PPI test is a poor predictor of reflux disease

Empiric acid suppression with the “PPI test” used to assess whether upper-GI symptoms are due to gastroesophageal reflux disease, actually performs poorly as a predictor of GERD.

Typically, clinicians perform a PPI test to diagnose GERD without the need for endoscopy. They gave patients a 2-week course of a proton pump inhibitor (PPI) and then determine whether the brief treatment ameliorated upper GI symptoms. If so, the symptoms are assumed to be acid related, Copenhagen University said.

But in their study, such a PPI test “showed a disappointingly low validity“ for diagnosing GERD and couldn’t reliably distinguish between reflux esophagitis and nonerosive reflux disease. Even when combined with a clinical diagnosis made by a primary care physician, a clinical diagnosis made by a gastroenterologist, or the results of a detailed diagnostic questionnaire, the outcome of a PPI test didn’t add reliable information allowing clinicians to separate patients who had GERD from those who did not, the researchers said.

Colleagues analyzed data originally collected in the DIAMOND clinical trial, an international study that found the Reflux Disease Questionnaire to be useful in diagnosing GERD among patients who consulted primary care physicians because of frequent upper GI symptoms.

Performed more detailed analyses of the data, comparing the diagnostic usefulness of PPI testing against state-of-the-art comprehensive diagnostic work-ups for GERD in 299 of the DIAMOND study subjects.

All of the subjects underwent endoscopy with concomitant wireless esophageal pH monitoring and symptom assessment. They then completed the detailed Reflux Disease Questionnaire and participated  in a 2-week PPI test using esomeprazole (Nexium).

A total of 69% of the patients who did have GERD showed a positive response to the PPI test. This means that 31% of the study participants  with GERD were not identified by PPI testing. Moreover, 51% of the patients who did not have GERD also showed a positive response to the PPI test, the investigators said.

Both patients who had GERD and patients who did not report that their symptom response to acid suppression increased over the course of the first 5 to 6 days of treatment and then leveled off for the remaining 8 to 9 days.

The PPI test performed only marginally better across various subgroups of patients, such as those whose physicians were certain of their GERD diagnosis (compared with patients whose physicians were uncertain about GERD).

For example, 48% of participants whose physicians predicted that they had GERD showed a positive response on PPI testing  — a rate that was nearly identical to the 47% of subjects whose physicians predicted that they had some other disorder.