Impact of the supine position versus left horizontal position on colonoscopy insertion: a 2-center, randomized controlled trial.

BACKGROUND AND AIMS: Colonoscopy insertion is painful for some patients and is one of the main barriers to screening colonoscopy. Few studies have assessed the impact of the supine position (SP) on colonoscopy insertion, especially for unsedated patients. The aim of this randomized controlled trial was to clarify this issue.

METHODS: Unsedated patients were randomized to SP or left horizontal position (LHP) as the starting position of colonoscopy insertion. The primary outcome measure was cecal intubation time (CIT), and the secondary outcome measures were descending colon intubation time (DIT), pain score of patients, difficulty score according to the endoscopist, and patients' acceptance of unsedated colonoscopy.

RESULTS: A total of 347 patients were randomized to the SP group (175) or the LHP group (172). The CIT in the SP group was significantly shorter than that in the LHP group (275.0 seconds [interquartile range (IQR), 234.0-328.5 seconds] versus 316.0 seconds [IQR, 261.0-370.0 seconds], P < .001). The DIT was also shorter in the SP group (64.5 seconds [IQR, 52.0-86.3 seconds] versus 74.0 seconds [IQR, 62.0-92.0 seconds], P = .001). Compared with the LHP, the SP had a lower pain score (3.3 versus 3.9, P = .002), a lower difficulty score (3.1 versus 3.7, P < .001), a lower frequency of position change (7.1% versus 38.0%, P < .001), and less need for abdominal compression (39.1% versus 45.5%, P = .02). SP was the only modifiable and independent factor identified to reduce CIT and pain score and improve patients' acceptance of unsedated colonoscopy.

CONCLUSIONS: As an economical and convenient method, SP can reduce CIT, ease pain, and improve patients' acceptance of unsedated colonoscopy. (Clinical trial registration number: NCT03289442.).