Evaluating prognostic value of the prognostic nutritional index, CRP-to-albumin ratio and lymphocyte-to-CRP ratio in patients with idiopathic pulmonary fibrosis

BACKGROUND: The clinical outcome of patients with idiopathic pulmonary fibrosis (IPF) exhibit significant variability. Inflammation, immune response, and nutritional status are critical factors influencing the progression of IPF. Consequently, the identification of biomarkers that integrate these three elements is essential for evaluating prognosis and optimizing treatment strategies in IPF patients. METHODS: We analyzed and compared baseline data from 240 IPF patients at the Second Xiangya Hospital of Central South University, covering the period from January 2011 to December 2020. Correlation analyses were conducted to assess the relationship between the prognostic nutritional index (PNI), C-reactive protein (CRP) to albumin ratio (CAR) and lymphocyte to CRP ratio (LCR) with pulmonary function, age, and body mass index (BMI). The predictive accuracy of PNI, CAR and LCR was assessed using Kaplan-Meier survival curves, receiver operating characteristic (ROC) curves, and calibration curves. Potential risk factors were identified through Cox regression analysis. RESULTS: Non-survivors and IPF-related deaths exhibited lower PNI and LCR and higher CAR compared to survivors. PNI demonstrated the strongest correlation with age and BMI, while LCR was most strongly correlated with pulmonary function. In terms of predictive ability, PNI outperformed CAR and LCR for both overall and IPF-related mortality. Univariate Cox regression analyses indicated that PNI, CAR, and LCR effectively discriminated between overall survival (OS) and IPF-related mortality. However, in multivariate analyses, PNI remained the sole independent predictor of OS and IPF-related mortality. CONCLUSION: PNI serves as a robust prognostic indicator for OS and IPF-related mortality in patients with IPF, demonstrating superior predictive capability compared to CAR and LCR.