Association between Systemic Immune-Inflammation Index and stress urinary incontinence in adult women: a population-based study

Abstract

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 recognised factors. The aim of this study was to explore the associations between SII and SUI in women. Methods Adult participants (≥ 20 years) from the 2007–2018 NHANES were included. The SII level was calculated as the platelet count×neutrophil count/lymphocyte count. Weighted multivariate logistic regression and subgroup analysis were conducted to determine the relationship between SII and SUI in women. 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 adult 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, P = 0.021). Moreover, when compared with the patients in the lowest SII tertile, those in the highest SII tertile had a 15% increased risk of SUI (OR: 1.15; 95%CI: 1.00-1.31, P = 0.049) after adjustment for all confounders. Subgroup analysis showed that there were consistent relationships between SII level and SUI across most subgroups. A non-linear relationship between log₂SII and SUI was observed by RCS analysis. Furthermore, the two-piecewise logistic regression demonstrated that the odds of being SUI increased with the SII level, and this rising trend gradually slowed down after passing the inflection point of 8.64. 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