Original ContributionsInterobserver reproducibility of Gleason grading of prostatic carcinoma: Urologic pathologists
Section snippets
Materials and methods
Two of the authors (W.C.A. and J.I.E.) collected, from several sources, 46 hematoxylin and eosin-stained glass slides of prostatic needle biopsies containing prostatic carcinoma. The amount of tumor on each slide ranged from microscopic foci to extensive. Examples of the spectrum of Gleason scores were included. No effort was made to make the cases particularly difficult.
The slides were distributed for Gleason grading to 9 additional urologic pathologists (M.B.A., D.G.B., P.A.H., E.C.J.,
Results
The overall κw for interobserver agreement for exact scores 2-10 for each of the urologic pathologists, used as the reference standard for each of the others (Table 1, pathologists not in alphabetical order), ranged from 0.56 to 0.70, with only one κw (0.56) less than 0.60 (substantial agreement).Empty Cell Reference Pathologist Comparison Pathologist 1 2 3 4 5 6 7 8 9 10 1 .63 .52 .70 .59 .58 .74 .66 .69 .84 2 .63 .59 .78 .74 .70
Discussion
There is some variability in interobserver agreement among urologic pathologists, but the overall κw for scores 2-10 are, with one exception (0.56), greater than 0.60 (substantial agreement). This is better agreement than most other studies in which κw was calculated. Some studies had similar or better exact or ±1 agreement, but these had only a pair of participating pathologists or a prestudy primer or agreement on criteria (reviewed in ref 2). Further, the overall interobserver agreement is
Acknowledgements
The authors thank Michelle Page and JoAnn Higdon for secretarial assistance, Laura McKie for preparing the Tables, and Cheryl Nichols for photographic assistance.
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