Dynamic Trajectories of White Blood Cell Counts Predict Short- and Long-Term Mortality in Stroke Patients: Insights From MIMIC-IV

Background: Stroke remains a leading cause of mortality and disability worldwide. Immune and inflammatory markers play a pivotal role in its pathophysiological mechanisms. This study investigates the dynamic trajectory patterns of white blood cell (WBC) counts during the first 7 days after admission to the intensive care unit (ICU) in patients with acute stroke, and analyzes their associations with 28-day mortality, 90-day mortality, and ICU mortality, aiming to provide novel indicators and a basis for the early identification of high-risk patients in clinical practice. Methods: A total of 4,194 patients with stroke were identified from MIMIC-IV. Group-based trajectory modeling was applied to characterize dynamic patterns of WBC during the first seven days of ICU admission. Multivariable Cox proportional hazards models were employed to evaluate associations between WBC trajectories and 28-day, 90-day, and ICU all-cause mortality. Subgroup and sensitivity analyses were performed to assess consistency and potential effect modifiers. Results: Two distinct WBC trajectories were identified: a stable pattern (trajectory 1) and a persistently fluctuating high-level pattern (trajectory 2). Patients in trajectory 2 demonstrated a significantly elevated risk of both 28-day mortality (HR = 1.36, 95% CI: 1.07-1.73, p < 0.05) and ICU mortality (HR = 1.56, 95% CI: 1.20-2.03, p < 0.01). Kaplan-Meier analyses demonstrated markedly higher survival rates among patients in trajectory 1 across both 28-day and 90-day follow-up periods. Subgroup analyses revealed a significant interaction between atorvastatin use and WBC trajectories in relation to mortality outcomes. Sensitivity analyses confirmed that early WBC trajectories primarily reflected intrinsic immune-inflammatory responses to stroke rather than short-term effects of mechanical ventilation, thereby reinforcing the robustness of the findings. Conclusion: WBC trajectories independently predict short-term outcomes in stroke patients. Persistently elevated and fluctuating patterns reflect immune-inflammatory dysregulation associated with poor prognosis. Monitoring dynamic inflammatory changes may improve risk assessment and guide targeted interventions.