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Overactive bladder is a condition whose prevalence increases with age. This, combined with the aging population, results in a greater number of elderly patients requiring treatment. The first line of treatment consists of detrusor relaxant medications, with the injection of botulinum toxin reserved for refractory patients. The deleterious effects of anticholinergic treatment are well-known, especially in elderly and frail patients, although the efficacy and safety profile of botulinum toxin in this patient group is not clearly established. (1)
The objective of the present study is to perform a comparative analysis of efficacy, safety, and treatment adherence with botulinum toxin in older and younger women (under 75 years) with overactive bladder, based on age.

A retrospective analysis was conducted on women with refractory overactive bladder who were treated for the first time with a 100 IU injection of onabotulinumtoxinA from January 2019 to March 2023. Patients with neurogenic history and those receiving second injections were excluded. The procedure was performed on an outpatient basis under sedation or local anesthesia, with a prior urine culture. Patients were evaluated preoperatively with a bladder diary and urodynamic study. Postoperative evaluation included subjective assessment of satisfaction level (0-10), number of pads used, and reevaluation of preoperative functional parameters. Complications after injection were evaluated according to the Clavien-Dindo classification. A comparative study was conducted between the age groups (under 75 years and 76 years and older). Group 1 consisted of patients aged 75 years and younger, and group 2 consisted of patients aged 76 years and older.
Data analysis was conducted using IBM® SPSS® v.22.0 (IBM Corp., Armonk, NY, USA). Parametric  continous data are expressed as means and standard deviations while categorical data are expressed as numbers and percentages. Pre and postoperative variables were compared using Student's t-test for paired samples in the case of variables with a normal distribution, the ANOVA test for variables with a non-normal distribution, and the chi-squared test for categorical variables.

A total of 74 patients were analyzed, with a mean age of 65 ± 14 years: 52 patients ≤75 years (18-75) and 22 patients ≥76 years (76-91), with a median follow-up of 19 ± 15 months.
Both groups were comparable in terms of BMI (27 vs. 28), daytime frequency of urination (10.3 vs. 10), nighttime frequency of urination (2.9 vs. 3.1), number of pads used (3 vs. 3.5), and Charlson comorbidity index (1.5 vs. 1.7). Group 1 had a higher rate of recurrent urinary tract infections (24% vs. 13%) and diabetes mellitus (15% vs. 11%), with this difference being statistically significant. Group 2 had a higher rate of patients with cognitive impairment (6% vs. 22%), mobility impairment (11% vs. 35%), and hypertension (26% vs. 62%), which was statistically significant. The baseline characteristics of the two groups and their differences are described in Table I.
After the injection, 50 patients in the first group reported a response to treatment (95%), while 16 patients in the second group were considered cured (74%), with this difference being statistically significant (p < 0.05). The decrease in daytime urination frequency was similar in both groups (2.5 vs. 2), but the elderly patients had a smaller decrease in nighttime urination frequency (1.4 vs. 0.6) and number of pads used (2.2 vs. 1). There were no differences between the two groups in terms of post-injection UTI rate (17% vs. 17%) or postvoid residual volume (102 vs. 104 cc). Younger patients had a higher rate of voiding symptoms post-injection (23% vs. 17%). All complications experienced by the patients were Clavien-Dindo grade I. The response time was longer in the second group (10.3 vs. 15.6), and both groups had the same rate of re-injections (54% vs. 54%).

Based on our comparative analysis, elderly patients did not experience higher complication rates compared to younger patients. In our series, elderly patients had similar comorbidities to younger patients, so these results may not be extrapolated to frail patients (2). Based on our results, elderly patients had poorer response compared to younger patients, likely due to the presence of other factors involved in incontinence (such as underlying sphincter function). Additionally, elderly patients showed less decrease in nighttime urination frequency, likely due to the multifactorial etiology of nocturia in these patients. Despite the worse results, elderly patients had longer response times with the same treatment adherence as younger patients.

Intradetrusor botulinum toxin injection  is a safe technique in elderly patients without major comorbidities, without increasing complications compared to younger women.
 However, we should caution about poorer results in this patient group compared to younger patients. categorical variables.

Efficacy and safety of botulinum neurotoxin in geriatric patients with an oberactive bladder: a multicenter study from Turkey. A Keles et al. Turk Geriatri Dergisi. June 2019.DOI: 10.31086/tjgeri.2019.93
Jiang Y-H, Liao C-H, Tang D-L, Kuo H-C (2014) Efficacy and Safety of Intravesical OnabotulinumtoxinA Injection on Elderly Patients with Chronic Central