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Split-dose preparation for colonoscopy increases adenoma detection rate: a randomised controlled trial in an organised screening programme
  1. F Radaelli1,
  2. S Paggi1,
  3. C Hassan2,
  4. C Senore3,
  5. R Fasoli4,
  6. A Anderloni5,
  7. F Buffoli6,
  8. M F Savarese6,
  9. G Spinzi1,
  10. D K Rex7,
  11. A Repici5
  1. 1Division of Digestive Endoscopy and Gastroenterology, Valduce Hospital, Como, Italy
  2. 2Endoscopy Unit, Nuovo Regina Margherita Hospital, Rome, Italy
  3. 3Centro di Prevenzione Oncologica (CPO Piemonte), AOU Città della Salute e della Scienza, Turin, Italy
  4. 4Division of Digestive Endoscopy, Imperia Hospital, Imperia, Italy
  5. 5Endoscopy Unit, IRCCS Istituto Clinico Humanitas, Rozzano, Milano, Italy
  6. 6Division of Digestive Endoscopy and Gastroenterology, A.O. Istituti Ospitalieri di Cremona, Cremona, Italy
  7. 7Division of Gastroenterology/Hepatology, Indiana University Medical Center, Indianapolis, Indiana, USA
  1. Correspondence to Dr F Radaelli, Division of Digestive Endoscopy and Gastroenterology, Valduce Hospital, Via Dante 11, Como 22100, Italy; francoradaelli01{at}


Objective Although a split regimen of bowel preparation has been associated with higher levels of bowel cleansing, it is still uncertain whether it has a favourable effect on the adenoma detection rate (ADR). The present study was aimed at evaluating whether a split regimen was superior to the traditional ‘full-dose, day-before’ regimen in terms of ADR.

Design In a multicentre, randomised, endoscopist-blinded study, 50–69-year-old subjects undergoing first colonoscopy after positive-faecal immunochemical test within an organised colorectal cancer organised screening programmes were 1:1 randomised to receive low-volume 2-L polyethylene glycol (PEG)-ascorbate solution in a ‘split-dose’ (Split-Dose Group, SDG) or ‘day-before’ regimen (Day-Before Group, DBG). The primary endpoint was the proportion of subjects with at least one adenoma. Secondary endpoints were the detection rates of advanced adenomas and serrated lesions at per-patient analysis and the total number of lesions.

Results 690 subjects were included in the study. At per-patient analysis, the proportion of subjects with at least one adenoma was significantly higher in the SDG than in the DBG (183/345, 53.0% vs 141/345, 40.9%, relative risk (RR) 1.22, 95% CI 1.03 to 1.46); corresponding figures for advanced adenomas were 26.4% (91/345) versus 20.0% (69/345, RR 1.35, 95% CI 1.06 to 1.73). At per-polyp analysis, the total numbers of both adenomas and advanced adenomas per subject were significantly higher in the SDG (1.15 vs 0.8, p <0.001; 0.36 vs 0.22, p<0.001).

Conclusions In an organised screening setting, the adoption of a split regimen resulted into a higher detection rate of clinically relevant neoplastic lesions, thus improving the effectiveness of colonoscopy. Based on such evidence, the adoption of a split regimen for colonoscopy should be strongly recommended.

Clinical trial registration number NCT02178033.


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  • Contributors FR, SP, CS, CH, AR: study concept and design; interpretation of results; drafting of the manuscript. FR, SP, CS: acquisition of data and statistical analysis. All the authors: critical revision of the article for important intellectual content and final approval of the article.

  • Competing interests None declared.

  • Ethics approval The protocol was approved by the Valduce Hospital ethics committee and afterwards by all other participating institutions.

  • Provenance and peer review Not commissioned; externally peer reviewed.