Study design, materials and methods
A retrospective review of all cystoplasty patients who underwent BTX-A injection at a tertiary centre between 2008-2019. Details including indications and time from cystoplasty, video-urodynamic, BTX-A dose and clinical outcomes were analysed. Telephone interview were performed for patients that requested repeat BTX-A injections. The interview included PGIC7 and UDI6 questionnaires. A positive clinical response was considered improvement of overactive symptoms sufficient to merit repeat BTX injection and a PGIC7 of 4 or above.
Interpretation of results
The only predictor of response in our series was peak detrusor pressure. This may reflect residual overactivity primarily in the bladder segment, as overactivity related to bowel peristalsis would be expected to be more consistent pressure, and compliance loss a steady state pressure related to volume. More work is required to assess whether this hypothesis can guide therapy and predict outcome.
This study is a reflection of our clinical experience with an uncommon and challenging patient cohort. As such, the study has limitations. The retrospective analyses did not allow assessment by the commonly used criteria for BTX-A studies, and indeed frequency-volume and incontinence charts would be difficult to achieve in many of these complex patients. We tried to compensate for this using phone administration of questionnaires. In future theses questionnaires will be used in a prospective fashion. The study is also limited by the heterogeneous population and small sample size, inherent to the rarity of the circumstances