BACKGROUND AND PURPOSE:

• Overactive bladder is a common condition with significant impact on quality of life
• 1^st and 2^nd line therapies
  • anti‐muscarinics or oral ß3 adrenoceptor agonists
• 3^rd line for refractory cases
  • OnabotulinumtoxinA (ONA), a specific formulation of Botulinum toxin type A (licensed in the US and Europe for neurogenic detrusor overactivity and idiopathic detrusor overactivity
• Another formulation, abobotulinumtoxinA (ABO), has also been shown to be of benefit in smaller, uncontrolled studies
• De Sá Dantas Bezerra et al. (Neurology and Urodynamics, 2018) sought to determine dosing for abobotulinumtoxinA (ABO) intravesical injections for the treatment of idiopathic overactive bladder (OAB)

METHODS:

• Randomized controlled trial
  • Women who failed conservative treatment
• Patients were randomized to 2 groups
  • 300 U of ABO
  • 500 U of ABO
• Drug injected using cystoscope
  • 30 injections, 1 ml per site, into detrusor muscle (not trigone)
  • Spinal or IV anesthesia in OR with antibiotic prophylaxis
• Patients assessed at baseline, 4, 12, and at 24 weeks post injection
• All treatments were evaluated by
  • Voiding diary
  • International Consultation on Incontinence Questionnaire OAB (ICIQ‐OAB)
  • Patient Global Impression of Improvement (PGI‐I)
  • Urodynamic testing as per ICS recommendations
  • Visual analogue scale (VAS) for treatment satisfaction
• Primary outcome: Change in maximum cistometric capacity (MCC)
• Secondary outcomes
  • Changes in urgency | Complete continence | Subjective success (VAS and PGI‐I) | Adverse events (urinary retention, UTI, and catheterization)
• Statistical analysis
  • 90% power to detect 30% difference in delta of MCC
  • Delta measured as the difference in MCC from baseline to post-treatment

RESULTS:

• 21 patients were included
• From baseline to 12 weeks, change in MCC was not significantly different between groups
  • 185.0 to 270.9 mL in the 300 U group
  • 240.8 to 311.7 mL in the 500 U group
• At 12 weeks, 91% of patients were dry in both groups
• At 24 weeks, episodes of incontinence had returned in
  • 50% (300 U)
  • 0% (500 U) (P = 0.013)
• Patients were better or much better (PGI‐I) in 12 weeks
  • 70% (300 U)
  • 88.9% (500 U)
• Better in 24 weeks
  • 50% (300 U)
  • 100% (500 U) (P = 0.027)
• Peak of post-void residual urine volume at 4 weeks:
• 300 U: 71.7 mL
• 400 U: 96.5 mL
• General UTI incidence was 35.7% with no difference between groups
  • Successfully treated with antibiotics
• One patient (500 U) required intermittent catheterization for 2 weeks
  • Spontaneous improvement

CONCLUSION:

• The long term efficacy/quality of life benefits of ABO was much higher when given in the 500 U dose, although there was no difference in the primary outcome (based on power of this current study)
• Limitations of study include lack of blinded independent interviewer
• Larger studies required to assess secondary outcomes, particularly safety

Learn More – Primary Sources:

A prospective randomized clinical trial comparing two doses of AbobotulinumtoxinA for idiopathic overactive bladder

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