Inflammatory markers and delirium in the intensive care unit

Background: Delirium is an important complication in patients admitted to intensive care unit (ICU). However, delirium prediction in patients admitted to the ICU is difficult. Considering the role of neuroinflammation in delirium, peripheral blood-based biomarkers of inflammation pressure could predict delirium. The aim of study was to retrospectively analyze ratios of neutrophil/high density lipoprotein (HDL) (NHR), lymphocyte/HDL (LHR), platelet/HDL (PHR), monocyte/HDL (MHR), as well as systemic immune-inflammation index (SII) and systemic inflammatory response index (SIRI) in ICU patients diagnosed with delirium. Methods: The study included a total of 2141 patients with or without delirium. The risk factors for delirium development and the predictive power of individual laboratory parameters were evaluated with the Pearson chi-square test, Mann-Whitney U test, Spearman correlation test, logistic regression, and receiver operating characteristic analyses. Results: Length of ICU stay (p < 0.001), NHR (p = 0.035), LHR (p < 0.001), PHR (p = 0.047), MHR (p < 0.001), SIRI (p < 0.001), and SII (p < 0.001) were significantly higher in patients who developed delirium compared to those who did not. A significant negative correlation was found between the duration of delirium and SII (r = −0.260; p = 0.004). Older age, a history of psychiatric treatment, prolonged hospitalization, and high LHR, SIRI, and SII values were determined as risk factors for delirium (p < 0.05 for all). Conclusions: Elevated LHR, SIRI, and SII levels before ICU admission are associated with an increased risk of hyperactive delirium. If confirmed by prospective evidence, readily available biomarkers for inflammation could be used to evaluate the hyperactive delirium risk in ICUs.

Intensive care; Delirium; Neutrophil/high-density lipoprotein; Lymphocyte/high-density lipoprotein; Platelet/high-density lipoprotein; Monocyte/high-density lipoprotein; Systemic immune-inflammation index; Systemic inflammatory response index

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