Abnormal blood 25-hydroxyvitamin D in critically ill patients: prevalence, predictors, and its association with in-hospital mortality

Background Abnormal vitamin D is prevalent in critical care settings, but its association with prognosis remains unclear. The study aimed to investigate the prevalence and predictors of abnormal blood 25-hydroxyvitamin D (25(OH)D), as well as its association with prognosis in critically ill patients. Methods Patients aged ≥ 18 years who were once admitted to the intensive care units (ICUs) of the Beth Israel Deaconess Medical Center between 2008 and 2019 with at least one measurement record of blood 25(OH)D were included as study population. Baseline characteristics associated with deficient or elevated blood 25(OH)D were investigated by univariable logistic regression analysis. The association between abnormal blood 25(OH)D and hospital mortality was examined by multivariable logistic regression analysis. Results A total of 1091 patients were included. Deficient 25(OH)D (< 30 ng/mL) was found in 790 (72.41%) patients and 17 (1.56%) were with an elevated level (> 60 ng/mL). A younger age, male, comorbid liver disease, and dialysis were risk factors of deficient blood 25(OH)D, while comorbid myocardial infarction, dementia, and rheumatic disease were protective factors evaluated by univariable logistic regression. Being admitted to cardiac vascular ICU or coronary care unit were associated with increased risk of elevated blood 25(OH)D. Patients with elevated blood 25(OH)D showed non-significantly higher hospital mortality compared to those with normal or deficient blood 25(OH)D (35.29% versus 14.44% and 14.56%, P = 0.058). After adjusted for potential confounding factors, elevated blood 25(OH)D was associated with increased risk of hospital mortality [odds ratio (OR) 3.80, 95% confidence interval (CI) 1.22–11.82, P = 0.021] when compared to those with normal blood 25(OH)D, but there was no significant association between deficient blood 25(OH)D and hospital mortality (OR 1.12, 95% CI 0.74–1.72, P = 0.589). Conclusions These findings suggest deficient blood 25(OH)D was rather common in critically ill patients, but was not an independent risk factor of hospital mortality, while elevated blood 25(OH)D was associated with worse prognosis.