608. ASSOCIATION BETWEEN SYSTEMIC IMMUNE-INFLAMMATION INDEX (SII) AND THE RISK OF ALL-CAUSE, CANCER, AND NON-CANCER MORTALITY IN THE GENERAL POPULATION

Abstract Background The system immune-inflammation index (SII), based on the counts of platelet, neutrophil and lymphocyte, was recognized as an accurate immunoinflammatory predictor. In order to identify the association between SII with all-cause, cancer and non-cancer mortality among general population, we conducted this prospective cohort study. Methods 25955 participants (≥ 18 years) were included from 2005-2018 National Health and Nutrition Examination Survey (NHANES) and grouped according to the SII quartiles. The association between SII and mortality was identified by multivariate Cox regression and restricted cubic spline (RCS) analyses. Survival outcomes were assessed using Kaplan-Meier analyse. Results In fully adjusted model, the adjusted hazard ratio (aHR) and 95% confidence intervals (CIs) of individuals in Q4 of SII were 1.24 (1.09, 1.41) for all-cause mortality and 1.41 (1.23, 1.63) for non-cancer mortality compared with Q1. The aHR and 95% CIs in Q2 of SII were 0.70 (0.50, 0.99) and in Q3 were 0.68 (0.52, 0.87) compared with Q1 for cancer mortality. In RCS analyses, J-shaped curves were observed in the association between SII with all-cause and non-cancer mortality. Additionally, a U-shaped curve was identified between SII and cancer mortality with a threshold SII value of 445.22. Conclusion Therefore, our findings imply that SII can serve as a potential prognosis indicator among general population. Elevated SII is associated with higher all-cause and non-cancer mortality. Besides, both lower and higher SII can serve as predictive factors for cancer mortality.