To what extent can bowel preparation quality be considered “adequate”?: a systematic review and meta-analysis

Background/Aims: While low-quality bowel preparation is known to reduce the adenoma detection rate (ADR), the distinction between intermediate- and high-quality preparations remains unclear.Methods: Electronic searches were conducted in PubMed and Embase through July 2024. Randomized controlled trials reporting ADR and the Boston bowel preparation scale (BBPS) were included, and outcomes were pooled according to bowel preparation quality using a random-effects model. The primary outcome was ADR in intermediate-quality (BBPS ≥6, and ≥2 in each segment) versus high-quality (BBPS≥8) bowel preparation. Secondary outcomes included advanced ADR.Results: Fourteen trials were included (5,246 in the high-quality group and 1,728 in the other group). There was no significant difference in ADR (risk difference [RD], –0.02; p=0.13; I2=21%). Subgroup analyses showed no significant difference with computer-aided detection (CADe; RD, –0.03; p=0.70; I2=81%) or linked color imaging (RD, 0.04; p=0.31; I2=0%). The heterogeneity observed with CADe may reflect differences in colonoscopist experience or CADe systems. The results were similar for advanced ADR. Funnel plot and Egger’s test indicated minimal publication bias.Conclusions: Intermediate-quality preparation allows adequate adenoma detection. When each BBPS subscore is ≥2, surveillance recommendations can generally be followed.