Diagnostic value of serum procalcitonin, IL-6 and C-reactive protein for community acquired pneumonia in elderly patients

doi:10.16150/j.1671-2870.2017.05.015

Abstract

Abstract: Objective: To investigate the auxiliary diagnostic value of serum procalcitonin (PCT), interleukin-6(IL-6) and C-reactive protein(CRP) for community acquired pneumonia (CAP) among elderly patients. Methods: A total of 103 elderly inpatients with CAP during January 1 to December 31, 2016 were enrolled in this study, and 50 cases of elderly patients with upper respiratory tract infection were served as controls. Sputum bacterial culture was positive in 45 of 103 CAP patients, and was negative in the other 58 patients. Levels of PCT, IL-6 and CRP were measured in all the patients. PCT>0.25 ng/mL, IL-6>7 pg/mL, CRP>8 mg/L were taken as cut-off value of positivity, and sensitivity and specificity for CAP were measured . Receiver operating characteristic (ROC) curve of the 45 cases with positive sputum bacterial culture was used to evaluate the diagnostic performance of PCT, IL-6 and CRP for CAP. Results: Serum levels of PCT, IL-6 and CRP were higher in CAP group than in control group (P<0.05). Sensitivity of CRP for diagnosing CAP (92.2%) was higher than those of IL-6 and PCT (P<0.05), and PCT had the highest specificity (94.0%) for the diagnosis of CAP(P<0.05). Meanwhile, the sensitivity of combined detection (parallel test: positive for any item) of these three biomarkers for the diagnosis of CAP were 96.1%, which was higher than the sensitivity of CRP-92.2% (P<0.05), however, the specificity of combined detection decreased slightly to 68%. In CAP patients, Pearson correlation coefficients revealed that PCT level was positively correlated with CRP level (r=0.528, P<0.001). Area under receiver operating characteristic(ROC) curve (AUC) for PCT, CRP and IL-6 were 0.773, 0.534, and 0.542, respectivlely; when PCT>0.21 ng/mL was taken as the cut-off value, the sensitivity and specificity for diagnosing CAP were 84.4% and 79.3%, respectively. Conclusions: PCT, IL-6 and CRP could be used as biomarkers in differentiating CAP from upper respiratory tract infection in elderly patients, and the combination of PCT, IL-6 and CRP might improve the diagnostic sensitivity for CAP. Meanwhile, PCT is more valuable than IL-6 and CRP for the auxiliary diagnosis of bacterial CAP.

Key words: Community acquired pneumonia, Elderly people, Procalcitonin, C reaction protein

CLC Number:

R562

WANG Linlin, ZHU Chengcheng, ZHANG Qingwu, CHEN Ting, WU Shun. Diagnostic value of serum procalcitonin, IL-6 and C-reactive protein for community acquired pneumonia in elderly patients[J]. Journal of Diagnostics Concepts & Practice, 2017, 16(05): 532-536.

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