Outcomes of a single trigone-only vs. 20 trigone-sparing injections of OnabotulinumtoxinA for refractory overactive bladder (OAB)

Purpose To compare the safety and durability of a single intravesical trigonal-only versus 20 trigone-sparing injections of OnabotulinumtoxinA (BTA) for refractory OAB. Methods A chart review of all idiopathic OAB patients treated with BTA from January 2016 to December 2018 was performed. Outcomes measures included: inter-injection interval, post-void residual (PVR), urinary tract infections (UTI), urinary retention requiring catheterization, and procedure time (min). Statistical analyses were performed using independent sample t-tests. Results Baseline characteristics were comparable for the two groups, data on 69 treatments (19 patients trigone-only) were compared to 105 treatments (26 patients trigone-sparing). There were no differences in the inter-injection intervals or rates of UTI. The trigone-only group exhibited a lower mean PVR (113 ml vs 160 ml, p < 0.02), lower proportion with PVR > 150 ml (23% vs. 39%, p < 0.03), lower rate of urinary retention (5.3% vs. 17.4%, p < 0.02), and shorter procedure time (4.3 min vs. 5.7 min, p < 0.01). There were no cases of vesico-ureteral reflux. Conclusion While interpretation remains speculative, the results of this observational study suggest that a single trigone-only injection appears to be as safe and durable as multiple trigone-sparing injections but maybe quicker to perform and appears to have a lower impact on voiding function. Larger series and adequately powered prospective randomized clinical trials are warranted to validate the findings of this pilot study.