Objective: To compare the quality of chance-corrected clinical diagnosis in two groups of dyspeptic patients, using endoscopy as the diagnostic standard.
Design: Structured interview before endoscopy and clinical predictions of endoscopic diagnosis as either malignancy, peptic ulcer, oesophagitis or non-ulcer dyspepsia. The quality of the predictions was corrected for chance using iota-correction. Patients gave a provisional prediction of their own endoscopic diagnosis.
Setting: Two endoscopy units in Odense and Svendborg, Denmark.
Patients: Two groups of dyspeptic outpatients: (1) 1026 patients referred for open-access endoscopy and (2) 207 empirically managed patients randomly assigned to prompt endoscopy as part of a clinical trial.
Results: The overall diagnostic validity for all diagnoses was equal in the two groups of patients (57 and 59%) and was mainly accounted for by positive predictive values for non-ulcer dyspepsia of 75%. Elimination of random accuracy for non-ulcer dyspepsia showed a validity of only 23 and 21%. Patients with a major pathologic lesion (cancer, ulcer, complicated oesophagitis) were misclassified clinically as non-ulcer dyspepsia in 36 and 38% of cases. The sensitivity of a clinical prediction of ulcer was only 52 and 36%, despite positive predictive values of 34%, and most valid when corrected for chance in the group of patients referred for open-access endoscopy. The patients' provisional diagnoses had no predictive value.
Conclusion: Clinical diagnosis in dyspepsia was unreliable as it misclassified one-third of patients with a major pathological lesion. Fifty percent of patients with ulcer were misclassified and that clinical diagnosis could only be confirmed in one-third of the cases. The chance-corrected validity of non-ulcer dyspepsia was only slightly better than chance. There was no predictive value of the patients' predictions of their own diagnosis.