Twenty-four-hour pH metry alone is inferior to additional impedance monitoring in the diagnosis of gastroesophageal reflux disease, particularly in presence of reduced gastric acid secretion.

Abstract

Current gold standard for the diagnosis of gastroesophageal reflux disease (GERD) is 24-hour pH metry though it fails to detect non-acidic reflux. The sensitivity of 24-hour pH metry alone (both catheter-based and Bravo capsule) is questionable, especially if gastric acid secretion is low due to reduced parietal cell mass, Helicobacter pylori-induced gastric atrophy and antisecretory therapy. Accordingly, we analyzed the diagnostic ability of 24-hour pH metry as compared to impedance monitoring in relation to the gastric pH without antisecretory therapy. A retrospective analysis of prospectively collected data from 150 patients with suspected GERD undergoing a 24-hour pH impedance study was done. Among 150 patients with symptoms suggestive of GERD, 106 (70.6%) had confirmed GERD diagnosed either by 24-hour pH metry alone (10 [9.4%]), impedance monitoring alone (49 [46.2%]) or both (47 [44.3%]). Abnormal reflux of acidic and non-acidic gastric contents was detected by 24-hour pH metry and 24-hour impedance monitoring in 57/106 (53.7%) and 96/106 (90.5%) of patients, respectively (p < .00001). Patients with GERD diagnosed by 24-hour impedance monitoring had a higher mean gastric pH (2.9 [median 1.3, IQR 5.3]) than those diagnosed by 24-hour pH metry (2.1 [median 1.4, IQR 2.6]) or both (1.6 [median 1.2, IQR 2.1]) (p = 0.001). Twenty-four-hour impedance monitoring detects GERD more often than 24-hour pH metry. Patients with higher mean gastric pH leading to non-acidic reflux were more often diagnosed by 24-hour impedance monitoring than 24-hour pH metry. Thus, 24-hour pH metry alone is inferior to additional impedance monitoring in the diagnosis of GERD, particularly in presence of reduced gastric acid secretion.