Abstract
Elevated neutrophil to lymphocyte ratio (NLR) upon ICU admission has been reported to be associated with disease progression, severity, or mortality in critically ill patients. However, the overtime trajectories of NLR after admission and their association with other markers of intensive care units patients’ immuno-inflammatory status have not be evaluated so far. In a cohort of 353 critically ill patients (sepsis, trauma, major surgery), we evaluated the association between NLR trajectories and patients’ deterioration (mortality or occurrence of nosocomial infection) both by a conventional analysis at each time-point and through K-means clustering analysis. Additionally, these trajectories were delineated alongside established markers of hyper-inflammation (e.g., IL-6) or immunosuppression (including HLA-DR expression on monocytes, proportion of immature neutrophils, and plasma IL-10 levels). The results showed that persistently elevated NLR values were associated with an increased risk of patient deterioration, as demonstrated in a multivariate analysis that included usual clinical confounders. Patients belonging to the persistently elevated NLR endotype simultaneously exhibited heightened inflammation and pronounced immunosuppression. In conclusion, by providing integrated information on both hyper-inflammation and immunosuppression, NLR measurement holds significant promise for monitoring the immune status of ICU patients. This straightforward and standardized marker could serve to assess immune organ failure in ICU and assist in guiding potential immunomodulation strategies.