Prevalence and Risk Factors of Urinary Incontinence and Overactive Bladder in Japanese Women

The prevalence of storage symptoms, including stress urinary incontinence (SUI) and overactive bladder (OAB), is high in women worldwide. In Japan, there have been few large-scale epidemiological surveys of lower urinary tract symptoms (LUTS), and the risk factors for these symptoms are unclear. The aim of this study was to explore the prevalence and risk factors of storage symptoms in Japanese women.

A cross-sectional Internet survey was conducted in Japan. Five thousand women aged 20-79 years were selected to answer demographic questionnaires, Japanese version of International Consultation on Incontinence Questionnaire-Short Form, and the Overactive Bladder Symptom Score (OABSS) pertaining to their symptoms in the previous month. Descriptive statistics were used to evaluate the prevalence of storage symptoms. Logistic regression analysis was performed to determine risk factors for SUI and OAB.

The answers from 4804 women (average age, 40.4 years) were analyzed. The prevalence of SUI was 16.7% (SUI, 13.0%; mixed urinary incontinence, 3.7%). The prevalence of OAB diagnosed on OABSS was 8.1%. The prevalence of SUI and OAB symptoms increased with age, and 68.0% of women had one or more storage symptoms. Age ≥40 years, body mass index ≥25 kg/m² , and constipation were common risk factors for SUI and OAB. Childbirth was an additional risk factor for SUI.

The prevalence of storage symptoms in Japanese women was high, and risk factors associated with these symptoms were similar to those reported in studies in other countries.