Chronic Kidney Disease in Idiopathic Pulmonary Fibrosis: A Cross-Sectional Study

Abstract Background Chronic kidney disease (CKD) is increasingly recognised as a relevant comorbidity in idiopathic pulmonary fibrosis (IPF), yet its burden may be underestimated. We aimed to determine the prevalence and clinical correlates of CKD in patients with IPF using contemporary Kidney Disease: Improving Global Outcomes (KDIGO) criteria, including albuminuria assessment. Methods We conducted a single-centre cross-sectional study including 101 consecutive patients with multidisciplinary-confirmed IPF enrolled between January 2025 and June 2026. Renal evaluation included serum creatinine, eGFR calculated using the 2021 CKD-EPI equation, and urinary albumin-to-creatinine ratio (UACR). CKD was defined - according to 2024 KDIGO criteria - as eGFR < 60 mL/min/1.73 m² and/or UACR ≥ 30 mg/g, with chronicity confirmed by measurements at least 3 months apart. Results CKD was identified in 28 patients (27.7%). Eleven had reduced eGFR with normal albuminuria, nine had isolated albuminuria with preserved eGFR, and four had both abnormalities. CKD prevalence was higher than that reported in the Italian CARHES population aged ≥ 65 years (27.7% vs 15.2%). Patients with CKD were older and more frequently affected by arterial hypertension, whereas pulmonary function did not differ between IPF patients with and without CKD. In the multivariable analysis, hypertension remained independently associated with CKD (adjusted OR 3.04, 95% CI 1.08–8.56; p = 0.036). Conclusion CKD is common in patients with IPF and may be missed when renal assessment is based on eGFR alone. Incorporating UACR into routine evaluation may improve detection of renal involvement and support a more comprehensive multidisciplinary approach to comorbidity assessment in IPF.