Performance Evaluation of the Syva EMIT Methotrexate Assay on the Toshiba 200FR NEO

Jinsook Lim; Jimyung Kim; Yong-Hak Sohn; Sun Hoe Koo; Gye Cheol Kwon

doi:10.3343/lmo.2014.4.4.187

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Lim, Kim, Sohn, Koo, and Kwon: Performance Evaluation of the Syva EMIT Methotrexate Assay on the Toshiba 200FR NEO

Original Article

Clinical Chemistry

Laboratory Medicine Online 2014; 4(4): 187-190.

Published online: 1 October 2014

DOI: https://doi.org/10.3343/lmo.2014.4.4.187

Performance Evaluation of the Syva EMIT Methotrexate Assay on the Toshiba 200FR NEO

Jinsook Lim, M.D.¹, Jimyung Kim, M.D.¹, Yong-Hak Sohn, M.D.², Sun Hoe Koo, M.D.¹, Gye Cheol Kwon, M.D.¹

¹Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea.

²Department of Laboratory Medicine, Eulji University Hospital, Daejeon, Korea.

Corresponding author: Gye Cheol Kwon. Department of Laboratory Medicine, Chungnam National University Hospital, 33 Munhwa-ro, Joong-gu, Daejeon 301-721, Korea. Tel: +82-42-280-7799, Fax: +82-42-257-5365, kckwon@cnu.ac.kr

Received 3 July 2013 Revised 3 April 2014 Accepted 7 April 2014

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Methotrexate (MTX) is an antifolate antagonist that is widely used for treating various malignancies and non-malignant diseases. MTX levels should be monitored when used in high concentration to determine when to start leucovorin rescue. In this study, we evaluated the analytical performance of the EMIT Methotrexate Assay on a 200FR NEO Chemistry Analyzer (Toshiba Medical System Co., Japan) and compared it with Viva-E Drug Testing System (Siemens Healthcare, Germany).

Methods

According to the Clinical Laboratory and Standards Institute (CLSI) Evaluation Protocol (EP) 5-A2, three concentrations of the Liquichek Therapeutic Drug Monitoring Control (Bio-Rad Laboratories, USA) were analyzed twice a day for 20 days to monitor assay precision. The 200FR NEO and Viva-E instruments were compared using 40 patients' sera, according to CLSI EP9-A2. The linearity and carry-over rate were also evaluated.

Results

Between-run CVs for low-, medium-, and high-level controls were 4.9%, 0.9%, and 2.0%, respectively, whereas between-day CVs for low-, medium-, and high-level controls were 8.1%, 1.3%, and 3.5%, respectively. In the linearity test, the coefficient of determination (R²) was 0.98 (0.06-1.92 µmol/L). In the comparison study, R² was 0.955, showing good correlation between the 200FR NEO and Viva-E instruments. The carry-over rate was 0.9%.

Conclusions

The EMIT assay showed good precision, linearity, and carry-over rate on the Toshiba 200FR. An excellent correlation was observed when comparing results obtained using the Toshiba and Viva-E instruments. In conclusion, the Syva EMIT MTX assay can be readily used for MTX monitoring on the Toshiba 200FR NEO.

Keywords: Methotrexate, EMIT, Therapeutic drug monitoring

Figures and Tables

Fig. 1

Comparison of MTX level determinations measured by the Viva-E and the Toshiba 200FR NEO. Differences in results from either instrument are shown in (A) a scatter plot with an ordinary linear fit (blue line), (B) a Bland-Altman difference plot, or (C) a Bland-Altman percent difference plot.

Fig. 2

Linearity of MTX values using the Syva EMIT Methotrexate Assay on the Toshiba 200FR NEO.

Table 1

Precision of the Syva EMIT Methotrexate Assay on the Toshiba 200FR NEO Chemistry Analyzer

Notes

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

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