Assessment of urodynamic and detrusor contractility variables in patients with overactive bladder syndrome treated with botulinum toxin-A: is incomplete bladder emptying predictable?

OBJECTIVE: To assess whether incomplete bladder emptying and the need for clean intermittent self-catheterization (CISC) is predictable, by analysing urodynamic and detrusor contractility variables in patients treated with botulinum toxin-A (BTX-A) for refractory idiopathic detrusor overactivity (IDO).

PATIENTS AND METHODS: Sixty-seven patients (mean age 50.3) with IDO, from two centres, had bladder injections of 200 U BTX-A. Patients with difficulty in emptying their bladder and/or persistent overactive bladder symptoms, with postvoid residual volumes (PVR) of >150 mL after treatment were started on CISC. Urodynamics were conducted at baseline, 4 and 12-16 weeks after injection with BTX-A. Detrusor contractility was assessed using the projected isovolumetric pressure (PIP1) in women and bladder contractility index (BCI) in men.

RESULTS: There were improvements in the mean maximum cystometric capacity, bladder compliance and maximum detrusor pressures during filling cystometry after BTX-A injections. The PVR was significantly increased at 4 but not at 12 weeks. Nineteen patients required CISC and when compared with those not needing CISC their pretreatment maximum flow rate (15 vs 22 mL/s, P = 0.003), PIP1 (43 vs 58, P = 0.02) and BCI (113 vs 180, P = 0.001) were lower. Receiver operator characteristic curve analysis suggested that a PIP1 of < or =50 in women (sensitivity 0.83; specificity 0.70; area under the curve 0.822) and BCI < or =120 (sensitivity 0.7; specificity 0.79; area 0.879) might predict the need for CISC.

CONCLUSION: The maximum flow rate, PIP1 and BCI were significantly lower in patients who required CISC after BTX-A treatment than in those who did not. A PIP1 of < or =50 in women and a BCI of < or =120 might be predictive of a need for CISC in this setting, and might help when counselling patients.