Botox for Overactive Bladder

Overactive bladder (OAB) is defined by the International Continence Society as urinary urgency, with or without urinary leakage, that is commonly associated with urinary frequency and nocturia (waking one or more times at night to void.) According to the ICS, this combination of symptoms suggest that detrusor instability is present, meaning that the bladder muscle is overactive. In the absence of proven infection or other pathology, overactive bladder, urge syndrome, or urge-frequency syndrome are terms used to describe the condition.

A double-blind placebo-controlled randomized trial was completed in the United Kingdom for 240 women who experienced "refractory" detrusor overactivity. 122 women with urodynamically proven detrusor overactivity were treated with onabotulinumtoxinA (onaBoNTA), and 118 women served as the placebo group. The medication is injected into the wall of the bladder during a cystoscope procedure. (The women in the placebo group received injections as well, only with 0.9% sodium chloride in saline solution.) The median voiding frequency within a 24 hour period was reduced from 9.67 voids to 8.33. Urgency episodes reduced from 6.33 to 3.83, and leakage episodes from 6.00 to 1.67. To summarize, urinary urgency and incontinence improved more than urinary frequency in this study. The authors conclude that, based on such a large, randomized study, the use of botulinum toxin is both safe and effective for women who have detrusor overactivity.

In reviewing this article, it also seems important to look beyond these recommendations, as clearly the use of this treatment is not safe for all involved, nor is it effective.

1. The authors defined a "refractory" condition as one that did not respond to an 8 week trial of an anticholinergic medication. Was behavioral training implemented? Could these women have benefited significantly from education in dietary and behavioral strategies? The authors admit that their definition was chosen arbitrarily.
2. 24.6% of the women in the treatment group did not report any significant improvement.
3. One third of the women who received the onaBoNTA reported urinary tract infections (UTI) while in the placebo group one tenth of the women reported UTI.
4. 16% of the women in the onaBoNTA group had voiding difficulties requiring intermittent catheterization compared to 4% of the placebo group.