Diffusing capacity for carbon monoxide (DLco) may predict appearance of pulmonary hypertension in idiopathic pulmonary fibrosis

Rationale: Pulmonary hypertension (PH) is frequently complicated in the natural course of idiopathic pulmonary fibrosis (IPF) and the complication makes its prognosis poor. In order to search non-invasive and concise markers predicting onset of PH, we investigated the relationship between data on echocardiography and clinical parameters including pulmonary function tests. Methods: From September 2009 to November 2012, we retrospectively investigated 67 patients with IPF in comparison with 11 with fibrotic NSIP (fNSIP). Tricuspid regurgitation pressure gradient (TRPG) > 30 mmHg determined by echocardiography was considered as PH in this study. Results: PH was complicated more in IPF (27/67, 40%) than in fNSIP (2/11, 18%). TRPG was significantly correlated to %VC, %DLco and AaDO2. In IPF, patients with PH showed significantly lower %VC and %DLco, higher AaDO2, and poorer survival than patients without PH. Multivariate analysis showed TRPG and %VC were independent predictors of prognosis. Eighteen of 27 IPF without PH were subjected to the second echocardiography during 1 to 2 years after the first time. Five (28%) of the 18 IPF had newly developed PH and showed significantly lower %DLco at the first time and poorer survival than 13 IPF without newly developed PH. Conclusions: PH, complicated frequently with IPF patients, is a poor prognostic factor. %DLco is a potentially useful non-invasive marker for early detection of PH.