Metabolic syndrome, obesity-related indicators, and incident urinary tract infection: a UK Biobank cohort study with TyG-related indices as core mediators

Objective To explore the causal association of metabolic syndrome (MetS) and obesity-related indicators with incident urinary tract infection (UTI), and the underlying mediating mechanisms. Methods A total of 382,791 participants free of baseline UTI from the UK Biobank were included, with a median follow-up of 13.05 years. Exposures were MetS and obesity-related indicators, outcome was incident UTI. IPW-adjusted and multivariable Cox proportional hazards models were used to assess the exposure-outcome association, RCS for nonlinear dose-response analysis, and counterfactual-based mediation analysis to explore the mediating effect of TyG-related indices. Results During follow-up, 19,097 participants developed incident UTI. MetS was identified as an independent risk factor for UTI, with a significant cumulative effect of increasing nMetS. RCS analysis demonstrated a significant L-shaped inverse association between LDL-C/TC levels and UTI risk (all P for nonlinearity < 0.05). TyG-derived indices were confirmed as the core mediators, with a mediated proportion ranging from 14.69% to 69.62%. Conclusions MetS is independently associated with an increased risk of incident UTI, mainly driven by central obesity and insulin resistance. Metabolic control and early intervention in high-risk individuals represent a promising public health approach for UTI prevention, rational antibiotic use and antimicrobial resistance mitigation.