O1037: Evaluation of the Efficacy of Botulinum Toxin a Injections Using Urodynamic Work and Pdet Theoretical Pressure: A More Quantitative Method

Background: The literature indicates that Botulinum Toxin A (BTX) injections are beneficial in managing neurogenic detrusor overactivity. Randomized trials by Austin et al and Franco et al have highlighted the effective doses and long-term safety and durability of treatments with BTX. When evaluating UDS there is evidence that reading of UDS is fraught with interobserver variability as documented by Dudley et al. Most drug trials evaluating medications rely on changes in bladder volume or end filling pressure as primary end points. Our aim was to investigate if patients that we have treated with intradetrusor injections of BTX had successful outcomes after injections utilizing urodynamic work (UW) and Pdet theoretical pressure (Pdetth).

Methods: A retrospective review of patients treated with BTX over 4 years was performed. UDS data was exported into a text delimited format and Python was utilized to calculate the area under the curve which describes UW. The vol, vol/EBC, Pdetfinal were recorded and UW and the Pdetth were calculated for each study. Bayes factors (BF)and p values were calculated for matched pairs. Moderate evidence (ME) or above (BF>3-10 or < 0.1-0.33) was considered significant. BF were calculated with Null hypothesis/alternative hypothesis. P-values were calculated for comparison purposes (p < 0.05 was significant). Cross tab analysis was performed on outcomes measures. Statistics were performed on SPSS ver 28 and Xlstat.

Results: 16 patients that had 1 or more BTX injections with repeat UDS within 6 months or less of the BTX injection were reviewed, 48 studies were evaluated (24 pre and 24 post).Pts ranged age from 7.12- 25.4 years (13.4±5.3). Analysis of all the results revealed ME that Pdetth and Pdetfinal differed after treatment with BTX (BF=0.262 p=0.011, 0.153 P=0.006). When success or failure of BTX injection was tested with the classic criteria of improvement in vol used in most trials vs a change in Pdetth with a cross tab analysis there was no difference in the methods predicting success outcomes between the 2 groups. When analyzing the results of this comparison it was evident that Pdetth is better supported by extreme evidence (BF=0.001, p,0.0001) that it can differentiate an improvement due to BTX than vol-based methods (ME (BF=0.05, p=0.002)). Pdetfinal only exhibited anecdotal evidence (BF=0.651 and 0.39) for both vol and Pdetth methods to determine success.

Conclusion: Our data confirms that Pdetth is a better method of determining post BTX outcomes when compared to volume or pressure based methods. The difficulties in determining final pressures or pressure to measure compliance is best replaced by a pressure determined over the whole course of the filling phase and then calculating a terminal theoretical pressure for the area under the curve while filling.