Association of stress urinary incontinence with serum 25-hydroxyvitamin D level in adult women: A cross-sectional analysis of the National Health and Nutrition Examination Survey (2005–2018) data

Objective To examine the association between serum 25-hydroxyvitamin D levels and stress urinary incontinence among women in the United States. Methods This cross-sectional analysis included data from 13,768 female participants of the National Health and Nutrition Examination Survey (2005–2018). Weighted multivariable logistic regression, subgroup analyses, and restricted cubic spline analysis were used to evaluate associations. Results Overall, 42% of the participants had stress urinary incontinence. In fully adjusted models, continuous serum 25-hydroxyvitamin D level was inversely associated with stress urinary incontinence (odds ratio = 0.98, 95% confidence interval: 0.96–1.00, p = 0.040). The highest quartile (fourth quartile, Q4) of 25-hydroxyvitamin D level also showed a significant inverse association with stress urinary incontinence (odds ratio = 0.81, 95% confidence interval: 0.68–0.96, p = 0.016). A significant interaction with smoking status was detected ( p < 0.001). Restricted cubic splines revealed a nonlinear relationship ( p -nonlinear = 0.012) with a threshold level of 73.8 nmol/L, and 25-hydroxyvitamin D levels beyond this value were associated with a reduced risk of stress urinary incontinence. Conclusion Higher 25-hydroxyvitamin D levels (≥73.8 nmol/L) are associated with a lower risk of stress urinary incontinence among women in the United States, indicating a nonlinear relationship. Further prospective studies are needed to confirm these findings.