Clinical utility of a composite scoring system including Charlson Comorbidity Index score in patients with interstitial lung disease

BACKGROUND: Prognostic factors have yet to be established for patients with interstitial lung disease (ILD). We aimed to clarify whether the Charlson Comorbidity Index score (CCIS) could help predict disease prognosis in patients with ILD. METHODS: Among ILD patients treated between April 2013 and April 2017, we retrospectively assessed the relationship between baseline clinical parameters including age, sex, CCIS, ILD diagnosis, pulmonary function test results, and 3-year ILD-related events including cause-specific death and first acute exacerbation (AE). RESULTS: We assessed 180 patients (mean age, 74 years), all of whom underwent pulmonary function testing including percentage predicted diffusion capacity for carbon monoxide (%D(Lco)). Underlying pathologies included idiopathic pulmonary fibrosis (IPF) in 57 cases, idiopathic nonspecific interstitial pneumonia (iNSIP) and collagen vascular disease-related interstitial pneumonia in 117 cases, and chronic hypersensitivity pneumonia (CHP) in 6 cases. A composite scoring system comprising IPF diagnosis, CCIS, and %D(Lco) provided a favorable C-index (0.825) for predicting 3-year ILD-related events. The nomogram for 3-year prognosis revealed the largest contributions from CCIS, %D(Lco) and IPF diagnosis. CONCLUSIONS: This composite scoring system accounting for IPF diagnosis, CCIS, and %D(Lco) could provide a useful tool for predicting prognosis in relatively mild ILD patients tolerated to pulmonary diffusion capacity testing.