BackgroundAcid reflux has been associated with poor outcomes following lung transplantation. Unlike surgical fundoplication, the role of noninvasive, pharmacologic acid suppression remains uncertain.AimsTo assess the relationship between post-transplant acid suppression with proton pump inhibitors (PPI) or histamine-2 receptor antagonists (H2RA) and onset of early allograft injury or chronic rejection following lung transplantation.MethodsThis was a retrospective cohort study of lung transplant recipients at a tertiary center in 2007–2014. Patients with pre-transplant antireflux surgery were excluded. Time-to-event analysis using the Cox proportional hazards model was applied to assess acid suppression therapy and onset of acute or chronic rejection, defined histologically and clinically. Subgroup analyses were performed to assess PPI versus H2RA use.ResultsA total of 188 subjects (60% men, mean age 54, follow-up 554 person-years) met inclusion criteria. During follow-up, 115 subjects (61.5%) developed rejection, with all-cause mortality of 27.6%. On univariate analyses, acid suppression and BMI, but not other patient demographics, were associated with rejection. The Kaplan–Meier curve demonstrated decreased rejection with use of acid suppression therapy (log-rank p = 0.03). On multivariate analyses, acid suppression (HR 0.39, p = 0.04) and lower BMI (HR 0.67, p = 0.04) were independently predicted against rejection. Subgroup analyses demonstrated that persistent PPI use was more protective than H2RA or no antireflux medications.ConclusionsPost-lung transplant exposure to persistent PPI therapy results in the greatest protection against rejection in lung transplant recipients, independent of other clinical predictors including BMI, suggesting that PPI may have antireflux or anti-inflammatory effects in enhancing allograft protection.