Objective:To explore the association between the systemic immune-inflammation index (SII) and obesity metabolic phenotypes, as well as metabolic features in children and adolescents.Methods:A cross-sectional study was conducted using the random cluster sampling method from March 2023 to May 2024. Children and adolescents aged 9-17 years in Guangzhou were surveyed through questionnaires, physical measurements, and blood tests. According to BMI and metabolic status, participants were classified into normal-weight groups [metabolically healthy normal weight (MHNW) and metabolically unhealthy normal weight (MUNW)] and overweight/obese groups [metabolically healthy overweight/obese (MHO/O) and metabolically unhealthy overweight/obese (MUO/O)]. After natural log-transformation of SII values (lnSII), multinomial logistic regression was used to assess the association between SII and obesity metabolic phenotypes, while binary logistic regression was applied to assess the relationship between SII and metabolic phenotypes in the overweight/obese subgroup. Linear regression model and restricted cubic spline (RCS) were employed to examine the relationship between SII and metabolic features among the entire population.Results:A total of 3 749 participants were included. After adjusting for covariates, for every unit increase in lnSII, the risk of MHO/O and MUO/O increased by 93% ( OR=1.93, 95% CI: 1.56-2.40, P<0.001) and 156% ( OR=2.56, 95% CI: 2.02-3.25, P<0.001), respectively. In the overweight/obesity subgroup, for every unit increase in lnSII, the risk of MUO/O increased by 37% ( OR=1.37, 95% CI: 1.01-1.87, P=0.045). Linear regression model and RCS showed that lnSII was positively correlated with systolic blood pressure (SBP) and diastolic blood pressure (DBP) (SBP: β=1.39, 95% CI: 0.67-2.11, P<0.001; DBP: β=1.27, 95% CI: 0.79-1.75, P<0.001). lnSII also had a non-linear relationship with triglyceride ( Pnonlinear=0.032) and high-density lipoprotein cholesterol ( Pnonlinear=0.002). Conclusion:Elevated SII levels are associated with unfavorable obesity metabolic phenotypes, higher blood pressure, and altered lipid profiles in children and adolescents. SII may be a potential driving factor for metabolic heterogeneity in children and adolescents.

Objective:To explore the association between the systemic immune-inflammation index (SII) and obesity metabolic phenotypes, as well as metabolic features in children and adolescents.Methods:A cross-sectional study was conducted using the random cluster sampling method from March 2023 to May 2024. Children and adolescents aged 9-17 years in Guangzhou were surveyed through questionnaires, physical measurements, and blood tests. According to BMI and metabolic status, participants were classified into normal-weight groups [metabolically healthy normal weight (MHNW) and metabolically unhealthy normal weight (MUNW)] and overweight/obese groups [metabolically healthy overweight/obese (MHO/O) and metabolically unhealthy overweight/obese (MUO/O)]. After natural log-transformation of SII values (lnSII), multinomial logistic regression was used to assess the association between SII and obesity metabolic phenotypes, while binary logistic regression was applied to assess the relationship between SII and metabolic phenotypes in the overweight/obese subgroup. Linear regression model and restricted cubic spline (RCS) were employed to examine the relationship between SII and metabolic features among the entire population.Results:A total of 3 749 participants were included. After adjusting for covariates, for every unit increase in lnSII, the risk of MHO/O and MUO/O increased by 93% ( OR=1.93, 95% CI: 1.56-2.40, P<0.001) and 156% ( OR=2.56, 95% CI: 2.02-3.25, P<0.001), respectively. In the overweight/obesity subgroup, for every unit increase in lnSII, the risk of MUO/O increased by 37% ( OR=1.37, 95% CI: 1.01-1.87, P=0.045). Linear regression model and RCS showed that lnSII was positively correlated with systolic blood pressure (SBP) and diastolic blood pressure (DBP) (SBP: β=1.39, 95% CI: 0.67-2.11, P<0.001; DBP: β=1.27, 95% CI: 0.79-1.75, P<0.001). lnSII also had a non-linear relationship with triglyceride ( Pnonlinear=0.032) and high-density lipoprotein cholesterol ( Pnonlinear=0.002). Conclusion:Elevated SII levels are associated with unfavorable obesity metabolic phenotypes, higher blood pressure, and altered lipid profiles in children and adolescents. SII may be a potential driving factor for metabolic heterogeneity in children and adolescents.