Botulinum toxin injections for adults with overactive bladder syndrome

Overactive bladder syndrome is a common condition with a significant negative impact on quality of life. Intravesical injection of botulinum toxin is increasingly used as an intervention for refractory overactive bladder, with a considerable body of case reports and series in the literature suggesting beneficial effects.

The objective was to compare intravesical botulinum toxin injection with other treatments for neurogenic and idiopathic overactive bladder in adults. The hypotheses addressed were whether intravesical injection of botulinum toxin was better: than placebo or no treatment, pharmacological and other non-pharmacological interventions, whether higher doses of botulinum toxin were better than lower doses, whether botulinum toxin in combination with other treatments was better than other treatments alone, whether one formulation of botulinum toxin is better than another, and whether one injection technique was better than another.

We searched the Cochrane Incontinence Group Specialised Trials Register (searched 22 November 2005). The register contains trials identified from MEDLINE, CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), and handsearching of journals and conference proceedings. Additionally, all reference lists of selected trials were searched. No limitations were placed on the searches.

All randomised or quasi-randomised controlled trials of treatment for overactive bladder syndrome in adults in which at least one management arm involved intravesical injection of botulinum toxin were included. Participants had either neurogenic or idiopathic overactive bladder with or without stress incontinence. Comparison interventions could include no intervention; placebo; lifestyle modification; bladder retraining; pharmacological treatments; surgery; bladder instillation techniques; neuromodulation; and different types, doses, and injection techniques of botulinum toxin.

Binary outcomes were presented as relative risk and continuous outcomes by mean differences. No data could be synthesised across studies due to differing designs and outcome measures. Data were tabulated where possible with results taken from trial reports where this was not possible. Where multiple publications were found, the reports were treated as a single source of data.

Eight studies met the inclusion criteria. Results varied between studies. For the most part, studies reported superiority of botulinum toxin A to placebo in such outcomes as incontinence episodes, bladder capacity, maximum detrusor pressure, and quality of life. Low doses of botulinum toxin (100U to150U) appeared to have beneficial effects, but higher doses (300U) may have been more effective. Botulinum toxin appeared to have beneficial effects in overactive bladder that quantitatively exceeded the effects of intravesical resiniferatoxin.

Intravesical botulinum toxin shows promise as a therapy for overactive bladder symptoms, but as yet too little controlled trial data exist on benefits and safety compared with other interventions, or with placebo. Practitioners should be aware that at present there is little more than anecdotal evidence, in the form of case reports to support the efficacy of intravesical botulinum toxin; there is not much in the way of substantial, robust safety data. Furthermore, the optimal dose of botulinum toxin for efficacy and safety has not yet been demonstrated.