Correlation of admission serum 25-hydroxyvitamin D levels and clinical outcomes in critically ill medical patients

Abstract

Summary: Purpose: The aim of this study was to determine the incidence of hypovitaminosis D and the correlation of admission serum 25-hydroxyvitamin D (25-OHD) levels and clinical outcomes in critically ill medical patients. Methods: A prospective, observational study was conducted. All critically ill medical patients admitted to the medical ICU were recruited. Blood sampling for serum 25-OHD was taken within 24 h after ICU admission. The levels of 25-OHD were dichotomized into deficiency and sufficiency groups. A serum 25-OHD level <20 ng/dL was defined as a vitamin D deficiency. All demographic data as well as biochemical tests were recorded. The primary outcome was incidence of hypovitaminosis D and 28-day mortality. The secondary outcomes were ICU and hospital mortality, ICU and hospital length of stay, mechanical ventilator days, and ICU-acquired infection. Results: From 116 cases, the incidence of hypovitaminosis D was 64.66%. The median serum 25-OHD was 15.1 (3.0, 67.2) ng/dL. There was no difference in 28-day mortality between the vitamin D statuses (20% vs. 17.1%, p = 0.70). However, the ICU-acquired infection tended to be higher in the vitamin D deficiency group but this was not statistically significant (25.3% vs. 19.5%, p = 0.07). Other secondary outcomes were comparable between the groups. Vitamin D levels were significantly correlated to the severity of illness of critically ill medical patients (r = −0.258, p = 0.005.) Conclusions: The incidence of hypovitaminosis D in critically ill medical patients in our region was high. In this current finding, vitamin D deficiency in critically ill medical patients may not related to 28-day mortality, ICU and hospital mortality, ICU and hospital length of stay, mechanical ventilator days or ICU-acquired infection, but vitamin D levels were significantly correlated to the severity of the illness. However, the larger study is required to confirm this finding. Trial registration: The study protocol is retrospectively registered at the Thai Clinical Trial Registry (TCTR) with the identification number TCTR20180211004. Keywords: 25-hydroxyvitamin D, Hypovitaminosis D, Vitamin D deficiency, Critically ill patients, Mortality