Associations between abdominal obesity and stress urinary incontinence in women: Findings from a cross-sectional study and Mendelian randomization analysis

Background Stress urinary incontinence (SUI) significantly impairs women's quality of life. Identifying modifiable risk factors is critical for interventions. Although abdominal obesity may be contributors, the roles of novel indices such as A Body Shape Index (ABSI) and the waist-to-hip ratio adjusted for BMI (WHRadjBMI) in SUI remain unclear. In this study, these associations were investigated using NHANES data and GWAS. Methods We analyzed 39,156 participants from NHANES (2011-2018) using weighted logistic regression and subgroup analyses to assess the relationship between ABSI and SUI. Two-sample Mendelian randomization (MR) analysis of GWAS data was used to evaluate the potential causal effect of genetically predicted WHRadjBMI on SUI risk. Heterogeneity was assessed via Cochrane's Q test and horizontal pleiotropy via MR-PRESSO. Results In the NHANES analysis, higher ABSI quartiles were significantly associated with increased SUI risk (Q4 vs. Q1) in model 1(OR = 2.565; 95%CI: 2.148-3.063; P < 0.001), model 2(OR = 2.359; 95%CI: 1.946-2.860; P < 0.001) and model 3 (OR = 2.080; 95%CI:1.627-2.660; P < 0.001). Subgroup analyses indicated consistent ABSI-SUI associations across strata ( P < 0.05). In the MR analysis, genetically predicted WHRadjBMI showed a positive but very modest association with SUI risk (OR = 1.004; 95%CI:1.001-1.006; P = 0.003), with no evidence of pleiotropy or heterogeneity ( P > 0.05). Conclusion Our cross-sectional findings indicate that abdominal obesity, as measured by ABSI, is associated with an increased risk of SUI in women. In addition, genetically proxied abdominal obesity (WHRadjBMI) shows a positive but very modest association with SUI risk in the MR analysis.