Prospective randomised controlled trial comparing trigone-sparing versus trigone-including intradetrusor injection of abobotulinumtoxinA for refractory idiopathic detrusor overactivity

Background: Botulinum toxin A is effective for treatment of idiopathic detrusor overactivity (IDO). The trigone is generally spared because of the theoretical risk of vesicoureteric reflux (VUR), although studies assessing injection sites are lacking.

Objective: Evaluate efficacy and safety of trigone-including versus trigone-sparing intradetrusor injections of abobotulinumtoxinA in patients with IDO.

Design, setting, and participants: Twenty-two patients from one centre were randomised to trigone-including or trigone-sparing injections.

Intervention: Injection of 500 U abobotulinumtoxinA diluted to 20ml into 20 trigone-including or trigone-sparing sites.

Measurements: The primary outcome measure was total overactive bladder symptom score (OABSS) at 6 wk. The OABSS questionnaire was completed at 0, 6, 12, and 26 wk. Baseline and postinjection urodynamic studies and micturating cystourethrograms were performed. Baseline values and subsequent time points were compared by t test. A mixed-effect model was used for repeated measures in time.

Results and limitations: For symptom scores at baseline compared with scores at 6 wk postinjection, the mean total OABSS improved from 22.4 to 8.7 (p<0.001) in the trigone-including group compared with 22.7 to 13.4 (p<0.03) in the trigone-sparing group. The difference in mean change from baseline was 4.4 points in favour of the trigone-including group (p=0.03). The total OABSS at 12 and 26 wk and the urgency subscale scores at 6, 12, and 26 wk showed significant improvement in favour of the trigone-including group. Mean postvoid residual volumes and clean intermittent self-catheterisation rates between the two groups were similar. No patients developed VUR. Performing injections under general anaesthetic was a limitation, as tolerability under local anaesthetic was not assessed. A further limitation is the lack of a trigone-only arm.

Conclusions: Trigone-including injections are superior to trigone-sparing injections for the treatment of refractory IDO and did not cause VUR in this study.