Aim: To determine the inter-observer variation in the histological diagnosis of colorectal polyps. Methods and results: Four hundred and forty polyps were randomly selected from a colorectal cancer screening programme. Polyps were first evaluated by a general (324 polyps) or expert (116 polyps) pathologist, and subsequently re-evaluated by an expert pathologist. Conditional agreement was reported, and inter-observer agreement was determined using kappa statistics. In 421/440 polyps (96%), agreement for their non-adenomatous or adenomatous nature was obtained, corresponding to a very good kappa value of 0.88. For differentiation of adenomas as non-advanced and advanced, consensus was obtained in 266/322 adenomas (83%), with a moderate kappa value of 0.58. For the non-adenomatous or adenomatous nature, both general and expert pathologists, and expert pathologists between each other, showed very good agreement {kappa values of 0.89 [95% confidence interval (CI) 0.83-0.95] and 0.86 (95% CI 0.73-0.98), respectively}. For categorization of adenomas as non-advanced and advanced, moderate agreement was found between general and expert pathologists, and between expert pathologists [kappa values of 0.56 (95% CI 0.44-0.67) and 0.64 (95% CI 0.43-0.85), respectively]. Conclusions: General and expert pathologists demonstrate very good inter-observer agreement for differentiating non-adenomas from adenomas, but only moderate agreement for non-advanced and advanced adenomas. The considerable variation in differentiating non-advanced and advanced adenomas suggests that more objective criteria are required for risk stratification in screening and surveillance guidelines.

Additional Metadata
Keywords Colorectal cancer screening, Colorectal polyps, Histological diagnosis, Interobserver variation
Persistent URL dx.doi.org/10.1111/j.1365-2559.2011.03822.x, hdl.handle.net/1765/26389
Citation
van Putten, P.M.A., Hol, L., van Dekken, H., van Krieken, J.H.J.M., van Ballegooijen, M., Kuipers, E.J., & van Leerdam, M.E.. (2011). Inter-observer variation in the histological diagnosis of polyps in colorectal cancer screening. Histopathology, 58(6), 974–981. doi:10.1111/j.1365-2559.2011.03822.x