Prospective Study of Vitamin D Status at Initiation of Care in Critically III Surgical Patients and Risk of 90-Day Mortality

Objectives: 1) To characterize vitamin D status at initiation of critical care in surgical ICU patients and 2) to determine whether this vitamin D status is associated with the risk of prolonged hospital length of stay, 90-day readmission, and 90-day mortality. Design: Prospective cohort study. Setting: A teaching hospital in Boston, MA. Patients: Hundred surgical ICU patients. Interventions: None. Measurements and Main Results: Mean ( sd) serum total 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels were 17 +/- 8 ng/mL and 32 +/- 19 pg/mL, respectively. Mean calculated bioavailable 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were 2.5 +/- 2.0 ng/mL and 6.6 +/- 5.3 pg/mL, respectively. Receiver-operating characteristic curve analysis demonstrated that all of four vitamin D measures predicted the three clinical outcomes; total 25-hydroxyvitamin D was not inferior to the other measures. Median (interquartile range) hospital length of stay was 11 days (8-19 d). Poisson regression analysis, adjusted for biologically plausible covariates, demonstrated an association of total 25-hydroxyvitamin D with hospital length of stay (incident rate ratio per 1 ng/mL, 0.98; 95% CI, 0.97-0.98). The 90-day readmission and mortality rates were 24% and 22%, respectively. Even after adjustment for biologically plausible covariates, there remained significant associations of total 25-hydroxyvitamin D with readmission (odds ratio per 1 ng/mL, 0.84; 95% CI, 0.74-0.95) and mortality (odds ratio per 1 ng/mL, 0.84; 95% CI, 0.73-0.97). Conclusions: Serum 25-hydroxyvitamin D levels within 24 hours of ICU admission may identify patients at high risk for prolonged hospitalization, readmission, and mortality. Randomized trials are needed to assess whether vitamin D supplementation can improve these clinically relevant outcomes in surgical ICU patients.