Lipid Biomarkers Predict Pneumonia Risk in Children with Influenza-Mycoplasma Co-infections: A Retrospective Cohort Study

Objective: This study evaluates the prognostic value of high-density lipoprotein (HDL-C) and low-density lipoprotein (LDL-C) levels for pneumonia risk in children co-infected with influenza and Mycoplasma pneumoniae (MP). Methods: We retrospectively analyzed 248 children with influenza-MP co-infection (January 1, 2020–October 30, 2024). Participants were grouped into pneumonia (P, n=195) and non-pneumonia (NP, n=53) based on chest imaging. Statistical comparisons of clinical parameters (WBC, lymphocytes, CRP, lipids) utilized Mann-Whitney U and chi-square tests. Variables with P<0.1 were included in logistic binary regression to identify independent risk factors. ROC analysis assessed diagnostic performance. Results: Significant differences were observed in lymphocytes (L), CRP, TG, HDL-C, and LDL-C levels between pneumonia and non-pneumonia groups (P < 0.05). CRP, HDL-C, and LDL-C were identified as independent risk factors for determining whether influenza-MP co-infections were complicated by pneumonia. CRP and LDL-C levels were risk factors associated with pneumonia risk (OR > 1), whereas HDL-C levels showed a strong protective factor association (OR < 1). The ROC curve analysis showed that the combined area under the curve (AUC) for HDL-C + LDL-C (0.878) was significantly higher than the AUCs for CRP + HDL-C (0.809), CRP + LDL-C (0.753), HDL-C (0.807), LDL-C (0.737), and CRP (0.601). The clinical DCA shows that HDL-C + LDL-C has a higher diagnostic value than CRP + HDL-C, CRP + LDL-C, HDL-C, LDL-C, or CRP alone. Conclusion: HDL-C and LDL-C levels independently predict pneumonia progression in influenza-MP co-infected children, with dual-marker assessment enhancing diagnostic accuracy.