SAN FRANCISCO—Slightly more than half of patients with refractory idiopathic detrusor overactivity (IDO) incontinence have complete restoration of continence one month after intradetrusor injections of botulinum toxin type A, according to results released here at the 39th Annual Meeting of the International Continence Society.
The study is the first to use a validated, self-administered questionnaire to assess the response of IDO patients to treatment with botulinum toxin type A, according to investigators.
“Even though patient-reported outcome measures are strongly recommended for monitoring overactive bladder symptoms, studies evaluating botulinum toxin type A treatment have relied exclusively on objective measures of treatment efficacy like urodynamic studies and bladder diary variables and have ignored subjective measures like patient-completed questionnaires, said Shahid Khan, MRCS, Honorary Research Assistant and Clinical Fellow at The National Hospital for Neurology and Neurosurgery in London.
Objective measures of treatment efficacy are problematic because they do not necessarily predict patient-reported outcomes, he added.
Dr. Khan and his associates examined patient-reported continence rates after intradetrusor injections of 200 units of botulinum toxin type A in 74 patients who were refractory to behavioral therapy and antimuscarinic therapy or unable to tolerate the side effects of antimuscarinic therapy for at least three months.
In the present study, changes in patient-reported urinary frequency, urgency incontinence, and stress incontinence were assessed using the short versions of the Urogenital Distress Inventory (UDI 6) before and four weeks after botulinum toxin type A treatment.
Overall, 38 patients, or 51%, had complete continence four weeks after treatment. Complete continence was defined as a score of 0 in both the urgency and stress incontinence subscales of the UDI 6 questionnaire.
The study also found that patients in whom complete continence was not achieved had a significant decrease in median urgency incontinence scores from 33 to 0, median stress incontinence scores from 33 to 0, and median urinary frequency scores from 100 to 33.
About 40% of patients needed clean intermittent self-catheterization (CISC) to empty their bladders after treatment.
Dr. Khan said that the findings are especially noteworthy “when we consider that all of our patients were refractory to or could not tolerate the side effects of antimuscarinic therapy, which is the standard first-line drug treatment for overactive bladder symptoms.”
While botulinum toxin type A is being increasingly accepted for second-line use in the management of refractory urinary incontinence, he emphasized that studies are needed to identify the optimal dose that can produce the best effect with the least likelihood of patients requiring CISC. Research will also need to determine the optimal injection site and injection technique, he added.
Although the new study is limited by its nonrandomized design, its diverse patient population, which reflects routine clinical practice, is a major strength, he said.