Inter-observer variation between general and specialist gastrointestinal pathologists when grading dysplasia in ulcerative colitis

(UC), Recently, pathologists have received unfavourable media attention con cerning other cancer screening programmes. The aim of this study was to det ermine whether colonic biopsy specimens should be examined by gastrointesti nal pathologists as opposed to generalists, by examining interobserver vari ation between the two groups, Fifty-one coded slides showing varying degree s of dysplasia were mailed to seven gastrointestinal and six general histop athologists, Pathologists allocated each biopsy into one of four categories without the benefit of a clinical history or an opportunity to use the 'in definite' category that is included in the Riddell classification, The resp onses were analysed using kappa statistics. The overall kappa statistic for gastrointestinal pathologists was 0.30 [95% confidence interval (CI)= 0.26 -0.34] and for general pathologists 0.28 (95% CI=0.23-0.32). Agreement was best for high-grade dysplasia (kappa of 0.54 and 0.61 for GI and general pa thologists, respectively). There was total concordance of the 13 pathologis ts in only four of the 51 slides (7.8%) (95% CI=0.4-15.2%). It is concluded from these results that gastrointestinal pathologists are no better than g eneralists when grading dysplasia in UC and that agreement is poor in both groups, There is therefore no evidence that there would be any benefit in h aving specialist histopathology centres concentrating specifically on the i nterpretation of all surveillance colonoscopy biopsies from around the UK, It must be made clear to the public that surveillance and screening program mes carry a significant rate of histological error and that perfection cann ot be expected or achieved with present methods, Copyright (C) 2001 John Wi ley & Sons, Ltd.