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KMID : 1100820210110040235
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Laboratory Medicine Online
2021 Volume.11 No. 4 p.235 ~ p.244
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Comparison of Three Automated Calcitonin Immunoassays for Evaluating the Equivalence Near the Clinical Decision Point
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Song Jun-Hyup
Cho Yong-Geun
Lee Sang-Guk
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Abstract
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Background: To date, only a few studies have focused on the standardization of the calcitonin assay, despite the fact that a lack of standardization of assays can lead to discrepancy in results. Here, we analyzed the concordance in serum calcitonin test results using three different assays.
Methods: The serum calcitonin levels in 104 residual specimens collected between January and February 2020 were measured using three different systems. The Spearman’s rank correlation coefficients and the slopes and y-intercepts were assessed to derive all possible pairs of analyzers. The agreement of classification according to a clinically relevant cut-off was also evaluated using Cohen’s kappa coefficient.
Results: The correlation coefficients for Cobas e801 versus LIAISON, Atellica IM-1600 versus LIAISON, and Cobas e801 versus Atellica IM-1600 were 0.77, 0.63, and 0.95, respectively. The kappa agreement of classification at a cut-off of 10 pg/mL was 0.81, 0.81, and 0.91, respectively. However, after excluding the data points for concentrations >20 pg/mL, the correlation coefficients decreased to 0.39, 0.22, and 0.90, respectively.
Conclusions: Despite acceptable correlations for the full analytical measuring range, we observed limited correlations at low concentrations, especially around the clinical decision threshold. Therefore, continuous joint efforts by all stakeholders are essential for standardizing calcitonin assays.
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KEYWORD
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Calcitonin, Standardization, Method comparison, Immunoassay
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