Journal List > Lab Med Online > v.6(1) > 1057317

Rim, Ahn, Yoon, Kim, Kim, Lim, and Yoo: Performance Evaluation of the ichroma SMART Analyzer in Measuring C-reactive Protein and Procalcitonin Levels

Abstract

Background

For monitoring infection and inflammation episodes, biomarkers of host response, such as C-reactive protein (CRP) and procalcitonin (PCT), are now being recognized as useful tools in the diagnostic process. We aimed at evaluating the analytical performance of the recently developed semi-automated ichroma SMART system (Boditech Med Inc., Korea), which allows measurements of both CRP and PCT.

Methods

We evaluated the analytical performance of the ichroma SMART system and the agreement between its results and the laboratory standards for CRP and PCT measurements. The precision and linearity as well as the method of measurement were compared to the DxC 800 (Beckman Coulter, USA) for CRP and to the VIDAS (bioMerieux SA, France) for PCT, according to corresponding CLSI guidelines. Additionally, we evaluated the carryover rates between specimens.

Results

The total precision (% CV) of the ichroma SMART system in measuring low, middle, and high level controls (level 1, 2, 3) was 6.32%, 5.75%, and 3.56% for CRP, and 8.07%, 6.24%, and 6.53% for PCT. In the linearity test, R2 was 0.9997 and 0.9982 for CRP (0.1-336.8 mg/L) and PCT (0.05-60.91 ng/mL), respectively. Good correlation was observed between ichroma SMART and DxC 800 for CRP (r=0.997), and between ichroma SMART and VIDAS for PCT (r=0.992). Carry-over effect was 0.02% for CRP and 0.04% for PCT.

Conclusions

The ichroma SMART system showed an adequate performance and appeared to be a suitable clinical analyzer with a simple operating procedure for the measurement of CRP and PCT.

Figures and Tables

Fig. 1

Linearity curves of measured value vs. expected value for CRP and PCT using ichroma SMART.

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Fig. 2

Comparison of CRP values measured by the DxC 800 and ichroma SMART.

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Fig. 3

Comparison of PCT values measured by the VIDAS and ichroma SMART.

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Table 1

Precision of measurement of CRP and PCT by ichroma SMART

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Items Level N Mean Within-run Total
SD CV (%) SD CV (%)
CRP (mg/L) 1 20 7.42 0.37 5.04 0.47 6.32
2 20 33.34 1.84 5.53 1.92 5.75
3 20 127.67 4.63 3.62 4.54 3.56
PCT (ng/mL) 1 20 0.51 0.03 6.18 0.04 8.07
2 20 1.13 0.05 4.40 0.07 6.24
3 20 11.94 0.45 3.74 0.78 6.53

Abbreviations: CRP, C-reactive protein; PCT, procalcitonin; SD, standard deviation; CV, coefficient of variation.

Table 2

Comparison of ichroma SMART with conventional analyzers at the medical decision levels by Passing-Bablok regression

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Analytes Slope (95% CI) Intercept (95% CI) Decision level Acceptable performance* Expected value Expected bias
CRP (mg/L) 1.067 (1.048-1.083) 0.119 (-0.772-0.585) 10 21.8% 10.79 7.9%
40 21.8% 42.80 7.0%
200 21.8% 213.52 6.8%
PCT (ng/mL) 0.836 (0.799-0.889) 0.052 (0.036-0.076) 0.5 6.9% 0.47 -5.9%

*Acceptable performance criteria were adapted from reference 8 and reference 9 for CRP and PCT, respectively.

Notes

This article is available from http://www.labmedonline.org

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