Pre-lung transplant measures of reflux on impedance are superior to pH testing alone in predicting early allograft injury.
OBJECTIVE
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.


CONCLUSIONS
Pre-transplant MII measures of bolus reflux perform better than their pH-testing counterparts in predicting early allograft injury post-lung transplantation.
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
WK
Lo
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.
Robert
R
Burakoff
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.
Hilary J
HJ
Goldberg
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.
Natan
N
Feldman
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.
Walter W
WW
Chan
D000328:Adult; D000368:Aged; D064591:Allografts; D019540:Area Under Curve; D017097:Electric Impedance; D050782:Esophageal pH Monitoring; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality; D006801:Humans; D055370:Lung Injury / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D016040:Lung Transplantation / Q000009:adverse effects* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D054328:Proton Pump Inhibitors / Q000627:therapeutic use; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
D054328:Proton Pump Inhibitors
Allograft injury; Gastroesophageal reflux; Lung transplant; Multichannel intraluminal impedance; pH-monitoring