Chronic Kidney Disease Predicts Survival in Patients with Idiopathic Pulmonary Fibrosis

The prevalence of chronic kidney disease (CKD) increases with age as with idiopathic pulmonary fibrosis (IPF).

We assessed the prevalence of CKD (stages 3-5) and investigated the relationship of CKD to clinical features and outcomes in patients with IPF.

This study comprised 123 patients with IPF; 61 subjects with chronic obstructive pulmonary disease (COPD), which was reportedly associated with CKD, were also enrolled as a disease control. CKD (stages 3-5) was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2.

Thirty-seven patients (30%) with IPF and 14 controls (23%) with COPD were diagnosed with CKD, and these frequencies were not significantly different. The patients with IPF and CKD were older (p < 0.01) and had a higher frequency of hypertension (p = 0.048) and ischemic heart disease (p = 0.02) than those with IPF but without CKD. Furthermore, the diffusing capacity of the lung for carbon monoxide (DLCO) and the 6-min walking distance in the patients with CKD were significantly lower (40.0 ± 13.2 vs. 45.9 ± 14.4%, p = 0.04, and 416 ± 129 vs. 474 ± 84 m, p = 0.01, respectively) than in the patients without CKD. The outcome of the patients with CKD showed significantly worse survival compared with the patients without CKD (p = 0.04). Moreover, eGFR remained an independent predictor of survival after adjusting for age and pulmonary function data.

A substantial percentage of IPF patients have CKD. CKD with a low eGFR was associated with decreased survival in IPF.