Interobserver agreement of endoscopic ultrasound (EUS) for evaluating submucosal masses

INTRODUCTION: EUS has been reported to be a very accurate means of evaluating and diagnosing submucosal lesions of the GI tract. AIMS OF STUDY: To determine interobserver reliability for classification of submucosal masses by EUS. METHODS: Twenty patients with submucosal mass lesions diagnosed at upper endoscopy underwent EUS evaluation Surgical findings or FNA cytology were available for 16 patients In 4 patients with obvious cystic/vascular structures (ie, varices) no surgical correlation was necessary. A blinded observer developed a study videotape including critical endoscopic and EUS data for each lesion. The videotape was then distributed to six endosonographers with at least one year of previous experience who then independently reviewed the tape and recorded their diagnosis based upon EUS features These endosonographers had previously agreed upon standardized EUS diagnostic criteria for each category of lesion (extrinsic compression, leiomyoma, vascular, lipoma, cyst, other submucosal lesion ie; carcinoid). The endosonographer independently categorized the lesions. A multiple observer kappa (k) statistic for agreement was calculated for each lesion category and an overall k calculated. Kappa accounts for agreement due to chance alone and standardized ranges are available. RESULTS; We found agreement was excellent for cystic lesions (k=0.80) and extrinsic compressions (k=0.94), good for lipoma (k=0.65), fair for leiomyoma and vascular lesions (k=0.53 & 0.54 respectively) and poor for other submucosal lesions (k=0.34). Overall agreement among observers was good (k=0.63) and highly statistically significant (z=21). CONCLUSION: Interobserver agreement is good for characterizing submucosal masses by EUS. However, it appears to be better for some lesion types than others. Experience may play an important role in the successful use of this modality to evaluate submucosal lesions.