Introduction: To examine whether very low levels of 25-hydroxyvitamin D {25(OH)D} upon admission to the intensive care unit (ICU) are associated with worse outcomes.
Methods: Retrospective observational cohort study of critically ill patients treated in a multidisciplinary ICU. Two hundred twenty seven initially non-septic, critically ill patients, in whom 25-hydroxyvitamin D was measured at ICU admission. An additional group of 192 healthy subjects was also used. Patients were categorized according to their vitamin D levels at admission; the two patient groups were those with severely low 25-hydroxyvitamin D levels (<7 ng/mL, N = 101) and those with vitamin D levels ≥7 ng/mL, N = 126.
Results: ICU admission 25-hydroxyvitamin D levels of critically ill patients were much lower than those of healthy subjects (P < 0.0001). The median time to sepsis for the two patient groups did not differ, nor did the length of ICU stay (days). Both groups exhibited similar hospital mortality rates. However, among the fraction of patients who eventually became septic (N = 145), the odds ratio (OR) for developing respiratory infections in patients with admission vitamin levels < 7 ng/mL compared with patients with admission vitamin D levels ≥7 ng/mL was 5.25 {95% confidence interval (CI) 1.5-18.32, P = 0.009}.
Conclusions: Initially non-septic critically ill patients appear to have very low ICU admission 25-hydroxyvitamin D levels. Among critically ill patients, severely low vitamin D levels (<7 ng/mL) at ICU admission do not predict sepsis development, increased risk of in-hospital mortality, or longer stay in the ICU. However, these severely low admission vitamin D levels in patients who will eventually develop sepsis are associated with development of respiratory tract infections.