Background: We preliminarily established the reference intervals for the systemic immune-inflammation index (SII), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and lymphocyte to monocyte ratio (LMR) in healthy adults in Jiangsu region in Eastern China to guide the interpretation and application of these indicators in clinical practice.
Methods: In total, 29,947 ostensibly healthy subjects from December 2020 to March 2021 were included in this study. The distributions of the SII, NLR, PLR, and LMR were analyzed using the Kolmogorov-Smirnov test. According to the C28-A3 guidelines, the 2.5th and 97.5th percentiles (P2.5 to P97.5) of the SII, NLR, PLR, and LMR were used to establish the reference intervals based on nonparametric methods.
Results: All SII, NLR, PLR, and LMR data were non-normally distributed. The levels of the SII, NLR, PLR, and LMR in healthy adults were significantly different between males and females (all p < 0.05). However, there were no significant differences in the SII, NLR, PLR or LMR among the different age groups, regardless of gender (all p > 0.05). Therefore, the reference intervals for the SII, NLR, PLR, and LMR were established based on the Sysmex testing platform for males (162 × 109/L - 811 × 109/L; 0.89 - 3.26; 63.15 - 191.34; 3.18 - 9.61) and females (165 × 109/L - 792 × 109/L; 0.87 - 3.16; 69.04 - 205.62; 3.46 - 10.96).
Conclusions: We have established the reference intervals for SII, NLR, PLR, and LMR in healthy adults based on the Sysmex detection platform and large sample size, which may provide important guidance for its clinical application.