Prognostic value of systemic immune-inflammatory index in hospitalized adolescent COVID-19 patients

Background: A new parameter called systemic immune-inflammatory index (SII), which is based on neutrophil-lymphocyte ratio (NLR) and platelet count, is used to examine the inflammatory and immune status of patients. The aim of this study was to evaluate the prognostic value of SII in adolescents diagnosed with COVID-19 and to compare SII with other biomarkers such as C-reactive protein (CRP)/albumin (Alb) ratio, D-dimer, lactate and NLR. Methods: The medical records of hospitalized adolescent COVID-19 patients between April 1, 2020, and March 31, 2022, were retrospectively reviewed. A cut-off value for SII was obtained to examine the predictive value of SII for intensive care unit (ICU) admission as the primary outcome. Results: A total of 177 patients with a mean age of 165.89 ± 26.60 months were included in the study. 97 (54.8%) of the patients were male. The most common presenting symptom was fever (n:102, 57.6%). Median (IQR) SII was 799 (951), lactate 1.9 (1.53), NLR 10.19 ± 6.77 and CRP/Alb ratio 1.55 (2.61). The cut-off value for SII in predicting ICU admission was ≥1111 (sensitivity, 78.6%; specificity, 75.2%; +likelihood ratio, (3.32); -likelihood ratio, 0.30; AUC:0.768) (p 0.05). Conclusion: The results of this study suggest that a high SII during hospitalization is associated with an increased likelihood of ICU admission in patients hospitalized with COVID-19. Although additional studies are needed to confirm and validate these findings, the evidence of this study supports SII is a valuable prognostic predictor of hospitilized patients with COVID-19.