Gender Differences in Quality of Bowel Preparation for Colonoscopy: Post Hoc Analysis of a Randomized Controlled Trial.

Objective: Bowel cleansing is a key element for a quality colonoscopy. Despite recent advances, not all predictors of successful cleansing are fully known. This post hoc analysis of an RCT aims to explore gender differences in bowel cleansing quality.

Methods: The "OVER" trial was a multicenter phase-4 RCT including 478 patients randomized 1:1 to receive split-dose 1L polyethylene glycol plus ascorbate (PEG+ASC) or 4L-PEG. In this post hoc analysis, multivariable logistic regression models were designed to assess predictors of cleansing success (CS) and adenoma detection rate (ADR) by gender.

Results: Of the 478 randomized patients, 50.2% were males and 49.8% females.Overall, CS was comparable between females and males (87.1% vs 88.4, P = 0.6), whereas CS in the right (95.7% vs 90.9, P = 0.049) and transverse colon (98.6% vs 93.9, P=0.011) was significantly higher in females.At multivariable regression analysis for CS outpatient setting (OR = 5.558) and higher withdrawal time (OR = 1.294) were independently associated with CS in females, whereas screening/surveillance indication (OR = 6.776) was independently associated with CS in males.At multivariable regression analysis for ADR, running time <5 hours (OR = 3.014) and higher withdrawal time (OR = 1.250) were independently associated with ADR in females, whereas older age (OR = 1.040) and higher withdrawal time (OR = 1.093) were independently associated with ADR in males.

Conclusions: This study showed different results in bowel preparation quality and different predictors of CS and ADR by gender. These findings suggest the need for further research to explore gender-specific approaches for bowel preparation.