Relationship Between Prognostic Nutritional Index and Stroke‐Associated Pneumonia in Elderly Patients: A Two‐Center Study of Spontaneous Intracerebral Hemorrhage

ABSTRACT Stroke‐associated pneumonia (SAP) is a common complication in elderly patients with spontaneous intracerebral hemorrhage (sICH), and nutritional‐immune status may influence the risk of infection. The prognostic nutritional index (PNI), which integrates nutritional and immune‐related markers, has been proposed as a potential indicator of clinical outcomes. However, evidence regarding its association with SAP remains limited. This two‐center retrospective study enrolled elderly patients with sICH admitted to Lanzhou University Second Hospital and Fujian Medical University Union Hospital. Patients were grouped according to the occurrence of SAP, and demographic characteristics, laboratory indicators, and imaging data were collected. Multivariate logistic regression analysis was performed to examine the association between PNI and SAP after progressively adjusting for potential confounding factors. Restricted cubic splines (RCS) were used to explore the dose–response relationship. Bayesian mediation analysis was conducted to assess the mediating effect of white blood cell count (WBC) between PNI and SAP, and stratified subgroup analysis was further performed to evaluate the stability of the association. Among 431 patients, the incidence of SAP was 64.0%. Multivariate logistic regression revealed a significant negative relationship between PNI and SAP risk (OR = 0.95, 95% CI: 0.90–1.00). Trend analysis indicated a linear relationship between elevated PNI levels and reduced SAP risk ( p trend < 0.05), whereas RCS analysis did not reveal significant nonlinear associations. Mediation analysis indicated that WBC partially mediated the relationship between PNI and SAP, with a mediation proportion of 10.14%. Subgroup analysis showed that this association was more pronounced in patients with GCS < 9 and greater blood loss ( p for interaction < 0.05). These findings suggest that reduced PNI is a significant risk indicator for the development of SAP in elderly patients with sICH, and PNI may influence infection risk partly through its intermediary effect on the inflammatory response.