Persistent lymphopenia is a risk factor for ICU-acquired infections and for death in ICU patients with sustained hypotension at admission

Christophe Adrie,Jean-François Timsit,Maxime Lugosi,Bertrand Souweine,Maité Garrouste-Orgeas,Romain Sonneville,Jean-Charles Cartier,Stéphane Ruckly,Carole Schwebel

doi:10.1186/s13613-017-0242-0

Abstract

BackgroundSeverely ill patients might develop an alteration of their immune system called post-aggressive immunosuppression. We sought to assess the risk of ICU-acquired infection and of mortality according to the absolute lymphocyte count at ICU admission and its changes over 3 days.MethodsAdults in ICU for at least 3 days with a shock or persistent low blood pressure were extracted from a French ICU database and included. We evaluated the impact of the absolute lymphocyte count at baseline and its change at day 3 on the incidence of ICU-acquired infection and on the 28-day mortality rate. We categorized lymphocytes in 4 groups: above 1.5 × 103 cells/µL; between 1 and 1.5 × 103 cells/µL; between 0.5 and 1 × 103 cells/µL; and below 0.5 × 103 cells/µL.ResultsA total of 753 patients were included. The median lymphocyte count was 0.8 × 103 cells/µL [0.51–1.29]. A total of 174 (23%) patients developed infections; the 28-day mortality rate was 21% (161/753). Lymphopenia at admission was associated with ICU-acquired infection (p < 0.001) but not with 28-day mortality. Independently of baseline lymphocyte count, the absence of lymphocyte count increase at day 3 was associated with ICU-acquired infection (sub-distribution hazard ratio sHR: 1.37 [1.12–1.67], p = 0.002) and with 28-day mortality (sHR: 1.67 [1.37–2.03], p < 0.0001).ConclusionLymphopenia at ICU admission and its persistence at day 3 were associated with an increased risk of ICU-acquired infection, while only persisting lymphopenia predicted increased 28-day mortality. The lymphocyte count at ICU admission and at day 3 could be used as a simple and reproductive marker of post-aggressive immunosuppression.

Highlights

Ill patients might develop an alteration of their immune system called post-aggressive immu‐ nosuppression
Severity of illness was evaluated on the first intensive care unit (ICU) day using the Simplified Acute Physiology Score (SAPS II), Sequential Organ Failure Assessment (SOFA) score, and Glasgow Coma Scale (GCS) score, and Knaus’ scale definitions were used to record preexisting chronic organ failures including respiratory, cardiac, hepatic, renal, and immune system failures
In order to decrease the risk of confusion bias between lymphopenia and acquired-ICU infection, we developed a propensity score aimed to predict the probability to have a nosocomial infection conditionally on variables recorded in the first 2 days of admission [17]

Summary

Introduction

Ill patients might develop an alteration of their immune system called post-aggressive immu‐ nosuppression. We sought to assess the risk of ICU-acquired infection and of mortality according to the absolute lymphocyte count at ICU admission and its changes over 3 days. Especially those with septic shock, after an initial phase of immune system hyperstimulation, dysfunction could appear secondarily. This is often called post-aggressive immunosuppression or compensatory anti-inflammatory response syndrome. It affects the innate and adaptive immune system [3, 4]. Persistence of CARS is associated with the risk of ICU-acquired infections and adverse outcome [7, 8]

Objectives

Methods

Results

Discussion

Conclusion