METHODS: Out of 21,046 patients admitted to a tertiary academic medical center with chronic lung conditions between July 2010 and June 2015, all admissions with a primary discharge diagnosis of acute exacerbation of COPD (International Statistical Classification of Disease [ICD-9] code of 491.21), rheumatoid lung disease, systemic sclerosis interstitial lung disease, and other CTD-ILDs (ICD9 of 714.81, 517.2, and 517.8, respectively), and IPF (ICD9 of 516.31) were included. We categorized the patients into three groups of COPD, CTD-ILD, and IPF groups. Primary outcome was total cost of hospitalization (cost), defined as sum up of fixed direct, indirect and variable costs. Secondary outcomes were daily cost (total cost per day), length of stay and ICU stay. Next, using multiple linear regression we examined how demographics, clinical, and type of provider correlate with cost among patients with IPF.