Can the Prognostic Nutritional Index Be a Predictor of Acute Exacerbation of Idiopathic Pulmonary Fibrosis?

Background/Objectives: Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease that can be accompanied by acute exacerbations. To investigate the predictive value of the prognostic nutritional index (PNI) for acute exacerbation in patients with IPF. Methods: Ninety-seven patients diagnosed with IPF between 03/2019 and 03/2024 were retrospectively evaluated. Patients were divided into two groups according to exacerbation status (acute exacerbation group n = 28, non-acute exacerbation group n = 69). PNI values were calculated. The predictive value of the PNI for acute exacerbation was analyzed between groups. ROC analysis and multivariable logistic regression were performed. Results: Of the 97 patients, 78 (80.4%) were male with a mean age of 71.31 ± 6.61 years. The mean disease duration was 24.77 ± 15.69 months. During follow-up, 28 patients (28.9%) had acute exacerbations. Lymphocyte count and albumin level were significantly lower in the acute exacerbation group (p < 0.001, p < 0.001, respectively). The mean PNI value was significantly lower in the acute exacerbation group (46.62 ± 6.28) compared to the non-acute exacerbation group (52.04 ± 5.46) (p < 0.001). In addition, FEV₁%, FVC%, and DLCO% values were significantly lower in the acute exacerbation group (p < 0.001, p < 0.001, p < 0.001, respectively). In ROC analysis, the cut-off value of PNI ≤ 48.50 had a sensitivity of 64.29% and specificity of 78.26% (AUC:0.744, p < 0.001). In multivariable logistic regression analysis, the PNI (OR = 0.857, p = 0.007) and FVC% (OR = 0.949, p = 0.008) were independent predictors of acute exacerbation. Conclusions: The PNI may serve as a negative biomarker for predicting acute exacerbation risk in IPF patients. This simple, cost-effective parameter could be useful in risk assessment.