Inter-observer variation in the histological diagnosis of polyps in colorectal cancer screening

Abstract

van Putten P G, Hol L, van Dekken H, Han van Krieken J, van Ballegooijen M, Kuipers E J & van Leerdam M E (2011) Histopathology 58, 974–981 Inter‐observer variation in the histological diagnosis of polyps in colorectal cancer screening 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.

Prevalence of advanced histological features in diminutive and small colon polyps

“…Pickhardt et al 18 [21][22][23][24][25] A recent study also found only moderate interobserver agreement (kappa ϭ 0.53) in pathologists abilities to diagnose any advanced histological features (villous features or high-grade dysplasia) in polyps Ͻ10 mm. 26 In addition, previous studies have not found either feature to be a consistent, independent predictor of subsequent advanced adenoma development. 27,28 As a result of this limited data, recent guidelines published by the European Union do not mandate a shorter surveillance interval for patients with adenomas containing villous components or high-grade dysplasia.…”

The clinical effectiveness of different surveillance strategies to prevent colorectal cancer in people with intermediate-grade colorectal adenomas: a retrospective cohort analysis, and psychological and economic evaluations

“…In terms of measurement error of pathological attributes of adenomas, a number of sources are available. [65][66][67][68][69] These indicate excellent histopathological measurement of adenoma size, with interobserver correlations among measures of the order of 0.98 and kappa values of the order of 0.85-0.90. 66,67 This would confer around a 2% bias in the estimates of logistic and Cox regression coefficients, 70 and around the same proportionate increase in size of 95% CIs -see Spiegelman et al 70 for mathematical details.…”

“…66,68 Determination of grade of dysplasia is generally observed to be good, with kappa values of the order of 0.6 and interobserve agreement as high as 94%. 65,67 Most studies find that determination of villous status (and further classification of villous adenomas) is subject to a greater degree of measurement error, with kappa values of 0.40-0.60. 65,67,69 However, in our sensitivity analyses, we found that this was not crucial to our results.…”

“…65,67 Most studies find that determination of villous status (and further classification of villous adenomas) is subject to a greater degree of measurement error, with kappa values of 0.40-0.60. 65,67,69 However, in our sensitivity analyses, we found that this was not crucial to our results. Thus, it is likely that measurement error of the pathological attributes of the adenomas, although not negligible, does not significantly alter the interpretation of our results.…”

In vivo Optical Diagnosis of Polyp Histology: Can We Omit Pathological Examination of Diminutive Polyps?

“…First, there is a substantial interobserver variability in the diagnosis of the villous component and even HGD, with kappa index ranging from 0.35 to 0.48 and 0.38 to 0.69 respectively [28,29]. This problem may be even greater in polyps less than 10 mm [30]. Second, it is not clear that villous component or HGD are independent predictors of the subsequent development of advanced adenomas during follow-up.…”