Intra-detrusor injection therapy with onabotulinumtoxinA is generally accepted as a highly effective, minimally invasive and well-tolerated day procedure for patients with refractory overactive bladder (OAB) and neurogenic detrusor overactivity (NDO). The aim of this study was to summarize currently available methods of assessing treatment efficacy and risk factors that may influence the therapeutic effect of this approach. We found that there are discrepancies in the assessment methods. The evaluation of intra-detrusor injections with onabotulinumtoxinA in clinical trials are not always transposable into day-to-day practice. Moreover, the primary endpoints in clinical trials do not explore the entirety of meaningful patient-centered outcomes. Therefore, in daily clinical practice with patients with overactive bladder syndrome, the therapy should be assessed with objective measures (bladder diaries) and patient-oriented outcomes analyzing the quality of life (questionnaires). In neurogenic individuals, therapeutic efficacy should be additionally evaluated with urodynamic studies. Potential risk factors that may influence the treatment outcomes include urodynamically proven detrusor overactivity, elevated maximum detrusor pressure, greater maximum cystometric capacity, impaired bladder compliance, older age, male gender, a higher baseline bother score, previous anticholinergic treatment, and repeated injections with a subsequent decline in efficacy. The risk of intermittent catheterization following injections seems to depend on the etiology of detrusor overactivity, the injected dose, the injection technique, and the definition of significant post-void residual urine requiring catheterization.
Keywords: failure; onabotulinumtoxinA; risk factors.