Monitoring of circulating monocyte HLA-DR expression in a large cohort of intensive care patients: relation with outcome and secondary infections

ABSTRACT Background post-injury acquired immunodepression (AID) is frequently assessed by the diminished expression of Human Leukocyte Antigen-D Related on circulating monocytes (mHLA-DR). The relation with mortality and the occurrence of ICU-acquired infections (IAI) requires confirmation in large cohorts of patients. This study tested in a large number of ICU patients from a single center the association of mHLA-DR with mortality and secondary infections. Methods This prospective, observational study in a surgical ICU of a French tertiary hospital reports mHLA-DR measurements (fixed flow cytometry protocol) done 1st within the 3 days post-admission and 2nd after the 7th day. The other collected parameters were: the SAPS II and SOFA scores, sex, age, comorbidity, mortality and ICU-acquired infections. The associations between mHLA-DR and outcomes were tested by adjusted Fine and Gray sub-distribution competing risk models. Findings 1053 patients were subdivided into 4 subgroups depending on the main motif for admission. Overall, 151 patients (14.3%) died in the ICU with an independent association with the amplitude of the first mHLA-DR decrease (HR = 0.71 [0.57; 0.95], p < 0.01); 592 patients had a 2nd mHLA-DR measurement of whom 223 patients (37.7%) complicated by IAI. These patients had a lower mHLA-DR than other patients (mHLA-DR = 9.0 log vs. 9.3 log, p < 0.01). IAI occurrence was independently associated with first, the 2nd mHLA-DR level regardless the initial severity (HR = 0.66 [0.51; 0.84], p = 0.001) and second, with the slope between the 1st and 2nd values (HR = 0.62 [0.43; 0.89], p = 0.009). Interpretation the association between the early mHLA-DR expression and ICU mortality does not improve the prediction given by the severity scores. The persistence or a decrease of low mHLA-DR expression are independent and reliable predictors of ICU-acquired infection. Funding no financial interest