Although the clinical usefulness of colonoscopy has been established, the procedure remains painful for many patients. This study was designed to clarify the factors predicting colonoscopy-related pain. We evaluated 283 consecutive patients who completed a first-ever, total colonoscopy without sedatives or analgesics. The severity of pain symptoms was evaluated by a numeric rating scale (NRS) in a questionnaire immediately after the colonoscopy. Patient backgrounds and endoscopic findings were analyzed to evaluate their association with pain. Out of 283 patients, 53 scored their pain 0-1 on the NRS while 48 scored it 6-10. We defined the colonoscopies of the former and latter patients as painless and painful, respectively, and compared the two. Multivariate analyses revealed that low body weight (OR 4.95, 95%CI 1.89-12.99) and longer intubation time (OR 3.63, 95%CI 1.46-9.03) were significant risk factors for painful colonoscopy. To identify factors contributing to the increased intubation time, we divided subjects into short- and long-intubation-time groups based on a median insertion time of 7 min. Older age (OR 2.28, 95%CI 1.31-3.98), previous abdominal surgery (OR 1.93, 95%CI 1.13-3.32) and findings of invasive cancer (OR 10.90, 95%CI 1.34-88.90) were significant factors for longer intubation time.
