Hypothesis / aims of study
Outpatient intravesical OnabotulinumtoxinA (BoNTA) is a well-established treatment for refractory overactive bladder (OAB) (1). However, there is a large variety in pain management during the procedure (e.q under general anethesia at the operation room, using sedatives or intravesical anesthetics). Previous studies suggest that lidocaine may have a limited effect on pain perception (2,3). This study evaluated whether lidocaine instillation provides analgesic benefit compared to no local analgesia prior to BoNTA procedure, hypothesizing there is no clinically relevant difference in pain perception.
Study design, materials and methods
This prospective observational study was conducted at four hospitals in the Netherlands. Patients underwent either BoNTA injections after an intravesical lidocaine instillation or with no intravesical analgesia, based on the standard local practice. In three hospitals patients received lidocaine instillation and in one hospital patients received no analgesia. Pain was assessed by Numeric Rating Scale (NRS) at five time points; before initiation of the procedure, after reaching the bladder with the cystoscope, after the first injection, after the fifth injection and after the tenth injection. The sample size with a significance level of 0.01 (compensated for repeated testing with Bonferroni method), a power of 80%, a ratio of 1:1, allowable difference of 0, standard deviation (SD) of 2, margin of 1 is used. With an expected dropout rate of 10%, a sample size is calculated at 116 participants per group, leading to a total sample size of 232 patients. Multivariable linear mixed models were performed to adjust for confounding factors. Secondary outcomes included patient satisfaction at the time of procedure, cost, and carbon footprint (kgCO₂e) associated with lidocaine use. Patient satisfaction was measured using an validated questionnaire.
Results
A total of 232 patients were included (lidocaine: n=116; no-analgesia: n=116). The baseline characteristic (age, sex, BMI, indication) of patients were similar in both groups. The mean NRS score over the five time-measurements was for the lidocaine group 2.2 (SD 1.6) and for the no-analgesia group 2.3 (SD 1.7), there was no significant difference between the two groups. Multivariable analyses showed no independent association between lidocaine instillation and pain scores over time (figure 1). All procedures were completed successfully. Patient satisfaction was high. A total of 98.6% of respondents who completed the questionnaire reported some degree of satisfaction, with no significant difference observed between the two groups. Omitting lidocaine saved €14.06 per procedure and reduced carbon emissions by 3.255 kgCO₂e.
Interpretation of results
Addition intravesical instillation with lidocaine prior to outpatient BoNTA injections did not result in clinical relevant lower NRS scores. These results are consistent with previous research suggesting limited analgesic benefit of lidocaine for this procedure. Additionally, patient satisfaction remained high in both groups, supporting the feasibility of omitting lidocaine.