Elsevier

Clinical Biochemistry

Volume 42, Issue 15, October 2009, Pages 1557-1560
Clinical Biochemistry

Comparison of procalcitonin measurement by a semi-quantitative method and an ultra-sensitive quantitative method in a pediatric emergency department

https://doi.org/10.1016/j.clinbiochem.2009.07.005Get rights and content

Abstract

Objective

To compare procalcitonin measurements between semi-quantitative and quantitative assays.

Method

Procalcitonin was measured with the PCT-Q® and the Kryptor® assays in a pediatric emergency department.

Results

Among the 359 pairs of results, 103 had discordant results. The linear weighted kappa was 0.44 (95% CI 0.36, 0.51). The concordant/discordant results distribution varied depending on the laboratory technician (p = 0.018).

Conclusion

Agreement between procalcitonin measured semi-quantitatively and quantitatively was moderate. This is probably due to a subjective interpretation of the assay result.

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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