To explore the risk factors for 30-day mortality among all the PMV-p patients, the following variables were entered into the backstep logistic regression model: age ≥ 65 years, RSV infection, diabetes mellitus, COPD, solid malignant tumor, smoking history, mental confusion, lymphocytes <0.8 × 109/L, hemoglobin <100 g/L, serum albumin <30 g/L, BUN > 7 mmol/L, PO2/FiO2 <250 mmHg, and systemic corticosteroid use (Supplementary Material 5). Here, ALB is linked to diabetes mellitus.