According to the a National Health Survey, the prevalence of overweight in >18 years old women in Spain is 30.1% and that of obesity is 16.7% [1]. Obesity is one of the main risk factors for urinary incontinence (UI) which is usually classified into stress (SUI), urgency (UUI) or mixed (MUI). It has been hypothesized that obesity increases abdominal pressure, thereby stressing the pelvic floor and contributing to SUI. However, abdominal pressure could also contribute to UI by causing detrusor instability. The lipotoxicity or adiposopathy hypothesis states that a chronic low-grade inflammation in the bladder of obese women can lead to an altered contractility of the bladder [2]. The aim of this study is to describe the relationship between Body Mass Index (BMI) and the type and severity or UI.

A retrospective analysis was performed on a sample of 308 women whose primary symptom was UI, between October 2022 and January 2024. Clinical data, physical examination and scores from the ICIQ-UI and ICIQ-OAB questionnaires were collected. The ICIQ-UI questionnaire quantifies the frequency, severity and impact on quality of life of UI and allows its classification into the different types of UI: SUI, UUI or MUI. The ICIQ-OAB quantifies the severity and impact on quality of life of polakiuria, nocturia, urgency and UUI. BMI (weight/height*height) was calculated and classified into normal weight (18-24.9), overweight (25-29.9) and obese (>30). The relationship between BMI and type and severity of UI was calculated (Kruskal-Wallis test). Similarly, the relationship between BMI and the severity of polakiuria, nocturia, urgency and UTI was determined.

Type of UI sample distribution was: SUI 27%, UUI 24.6%, MUI 48.4% and other types of UI 18.2%. A statistically significant relationship was found between BMI and UI severity (median ICIQ- UI score) in patients with UUI (normal weigth 11, overweight 14, obesity 15, p<0.05), but not in SUI (normal weight 10.5, overweight 13, obesity 14.5, p=0.143) nor MUI (15.5; 15 and 18, respectively, p=0.072). There were significant differences in OAB symptoms by BMI: nocturia in SUI (1, 1, 2, p<0.05), for nocturia, urgency and UUI in UUI (1, 2, 2, 2, p<0.005; 2, 2, 3, p<0.05 and 1, 1, 2, p<0.05 respectively) and UUI in MUI (1, 1, 3, p<0.05) (Table 1).

The type and severity of UI is closely related to BMI. In fact, UUI is more strongly related to overweight and obesity than SUI. Furthermore, BMI is an independent factor for all OAB symptoms except frequency.

There is a stronger relationship between OAB symptoms and obesity than for other types of UI.

1. Enrique GG. "Prevalencia de sobrepeso y obesidad en España en el informe “The heavy burden of obesity” (OCDE 2019) y en otras fuentes de datos".  2019. Spanish Department of Health.
2. Vissers D, Neels H, Vermandel A, De Wachter S, Tjalma W a. A, Wyndaele JJ, et al. The effect of non-surgical weight loss interventions on urinary incontinence in overweight women: a systematic review and meta-analysis. Obesity Reviews. 2014;15(7):610-7.