Systemic Immune-Inflammation Index and Neutrophil-To-Lymphocyte Ratio: U-Shaped Association With Overactive Bladder

This study aims to examine the association of systemic immune-inflammation index (SII) and neutrophil-to-lymphocyte ratio (NLR) with the prevalence of overactive bladder (OAB).

This cross-sectional study analyzed data from 22,343 participants (≥ 20 years) in the National Health and Nutrition Examination Survey (2005-2018). We applied weighted multivariate logistic regression, restricted cubic spline (RCS) regression, subgroup, and sensitivity analyses to assess the associations between SII, NLR, and OAB.

RCS analysis revealed U-shaped relationships with inflection points at 6.13 for ln(SII) and 0.65 for ln(NLR). In the fully adjusted model, ln(SII) ≤ 6.13 showed a negative correlation with OAB (OR = 0.83; 95% CI: 0.70-0.99), while ln(SII) > 6.13 was positively correlated (OR = 1.32; 95% CI: 1.10-1.58). Similarly, ln(NLR) > 0.65 correlated positively with OAB (OR = 1.40; 95% CI: 1.16-1.71). Subgroup analyses revealed significant differences in alcohol use subgroups for ln(SII) ≤ 6.13 and ln(NLR) ≤ 0.65 (P for interaction < 0.05).

SII and NLR may serve as biomarkers for assessing OAB risk.