Retrospective Cohort Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 14, 2015; 21(30): 9111-9117
Published online Aug 14, 2015. doi: 10.3748/wjg.v21.i30.9111
Pre-lung transplant measures of reflux on impedance are superior to pH testing alone in predicting early allograft injury
Wai-Kit Lo, Robert Burakoff, Hilary J Goldberg, Natan Feldman, Walter W Chan
Wai-Kit Lo, Robert Burakoff, Natan Feldman, Walter W Chan, Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women’s Hospital, Boston, MA 02115, United States
Wai-Kit Lo, Department of Gastroenterology, VA Boston Healthcare System, Boston, MA 02130, United States
Wai-Kit Lo, Robert Burakoff, Hilary J Goldberg, Walter W Chan, Harvard Medical School, Boston, MA 02115, United States
Hilary J Goldberg, Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital, Boston, MA 02115, United States
Author contributions: Chan WW and Lo WK initiated the study concepts and design; Lo WK, Feldman N and Goldberg HJ contributed to data acquisition; Chan WW, Lo WK, Goldberg HJ and Burakoff R analyzed and interpreted the data; Chan WW and Lo WK drafted the manuscript; Chan WW, Lo WK, Goldberg HJ and Burakoff R contributed to the critical revision of the manuscript for important intellectual content; Chan WW and Lo WK performed the statistical analyses; Chan WW provided administrative support and overall study supervision.
Institutional review board statement: The study was approved by the Partners Healthcare Institutional Review Board prior to inception.
Informed consent statement: Informed consent was waived with permission of the IRB board because of retrospective nature of the study, and the low risk to participants.
Conflict-of-interest statement: The authors report no conflict of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Walter W Chan, MD, MPH, Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, United States. wwchan@partners.org
Telephone: +1-617-5250338 Fax: +1-617-7326389
Received: February 10, 2015
Peer-review started: February 10, 2015
First decision: April 13, 2015
Revised: April 15, 2015
Accepted: June 9, 2015
Article in press: June 10, 2015
Published online: August 14, 2015
Processing time: 188 Days and 5.1 Hours
Abstract

AIM: To evaluate pre-lung transplant acid reflux on pH-testing vs corresponding bolus reflux on multichannel intraluminal impedance (MII) to predict early allograft injury.

METHODS: This was a retrospective cohort study of lung transplant recipients who underwent pre-transplant combined MII-pH-testing at a tertiary care center from January 2007 to November 2012. Patients with pre-transplant fundoplication were excluded. Time-to-event analysis was performed using a Cox proportional hazards model to assess associations between measures of reflux on MII-pH testing and early allograft injury. Area under the receiver operating characteristic (ROC) curve (c-statistic) of the Cox model was calculated to assess the predictive value of each reflux parameter for early allograft injury. Six pH-testing parameters and their corresponding MII measures were specified a priori. The pH parameters were upright, recumbent, and overall acid reflux exposure; elevated acid reflux exposure; total acid reflux episodes; and acid clearance time. The corresponding MII measures were upright, recumbent, and overall bolus reflux exposure; elevated bolus reflux exposure; total bolus reflux episodes; and bolus clearance time.

RESULTS: Thirty-two subjects (47% men, mean age: 55 years old) met the inclusion criteria of the study. Idiopathic pulmonary fibrosis (46.9%) represented the most common pulmonary diagnosis leading to transplantation. Baseline demographics, pre-transplant cardiopulmonary function, number of lungs transplanted (unilateral vs bilateral), and post-transplant proton pump inhibitor use were similar between reflux severity groups. The area under the ROC curve, or c-statistic, of each acid reflux parameter on pre-transplant pH-testing was lower than its bolus reflux counterpart on MII in the prediction of early allograft injury. In addition, the development of early allograft injury was significantly associated with three pre-transplant MII measures of bolus reflux: overall reflux exposure (HR = 1.18, 95%CI: 1.01-1.36, P = 0.03), recumbent reflux exposure (HR = 1.25, 95%CI: 1.04-1.50, P = 0.01) and bolus clearance (HR = 1.09, 95%CI: 1.01-1.17, P = 0.02), but not with any pH-testing parameter measuring acid reflux alone.

CONCLUSION: Pre-transplant MII measures of bolus reflux perform better than their pH-testing counterparts in predicting early allograft injury post-lung transplantation.

Keywords: Gastroesophageal reflux; Lung transplant; Multichannel intraluminal impedance; pH-monitoring; Allograft injury

Core tip: Gastroesophageal reflux has been associated with poor lung transplant outcomes, including allograft injury and rejection. While ambulatory pH-testing only measures acid reflux, multichannel intraluminal impedance (MII) assesses total bolus reflux, regardless of acidity. Comparison of pH-testing and MII measures of reflux in the prediction of lung transplant outcomes may improve and standardize pre-transplant reflux testing. Our study demonstrated that pre-transplant MII measures of bolus reflux perform better than their pH-testing counterparts to predict early allograft injury post-lung transplantation. MII should be performed alongside pH testing for reflux assessment during pre-lung transplant evaluation.