Effects of comorbid chronic kidney disease on mortality in idiopathic pulmonary fibrosis patients and influence of pirfenidone.

Chronic kidney disease (CKD) is a comorbidity in idiopathic pulmonary fibrosis (IPF), and managing IPF with CKD is challenging due to limited options for antifibrotic therapy. The aim of this study was to examine the prevalence of CKD and prescription status of pirfenidone in IPF patients and to analyze its impact on mortality. Data from the Korean National Health Insurance Service (NHIS) database between October 2015 and September 2021 were used. IPF and CKD were defined based on both International Classification of Diseases 10th Revision (ICD-10) codes and Rare Intractable Disease (RID) codes. The risk of mortality was assessed based on accompanying CKD with or without antifibrotic therapy. Among 5038 patients with IPF, 8.4% had comorbid CKD and 83.3% with CKD did not receive renal replacement therapy (RRT). Patients with IPF and CKD were older, predominantly male, and had more frequent comorbidities such as cardiovascular disease and diabetes mellitus than subjects without CKD. Pirfenidone was prescribed to 105 (24.6%) of 426 CKD patients, and 89.5% of them did not receive RRT. Pirfenidone was also prescribed to 775 (16.8%) of 4612 IPF patients without CKD. Significant difference was not found in all-cause mortality between the IPF patients with or without CKD regardless of pirfenidone treatment. The use of antifibrotics in IPF patients with CKD is limited due to CKD severity; however, evidence is lacking. Mortality did not increase with accompanying CKD regardless of antifibrotic use. Further research on IPF and CKD is needed.