Variation in Defining Retention After Onabotulinum Toxin A for Overactive Bladder: A Systematic Review.

Importance: Urinary retention is a common adverse effect after intravesical injection of onabotulinum toxin A (BTX) for overactive bladder (OAB). Reported retention rates range from 1.6% to more than 40%. This variation may be due to varying definitions of retention in the literature.

Objective: We aimed to assess the variation in definitions of urinary retention across studies of BTX for the treatment of OAB.

Study design: We performed a systematic review of studies of BTX for OAB by querying MEDLINE and EMBASE according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included original research studies on adults with overactive bladder treated with BTX and urinary retention reported as an outcome from January 2000 to December 2020.

Results: From 954 results, we identified 53 articles that met inclusion criteria. There were 6 definitions for urinary retention. The majority of studies (60.4%) reported initiating clean intermittent catheterization (CIC) as the metric for retention. Five (9.5%) studies provided no definition despite reporting retention as an adverse event. Twenty studies (37.7%) specified a postvoid residual volume (PVR) threshold for initiating CIC in asymptomatic patients; 19 (35.8%) specified a PVR threshold for CIC in symptomatic patients. The PVR thresholds ranged from 100 to 400 mL. Twenty-three studies (43.4%) did not address asymptomatic elevation of PVR, and 22 (41.5%) did not address how symptomatic patients were managed.

Conclusions: Urinary retention after BTX injection is inconsistently defined in the literature. Lack of standardization in reporting retention after intravesical BTX prevents accurate assessment of the risk of urinary retention and comparison of outcomes between studies.