Clinical predictors of symptom and quality-of-life improvement with antimuscarinics in overactive bladder: a 12-month prospective cohort study in Türkiye

Antimuscarinic therapy is a first-line pharmacological treatment for overactive bladder (OAB), but individual response is highly variable. This study aimed to evaluate the effects of antimuscarinic therapy on symptom severity and quality of life (QoL) and to identify key clinical predictors of treatment response in a prospective cohort. A prospective observational cohort study was conducted at a gynecology outpatient clinic between August 2023 and August 2024. A total of 168 patients diagnosed with OAB who completed one year of antimuscarinic therapy (solifenacin, tolterodine, fesoterodine, or oxybutynin) were included. Disease-specific QoL was assessed using the Incontinence Quality of Life (I-QOL) questionnaire, and symptom severity was measured with the Incontinence Severity Index (ISI) at baseline and after three months. Multiple linear regression analysis was performed to identify independent predictors of changes in I-QOL and ISI scores. Antimuscarinic therapy led to significant improvements in both QoL and symptom severity. The mean total I-QOL score increased from 35.42 (± 13.32) to 61.18 (± 15.10) (p < 0.001), and the mean ISI score decreased from 10.68 (± 1.59) to 6.69 (± 1.70) (p < 0.001). However, regression analysis revealed that the therapeutic response was significantly moderated by specific factors. The experience of moderate to severe side effects, particularly dry mouth and constipation, was the strongest negative predictor of QoL improvement (β = -5.87, p = 0.001). Furthermore, increasing age (β = -0.028, p = 0.007), postmenopausal status (β = 0.585, p = 0.045), and the presence of metabolic comorbidities (diabetes/hypertension) were independently associated with diminished improvement in incontinence severity. While effective, the benefit of antimuscarinic therapy in OAB is not uniform and is substantially limited by treatment-related side effects, advanced age, menopausal status, and metabolic comorbidities. These easily identifiable clinical factors should be used to personalize treatment selection, optimize patient counseling, and improve long-term management strategies, moving beyond a one-size-fits-all approach to OAB care.