended dietary allowance (RDA) are 600-800 IU. Several randomized trials of vit D therapy did not use serum levels to target dosing, rather utilized doses from 2000 to 4000 IU daily. The Target-D trial utilizes an achieved vit D serum (>40 ng/mL) strategy. We provide an initial overview of dosing and titration to achieve vit D serum levels >40 ng/mL. Methods: Target-D (NCT: 02996721), a randomized event-driven trial, enrolled (April 2017-May 2023) a total of 632 (316/arm) acute coronary syndrome (ACS) patients to targeted vit D 3 treatment or standard of care. Vit D 3 supplementation was based on a dosing algorithm (Table 1). For baseline serum vit D >40, no supplementation is given, and participants return at 12-months for reassessment. Those with a baseline serum vit D ≤40, the algorithm is applied, and participants return in 3-month intervals for assessment and dosing adjustment, until levels are >40 ng/mL. Results: Of the 316 (62.8±11.3 yrs, 23.1% female, 90% white) treatment participants, 89.4% (n=279) required vit D 3 dosing. Mean serum vit D was 25.9±11.5 ng/mL (median: 24, range: 5-84). Table 2 shows the percent of participants achieving >40 ng/mL at each interval by dose. Only 13.5% of participants were able to achieve >40 ng/mL using < 2000 IU, 20.8% needed 3000-4000 IU, 51% needed 5000-8000 IU, and 14.6% required > 10,000 IU. Conclusions: At our center, ACS patients have low serum vit D levels. Participants randomized to vit D 3 required doses well above US daily RDA, with 86.5% requiring >2,000 daily and 14.6% requiring > 10,000 IU. Less than 65% achieved >40 at 3 months, another 25% required 6 months. Contemporary vit D studies may have underdosed study participants, potentially achieving treatment serum levels less than “therapeutic”.