Predictive value of procalcitonin for excluding bloodstream infection: results of a retrospective study and utility of a rapid, quantitative test for procalcitonin.
OBJECTIVE
To assess retrospectively the diagnostic value of procalcitonin (PCT) in excluding suspected bloodstream infection, establish cut-off values for PCT levels, and compare PCT with other clinical markers.


METHODS
The predictive accuracy of different continuous parameters was estimated by univariate analysis of the area under the receiver operating characteristic curve. Optimized cut-off points for the parameters were selected according to the maximum Youden index values, which in turn were used to define positive and negative predictive values of different parameters in diagnosing bloodstream infection.


RESULTS
The PCT level yielded a statistically significant area under the receiver operating characteristic curve of 0.765, with a best cut-off value of 0.80 ng/ml (83% sensitivity; 65% specificity, Youden index, J = 0.48). Positive and negative predictive values at this cut-off value were 38% and 94%, respectively. Mann-Whitney U-test revealed significantly higher values for PCT, C-reactive protein and percentage of neutrophils, but not for white blood cell count, in patients with bloodstream infection.


CONCLUSIONS
The serum PCT level can potentially be used as surrogate marker to exclude bacteraemia and to inform critical management decisions regarding antibiotic usage, in patients admitted with suspected bloodstream infection.
Chinese PLA General Hospital & Chinese PLA Medical School, Beijing, China.
Huan
H
Wang
Fan
F
Yin
Ding-Xia
DX
Shen
You-Jiang
YJ
Zhang
Yan-Ping
YP
Luo
Chao-Jun
CJ
Liu
Kai-Fei
KF
Wang
Guang
G
Zhou
Li-Yan
LY
Ye
Gang
G
Chen
Xiao-Ning
XN
Wang
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D012189:Retrospective Studies; D018805:Sepsis / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology; D018709:Statistics, Nonparametric
D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide
C-reactive protein; Procalcitonin; area under the curve; bloodstream infection; percentage of neutrophils; predictive value