Thursday, April 13, 2017

Diagnostic accuracy of routine blood examinations and CSF lactate level for post-neurosurgical bacterial meningitis

Zhang Y, Xiao X, Zhang J, Gao Z, Ji N, Zhang L. Diagnostic accuracy of routine blood examinations and CSF lactate level for post-neurosurgical bacterial meningitis. Int J Infect Dis. 2017 Apr 6. pii: S1201-9712(17)30111-X. doi:10.1016/j.ijid.2017.03.026. [Epub ahead of print]

Abstract
OBJECTIVE:
To evaluate the diagnostic accuracy of routine blood examinations and Cerebrospinal Fluid (CSF) lactate level for Post-neurosurgical Bacterial Meningitis (PBM) at a large sample-size post-neurosurgical patients.
METHODS:
The diagnostic accuracies of routine blood examinations and CSF lactate level to distinguish between PAM and PBM were evaluated with the values of the Area Under the Curve of the Receiver Operating Characteristic (AUC-ROC) by retrospectively analyzing the datasets of post-neurosurgical patients in the clinical information databases.
RESULTS:
The diagnostic accuracy of routine blood examinations was relatively low (AUC-ROC <0.7). The CSF lactate level achieved rather high diagnostic accuracy (AUC-ROC=0.891; CI 95%, 0.852-0.922). The variables of patient age, operation duration, surgical diagnosis and postoperative days (the interval days between the neurosurgery and examinations) were shown to affect the diagnostic accuracy of these examinations. The variables were integrated with routine blood examinations and CSF lactate level by Fisher discriminant analysis to improve their diagnostic accuracy. As a result, the diagnostic accuracy of blood examinations and CSF lactate level was significantly improved with an AUC-ROC value=0.760 (CI 95%, 0.737-0.782) and 0.921 (CI 95%, 0.887-0.948) respectively.
CONCLUSIONS:
The PBM diagnostic accuracy of routine blood examinations was relatively low, whereas the accuracy of CSF lactate level was high. Some variables, that are involved in the incidence of PBM, can also affect the diagnostic accuracy for PBM. Taking into account of the effects of these variables significantly improve the diagnostic accuracies of routine blood examinations and CSF lactate level.
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From the manuscript

The value of CSF examinations, such as measurements of the cell counts, protein concentration and glucose levels, is limited, especially in distinguishing PBM from Post-neurosurgical Aseptic Meningitis (PAM).  PAM is triggered by an aseptic inflammatory response to hemolysis products, tumor antigens , bone dust and implants, which are usually produced during neurosurgery…
Although several studies have reported that the blood  WBC counts are significantly higher in PBM than in PAM patients, the actual diagnostic accuracy for PBM of blood WBC counts and other routine blood examinations has not be comprehensively evaluated…

CSF lactate originates from anaerobic glycolysis inside bacteria and ischemic brain tissue caused by bacterial infection. The CSF lactate level reportedly is a good marker to distinguish bacterial meningitis from aseptic meningitis…

A total of 8524 patients were operated at the period. More than 3 million datasets from the three databases were extracted and matched to exclude redundancy and incompleteness…

The routine CSF examination was considered positive when it met both of the following criteria: 1) CSF WBC count ≥ 1000/L [should be > 1000/microliter]and polykaryocyte percentage ≥ 75%, and 2) CSF glucose <2.5 mmol/L or ratio of CSF glucose to blood glucose ><0.4…

CSF bacterial culture has been reported to remain negative in up to 70% of suspected clinical cases , and its positive detection rate has been as low as 6-8% in our center…

The routine blood examinations include the WBC counts (bWBC), neutrophil proportion (bNeuT%), platelet counts (bPLT) and sodium concentration (bNa). Supplemental Table 1 shows that the levels of these examinations significantly differed between PBM and PAM…

Among these blood examinations, the bPLT and bNa performed slightly better than bWBC and bNeuT%...

Similar to the findings of previous studies, CSF lactate level could accurately distinguish PAM from PBM, with an AUC-ROC value of 0.891 (CI 95%, 0.852-0.922); this value was much higher than those blood examinations.


Courtesy of:  https://www.mdlinx.com/neurology/medical-news-article/2017/04/13/diagnostic-accuracy-post-neurosurgical-bacterial-meningitis/7127265/?category=latest&page_id=1


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