A型肉毒桿菌素注射治療間質性膀胱炎/膀胱疼痛症候群之成功預後因子探討林琮翊¹、游婉茹²、張天霖¹、李宇坤¹、楊家誠¹、黃子修¹、劉民慶¹、張嘉峰¹、
江元宏¹、郭漢崇¹

¹佛教慈濟醫療財團法人花蓮慈濟醫院 泌尿部，²護理部

Predictive Factors for a Successful Treatment Outcome of Botulinum Toxin A Injection on Interstitial Cystitis / Bladder Pain Syndrome
Tsung-Yi Lin¹, Wan-Ru Yu², Tien-Lin Chang¹, Yu Khun Lee¹, Chia-Cheng Yang¹, Tsu-Hsiu Huang¹, Ming-Ching Liu¹, Jia-Fong Jhang¹, Yuan-Hong Jiang¹, Hann-Chorng Kuo¹

Department of Urology¹ and Nursing², Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University, Hualien, Taiwan

Purpose: Interstitial cystitis / bladder pain syndrome (IC/BPS) is a debilitative disease of not well determined etiology. In clinical trial for human IC/BPS, the functional bladder capacity (FBC), cystometric bladder capacity (CBC), bladder pain visual analog scale (VAS) were increased after BoNT-A injection. However, not all IC/BPS patients can benefit from BoNT-A treatment, the success rate was reported around 60% or less in the large cohort clinical trial. This study retrospectively analyzed our previous enrolled IC/BPS patients who were treated with intravesical BoNT-A injection, and search for the predictive factors for a successful treatment outcome.

Materials and Methods: A total of 433 patients with bladder-centric IC/BPS were analyzed. All patients received comprehensive urological examination, videourodynamic study, and cystoscopic hydrodistention, and the cystoscopic maximal bladder capacity (MBC) and glomerulation grade were documented. Patients received consecutive intravesical BoNT-A 100U injections every 6 months. The patients’ clinical responses were assessed at baseline and at 3 months after BoNT-A injection; and the overall satisfaction to the BoNT-A treatment was requested to report by the Global Response Assessment (GRA). The clinical demographics, IC/BPS subtypes, cystoscopic parameters, and VUDS parameters were compared between successful and failed subgroups. Predictive factors for treatment success were analyzed using logistic regression.

Results: In total, 203 (48.0%) patients achieved a successful treatment outcome, including 33 (7.6%) with a GRA of 3 and 175 (40.4%) with a GRA of 2. Conversely, 235 (52.0%) patients failed the treatment, consisting of 136 (31.4%) with a GRA of 1 and 89 (20.6%) with a GRA of 0. Regarding adverse events, dysuria was reported by 130 (30.0%) patients, though it did not significantly affect the treatment outcome. However, urinary tract infection (UTI) following BoNT-A injection appeared to correlate with poorer results: 68.5% (22/32) of patients with UTI experienced treatment failure, while only 30.3% reported success.

A comparison between the successful (GRA 2 and 3) and failed (GRA 0 and 1) treatment groups revealed significant physiological differences. Patients with a successful outcome had significantly greater Maximal Bladder Capacity (MBC) (820 ± 162 mL vs 625 ± 196 mL, p < 0.001), a lower grade of glomerulation (1.23 ± 0.9 vs 1.68 ± 0.9, p < 0.001), and larger bladder capacity in both voided volume (247 ± 126 mL vs 201 ± 100 mL, p < 0.001) and cystometry (283 ± 122 mL vs 231 ± 106 mL, p < 0.001). Other Video-Urodynamic Study (VUDS) findings did not show a significant impact on the outcome. Notably, among the 23 patients with Hunner’s IC/BPS, 19 (82.6%) failed the treatment, resulting in a success rate of only 17.4% for this specific subtype.

Logistic regression analysis further clarified these relationships. In univariate analysis, MBC, glomerulation grade, presence of Hunner’s IC (HIC), and bladder capacity parameters were all significantly different between the successful and failed groups. Subsequent multivariate analysis confirmed that a higher MBC and a lower glomerulation grade are independent predictors of a successful treatment outcome after intravesical BoNT-A injection for IC/BPS.

Conclusions: Intravesical BoNT-A injection is successful in 48.0% of patients with IC/BPS. Only 17.4% of patients with Hunner’s IC/BPS can benefit from this treatment. Patients with a successful treatment outcome had a higher MBC and lower grade of glomerulation, suggesting BoNT-A injection is effective on IC/BPS with a lower degree of bladder inflammation. Patients with failed treatment outcome may require alternative therapeutic strategies or repeated injections.