552 Exploring the Role of Gastrointestinal Motility and Non-Acid Reflux in Lung Transplant Prognosis and Risk of Acute Rejection

Abstract

INTRODUCTION: Lung transplant patients are at risk of developing acute rejection leading to bronchiolitis obliterans syndrome (BOS). Lung transplant patients are also known to have and/or develop gastroesophageal reflux. Acid gastroesophageal reflux has been correlated with risk of acute rejection and consequently BOS. There is however a paucity of data correlating non-acid reflux with risk of acute rejection. Our study investigated the role of non-acid reflux with lung transplant rejection. METHODS: 131 lung transplant recipients who had post-transplant evaluation between 2012 and 2019 were studied. A total of 64 lung transplant recipients had at least 3 months of post-transplant follow up consisting of 24 hour impedance pH testing, and high-resolution manometry (HREM). Patient characteristics were summarized with counts and percentages, means and SD, or medians and interquartile ranges (IQR) as appropriate to scale and distribution. The characteristics of those with and without rejection diagnoses was compared with Fisher's exact test for categorical variables and the Wilcoxon rank sum test for quantitative variables. Analyses were conducted in the open source R software environment. RESULTS: 60 of 64 patients (94%) were alive at one-year post- lung transplant. The majority of patients had bilateral transplants and were Caucasian males with average age of 59 years. At one year there were 12 deaths. Patients with a diagnosis of acute rejection were less likely to exhibit gastroparesis (1% vs. 9%) and abnormal pH (28% vs. 45%). Acute rejection patients were more likely to exhibit GERD (53% vs. 45%), more non-acid episodes (median 19 vs. 15.5), higher reported symptom association (51% vs. 41%), on impedance pH; abnormal UES (56% vs. 45%), and abnormal body (86% vs. 77%) on HREM (Table 1). However, no differences were statistically significant (all P > .18), and conclusions cannot be generalized. CONCLUSION: Patients undergoing lung transplantation were found to have a high incidence of abnormal gastroesophageal motility studies, including both acid and non-acid reflux. Developing a protocolized pre- and post- transplant motility evaluation process for lung transplant patients may help identify those at greatest risk for acute rejection. Continued evaluation post-transplantation to establish therapeutic interventions in both acid and non-acid reflux patients to prevent lung transplant rejection appears warranted.