Supplementary Material for: The Interstitial Lung Disease-Gender-Age-Physiology Index Can Predict the Prognosis in Surgically Resected Patients with Interstitial Lung Disease and Concomitant Lung Cancer

Background: The interstitial lung disease-gender-age-physiology (ILD-GAP) index and staging system have been reported as a clinical prognostic factor for ILD, including all ILD subtypes. Objectives: The purpose of this study was to clarify the association of various prognostic indices, including the ILD-GAP index, with the prognosis, the incidence of acute exacerbations of ILD (ILD-AE), and the use of long-term oxygen therapy (LTOT) after surgery in surgically resected patients with ILD and concomitant lung cancer, to provide additional information when considering whether it is safe to perform surgery. Methods: The medical records of patients with ILD and concomitant lung cancer who had undergone surgery at Shinshu University Hospital between August 2001 and September 2016 were retrospectively analyzed. Results: There were significant differences in survival between the ILD-GAP index: 0–1 and ≥4 groups (p = 0.0001) and between the ILD-GAP index: 2–3 and ≥4 groups (p = 0.0236). A higher ILD-GAP index was independently associated with the risk of death (hazard ratio [HR] 1.32030; p = 0.0059). A higher body mass index (BMI) and a higher serum C-reactive protein (CRP) level were independently associated with the incidence of ILD-AE (HR 1.28336; p = 0.0206 and HR 26.3943; p = 0.0165, respectively). A higher severity of ILD on chest high-resolution computed tomography (HRCT) was independently associated with the use of LTOT (HR 2.78670; p = 0.0313). Conclusions: The ILD-GAP index can predict the prognosis in surgically resected patients with ILD and concomitant lung cancer. The BMI and serum CRP levels were independent determinants that predicted the incidence of ILD-AE. The severity of ILD on chest HRCT was an independent determinant that predicted the use of LTOT.