Mo1884 Inter-Rater and Inter-Device Agreement for the Diagnosis of Primary Esophageal Motility Disorders Based on Chicago Classification Between Solid-State and Water-Perfused HRM System -A Prospective, Randomized, Double Blind, Crossover Study

Abstract

Background:High ResolutionManometry (HRM) is a new technique for intraluminal esophageal pressure measurement that employs an increased number of pressure sensors spaced closely together. Two systems have now become widely available: the 36 solid-state (SS) pressure transducers system, used to create the new Chicago Classification (CC) for Primary Esophageal Motility Disorders, and the recently introduced 24-channel water perfused (WP) system. Comparative data in terms of inter-device pressure parameters variability and diagnostic accuracy are lacking. Aim: To assess and compare normal values for pressure measurements between the 36-SS and the 24-WP HRM systems. Moreover, diagnostic inter-rater and inter-device agreement in a group of patients with esophageal symptoms were assessed. Methods: In this prospective, randomized, double blind, crossover study, 20 healthy volunteers [HVs; 11M/9F; median age 29 (IQR 26-33)] and 20 patients [11M/9F; 48 (43-55)] with esophageal symptoms (i.e. reflux symptoms, chest-pain or dysphagia) underwent HRM with both 36-SS (Given Imaging, Los Angeles, CA) and 24-WP (EB Neuro, Firenze, Italy) systems, in random order. Normal values from HVs were obtained and compared using non-parametric statistical analysis. Two expert reviewers (RS, ES) performed a blindfolded analysis of the patients tracings. Diagnoses based on CC in patients with esophageal symptoms were formulated. Inter-rater and inter-device agreement for each reviewer were evaluated by means of Cohen's k value. Results: As shown in the Figure, there were significant differences between the 2 HRM systems, mainly regarding the measurements of Lower Esophageal Sphincter (LES) and Upper Esophageal Sphincter (UES) basal pressure (p<0.01 and p=0.02, respectively), wave amplitude at 3 cm above the LES (p<0.01) and wave duration at 3, 7 and 11 cm above the LES (p<0.01, p<0.01 and p=0.01, respectively). Almost, all CC parameters were significantly different between the two HRM systems: Integrated Relaxation Pressure (IRP) (p=0.01), Distal Contractile Integral (DCI) (p=0.02) and Distal Latency (DL) (p<0.01). Diagnostic inter-rater agreement was higher for SS system (k=1) than for WP system (k=0,68). Diagnostic inter-device agreement was moderate for both reviewers (k[RS]= 0.5; k[ES]=0.4).Conclusions:Compared to the SS system, theWP technique underestimated almost all pressure measurements, including the CC parameters. This is likely due to the increased compliance of the WP system at low water perfusion rates, leading to poor interrater diagnosis reproducibility and inter-device agreement. By contrast, the SS system appears high reproducible in terms of inter-rater agreement. Thus, caution about the interpretation and application of CC in all HRM systems is recommended.