Predictive value of procalcitonin in intensive care unit delirium

Objective To analyze the risk factors of delirium in intensive care unit (ICU) patients, and to investigate the predictive value of C-reactive protein (CRP), procalcitonin (PCT), lactic acid (Lac) and neuron-specific enolase (NSE) in the diagnosis of ICU delirium. Methods The patients admitted to central ICU and respiratory medicine ICU of Changzhou First People's Hospital from August 2016 to November 2017 were enrolled. The patients were divided into two groups according to whether delirium occurred within 7 days or not, which was evaluated by using the confusion assessment method for ICU (CAM-ICU). The gender, age and blood CRP, PCT, Lac, NSE levels were compared between the two groups. Multivariate Logistic regression model was used to analyze the risk factors of ICU delirium. Receiver operating characteristic curve (ROC) was drawn to assess the predictive value of CRP, PCT, Lac and NSE in the occurrence of ICU delirium. Results 133 patients were enrolled. Delirium occurred in 67 patients, and did not occurred in 66 patients, with a prevalence rate of 50.4%. There was no significant difference in gender or age between the two groups. Compared with non-delirium group, blood CRP, PCT and Lac levels in delirium group were significantly increased [CRP (mg/L): 110.75±77.31 vs. 51.32±36.51, PCT (μg/L): 3.95 (1.01, 23.90) vs. 0.09 (0.06, 0.36), Lac (mmol/L): 2.40 (1.70, 4.30) vs. 1.20 (0.90, 2.00), all P 0.05].② It was shown by multivariate Logistic regression analysis that blood PCT and Lac were risk factors of ICU delirium [PCT: odds ratio (OR) = 1.185, 95% confidence interval (95%CI) = 1.006-1.396, P = 0.042; Lac: OR = 1.398, 95%CI = 1.011-1.934, P = 0.043].③ROC curve analysis showed that blood CRP, PCT and Lac had certain predictive value for ICU delirium, and the area under the ROC curve (AUC) of PCT was the highest (0.840 vs. 0.694 and 0.751). When the cut-off value of PCT ≥ 0.55 μg/L, the sensitivity was 72.7%, the specificity was 86.2%, positive predictive value was 84.48%, and negative predictive value was 75.68%. Blood NSE had no predictive value for ICU delirium (AUC = 0.446, P = 0.290). Conclusions Blood PCT and Lac are the risk factors of ICU delirium. PCT has predictive value for ICU delirium. Key words: Delirium; Procalcitonin; C-reaction protein; Lactic acid; Neuron-specific enolase