BACKGROUND: Determining whether a colonoscopy is performed for screening or nonscreening purposes can facilitate clinical practice and research. However, there is no simple method to determine the colonoscopy indication using patient medical files or health administrative databases.OBJECTIVE: To determine patient-endoscopist agreement on the colonoscopy indication.METHODS: A cross-sectional study was conducted among staff endoscopists and their patients at seven university-affiliated hospitals in Montreal, Quebec. The study participants were 50 to 75 years of age, they were able to understand English or French, and were about to undergo colonoscopy. Self- (endoscopist) and interviewer-administered (patient) questionnaires ascertained information that permitted classification of the colonoscopy indication. Patient colonoscopy indication was defined as the following: perceived screening (routine screening, family history, age); perceived nonscreening (follow-up); medical history that implied nonscreening; and a combination of the three preceding indications. Agreement between patient and endoscopist indications was measured using concordance and Kappa statistic.RESULTS: In total, 702 patients and 38 endoscopists participated. The three most common reasons for undergoing colonoscopy were routine screening/regular check-up (33.8%), follow-up to a previous problem (30.2%) and other problem (24.6%). Concordance (range 0.79 to 0.85) and Kappa (range 0.58 to 0.70) were highest for perceived nonscreening colonoscopy. Recent large bowel symptoms accounted for 120 occurrences of disagreement in which the patient perceived a nonscreening colonoscopy while the endoscopist perceived a screening colonoscopy.CONCLUSIONS: Patient self-report may be an acceptable means for rapidly assessing whether a colonoscopy is performed for screening or nonscreening purposes. Delivery of patient-centred care may help patients and endoscopists reach a shared understanding of the reason for colonoscopy.