IncontinenceAdverse Events of Intravesical Botulinum Toxin A Injections for Idiopathic Detrusor Overactivity: Risk Factors and Influence on Treatment Outcome
Introduction
Intravesical injection of botulinum toxin type A (BoNTA) has emerged as a novel treatment for patients with overactive bladder (OAB) or idiopathic detrusor overactivity (IDO) refractory to antimuscarinic therapy [1], [2]. The success rate of BoNTA treatment for OAB has been reported to range from 50–80% in patients with or without detrusor overactivity (DO) [3], [4], [5]. For treatment of OAB or DO, the dose of BoNTA has decreased from 300 U to 100 U of Botox (Allergan, Irvine, CA, USA), and similar therapeutic effects are observed at this dose [5], [6], [7], [8]. However, the incidence of reported treatment-related adverse events (AEs) remains high [8], [9].
Recent studies demonstrated significant dose-dependent improvements in urinary symptoms and urodynamic parameters in patients with OAB [10], [12], [13], [14]. However, the incidence of AEs is also associated with increasing dose of BoNTA [8], [14]. The main AEs associated with BoNTA injection are acute urinary retention (AUR), large postvoid residual (PVR), difficulty in urination, and urinary tract infection (UTI), which occurred in approximately 20–43% of patients [1], [2], [8], [10], [11]. Large PVR after BoNTA injection was clinically relevant and clean intermittent catheterization (CIC) was necessary [4], [8], [11]. In a recent report, complete continence after 200 U Botox injection was 51% at 4 wk [15]. Although patients without complete continence may experience improvement in urgency incontinence, they might not be satisfied with the treatment outcome due to these bothersome AEs.
In urologic practice, elderly patients may have comorbidities with OAB. Although detrusor BoNTA injection for refractory OAB in elderly patients was safe [16], the high rate of AEs deserves special attention before this treatment is recommended to this group. This study aimed to analyze the risk factors associated with the increasing incidence of AEs after intravesical BoNTA injection.
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Patients and methods
A total of 217 patients who received intravesical BoNTA injection for refractory IDO for the first time were enrolled in this study. These patients had participated in previous prospective clinical trials and a new prospective trial at the authors’ hospital from 2004 to 2009. The inclusion criteria were urodynamic DO with or without urinary incontinence refractory to previous antimuscarinics for >3 mo. Exclusion criteria were UTI, bladder outlet obstruction (BOO), neurogenic bladder, abnormal
Results
A total of 217 patients aged 18–94 yr (mean ± SD: 70.5 ± 14.7) were studied. The patient characteristics are listed in Table 1. There was no significant difference in the mean age among all subgroups.
At 3 mo, 144 patients reported successful results (96 dry, 48 moderately improved; total 66.3%), 36 (16.6%) showed mild improvement, and 37 (21 no change, 16 getting worse; total 17.1%) reported treatment failure. Fig. 1 shows changes in the bladder capacity, Qmax, PVR, and VE from baseline to 12 mo
Discussion
In recent decades, intravesical botulinum neurotoxin (BTX) injection has been shown to be an effective therapeutic alternative for IDO refractory to antimuscarinics. Urinary urgency and episodes of incontinence were found to improve after BTX injection [20], [21]. The maximum effect on significant increases in cystometric capacity was observed at 4 wk, but PVR also increased at 4 wk [10]. Large PVR is associated with subsequent UTI [11].
Injecting dose and injection sites have not affected
Conclusions
Male gender, baseline PVR ≥100 ml, comorbidity, and BoNTA dose >100 U are risk factors for increasing incidence of AEs after intravesical BoNTA injection for IDO.
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