Post-reflux swallow-induced peristaltic wave index: a new parameter for the identification of non-acid gastroesophageal reflux-related chronic cough

Abstract

Background: The current available diagnostic criteria for gastroesophageal reflux-related chronic cough (GERC) dominated by non-acid reflux is imperfect. The post-reflux swallow-induced peristaltic wave index (PSPWI) is a parameter reflecting esophageal clearance function. Objectives: This study aims to investigate its diagnostic value for non-acid GERC. Design: This study sought to compare the diagnostic value of PSPWI in different types of GERC, particularly non-acid GERC, and explore the clinical significance of PSPWI in the diagnosis of non-acid GERC through diagnostic experiments. Methods: A retrospective analysis was performed based on 223 patients with suspected GERC who underwent multichannel intraluminal impedance-pH monitoring (MII-pH) in the outpatient clinic of our department from August 2016 to June 2021. Their clinical information, laboratory test results, and treatment responses were assessed and the underlying etiologies of chronic cough were categorized. The predictive value of the PSPWI in diagnosing different types of GERC, especially non-acid GERC, was analyzed and compared. Results: A total of 195 patients with chronic cough who met the inclusion criteria underwent MII-pH monitoring. 143 patients had a definitive diagnosis of GERC, including 98 with acid GERC and 45 with non-acid GERC. The diagnostic value of PSPWI alone was moderate for GERC with an area under the working curve (AUC) 0.760, but poor for non-acid GERC with an AUC of 0.569. However, PSPWI < 39.8% combining with acid exposure time (AET) ⩽ 6.2% demonstrated a moderate diagnostic value for non-acid GERC, with an AUC of 0.722. When PSPWI < 39.8% combined with a non-acid reflux ratio >68.75%, the diagnostic value for non-acid GERC was improved (AUCROC = 0.80 versus AUCROC = 0.722, p < 0.05), which was significantly superior to non-acid symptom index (AUCROC = 0.804 versus AUCROC = 0.550, p < 0.05) and non-acid symptom association probability (AUCROC = 0.804 versus AUCROC = 0.571, p < 0.05). Conclusion: PSPWI < 39.8% and AET ⩽ 6.2% have demonstrated good diagnostic value for non-acid GERC. The diagnostic value was further improved when combined with non-acid reflux ratio >68.75%.