ABSTRACT
<p><b>BACKGROUND</b>Hospitalized patients often have higher rate of vitamin D deficiency than healthy people. Vitamin D levels below normal are associated with hospital stay, increased incidence of adverse prognosis and increased mortality of a number of diseases. Whether there is a relationship between vitamin D levels and infection or sepsis in the critically ill is still unclear. This study will explore the relationship between vitamin D levels and risk of infection, assessment for disease severity, and predictor of mortality.</p><p><b>METHODS</b>To evaluate the value of vitamin D in intensive care unit (ICU) cases to sepsis, severity and prognosis assessment, high performance liquid chromatography and tandem mass spectrometry were used to measure the concentrations of vitamin D in sera of critically ill patients. The serum samples were drawn within the first 24 hours of ICU admission.</p><p><b>RESULTS</b>The study included 206 people, 50 healthy controls, 51 ICU control patients and 105 ICU diagnosed with sepsis. Critically ill ICU patients (ICU sepsis and ICU control group) had lower vitamin D concentration than normal people, but septic patients showed no significant reduction of vitamin D concentration when compared with critically ill patients with no positive etiological evidence. For assessment of disease severity, there were very low negative correlations between APACHE II, SAPS II and SOFA scores and vitamin D level. Additionally, patients of different 25-(OH)D levels showed no difference whether in terms of 28-day survival (X(2) = 1.78, P = 0.776) or 90-day survival (X(2) = 4.12, P = 0.389). Multivariate Logistic regression demonstrated that APECHE II and SAPS II scores were independent risk factors to deaths caused by sepsis.</p><p><b>CONCLUSION</b>Clinically, serum concentration of vitamin D is not an indicator for diagnosis and assessment in critically ill patients (ClinicalTrial.gov identifier NCT01636232).</p>