Botulinum toxin injections for adults with overactive bladder syndrome

Overactive bladder syndrome (OAB) is a common condition with a significant negative impact on quality of life characterised by urgency with or without urge incontinence, frequency and nocturia.  Intravesical botulinum toxin is being increasingly used to treat severe overactive bladder refractory to standard management.  An increasing body of literature is forming that supports this technique as effective, well tolerated, and safe.  This review is a substantial update of the 2007 review of the same title.

The objective was to compare intravesical botulinum toxin with other treatments for neurogenic and idiopathic overactive bladder in adults. The hypothesis to be 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 23 February 2010). 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 and relevant review papers were searched. No limitations were placed on the searches.

All randomised or quasi-randomised controlled trials of treatment for OAB in adults in which at least one management arm involved intravesical injection of botulinum toxin were included. Participants had either neurogenic OAB or idiopathic OAB 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. Little data could be synthesised across studies due to differing study designs and outcome measures. Where applicable standard deviations were calculated from P values according to the formula described in section 7.7.3.3 of the Cochrane Handbook of Systematic Reviews of Interventions. 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.

Nineteen studies were identified that met the inclusion criteria.  Most patients in the studies had neurogenic OAB, but some included patients with idiopathic OAB.  All studies demonstrated superiority of botulinum toxin to placebo.  Lower doses of botulinum toxin (100 to 150 U) appeared to have beneficial effects, but larger doses (300 U) may have been more effective and longer lasting, but with more side effects.  Suburothelial injection had comparable efficacy to intradetrusor injection. The effect of botulinum toxin may last for a number of months and is dependent upon dose and type of toxin used. Patients receiving repeated doses do not seem to become refractory to botulinum toxin. Botulinum toxin appeared to have beneficial effects in OAB that quantitatively exceeded the effects of intravesical resiniferatoxin. Intravesical botulinum toxin appeared to be reasonably safe; however, one study was halted due to a perceived unacceptable rate of urinary retention.

Intravesical botulinum toxin appears to be an effective therapy for refractory OAB symptoms, but as yet little controlled trial data exist on benefits and safety compared with other interventions, or with placebo. Further robust data are required on long term outcomes, safety, and optimal dose of botulinum toxin for OAB.