[709] Reproducibility of Villous Component and High Grade Dysplasia in Colorectal Adenomas < 1 cm: Implications for Endoscopic Surveillance

Dipti Mahajan, Erinn Downs-Kelly, Xiuli Liu, Rish Pai, Deepa T Patil, Lisa Rybicki, Ana Bennett, Thomas Plesec, Oscar Cummings, Douglas K Rex, John R Goldblum. Cleveland Clinic, Cleveland, OH; Indiana University Hospital, Indianapolis, IN

Background: In patients with 1 or 2 adenomas < 1 cm, the presence of high grade dysplasia (HGD) or villous component (VC) define an advanced adenoma (AA). Current consensus guidelines recommend that patients with AA undergo more intense post-polypectomy surveillance. In these clinical situations, the interobserver reliability in determining VC and HGD would play a major role in the credibility of these consensus guidelines. Therefore, the purpose of this study was to evaluate interobserver variability of VC and HGD in polyps < 1 cm before and after the development of consensus criteria among gastrointestinal (GI) pathologists.
Design: 5 expert GI pathologists evaluated 107 colorectal adenomas < 1 cm independently and classified them into tubular adenomas (TA), or adenomas with a villous component (A-VC) and into low grade dysplasia or HGD. After round 1; a consensus conference was held and consensus criteria for VC and HGD were developed by group review. The same set of 107 slides were re-reviewed independently by the same 5 GI pathologists. Interobserver variability utilizing kappa statistical analysis before and after the application of consensus criteria was assessed. A one-sided z-test was used to determine if kappa scores increased after the consensus conference.
Results: Interobserver agreement both before and after the consensus conference was poor for assessment of A-VC, HGD and AA (either A-VC or HGD).

Table 1: Kappa Indices for Interobserver Agreement

Feature	Kappa	P	95% CI	Interobserver agreement*
Pre-consensus diagnosis
A-VC	0.21	<0.001	0.15 - 0.27	Poor
HGD	0.26	<0.001	0.20 - 0.32	Poor
AA	0.29	<0.001	0.23 - 0.35	Poor
Post-consensus diagnosis
A-VC	0.37	<0.001	0.31 - 0.43	Poor
HGD	0.31	<0.001	0.25 - 0.37	Poor
AA	0.34	<0.001	0.28 - 0.40	Poor

* agreement beyond chance; poor: kappa<0.40 moderate: 0.400.75 ; Improvement in kappa (one-sided z-test): P=0.038 A-VC; P=0.11 HGD; P=0.14 AA


Conclusions: These data raise significant doubt regarding pathologists' ability to reliably discriminate advanced elements (A-VC or HGD) in adenomas < 1 cm, and hence calls in to question the validity of basing clinical decisions on this distinction.
Category: Gastrointestinal

Monday, March 19, 2012 1:00 PM

Poster Session II # 118, Monday Afternoon