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

Abstract

Intravesical 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. A 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. We 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). Although 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.