Receiver Operator Characteristic Analysis of Endoscopy as a Test for Gastritis

Abstract

Endoscopic evaluation of the presence or absenceof gastritis is often performed in lieu of biopsy andhistologic diagnosis. The purpose of our study was toassess the value of endoscopic examination as a diagnostic test for gastritis. Twoendoscopists prospectively assessed the antrum of 73patients undergoing upper gastrointestinal endoscopy andgraded, on a scale of 0-4 (0 = completely absent, 4 = definitely present), the likelihood ofgastritis. The following features were also assessed atthe time of endoscopy: erythema, nodularity, erosion,edema, and friability. Two concomitant antral biopsies (3 cm from the pylorus on the greater curvatureof the stomach) were performed regardless of theendoscopic impression. The histologic findings weregraded independently on a scale of 0-3 by twopathologists who were not aware of the endoscopic findings.The following histologic features were graded: acuteinflammation, chronic inflammation, lymphoid aggregates,intestinal metaplasia, and quantity of Helicobacter pylori organisms. Receiver operatorcharacteristic analysis, a method derived from signaldetection theory, assesses the trade-off of sensitivityand specificity over all cutoff points of a test and is considered the best method by which to comparetests and determine the diagnostic utility of a giventest. Receiver operator characteristic analysis gave anarea of 0.65 ± 0.01 SE for endoscopy as a test for gastritis (0.5 = chance, 1 = perfect) asdefined by the histologic presence of inflammation.Additionally, endoscopy as a test for the presence ofhistologically proven Helicobacter pylori gave an area of 0.55 ± 0.01 SE. All endoscopicallygraded features treated as separate tests for gastritisand/or H. pylori gave areas of approximately 0.44-0.61,indicative of a poor test. While H. pylori was always associated with at least some degree ofinflammation, linear regression analysis revealed nocorrelation among any of the histologic features or ofany histologic feature with any endoscopic feature. We conclude that a tissue diagnosis is essentialfor the proper diagnosis of gastritis.