Comparison of procalcitonin measurement by a semi-quantitative method and an ultra-sensitive quantitative method in a pediatric emergency department
Introduction
Almost 10 years ago, Gendrel et al. [1] demonstrated the superiority of procalcitonin (PCT) over C-reactive protein (CRP) in distinguishing bacterial from viral infections in children in the emergency department. This initial observation has since been confirmed by others [2], [3], [4], [5], [6], [7].
PCT can be measured by various methods: with a semi-quantitative assay (PCT-Q®, Brahms, Germany) or with a quantitative assay such as the luminometric immunoassay (Lumitest®, Brahms, Germany) or the ultra-sensitive immunoassay using TRACE (Time Resolved Amplified Cryptate Emission) technology (Kryptor®, Brahms, Germany). In the emergency department where results need to be obtained rapidly so timely clinical decisions can be made (use of antibiotic or not, and discharge or hospitalization), a simple immunochromatographic assay such as PCT-Q® is highly desirable. It is easy to use, inexpensive and does not require calibration. Nevertheless, the color intensity of the band (result) must be evaluated by a technician, and is therefore subject to individual observer variation.
The objective of our study was to compare PCT values obtained from the semi-quantitative PCT-Q® assay to those obtained from the most sensitive and precise quantitative immunoassay, Kryptor®, when the former was performed by various laboratory technicians in real-time 24/24 h, 7 days a week in 1 to 36-month-old children presenting to a pediatric emergency department (ED) with a fever without a source.
Section snippets
Method
The prospective cohort study was part of a randomized controlled trial (RCT) assessing the impact of PCT on the management of children aged 1 to 36 months presenting to a pediatric ED with fever without a source [8] and took place in a tertiary pediatric hospital emergency department with an annual census of more than 60,000 visits. The CHU Sainte-Justine's Institutional Review Board approved the study.
Inclusion criteria consisted of children between 1 and 36 months with a rectal temperature
Results
A pair of PCT-Q®–PCT Kryptor® results was available for 359 children among the 384 children that were initially included in the randomized controlled trial between November 25th, 2006 and November 21st, 2007. No plasma was available for the other 25 children. The median age of the children was 11 months (IQR 6, 17). During the study, 53 urinary tract infections, 4 pneumonia, 1 occult bacteremia (Streptococcus pneumoniae) and 1 bacterial meningitis (Neisseria meningitidis) were diagnosed.
The
Discussion
Our study demonstrates that, in the context described, agreement between procalcitonin results measured semi-quantitatively (PCT-Q®) and quantitatively (PCT Kryptor®) is moderate.
Few studies have examined the agreement between the semi-quantitative assay and the quantitative measurement of PCT. In 2000, Guerin [12] compared the PCT-Q® assay with the Lumitest®. He selected 75 frozen serum samples previously measured with Lumitest® to cover a wide range of concentrations. The results demonstrated
Financial disclosure
We received 200 PCT-Q® from Brahms (Germany). Reactants for Kryptor® PCT dosages were provided by Brahms (Switzerland).
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Comparison of the test characteristics of procalcitonin to C-reactive protein and leukocytosis for the detection of serious bacterial infections in children presenting with fever without source: A systematic review and meta-analysis
2012, Annals of Emergency MedicineCitation Excerpt :The risk is greatest among infants and children younger than 36 months, making proper diagnosis and management paramount. For decades, investigators have attempted to find clinical or laboratory markers that can accurately differentiate severe bacterial infection from localized or viral infections in young children with fever without source21-28; unfortunately, no single, ideal marker has been identified.7,10,12,13,29-39 The WBC count is routinely recommended as an initial screening marker in children with fever without source.
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