Mediating role of SII in the association between LC9 and overactive bladder

Extensive research suggests a potential association between the overactive bladder (OAB), Life's Crucial 9 (LC9), and the systemic immune-inflammation index (SII). However, the exact mechanisms linking LC9 and OAB through inflammation-related pathways remain unclear. LC9 is a novel composite index for assessing cardiovascular health, while SII is an emerging marker that reflects systemic immune-inflammatory status. This study aims to explore the relationship between LC9 and OAB and to evaluate whether SII mediates this association. The association between LC9 and OAB was investigated using subgroup analysis, restricted cubic splines (RCS), and multivariable logistic regression. A mediation analysis was also conducted to investigate any possible correlation between SII levels and the link between LC9 and OAB. The analysis included 25,634 participants, of whom 5,162 reported incidents of OAB. After adjusting for all covariates using multivariable logistic regression, a 10-point increase in LC9 was associated with a 27% reduction in OAB incidence (OR = 0.73, 95% CI: 0.70, 0.76), while per 100-unit increase in SII was linked to a 2% rise in OAB incidence (OR = 1.02, 95% CI: 1.01, 1.04). Restricted cubic spline (RCS) analysis revealed a linear relationship between LC9 and OAB risk. Mediation analysis indicated that SII mediated 1.39% of the association between LC9 and OAB (p = 0.022). This study found a significant negative correlation between LC9 and OAB, with SII playing a partial mediating role in this relationship. These findings emphasize the potential link between cardiovascular health and OAB and highlight the importance of anti-inflammation in reducing the incidence of OAB.