Positive predictive value and examiner variability in diagnosing duodenal ulcer.
The positive predictive value of a diagnosis of duodenal ulcer was studied in 255 patients with 274 ulcers diagnosed radiographically. Retrospective analysis of the radiographic examinations and correlation with endoscopy assessed examiner variability, ulcer size, duodenal bulb deformity, and the confidence level of the ulcer diagnoses. For all diagnoses, the overall positive predictive value was 57% with individual predictive values of 47%, 54%, and 70% among three examiners. The individual predictive values correlated directly with the average level of confidence of the diagnoses for each examiner. The sensitivity of the individual examiner for ulcer detection had an inverse relation to the examiner's positive predictive value, confirming that higher sensitivities are achieved at the expense of an increased false-positive rate.