BackgroundSevere community-acquired pneumonia (SCAP) is one of the most common critical and acute diseases in the respiratory and acute medicine department. The expression and significance of lncRNA RPPH1 (RPPH1) in SCAP were assessed aiming to explore a biomarker assisting in the screening and management of SCAP.MethodsThis study is a retrospective study enrolled 97 SCAP patients, 102 mild community-acquired pneumonia (MCAP) patients, and 65 healthy individuals. The serum expression of RPPH1 of study subjects was evaluated using PCR. The diagnostic and prognostic significance of RPPH1 in SCAP was evaluated by ROC and Cox analyses. Meanwhile, the correlation of RPPH1 with patients’ clinicopathological features was evaluated by spearman correlation analysis to evaluate its role in assessing disease severity.ResultsA significant downregulation of RPPH1 was observed in the serum of SCAP patients compared with MCAP and healthy individuals. RPPH1 was positively correlated with ALB (r= 0.74) and negatively correlated with C-reactive protein (r= -0.69), neutrophil-to-lymphocyte ratio (r= -0.88), procalcitonin (r= -0.74), and neutrophil (r= -0.84) of SCAP patients, which are associated with the development and severity of SCAP. Additionally, reduced RPPH1 was closely associated with the 28-day development-free survival of SCAP patients and served as an adverse prognostic indicator together with procalcitonin.ConclusionsDownregulated RPPH1 in SCAP could act as a diagnostic biomarker screening SCAP from healthy and MCAP individuals and act as a prognostic biomarker predicting patients’ disease conditions and outcomes. The demonstrated significance of RPPH1 in SCAP could assist the clinical antibiotic therapies of SCAP patients.