Absolute lymphocyte count trajectory predicts clinical outcome in severely injured patients

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.

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).

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.

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.