Lutgens 2009.

Methods	Cohort study
Participants	149 patients with IBD‐associated CRC were identified Patients were assigned to the surveillance group when they had undergone one or more surveillance colonoscopies before a diagnosis of CRC Patients who had not undergone surveillance served as controls
Interventions	Colonoscopic surveillance versus no surveillance
Outcomes	1. CRC related 2. Tumour stage 3. Death
Notes	Attempts to control for bias: 1. Statistical analysis: (a) Patient characteristics using the X2 test, Fischer's exact test and Student's t‐test compared the patient characteristics between the two groups (b) Kaplan‐Meier and cox regression analyses were used for survival calculations