Subjective Improvement After 20 vs 6 Intravesicular Onabotulinum-A Injections

Objectives: The optimal number of intravesicular onabotulinum-A (BoNT-A) injections for treatment of overactive bladder has been studied; however, no consensus has been made yet. The objective of this study was to determine if there was a difference in subjective improvement of symptoms between patients receiving 20 vs 6 intravesicular injections for overactive bladder.

Methods: This was a retrospective cohort study of patients aged 18 or older who received 20 vs 6 BoTN-A injections by a single surgeon within a single hospital system. Patients must have attended a post-operative appointment. Patients with recurrent urinary tract infections and neurogenic bladders were excluded. Subjects were identified using CPT code 52287. Data was collected from electronic medical records and included: demographics, number of injection sites, prior history of BoTN-A injection procedures, subjective patient improvement, postvoid residual (PVR), and if there was a positive post-operative urine culture. The primary outcome was subjective improvement of symptoms reported at the post-operative appointment. Secondary outcomes included PVR and positive post-operative urine cultures. Chi square and Fischer exact test were used to assess the primary outcome. Independent samples t-test was used to assess the secondary outcomes.

Results: Of the 87 patients that met criteria for the study, 14 patients (16.1%) received 6 intravesicular injections and 73 patients (83.9%) received 20 intravesicular injections. Due to low sample size, power was not met for this study. Subjective improvement was seen in 10/14 (71.4%) of patients receiving 6 injections and 58/73 (79.5%) of those receiving 20 injections (P < 0.495). The mean PVR was 101.4cc for patients receiving 6 injections and 72.5cc for patients receiving 20 injections. No significant difference was found (P < 0.35). Positive post-operative urine cultures were seen in the 2/14 (14.3%) for patients receiving 6 injections and 8/73 (11.4%). No significant difference was found (P < 0.67).

Conclusions: No difference in subjective improvement or postoperative complications was appreciated between 20 vs 6 intravesicular BoTN-A injections in this retrospective cohort study. Further research is warranted to clarify whether fewer injections are as efficacious as the standard 20 injections sites. Additionally, fewer injections may lead to decreased pain and decreased procedural time, both factors which may be particularly important in the office setting.