BACKGROUND: Systemic immune-inflammation index (SII) is a novel inflammatory marker, and inflammation may contribute significantly to the aetiology of stress urinary incontinence (SUI), in addition to recognized factors. This study aims to explore the association between SII and SUI in women. METHODS: Adult participants from the 2007-2018 NHANES were included. Weighted multivariate logistic regression and subgroup analysis were conducted to determine the relationship between SII and SUI. The non-linear relationship between SII and SUI risk was evaluated using restricted cubic splines (RCS), and the inflection point was determined by two-piecewise logistic regression. RESULTS: A total of 10,776 women were included, of whom 4407 (40.9%) had SUI. After adjusting for all confounders, a significant positive association between SII and SUI risk was observed (OR: 1.09
95% CI: 1.01-1.19, CONCLUSION: Our findings suggest an association between elevated SII levels and an increased likelihood of SUI in women. Further well-designed prospective studies are needed to substantiate our results.