BACKGROUND: Supragastric belching (SGB) and rumination are behavioral disorders associated with proton pump inhibitor (PPI) non-response and can be diagnosed using multichannel intraluminal impedance-pH (MII-pH) and post-prandial high-resolution impedance manometry (PPHRIM). This pilot study compared diagnostic yield and inter-rater agreement for SGB and rumination using MII-pH and PPHRIM. METHODS: Three esophageal physiologists performed blinded interpretations of MII-pH and PPHRIM in 22 PPI non-responders. Raters selected from 4 diagnostic impressions (normal, GERD, behavioral disorders, GERD+behavioral disorders) without clinical context. Primary outcomes were diagnostic impressions compared against clinical gold standard impression, between raters, and between test modalities. Following a 28-month wash-out period, raters re-interpreted MII-pH with clinical context and under consensus definition of diagnostic criteria. KEY RESULTS: Compared to gold standard, rater accuracy for presence of behavioral disorders ranged from 45 to 77% on MII-pH and 45-59% on PPHRIM. On MII-pH, inter-rater agreement was fair for diagnosis (ĸ0.32, p < 0.01) and suboptimal for presence of behavioral disorders (ĸ0.13, p = 0.14). On PPHRIM, inter-rater agreement was suboptimal for both diagnosis (ĸ0.03, p = 0.34) and presence of a behavioral disorder (ĸ-0.22, p = 0.96). Inter-rater agreement improved in post hoc MII-pH interpretations. Rumination was more frequently identified on PPHRIM (23, 35%) compared to MII-pH (7, 11%). CONCLUSIONS AND INFERENCES: Diagnostic accuracy and inter-rater agreement are higher for MII-pH than PPHRIM, and behavioral disorders are more frequently identified on PPHRIM. Identifying behavioral disorders on MII-pH and PPHRIM has implications for clinical evaluation of PPI non-response; clinical context is essential for accurate study interpretation. Further work is needed to standardize definitions and interpretations.

Chicago Classification v4.0 (CCv4.0) is the updated classification scheme for esophageal motility disorders using metrics from high-resolution manometry (HRM). Fifty-two diverse international experts separated into seven working subgroups utilized formal validated methodologies over two-years to develop CCv4.0. Key updates in CCv.4.0 consist of a more rigorous and expansive HRM protocol that incorporates supine and upright test positions as well as provocative testing, a refined definition of esophagogastric junction (EGJ) outflow obstruction (EGJOO), more stringent diagnostic criteria for ineffective esophageal motility and description of baseline EGJ metrics. Further, the CCv4.0 sought to define motility disorder diagnoses as conclusive and inconclusive based on associated symptoms, and findings on provocative testing as well as supportive testing with barium esophagram with tablet and/or functional lumen imaging probe. These changes attempt to minimize ambiguity in prior iterations of Chicago Classification and provide more standardized and rigorous criteria for patterns of disorders of peristalsis and obstruction at the EGJ.