The Value of NLR, PLR, MLR, and SII Combined with Lower Respiratory Tract Symptoms in Predicting Pulmonary Complications in Non-Risk-Factor Influenza A Patients

To analyze the predictive value of blood cell count results, derived indicators, and patient symptoms for pulmonary complications in non-risk-factor influenza A patients.

A retrospective cohort study analyzed 54 non-risk-factor influenza A patients. Those with pulmonary complications were assigned to the PC group, while the others were placed in the NPC group. Blood cell count and its derived indices, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and systemic immune-inflammation index (SII), were compared between the two groups. Four prediction models with different symptoms were established, and the ROC curve was used to verify their predictive value for pulmonary complications in non-risk-factor influenza A patients. Multivariate logistic regression was applied to the optimal prediction model.

Lower respiratory tract symptoms were present in 63.6% of patients in the PC group, which was significantly higher than the 25.6% in the NPC group (P < 0.05). The PC group exhibited significantly higher levels of white blood cell (WBC) count (9.38 ± 3.98×10⁹/L vs. 6.54 ± 2.37×10⁹/L), neutrophil count (8.05 ± 3.94×10⁹/L vs. 5.16 ± 2.25×10⁹/L), NLR (13.36 ± 7.26 vs. 7.42 ± 4.04), and SII (2548.87 ± 1967.89 vs. 1437.40 ± 892.69) compared with the NPC group. In ROC, WBC, neutrophils, and NLR were valid predictors of pulmonary complications. Among them, NLR showed the best individual predictive performance (AUC = 0.746). All four combined models achieved higher AUC values than NLR alone, and Model 4 (lower respiratory tract symptoms + NLR) presented the highest AUC of 0.829. Multivariate logistic regression identified that an elevated NLR (OR = 1.34, 95% CI: 1.10-1.63, P = 0.004) and lower respiratory tract symptoms (OR = 15.26, 95% CI: 1.95-119.31, P = 0.009) were independent risk factors for pulmonary complications.

Elevated NLR and lower respiratory tract symptoms are independent predictors of pulmonary complications in non-risk-factor influenza A patients. Their combination offers more accurate and effective predictive value for early risk stratification.