Increased Risk of Large Post-Void Residual Urine and Decreased Long-Term Success Rate After Intravesical OnabotulinumtoxinA Injection for Refractory Idiopathic Detrusor Overactivity

PurposeIntravesical injection of onabotulinumtoxinA is effective for idiopathic detrusor overactivity refractory to antimuscarinics. However, safety is a major concern, especially in elderly individuals. We investigated the efficacy and safety of intravesical onabotulinumtoxinA injection for refractory idiopathic detrusor overactivity in the frail elderly population.Materials and MethodsA total of 166 patients with urodynamic idiopathic detrusor overactivity refractory to previous antimuscarinics for more than 3 months received 1 intravesical 100 U onabotulinumtoxinA injection from 2004 to 2009. Frail elderly was defined as age greater than 65 years and 3 or more of certain criteria, including unintentional weight loss, self-reported exhaustion, weakness, slow walking speed and/or low physical activity. Treatment results were assessed by the Patient Perception of Bladder Condition, voiding diary, urodynamic parameters and Kaplan-Meier estimates of survival plots.ResultsWe evaluated 61 frail elderly patients, 63 who were elderly without frailty and 42 younger than 65 years. Large post-void residual urine volume (greater than 150 ml) after onabotulinumtoxinA injection was significantly higher in the frail elderly group than in the other groups (60.7% vs 39.7% and 35.7%, respectively, p = 0.018). Urinary retention developed in 7 frail elderly patients (11.5%), 4 (6.3%) who were elderly without frailty and 1 younger patient (2.4%) (p = 0.203). Recovery duration was significantly longer in frail elderly patients. The cumulative success rate was significantly lower in the frail elderly group than in the other 2 groups (p = 0.009).ConclusionsAlthough safety and efficacy were similar between elderly patients without frailty and younger patients, an increased risk of large post-void residual urine volume and a lower long-term success rate in frail elderly patients were noted after intravesical onabotulinumtoxinA injection for refractory idiopathic detrusor overactivity.