Intradetrusor onabotulinumtoxinA injections for refractory neurogenic detrusor overactivity incontinence: do we need urodynamic investigation for outcome assessment?

OBJECTIVE: To evaluate if urinary continence in patients with refractory neurogenic detrusor overactivity (NDO) incontinence after intradetrusor onabotulinumtoxinA injections is sufficient for appropriate outcome assessment or if urodynamic investigation (UDI) is needed.

PATIENTS AND METHODS: A consecutive series of 148 patients undergoing intradetrusor onabotulinumtoxinA injections for refractory NDO incontinence were prospectively evaluated. Patients underwent UDI before and at 6 weeks after onabotulinumtoxinA injections. The primary outcome was the prevalence of maximum storage detrusor pressure (Pdetmax storage) of >40 cmH2 O in continent patients at 6 weeks after treatment. The secondary outcomes were treatment effects on other clinical and video-urodynamic variables.

RESULTS: At 6 weeks after intradetrusor onabotulinumtoxinA injections, 98 of the 148 patients (66%) with NDO incontinence were continent. Of these patients, 18 (18%, confidence interval 12-27%) had a Pdetmax storage of >40 cmH2 O. Gender, underlying neurological disorder, and high Pdetmax storage before treatment appear to increase the risk of poor urodynamic outcomes.

CONCLUSIONS: Urinary continence is not sufficient for outcome assessment after intradetrusor onabotulinumtoxinA injections, as high intravesical pressures threatening the upper urinary tract may be missed in a relevant proportion of continent patients. Therefore, we strongly recommend UDI as a routine part of the follow-up.