*Statistical Analysis*

Statistical analysis was performed using SPSS version 25 (IBM, Armonk, NY, USA); a *p* value of <0.05 was considered statistically significant. Data were expressed as mean and standard deviations for continuous variables, and categorical variables were presented as counts and proportions. Between-group statistical comparisons were tested for categorical variables using either Pearson's chi-square or Fisher's exact test, and additionally using an independent t-test for continuous variables, excluding outliers of urinary biomarkers.

To examine the association of treatment outcomes, logistic regression models were further estimated for subjective and objective factors in an attempt to predict the factors which influence the expected treatment outcomes. Logistic regression was used to analyze the relationship between IC/BPS patients' characteristics, VUDS parameters, and IC/BPS bladder phenotype and self-reported satisfactory treatment outcomes.

**Author Contributions:** Conceptualization: W.-R.Y. and H.-C.K.; data curation: W.-R.Y. and W.- C.C.; project administration: W.-R.Y. and H.-C.K.; methodology: W.-R.Y., J.-F.J., Y.-H.J. and H.-C.K.; investigation and formal analysis: W.-R.Y., J.-F.J., Y.-H.J. and H.-C.K.; writing—original draft: W.-R.Y.; writing—review and editing: H.-C.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Buddhist Tzu Chi Medical Foundation grants TCMF-SP 108-01 and TCMF-MP 110-03-01.

**Institutional Review Board Statement:** This study was performed in line with the principles of the Declaration of Helsinki. Approval for convenience sampling at a medical center was granted by the Ethics Committee of Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation (Code: IRB: 105-25-B, approved date: 21 June 2017).

**Informed Consent Statement:** The requirement for obtaining patient informed consent was waived due to the retrospective nature of the study.

**Data Availability Statement:** Data are available if requested from the corresponding authors.

**Acknowledgments:** We thank the patients who participated in the trial, their families, and the staff at the Department of Urology, Hualien Tzu Chi Hospital who collected and validated the data. We also thank our colleagues throughout the system who referred cases.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **Appendix A. The Inclusion and Exclusion Criteria of Intravesical BoNT-A Injection for IC/BPS**

