Association of Synergistic Trajectories Between Early Mobilization Potential and Actual Implementation with Clinical Outcomes Among ICU Patients with Pneumonia: A Multivariate Latent Class Mixed Model Analysis

Background: Although early mobilization is a key intervention in the management of patients admitted to the Intensive Care Unit (ICU), its effects on patients remain controversial in previous studies. This study aimed to explore the synergistic trajectories of early mobilization potential and actual implementation in ICU patients with pneumonia and their impacts on clinical outcomes.

Methods: Data were extracted from the Medical Information Mart for Intensive Care (MIMIC) database. Multivariate Latent Class Mixed Model (MLCMM) was adopted to identify mobilization trajectories within the first 72 hours of ICU admission among patients with pneumonia and perform subgroup stratification. Linear regression analysis was applied to investigate the association between early mobilization and length of stay (LOS) in the ICU across each subgroup. Subgroup analyses were conducted to explore the heterogeneity of the above association in populations with different characteristics. Kaplan-Meier curves were used to depict survival disparities, and Sankey diagrams were applied to illustrate discharge destinations.

Results: A total of 3,226 patients with pneumonia were included. In the fully adjusted model, Class 2 showed no statistically significant difference in ICU LOS relative to Class 1 (β = −0.04, 95% CI: −0.11 to 0.04, P = 0.351). Class 3 (β = −0.43, 95% CI: −0.51 to −0.35, P < 0.001) and Class 4 (β = −0.42, 95% CI: −0.50 to −0.33, P < 0.001) were associated with shorter ICU LOS. Sensitivity analyses yielded results consistent with the primary analysis. Significant interaction effects were observed in the subgroups of age (P for interaction=0.013) and mechanical ventilation (P for interaction<0.001) on the above association. Compared with Class 1, the other three subgroups were associated with higher survival probabilities (Log-rank P < 0.0001). The Sankey diagram revealed that Class 1 was characterized by adverse clinical prognoses.

Conclusions: This study demonstrates that low-level stable early mobilization is associated with longer ICU LOS and lower survival rate in patients with pneumonia. These findings suggest that distinct mobilization trajectories may reflect patients’ early recovery status.