Association between the aggregate index of systemic inflammation and chronic kidney disease in adults: A cross-sectional study of NHANES 2007–2018

Chronic kidney disease (CKD) is closely linked to chronic inflammation, which plays a key role in its progression. The study aimed to investigate the association between the aggregate index of systemic inflammation (AISI) and CKD prevalence. We analyzed data from the National Health and Nutrition Examination Survey, which was conducted between 2007 and 2018. Multivariate logistic regression analyses were used to assess the independent relationship between AISI and CKD. Nonlinear relationships between AISI and CKD were examined through smooth curve fitting and threshold effect analyses. A total of 24,386 adult participants were included. After controlling for possible confounding variables, a significant positive association between AISI and CKD was identified (OR = 1.05, [95% CI: 1.03-1.07], P < .001). Subgroup analyses and interaction tests revealed significant differences in this association across diabetes strata (P < .05). Smoothing curve analysis demonstrated a nonlinear positive correlation between AISI and CKD. Moreover, threshold analysis revealed a saturation effect with an inflection point at 720 (1000 cells/μL). Below this threshold (AISI < 720, 1000 cells/μL), AISI was significantly positively associated with CKD, while no significant association was observed above the threshold (AISI > 720, 1000 cells/μL). These findings reveal a notable positive correlation between AISI and CKD among adults in the United States, with an inflection point at 720 (1000 cells/μL). The AISI shows potential as an indicator associated with CKD, but further comprehensive prospective studies are needed to confirm its role in CKD development and its utility in clinical practice.