Background: The management of septic patients hospitalized in Internal Medicine wards represents a challenge due to their complexity and heterogeneity, and a high mortality rate. Among the available prognostic tools, procalcitonin (PCT) is considered a marker of bacterial infection. Furthermore, an association between vitamin D deficiency and poor sepsis-related outcomes has been described. Objectives: To evaluate the prognostic accuracy of two consecutive PCT determinations (Delta-PCT) and of vitamin D levels in predicting mortality in a population of patients with microbiological identified sepsis admitted to Internal Medicine wards. Methods: This is a sub-analysis of a previous prospective study. A total of 80 patients had at least two available consecutive PCT determinations, while 63 had also vitamin D. Delta-PCT was defined as a reduction of PCT > 50% after 48 h, >75% after 72 h, and >85% after 96 h. Mortality rate at 28- and 90-days were considered as main outcome. Results: Mortality rate was 18.7% at 28-days and 30.0% at 90-days. Baseline PCT levels did not differ between survived and deceased patients (28-days: p = 0.525; 90-days: p = 0.088). A significantly higher proportion of survived patients showed Delta-PCT (28-days: p = 0.002; 90-days: p p = 0.007; OR = 0.12, 95%CI 0.02–0.46) and 90-days mortality (p = 0.001; OR = 0.17, 95%CI 0.06–0.48). A significantly higher proportion of deceased patients showed severe vitamin D deficiency (28-days: p = 0.047; 90-days: p = 0.049). Severe vitamin D deficiency was associated with a higher 28-days (p = 0.058; OR = 3.95, 95%CI 1.04–19.43) and 90-days mortality (p = 0.054; OR = 2.94, 95%CI 1.00–9.23). Conclusions: Delta-PCT and vitamin D represent two useful tests for predicting prognosis of septic patients admitted to Internal Medicine wards.
