The association between the metabolic score for insulin resistance (METS-IR) index and urinary incontinence in the United States: results from the National Health and Nutrition Examination Survey (NHANES) 2001–2018

Abstract

Background The association between insulin resistance and urinary incontinence (UI) has not been investigated widely. The purpose of this study is to assess the relationship between a novel indicator for assessing insulin resistance the metabolic score for insulin resistance (METS-IR) index and urinary incontinence (UI). Methods This study utilized data from National Health and Nutrition Examination Survey (NHANES) 2001–2018. Weighted multivariable logistic regression models were conducted to explore the association of METS-IR index with three types of UI [stress UI (SUI), urgency UI (UUI), and mixed UI (MUI)]. Smooth curve fitting was utilized to investigate the linear relationship. Subgroup analysis was used to examine the stability of the connection between METS-IR index and UI in different stratifications. Results A total of 17,474 participants were included in this study, of whom 23.76% had SUI, 20.05% had UUI, and 9.59% had MUI. METS-IR index was positively associated with three types of UI with full adjustment [SUI: odds ratio (OR) = 1.023, 95% confidence interval (CI) 1.019–1.027; UUI: OR = 1.015, 95% CI 1.011–1.019; MUI: OR = 1.020, 95% CI 1.016–1.025, all p < 0.001]. After transferring METS-IR index into a categorical variable by quartiles, the positive connection between METS-IR index and UI was still observed in the highest METS-IR group compared to the lowest METS-IR interval (SUI: OR = 2.266, 95% CI 1.947–2.637, p < 0.001; UUI: OR = 1.534, 95% CI 1.344–1.750, p < 0.001; MUI: OR = 2.044, 95% CI 1.707–2.448, p < 0.001). The analysis of smooth curves fitting showed that METS-IR index was positively linearly related to three types of UI. Moreover, the association between METS-IR index and SUI was more significant in females compared to males (p for interaction < 0.05). Conclusion An elevated METS-IR index was related to increased risks of three types of UI (SUI, UUI, and MUI) in the United States population. METS-IR index was more significantly connected to SUI in females than males. The association between insulin resistance and UI needs to be explored with more studies.