Potential Utility of Combined Presepsin and LDH Tracking for Predicting Therapeutic Efficacy of Steroid Pulse Therapy in Acute Exacerbation of Interstitial Lung Diseases: A Pilot Study

<b>Background/Objectives</b>: The usefulness of presepsin, which is released from macrophages, in acute exacerbation of interstitial lung diseases (AE-ILDs) is unknown. We aimed to investigate the utility of monitoring presepsin with other AE-ILD markers before and after steroid pulse therapy in AE-ILDs. <b>Methods</b>: This pilot single-center retrospective observational study involved 16 patients with AE-ILDs, including the AE of idiopathic pulmonary fibrosis and idiopathic nonspecific interstitial pneumonia and rapidly progressive connective tissue disease-associated ILD. Patients who survived 90 days were assigned to the survival group (<i>n</i> = 9). The remaining patients were classified in the non-survivor group (<i>n</i> = 7). To evaluate the therapeutic efficacy of steroid pulse therapy, specific serum markers were selected-presepsin, as a novel AE-ILD marker, and surfactant protein D, C-reactive protein, and lactate dehydrogenase (LDH), as classical AE-ILD markers. <b>Results</b>: Thirteen out of sixteen patients with AE-ILDs showed high presepsin levels (presepsin ≥ 470 pg/mL) before steroid pulse therapy. The post-/pre-presepsin ratio and the post-/pre-LDH ratio, calculated by dividing the presepsin and LDH levels after therapy by the levels before therapy, respectively, showed a positive correlation (r = 0.579, <i>p</i> = 0.021). As a result of this correlation, the post-/pre-presepsin-LDH index was created, obtained from the "post-/pre-presepsin ratio" multiplied by the "post-/pre-LDH ratio". In a receiver operating characteristic curve analysis for non-survival, the post-/pre-presepsin-LDH index showed good discrimination as a prognostic marker for a poor outcome (AUC: 0.873, 95% confidence interval: 0.655-0.999). <b>Conclusions</b>: Tracking presepsin and LDH simultaneously may be useful for determining treatment response to steroid pulse therapy in the clinical management of AE-ILDs.