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Injection site number and outcomes of intradetrusor onabotulinumtoxinA for refractory overactive bladder syndrome: a randomized clinical trial

Int Urogynecol J. 2023 Nov 22. doi: 10.1007/s00192-023-05685-0. Online ahead of print.


INTRODUCTION AND HYPOTHESIS: The optimal number of onabotulinumtoxinA injections for the treatment of refractory overactive bladder syndrome is unknown. Our primary objective was to determine whether 10-injections sites with 100 units of onabotulinumtoxinA each were associated with less pain than 20-injections sites.

METHODS: In a single-blinded randomized trial, 100 units of onabotulinumtoxinA was administered, either as 10 × 1 ml or as 20 × 0.5 ml injections following the instillation of 30 ml of bupivacaine and 5 ml of NaHCO3 solution for 15 min. The primary outcome was procedural pain, as measured on an 11-point Numerical Pain Rating Scale (NPRS) immediately following the procedure. A power calculation estimated that 16 subjects in each arm were needed to detect a mean difference of 1 with a standard deviation of 1, on the NPRS score between the two treatment groups, with α 0.05 and power 80%. To adjust for an estimated 20% dropout rate, the final sample size was planned for 20 patients per group.

RESULTS: From October 2020 to November 2022, a total of 56 patients were approached and 40 were enrolled and randomized to two groups (21 in the 10-injections group and 19 in 20-injections group). The difference in the median pain score between the group was not statistically significant (4 [1.5-5] for 10 injections vs 3 [1-4] for 20 injections, p=0.823).

CONCLUSION: Patients’ perception of pain, efficacy, and adverse events did not significantly differ between patients receiving 10 and those receiving 20 injections of 100 units of onabotulinumtoxinA.

PMID:37991564 | DOI:10.1007/s00192-023-05685-0

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