**1. Introduction**

Urinary incontinence is a common disease observed in women, with an approximately 29–75% prevalence [1]. The common types of incontinence are stress urinary incontinence (SUI) and urge urinary incontinence (UUI). Management options for SUI include conservative treatment, pelvic floor training, and mid-urethral sling (MUS) operation. Treatments for UUI include behavioral modification

and administration of antimuscarinic or beta-3 agonist agents. Furthermore, intravesical injection of botulinum toxin A (BoNT-A) is reserved for refractory patients. BoNT-A significantly decreases the number of UUI episodes and improves health-related quality of life in patients with overactive bladder (OAB) [2–5].

A high incidence of mixed urinary incontinence (MUI) is observed, or SUI and UUI coexist [6]. According to a previous study in women with MUI receiving MUS, approximately 53–79% of women experienced an improvement of UUI. However, 25–35% of women still experienced overactive bladder symptoms or de novo UUI [7].

We made a hypothesis that combining MUS and intravesical BoNT-A injection could have a therapeutic effect on MUI better than that of MUS alone. This study aimed to compare the efficacy and safety of MUS with or without intravesical BoNT-A injection in women who have MUI. The primary endpoints are changes in UUI episodes from baseline to week three. The secondary endpoints are add-ons in antimuscarinic agents or beta-3 agonists compared with baseline. Safety assessments included all common potential adverse events of MUS and BoNT-A intravesical injection, including urinary retention, increased postvoid residual volumes, and urinary tract infection (UTI).
