Lung disease severity in idiopathic pulmonary fibrosis is more strongly associated with impedance measures of bolus reflux than pH parameters of acid reflux alone

S Gavini; L F Borges; R T Finn; W-K Lo; H J Goldberg; R Burakoff; N Feldman; W W Chan

doi:10.1111/nmo.13001

Lung disease severity in idiopathic pulmonary fibrosis is more strongly associated with impedance measures of bolus reflux than pH parameters of acid reflux alone

Neurogastroenterol Motil. 2017 May;29(5). doi: 10.1111/nmo.13001. Epub 2016 Dec 16.

Authors

S Gavini^{1

2}, L F Borges^{1

2}, R T Finn^{2

3}, W-K Lo^{1

2}, H J Goldberg^{2

4}, R Burakoff^{1

2}, N Feldman¹, W W Chan^{1

2}

Affiliations

¹ Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Boston, MA, USA.
² Harvard Medical School, Boston, MA, USA.
³ Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
⁴ Division of Pulmonary Medicine, Brigham and Women's Hospital, Boston, MA, USA.

PMID: 27987250
DOI: 10.1111/nmo.13001

Abstract

Background: Gastroesophageal reflux (GER) has been associated with idiopathic pulmonary fibrosis (IPF). Pathogenesis may be related to chronic micro-aspiration. We aimed to assess objective measures of GER on multichannel intraluminal impedance and pH study (MII-pH) and their relationship with pulmonary function testing (PFT) results, and to compare the performance of pH/acid reflux parameters vs corresponding MII/bolus parameters in predicting pulmonary dysfunction in IPF.

Methods: This was a retrospective cohort study of IPF patients undergoing prelung transplant evaluation with MII-pH off acid suppression, and having received PFT within 3 months. Patients with prior fundoplication were excluded. Severe pulmonary dysfunction was defined using diffusion capacity of the lung for carbon monoxide (DLCO) ≤40%. Six pH/acid reflux parameters with corresponding MII/bolus reflux measures were specified a priori. Multivariate analyses were applied using forward stepwise logistic regression. Predictive value of each parameter for severe pulmonary dysfunction was calculated by area-under-the-receiver-operating-characteristic-curve or c-statistic.

Key results: Forty-five subjects (67% M, age 59, 15 mild-moderate vs 30 severe) met criteria for inclusion. Patient demographics and clinical characteristics were similar between pulmonary dysfunction groups. Abnormal total reflux episodes and prolonged bolus clearance time were significantly associated with pulmonary dysfunction severity on univariate and multivariate analyses. No pH parameters were significant. The c-statistic of each pH parameter was lower than its MII counterpart in predicting pulmonary dysfunction.

Conclusions & inferences: MII/bolus reflux, but not pH/acid reflux, was associated with pulmonary dysfunction in prelung transplant patients with IPF. MII-pH may be more valuable than pH testing alone in characterizing GER in IPF.

Keywords: gastroesophageal reflux; idiopathic pulmonary fibrosis; lung transplant; multichannel intraluminal pH-impedance study; pH/impedance study.

MeSH terms

Electric Impedance
Esophageal pH Monitoring / methods*
Female
Gastroesophageal Reflux / complications
Gastroesophageal Reflux / diagnosis*
Humans
Hydrogen-Ion Concentration
Idiopathic Pulmonary Fibrosis / complications
Idiopathic Pulmonary Fibrosis / diagnosis*
Lung Diseases / complications
Lung Diseases / diagnosis*
Male
Middle Aged
ROC Curve
Retrospective Studies
Severity of Illness Index