Remission and Transition of Female Urinary Incontinence and Its Subtypes and the Impact of Body Mass Index on This Progression: A Nationwide Population-Based 4-Year Longitudinal Study in China

We estimated the remission and transition rate between urinary incontinence (UI) subtypes in women with UI and evaluated the impact of body mass index (BMI) on this process. MATERIALS AND METHODS: A Chinese population-based longitudinal study was conducted. Women aged ≥20 years were included using a multistage, stratified, cluster sampling method. Self-reported data on demographics, medical history, and physiological and anthropometric information were collected. UI was identified using 2 questions about any leaking symptom of stress UI (SUI) and urgency UI (UUI) in the past 6 months. Predicted probabilities of UI subtypes were calculated using multinomial logistic regression. RESULTS: Analyses included 5,189 women (mean age 52.6 years, mean BMI 23.8 kg/m(2)), of whom 98.5% were parous. The median followup time was 4.0 years. Overall, the annual remission rate of UI was 12.7% among adult women. Regarding UI subtypes, the remission rates for UUI and SUI were similar, but higher than that for mixed urinary incontinence (MUI; p <0.05). In total, 7.6% of SUI patients and 16.4% of UUI patients developed MUI, and 35.3% of MUI patients continued to report MUI after 4 years. For women aged ≥60 years with a BMI ≥24 kg/m(2) and MUI at onset, the predicted remission rate (95% CI) was only 0.32 (0.29–0.35), but the predicted probability of the MUI remaining reached 0.50 (0.46–0.54). CONCLUSIONS: The annual remission rate of UI was 12.7% among adult women. Women with a higher BMI had less remission and a higher predicted probability of MUI 4 years later.