Water Exchange Method Significantly Improves Adenoma Detection Rate: A Multicenter, Randomized Controlled Trial

OBJECTIVES: Adenoma detection rate (ADR) is a key colonoscopy quality indicator in Western clinical literature. Our low ADR prompted us to assess novel methods to improve performance. Western retrospective reports suggested that water exchange (WE) could increase ADR. However, most of these studies used pain score or intubation rate as the primary outcome. Here we test the hypothesis that WE significantly increases ADR among Chinese colonoscopists and design a prospective randomized controlled trial using ADR as our primary outcome. METHODS: This prospective, randomized controlled trial was performed at six centers in China. Screening, surveillance, and diagnostic cases were randomized to be examined by WE or traditional air insufflation (AI) method. The primary outcome was ADR. RESULTS: From April 2014 to July 2015, 3,303 patients were randomized to WE (n = 1,653) and AI (n = 1,650). The baseline characteristics were comparable. Overall ADR was 18.3% (WE) and 13.4% (AI) (relative risk 1.45, 95% confidential interval: 1.20-1.75, P < 0.001). ADR in screening patients using AI was 25.8% (male) and 15.7% (female). ADR in screening patients aged > 50 years old was 29.4% (WE) and 22.9% (AI) (relative risk 1.09, 95% confidential interval: 1.00-1.19, P = 0.040). The increase by WE was reproducibly observed in all indication categories, and significant in screening and diagnostic cases. The limitation imposed by the unblinded investigators was mitigated by comparable inspection times in cases without polyps, similar adenoma per positive colonoscopy, and reproducible enhancement of ADR and adenoma per colonoscopy by WE across all eight investigators. CONCLUSIONS: This prospective study confirms Western retrospective data that WE significantly improves ADR among Chinese colonoscopists. WE may be superior to AI for screening colonoscopy in China. Colonoscopists elsewhere with low ADR might consider evaluating WE for performance improvement.