11 Vitamin D Deficiency on Admission and the Association with Length of Stay in Patients with Thermal Injury: A Multi-center Analysis

Abstract

Abstract Introduction In burn patients, vitamin D deficiency has been associated with increased incidence of sepsis. The objective of this study was to assess the impact of vitamin D deficiency in adult burn patients on hospital length of stay (LOS). Methods This was a multi-center retrospective study of adult patients at 7 burn centers admitted between January 1, 2016 and July 25, 2019 who had a 25-hydroxyvitamin D (25OHD) concentration drawn within the first 7 days of injury. Patients were excluded if admitted for a non-burn injury, total body surface area (TBSA) burn less than 5%, pregnant, incarcerated, or made comfort care or expired within 48 hours of admission. The primary endpoint was to compare hospital LOS between burn patients with vitamin D deficiency (defined as 25OHD < 20 ng/mL) and sufficiency (25OHD ≥ 20 ng/mL). Secondary endpoints include in-hospital mortality, ventilator-free days of the first 28, renal replacement therapy (RRT), length of ICU stay, and days requiring vasopressors. Additional data collected included demographics, Charlson Comorbidity Index, injury characteristics, form of vitamin D received (ergocalciferol or cholecalciferol) and dosing during admission, timing of vitamin D initiation, and form of nutrition provided. Dichotomous variables were compared via Chi-square test. Continuous data were compared via student t-test or Mann-Whitney U test. Univariable linear regression was utilized to identify variables associated with LOS (p < 0.05) to analyze further. Cox Proportional Hazard Model was utilized to analyze association with LOS, while censoring for death, and controlling for TBSA, age, presence of inhalation injury, and potential for a center effect. Results Of 1,147 patients screened, 412 were included. Fifty-seven percent were vitamin D deficient. Patients with vitamin D deficiency had longer LOS (18.0 vs 12.0 days, p < 0.001), acute kidney injury (AKI) requiring RRT (7.3 vs 1.7%, p = 0.009), more days requiring vasopressors (mean 1.24 vs 0.58 days, p = 0.008), and fewer ventilator free days of the first 28 days (mean 22.9 vs 25.1, p < 0.001). Univariable analysis identified burn center, AKI, TBSA, inhalation injury, admission concentration, days until concentration drawn, days until initiating supplementation, and dose as significantly associated with LOS. After controlling for center, TBSA, age, and inhalation injury, the best fit model included only deficiency and days until vitamin D initiation. Conclusions Patients with thermal injuries and vitamin D deficiency on admission have increased length of stay and worsened clinical outcomes as compared to patients with sufficient vitamin D concentrations.