Urodynamic assessment of poor responders after botulinum toxin-A treatment for overactive bladder

Botulinum toxin-A (BTX-A) is effective in treating overactive bladder (OAB) refractory to anticholinergics. Most patients have improvements in symptoms, urodynamic parameters, and quality of life, and a poor response is uncommon. The aim of this study was to determine whether poor responders could be predicted from preoperative urodynamic parameters.

Data were collected prospectively from 33 OAB patients with idiopathic detrusor overactivity. All patients underwent intradetrusor injections of 200 U BTX-A. Response to treatment was assessed by patient perception, OAB symptoms, and quality of life data. Urodynamics were conducted at baseline and 4, 12, and 24 weeks postinjection. We performed statistical analysis using the Wilcoxon matched pairs, Mann-Whitney, two-sample, and paired t-tests. Receiver operator characteristic (ROC) curves were plotted for relevant parameters.

Five patients had a poor response to treatment. Significant increases in maximum cystometric capacity (MCC), reflex detrusor volume (RDV), and bladder compliance with decreases in maximum detrusor pressures (MDP) on filling were observed in the responders over 24 weeks. Minimal urodynamic benefit was observed in the poor responders group over the same period. When comparing the two groups, baseline MDP in poor responders was 138.0 +/- 30.7 compared with 74.4 +/- 32.6 in the responders (P = 0.0028). ROC analysis suggested that a pretreatment MDP greater than 110 may have predictive value (AUC, 0.946; sensitivity, 0.86; specificity, 1.0) for a poor response to treatment.

Very high MDP greater than 110 may predict a poor response to treatment with 200 U of BTX-A. Higher doses may be necessary in these patients.