Skeletal muscle atrophy and short-term mortality in patients with acute exacerbation of idiopathic pulmonary fibrosis: an observational cohort study.

ABSTRACT

BACKGROUND: Skeletal muscle atrophy, a common complication of idiopathic pulmonary fibrosis (IPF), and its presence upon diagnosis can indicate a poor prognosis. Patients with IPF frequently experience acute exacerbations (AE), which is associated with a high mortality rate. However, the association between skeletal muscle atrophy and short-term mortality remains unknown. METHODS: We performed a retrospective, multicenter cohort study of patients admitted for AE-IPF in Japan. The cross-sectional areas of the erector spinae muscle (ESMCSA) and the pectoralis muscle (PMCSA) were analyzed via single-slice computed tomography (CT). The primary outcome was 90-day mortality. Survival probability was estimated using the Kaplan-Meier method, and the log-rank test was used between the low and high groups of ESMCSA and PMCSA. We used multivariable Cox proportional-hazards models to evaluate the association between ESMCSA and PMCSA and prognosis. RESULTS: Of the 212 patients included, 94 (44%) died during the observation period. The low ESMCSA group (<25.6 cm2) had a significantly worse prognosis than that of the high ESMCSA group (≥25.6 cm2) (hazard ratio (HR) [95% confidence interval (CI)] 1.52 [1.00-2.33], P = 0.049). Multivariable analyses showed that all-cause mortality was associated with low ESMCSA (model 1, adjusted HR [95% CI] 1.59 [0.98-2.60]; model 2, 1.55 [0.95-2.56], and model 3, 1.67 [1.00-2.78], respectively). The adjusted HR of low PMCSA (<20.4 cm2) vs. high PMCSA (≥20.4 cm2) was 1.39 (95% CI 0.88-2.20). CONCLUSIONS: Low ESMCSA on CT images is associated with a high 90-day mortality rate in patients with AE-IPF.