OnabotulinumtoxinA 200-U injection provides longer OAB symptom improvement than 100-U injection
Abdelwahab O, Sherif H, Soliman T, Elbarky I, Eshazly A. Efficacy of botulinum toxin type A 100 units versus 200 units for treatment of refractory idiopathic overactive bladder. Int Braz J Urol. 2015;41(6):1132-1140.
Abdelwahab and colleagues conducted a single-center, randomized clinical trial to investigate the safety and efficacy of a single injection of intradetrusor onabotulinumtoxinA in 2 different doses (100 U and 200 U) for treatment of OAB.
Details of the study
Eighty adults (63 women, 17 men) who did not benefit from anticholinergic medication during the previous 3 months were randomly assigned to receive either a 100-U (n = 40) or a 200-U (n = 40) injection of onabotulinumtoxinA. Exclusion criteria were PVR urine volume greater than 150 mL and previous radiation therapy or chemotherapy.
Initial assessments -- completed at baseline and at 1, 3, 6, and 9 months -- included the health-related quality-of-life (HR-QOL) questionnaire (maximum score, 100; higher score indicates better quality of life), an abbreviated OABSS questionnaire (4 questions; score range, 0-15; higher score indicates more severe symptoms), and urodynamic evaluation. Outcomes included OABSS, HR-QOL score, and urodynamic parameters at the various time points.
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Higher dose, greater symptom improvement and higher adverse event rate
At baseline, participants (average age, 31 years) had an average (SD) OABSS of 1.7 (1.6). OnabotulinumtoxinA treatment with both a 100-U and a 200-U dose resulted in significant improvements (compared with baseline levels) in frequency, nocturia, UUI episodes, OABSS, and urodynamic parameters throughout the 9 months. At 9 months, however, the group treated with the 200-U dose had greater improvements, compared with the group who received a 100-U dose, in urinary frequency symptom scores (mean [SD], 0.32 [0.47] vs 1.1 [0.51]; P<.05), nocturia symptom scores (mean [SD], 0.13 [0.34] vs 0.36 [0.49]; P<.05), UUI symptom scores (mean [SD], 0.68 [0.16] vs 1.26 [1.1]; P<.05), and mean (SD) total OABSS (2.6 [2.31] vs 5.3 [2.11]; P<.05). Similarly, at 9 months the 200-U dose resulted in greater improvements in volume at first desire (mean [SD], 291.8 [42.8] vs 246.8 [53.8] mL; P<.05), volume at strong desire (mean [SD], 392.1 [37.3] vs 313.1 [67.4] mL; P<.05), detrusor pressure (mean [SD], 10.4 [4.0] vs 19.2 [7.8] cm H2O; P<.05), and maximum cystometric capacity (mean [SD], 430.5 [34.2] vs 350 [69.1] mL; P<.05) compared with the 100-U dose.
Adverse events. No participant had a PVR urine volume greater than 100 mL at any follow-up visit. Postoperative hematuria occurred in 23% of the group treated with onabotulinumtoxinA 200 U versus in 15% of those treated with a 100-U dose. Similarly, UTIs occurred in 17.5% of the 200-U dose group and in 7.5% of the 100-U dose group. Dysuria was reported in 37.5% and 15% of the 200-U and 100-U dose groups, respectively.
Strengths and limitations. This randomized, open-label trial comparing a single injection of 100 U versus 200 U of onabotulinumtoxinA included mostly women. OAB symptoms and urodynamic parameters improved after treatment with both dose levels, but a longer duration of improvement was seen with the 200-U dose. The cohort had a low baseline OAB severity, based on the OABSS questionnaire, and a young average age of participants, which limits the generalizability of the study results to a population with refractory OAB. The 0% rate of clean intermittent self-catheterization postinjection might be based on the study's criteria for requiring clean intermittent catheterization. In addition, the initial postinjection visit occurred at 1 month, possibly missing participants who had symptoms of retention soon after injection.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Two dose levels (100 U and 200 U) of a single injection of onabotulinumtoxinA are associated with comparable OAB symptom and urodyanamic improvements. The benefits of a longer duration of effect with the 200-U dose must be weighed against the possible higher risks of transient hematuria, dysuria, and UTI.
Read: onabotulinumtoxinA vs sacral neuromodulation therapy for UUI.