Association Analysis of White Blood Cell Trajectories and 30‐Day Mortality in Ventilator‐Associated Pneumonia Patients: A Cohort Study Based on the MIMIC‐IV Database

Abnormal white blood cell (WBC) counts have been associated with ventilator-associated pneumonia (VAP). However, the prognostic value of WBC trajectory changes in VAP patients remains understudied. This study aimed to explore the correlation between WBC trajectory changes and the 30-day mortality rate in VAP patients. Data from VAP patients in the MIMIC-IV database were included. Group-based trajectory analysis was used to categorize patients based on their WBC patterns within 7 days of ICU admission. Cox proportional hazards regression analysis was conducted to assess the association between WBC trajectories and 30-day mortality. A total of 1194 eligible VAP patients were included. Five distinct WBC trajectories were identified. Compared to the trajectory group with continuously normal WBC levels (Class 5), the group with initially high levels but subsequent decrease (Class 2) and the group with continuously increasing WBC levels (Class 3) showed independent associations with increased mortality (OR > 1, p < 0.05). Additionally, restricted cubic splines (RCS) results indicated a possible linear relationship between WBC counts on the 6th and 7th days and the 30-day survival status of VAP patients. Within the first week of ICU admission, both the group with initially low levels but persistently increasing WBC trajectories and the group with initially high levels but continuously decreasing WBC trajectories were associated with increased 30-day mortality in VAP patients. This finding offers insights into predicting short-term mortality risks related to VAP and aids clinicians in early identification of high-risk patients.