[Predictive value of white blood cell, procalcitonin and high-sensitivity C-reactive protein for the bloodstream infection in the super-elderly critically-ill patients]

Objective: To investigate the ability of white blood cell (WBC), procalcitonin (PCT) and high-sensitivity C-reactive protein (hs-CRP) in the super-elderly patients with bloodstream infection. Methods: It was a retrospective study. A total of 77 patients (≥85 years) admitted to the ICU of Peking Union Medical College Hospital from June, 2016 to December, 2017 were enrolled. The patients included 67 males and 10 females, with an age of 85-105 years and the average age was (92±5) years. According to the results of blood culture, patients were divided into positive blood culture group (n=50) and negative blood culture group (n=27). The data which obeyed normal distribution were compared with single sample t test between the two groups. Results: There was no significant difference in WBC level between the positive blood culture group and the negative blood culture group[12.4(7.8, 36.6)×10(9)/L vs 10.7(8.5, 18.7)×10(9)/L, U=0.109, P=0.124]. Compared to the positive blood culture group, the PCT level [2.6(0.8, 7.4)μg/L vs 1.5(0.6, 5.3)μg/L, U=3.015, P=0.004] and hs-CRP level [119(62, 220) mg/vs 54 (24, 80) mg/L, U=7.791, P<0.001] were significantly higher in the negative blood culture group. The ROC analysis showed that the area under the curves (AUC) of WBC, PCT and hs-CRP was 0.704(95%CI: 0.586-0.822, P<0.01), 0.896(95%CI: 0.829-0.964, P<0.01) and 0.864(95%CI: 0.778-0.949, P<0.01), respectively. The best cutoff value of PCT for discrimination of positive blood culture was 0.44 μg/L, which resulted in a sensitivity of 70.0% and a specificity of 92.6%. The best cutoff value of hs-CRP was 50.35 mg/L, which resulted in a sensitivity of 62.0% and a specificity of 88.9%. Conclusion: Compared to WBC, both PCT and hs-CRP have a better ability to predict bloodstream infection in the Super-elderly patients.