Baseline impedance measured during high‐resolution esophageal impedance manometry reliably discriminates GERD patients. Issue 5 (24th October 2016) - Ravi, K.
Abstract: Background: Baseline impedance measured with ambulatory impedance pH monitoring (MII‐pH) and a mucosal impedance catheter detects gastroesophageal reflux disease (GERD). However, these tools are limited by cost or patient tolerance. We investigated whether baseline impedance measured during high‐resolution impedance manometry (HRIM) distinguishes GERD patients from controls. Methods: Consecutive patients with clinical HRIM and MII‐pH testing were identified. Gastroesophageal reflux disease was defined by esophageal pH <4 for ≥5% of both the supine and total study time, whereas controls had an esophageal pH <4 for ≤3% of the study performed off PPI. Baseline impedance was measured over 15 seconds during the landmark period of HRIM and over three 10 minute intervals during the overnight period of MII‐pH. Key Results: Among 29 GERD patients and 26 controls, GERD patients had a mean esophageal acid exposure time of 22.7% compared to 1.2% in controls ( P <.0001). Mean baseline impedance during HRIM was lower in GERD (1061 Ω) than controls (2814 Ω) ( P <.0001). Baseline mucosal impedance measured during HRIM and MII‐pH correlated ( r =0.59, P <.0001). High‐resolution esophageal manometry baseline impedance had high diagnostic accuracy for GERD, with an area under the curve (AUC) of 0.931 on receiver operating characteristics (ROC) analysis. A HRIM baseline impedance threshold of 1582 Ω had a sensitivity of 86.2% and specificity of 88.5% for GERD, with a positive predictive value of 89.3% and negative predictive value of 85.2%. Conclusions & Inferences: Baseline impedance measured during HRIM can reliably discriminate GERD patients with at least moderate esophageal acid exposure from controls. This diagnostic tool may represent an accurate, cost‐effective, and less invasive test for GERD. Abstract : Previous studies have demonstrated that baseline impedance measured during ambulatory impedance pH monitoring has reliable diagnostic accuracy for GERD. In this study of 29 patients with at least moderate acid reflux and 26 controls, baseline impedance measured during the initial landmark period of a high‐resolution esophageal manometry (HRIM) study demonstrated excellent diagnostic accuracy for GERD, with an AUC of 0.931 on ROC analysis. These findings suggest that HRIM determined baseline impedance may represent an accurate, cost‐effective, and less invasive tool for the diagnosis of GERD.