Association between systemic immune-inflammation index and serum uric acid in U.S. adolescents: A population-based study

Background and aims Serum uric acid (SUA) has been reported to be associated with inflammation, and elevated SUA is increasingly prevalent in adolescents. The systemic immune-inflammation index (SII) is an innovative and integrated inflammatory indicator that has not yet been studied with SUA in adolescents. We therefore aimed to investigate the potential relationship between SII and SUA in U.S. adolescents. Methods and results A total of 5,568 adolescents aged 12–19 years from NHANES 2009–2018 were analyzed. SII was calculated as platelet count × neutrophil count/lymphocyte count. Elevated SUA was defined as ≥ 5.5 mg/dL. SII was Ln-transformed for analysis for the skewed distribution. Multivariate linear and multiple logistic regression analyses were conducted to explore the association of SII with SUA and elevated SUA. A generalized additive model and a fitted smoothing curve were also performed. The prevalence of elevated SUA was 35.4%. Multivariate linear regression analyses indicated that LnSII was positively associated with SUA level (β = 0.15, 95% CI: 0.09–0.20). Multiple logistic analyses indicated that LnSII was associated with a 38% increased risk of elevated SUA (OR = 1.38, 95% CI: 1.11–1.70). The smooth curve fitting showed that the associations of LnSII with SUA and elevated SUA were linear. Besides, subgroup analyses showed a stronger association between LnSII and SUA in adolescents aged ≥ 17 years (P for interaction < 0.05). Conclusions SII was positively associated with SUA level and elevated SUA in U.S. adolescents, particularly in populations aged ≥ 17 years.