Quantitative computed tomography measures of skeletal muscle mass in patients with idiopathic pulmonary fibrosis according to a multidisciplinary discussion diagnosis: A retrospective nationwide study in Japan.

Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive disease often accompanied by skeletal muscle wasting. We investigated whether skeletal muscle mass and muscle attenuation on computed tomography (CT) are predictors of mortality in IPF patients, using a nationwide cloud-based database and web-based multidisciplinary discussion (MDD) system. IPF patients diagnosed using MDD from April 2009 to March 2014 were included. We analyzed the cross-sectional area (CSA) of the erector spinae muscle (ESMCSA) and the pectoralis muscle (PMCSA), muscle attenuation of the ESM (ESMMA), and PM (PMMA) on single-slice axial CT. Survival probability was assessed using the Kaplan-Meier method and compared by the log-rank test. Multivariate Cox proportional hazards models were used to evaluate the relationship among the ESMCSA, PMCSA, ESMMA, PMMA, clinical parameters, and prognosis. A total of 199 IPF patients were enrolled. Seventy-four patients died during the study period and the most frequent cause was acute exacerbation (13.1%). The group with the lowest quartile of ESMCSA had significantly worse survival than other groups (P=0.009). Survival rates of the groups with the lowest quartile of PMCSA, lower ESMMA, and lower PMMA did not differ from those of other groups. According to multivariate analysis, ESMCSA<lower quartile was significantly associated with all-cause mortality (hazards ratio, 1.96; P=0.030), whereas, ESMMA<median, PMCSA<lower quartile, and PMMA<median were not. Low ESMCSA on CT images may be a strong risk factor for all-cause mortality in IPF patients based on MDD diagnosis.