Absolute lymphocyte count trajectory predicts clinical outcome in severely injured patients.

Purpose: Lymphopenia is associated with adverse clinical outcome in trauma, but no immunomonitoring method is established to identify patients at risk. Absolute lymphocyte count (ALC) represents a promising biomarker and may support clinical decision-making in the intensive care unit (ICU). This study examined the temporal patterns of ALC in severely injured patients and their correlation with clinical outcomes.

Methods: 38 severely injured patients with an Injury Severity Score (ISS) of 18 and greater were enrolled. Blood samples were collected on admission and after 8, 24 and 48 h and 5 and 10 days. 38 healthy volunteers served as controls. Patients were classified into four groups after 48 h based on their dynamic ALC: persistent lymphopenia (PL), rapidly decreasing (RD), slowly rising (SR) and normal fluctuation (NF). The groups were compared regarding physical performative outcome - defined as unfavorable when patients died or new functional disability necessitated long term care, in-hospital mortality, ICU length of stay (LOS), and incidence of multi-organ dysfunction syndrome (MODS).

Results: A significant reduction in ALC was observed in all patients over 10 days when compared to healthy volunteers, with all patients trending towards a recovery of their ALC after 10 days. PL and RD were associated with an unfavorable physical performative outcome, increased in-hospital mortality, ICU LOS and incidence of MODS.

Conclusion: The dynamic course of ALC represents a cheap and clinically implementable approach for immunomonitoring within 48 h in severely injured patients. The ALC dynamic may early identify severely injured patients at risk, thus facilitating more informed clinical decision-making.