Does BMI affect treatment outcomes following intradetrusor onabotulinumtoxinA (Botox) injection in patients with Overactive Bladder (OAB)?

Overactive bladder (OAB) is a common condition among women, often impairing quality of life and frequently associated with obesity. Intradetrusor onabotulinumtoxinA (BoNT/A) is an established treatment for refractory OAB; however, the influence of body mass index (BMI) on treatment outcomes remains unclear. This retrospective cohort study examined whether obesity impacts subjective and objective treatment responses in women undergoing BoNT/A injections for refractory OAB. Data were collected from the British Society of Urogynaecology (BSUG) database for patients treated between 2013 and 2023 at a tertiary Urogynaecology Centre in the United Kingdom. Of 522 initial cases, 285 women met inclusion criteria. Patient-reported satisfaction at 6 months post-injection and changes in International Consultation on Incontinence Questionnaire - Overactive Bladder (ICIQ-OAB) scores were evaluated. Women were stratified into BMI <30 and BMI ≥30 groups. Satisfaction rates were high and nearly identical between groups (76.8 % vs. 77.0 %, p = 0.973). Likewise, mean change in ICIQ-OAB scores showed minimal and statistically insignificant differences between BMI categories (p = 0.71). Logistic and linear regression analyses, adjusting for age and BoNT/A dose, confirmed that BMI was not a significant predictor of either patient satisfaction or symptom score improvement. Neither age nor BoNT/A dose significantly influenced outcomes. These findings suggest that BMI does not affect the efficacy of BoNT/A treatment for OAB, supporting its use irrespective of weight status. Clinically, BoNT/A remains a valuable therapeutic option for women with refractory OAB, while weight loss should continue to be encouraged for its broader health benefits, including improvements in urinary continence.