Does symptom severity predict response to low-dose onabotulinumtoxinA for the treatment of urgency urinary...

Intradetrusor onabotulinumtoxinA is a third-line treatment for urgency urinary incontinence (UUI) which is customarily reserved for severe disease. We sought to determine if symptom severity predicts the proportional response to onabotulinumtoxinA and whether low-dose injection may be an appropriate treatment for mild-moderate symptoms.

This prospective cohort study compared patients with urgency urinary incontinence who were recruited from the Urogynecology Clinic with mild-moderate (2-9 episodes/3-day diary) and severe UUI (>9 episodes/3-day diary) symptoms. Twenty-eight subjects were treated (11 mild-moderate, 17 severe) with 50 units of intradetrusor onabotulinumtoxinA. Voiding diaries and validated questionnaires (UDI-6 and IIQ-7) were collected at baseline and one, six, and twelve months post-treatment. The primary outcome was the difference in percent reduction in UUI episodes per 3-day diary at one month. Secondary outcomes included differences in absolute reduction of UUI events, treatment success rate (defined as greater than 50% reduction in UUI episodes), changes in UDI-6 and IIQ-7 questionnaire scores, and rates of urinary retention, self-catheterization, and urinary tract infection. Normally distributed data are presented as means with standard deviations (SD) and groups were compared using the two sample t-test. Data that were not normally distributed are presented as medians with the interquartile range (IQR) and were compared using the Wilcoxon rank sum test.

The mild-moderate group showed median improvement; 100% (IQR: 100%, 100%) and severe group; 81% (IQR: 35%, 100%), p < 0.019. Both had significant improvement in UUI episodes; the mild-moderate group decreased by four and the severe group by 15. No differences were noted in percent reduction between groups. There was no association between baseline severity and percent reduction in UUI episodes (rs = 0.127, p = 0.544); however, absolute reduction was highly correlated (rs = -0.821, p < 0.001). Treatment success was 90% in mild-moderate and 73% in the severe group (p = 0.615). Complications included urinary tract infections (25%) and intermittent catheterization (3.6%).

Patients with both mild-moderate and severe symptoms showed a statistically significant improvement in UUI events from baseline to one month, but no difference between the groups in proportional improvement or treatment success.