Effect of Vitamin D Supplementation on Bone Turnover Markers During PrEP in MSM

Overview

CCTG 595 is an open-label clinical trial of the effect of a text messaging intervention vs. standard of care on adherence to Truvada as PrEP in MSM at increased risk for HIV infection (ClinicalTrials.gov Identifier: NCT01761643). Eligible subjects for this matched case control substudy will receive vitamin D 4000 IU/day for 24 weeks, from week 24 through week 48. In CCTG 595, plasma from participants are being collected and stored at entry and every 12 weeks. These plasma samples will be used to measure P1NP, CTX, PTH, and vitamin D levels in both cases and controls at entry, week 24, and week 48.

A total of 50 HIV-uninfected men who have sex with men (MSM) and male to female (M to F) transgender individuals already enrolled in CCTG 595 will be offered participation in the sub-study at Week 24 of the main study. All subjects enrolled into the sub-study will be provided Vitamin D 4000 IU/day supplements in addition to their PrEP at Weeks 24 and 36; clinic visits will proceed normally per main study protocol. Upon completion of the sub-study subjects will continue on the main study. The primary endpoint, bone turnover markers, will be measured from Week 24 to Week 48 via plasma samples collected through the main study. Concurrent controls who are not enrolled in the vitamin D substudy who are reporting supplementation with \< 400 IU of vitamin D/day will be matched 1:1 by randomization arm in the CCTG 595 main study (text messaging arm vs. standard of care), age (± 5 years), race/ethnicity, season of study entry, and BMI (± 3 kg/m2).

Conditions