Abnormal bolus reflux on impedance-pH testing independently predicts 3-year pulmonary outcome and mortality in pulmonary fibrosis

Background and Aim: Gastroesophageal reflux has been associated with idiopathic pulmonary fibrosis (IPF), although the directionality of the relationship has been debated. Data on the value of objective reflux measures in predicting IPF disease progression and mortality remain limited. We aimed to evaluate the association between multichannel intraluminal impedance and pH testing (MII-pH) and 3-year pulmonary outcomes in IPF patients. Methods: This was a retrospective cohort study of adults with IPF who underwent pre-lung transplant MII-pH off acid suppression at a tertiary center. Patients were followed for 3 years after MII-pH for poor pulmonary outcomes (hospitalization for respiratory exacerbation or death). A secondary analysis was performed using mortality as outcome of interest. Time-to-event analyses using Kaplan–Meier and Cox regression were performed to evaluate associations between MII-pH and poor outcomes. Results: One hundred twenty-four subjects (mean age = 61.7 ± 8 years, 62% male) were included. Increased bolus exposure time (BET) on MII-pH was associated with decreased time to poor pulmonary outcomes and death (log-ranked P-value = 0.017 and 0.031, respectively). On multivariable Cox regression analyses controlling for potential confounders including age, sex, smoking history, body mass index, proton pump inhibitor use, baseline pulmonary function, and anti-fibrotic therapy, increased BET was an independent predictor for poor pulmonary outcomes [hazard ratio 3.18 (95% confidence interval: 1.25–8.09), P = 0.015] and mortality [hazard ratio 11.3 (95% confidence interval: 1.37–63.9), P = 0.025] over 3 years. Conclusions: Increased BET on MII-pH is an independent predictor of poor pulmonary outcomes and mortality over 3 years in IPF patients. These findings also support a role for gastroesophageal reflux in IPF disease progression and the potential impact of routine reflux testing and treatment.