Botulinum Toxin A Versus Placebo for Refractory Detrusor Overactivity in Women: A Randomised Blinded Placebo-Controlled Trial of 240 Women (the RELAX Study)

BACKGROUND: Emerging data suggest botulinum toxin is an effective treatment for detrusor overactivity (DO), but large studies confirming efficacy and safety are lacking. OBJECTIVE: Study the efficacy and safety of onabotulinumtoxinA (onaBoNTA) for the treatment of DO. DESIGN, SETTING, AND PARTICIPANTS: A double-blind placebo-controlled randomised trial in eight UK urogynaecology centres was conducted between 2006 and 2009. A total of 240 women with refractory DO were randomised to active or placebo treatment and followed up for 6 mo. INTERVENTION: Treatment consisted of 200 IU onaBoNTA or placebo injected into the bladder wall (20 sites; 10 IU per site in 1ml saline). MEASUREMENTS: Primary outcome was voiding frequency per 24h at 6 mo. Secondary outcomes included urgency and incontinence episodes and quality-of-life data. Intention-to-treat analysis was used with imputation of missing data. RESULTS AND LIMITATIONS: A total of 122 women received onaBoNTA and 118 received the placebo. Median (interquartile range) voiding frequency was lower after onaBoNTA compared with placebo (8.3 [6.83-10.0] vs 9.67 [8.37-11.67]; difference: 1.34; 95% confidence interval [CI], 1.00-2.33; p=0.0001). Similar differences were seen in urgency episodes (3.83 [1.17-6.67] vs 6.33 [4.0-8.67]; difference: 2.50; 95% CI, 1.33-3.33;