The Systemic Inflammation Index on admission is independently associated with length of stay in hospitalized COVID-19 patients

Zinellu, A.; Scano, V.; Masotto, E.; De Riu, G.; Vaira, L. A.; Carru, C.; Pirina, P.; Babudieri, S.; Mangoni, A. A.; Fois, A. G.

BACKGROUND: The early detection of factors predicting hospital length of stay (LOS) in patients affected by severe acute respiratory syndrome in Coronavirus 2 (SARS-CoV-2) disease (COVID-19) might facilitate therapeutic decisions and patient flow management. METHODS: We collected routine clinical and laboratory parameters and derived inflammatory indexes on admission in 65 consecutive COVID-19 patients transferred to the Unit of Respiratory and Infectious Disease of the University Hospital of Sassari (North-Sardinia, Italy) who were alive on discharge. RESULTS: Patients with prolonged length of stay (LOS) (PLOS >= 26 days, N.=22) had significantly higher chest CT severity scores, neutrophils, neutrophil lymphocyte ratio (NLR), aggregate index of systemic inflammation, Systemic Inflammation Response Index, Systemic Inflammation Index (SII), aspartate aminotransferase, lactate dehydrogenase (LDH), and rates of obesity and respiratory support, than non-PLOS patients (N.=43). In univariate analysis, LOS was significantly and negatively correlated with lymphocytes and monocytes, and positively correlated with Body Mass Index (BMI), intensity of care, chest CT severity score, NLR, platelet lymphocyte ratio, SII and LDH. In multivariate regression analysis, only the SII was significantly associated with LOS (beta=0.506, P=0.002) after adjusting for BMI, intensity of care, chest CT severity score and LDH. CONCLUSIONS: SII values on admission were independently associated with LOS in COVID-19 patients. Prospective studies in larger cohorts are required to confirm our findings and to determine the role of the SII in clinical decision making.