Pre-treatment neutrophil-to-platelet ratio as a potential indicator for adult severe influenza in China: a retrospective study based on real-world data

High neutrophil-to-platelet ratio (NPR) values are closely associated with the prognosis of various diseases, but the potential value of pre-treatment NPR for distinguishing and assessing severe influenza in adults has rarely been reported in China. This study investigated the potential value of pre-treatment NPR in differentiating and evaluating influenza severity in adults in China. This retrospective study included 1,091 adults with influenza. Clinical data were collected at Guangdong Second Provincial General Hospital between March 1, 2016 and December 31, 2023, according to predefined inclusion and exclusion criteria. Baseline characteristics and laboratory parameters were collected and analyzed. Scatter-dot plots were used to compare the severe and non-severe groups. Associations between pre-treatment NPR and other indicators were evaluated using Spearman correlation analysis. Logistic regression models were used to identify independent predictors of severe influenza. Clinical characteristics and indicator levels differed between patients with influenza A and B. Combining pre-treatment NPR with lymphocyte count distinguished healthy individuals from adults with influenza better than either indicator alone for both influenza A and B ( P < 0.05). Compared with patients with non-severe influenza, pre-treatment NPR levels were significantly higher in those with severe influenza A or B, and they decreased markedly after treatment ( P = 0.012 and 0.028, respectively). Spearman correlation analysis showed a positive correlation between pre-treatment NPR and interluekin-6 (IL-6) levels ( P < 0.0001). In addition, pre-treatment NPR was identified as an independent predictor of severe influenza ( P = 0.001 for influenza A and P < 0.0001 for influenza B), and a high pre-treatment NPR value was associated with an increased risk of severe influenza. Pre-treatment NPR levels may reflect the severity of influenza. Given this clinical value, pre-treatment NPR may serve as a screening and prognostic indicator of severe influenza in adult patients. Not applicable.