OnabotulinumtoxinA for Urgency Urinary Incontinence

As many as 19% of women in the United States are affected by urgency urinary incontinence, a condition characterized by unpredictable loss of urine that occurs disproportionately in women.

Primary treatment for urgency urinary incontinence utilizes anticholinergic medications. A previous systemic review of trials involving 6 such medications found that none of the drugs evaluated were superior to another in treating the condition. In addition, the review demonstrated that current evidence is not sufficient to guide a choice among other available therapies.

One such therapy involves injections of botulinum toxin. OnabotulinumtoxinA has been shown to be effective in treating anticholinergic-resistant urgency urinary incontinence; however, it has also been associated with incomplete emptying of the bladder, resulting in the need for temporary bladder catheterization.

There are limited data available that directly compare onabotulinumtoxinA with anticholinergic agents. Researchers recently conducted a randomized trial to compare a regimen of oral anticholinergic medication with a single injection into the detrusor muscle of onabotulinumtoxinA in women with urgency urinary incontinence to determine the reduction in episodes of urgency urinary incontinence over the course of 6 months. The trial also measured improvement in quality of life and side effects of the treatments. They reported trial results in the New England Journal of Medicine [2012;367(19):1803-1813].

The ABC (Anticholinergic versus Botulinum Toxin Comparison) study was a randomized, double-blind, double-placebo–controlled trial conducted at 10 centers. Participants included women with no neurologic disease who had moderate-to-severe urgency urinary incontinence. The study was conducted from February 2, 2010, through May 2, 2012.

The primary study outcome was reduction from baseline in mean episodes of urgency urinary incontinence per day over a 6-month study period. Secondary outcomes included complete resolution of urgency urinary incontinence, quality of life, use of catheters, and adverse events.

Women with ≥5 episodes of urgency urinary incontinence, as recorded in a 3-day diary, and urgency-predominant urinary incontinence were invited to participate. Exclusion criteria included previous use of anticholinergic drugs or previous receipt of up to 2 anticholinergic medications other than solifenacin, darifenacin, or trospium chloride. Women who had a residual urine volume of ≥150 ml after voiding and those who reported previous therapy for urgency urinary incontinence with onabotulinumtoxinA were also excluded.

The researchers randomly assigned the participants to 1 of 2 groups: group 1 (n=118) received the oral anticholinergic drug solifenacin (at an initial dose of 5 mg daily, with possible escalation to 10 mg and, if necessary, subsequent switch to trospium XR, 60 mg) plus 1 intradetrusor injection of saline; group 2 (n=113) received 1 intradetrusor injection of 100 U of onabotulinumtoxinA plus daily oral placebo.

At baseline, participants in both groups reported a mean of 5.0 episodes of urgency urinary incontinence. Over the course of the 6-month study period, the mean reduction in episodes was 3.4 in the anticholinergic group and 3.4 in the onabotulinumtoxinA group. Complete resolution of urgency urinary incontinence was reported by 13% of the anticholinergic group and 27% of the onabotulinumtoxinA group (P=.003).

There were no significant differences between the 2 groups in improvement in quality of life.

In terms of adverse effects, participants in the anticholinergic group reported a higher rate of dry mouth compared with the onabotulinumtoxinA group (46% vs 31%; P=.02), but lower rates of catheter use at 2 months (0% vs 5%; P=.010) and urinary tract infections (13% vs 33%; P<.001).

In summary, the researchers said, “Oral anticholinergic therapy and onabotulinumtoxinA by injection were associated with similar reductions in the frequency of daily episodes of urgency urinary incontinence. The group receiving onabotulinumtoxinA was less likely to have dry mouth and more likely to have complete resolution of urgency urinary incontinence, but had higher rates of transient urinary retention and urinary tract infections.”