Evaluation of new Beckman Coulter 25(OH) Vitamin D assay and potential improvement of clinical interpretation

Abstract

IntroductionThe aim of this study was to assess the analytical performances of the newly developed Access2 25-hydroxyvitamin D (25(OH)D) total immunoassay on two analysers, DxI800 and Access2 (Beckman Coulter, Brea, CA, USA), and compare these two and a recalibrated Modular E 170 25(OH)D assay (Roche Diagnostics, Penzberg, Germany) with reference liquid chromatography tandem-mass spectrometry (LC-MS/MS) with special emphasis on clinical diagnosis.Materials and methodsBeckman immunoassays were assessed for imprecision, accuracy, limit of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ), linearity, interference, and carryover. One hundred and nineteen samples were run on DxI 800, Access2, and E 170, and agreement with the LC-MS/MS method was evaluated.ResultsDxI 800 and Access2 assays showed good performances in terms of LoB, LoD, LoQ, linearity, and interference. All immunoassays showed negative biases ranging from - 8.6% (DxI 800) to - 19.2% (Access2). DxI 800 and Access2 systems had proportional biases, and the E170 system had a constant bias with the largest random error. Concordance correlation coefficient values ranged from 0.941 (CI: 0.917–0.958) for DxI800 to 0.854 (CI: 0.811–0.889) for Access2. Kappa (κ) coefficients were found moderate for Dxl (0.709; CI: 0.581–0.837) and E170 (0.771; CI: 0.587–0.844) and fair for Access2 (0.572; CI: 0.428–0.716).ConclusionsAll immunoassays can be used in routine 25(OH)D measurements, still fairly diagnosing patients’ status. Recent standardization attempts seem not to contribute too much to clinical diagnosis. A clinical laboratory must at least be aware of its method to avoid misinterpretation of results.

A Comparison between Three Different Automated Total 25-hydroxyvitamin D Immunoassay Methods and Ultra Performance Liquid Chromatography

“…Also, clinically 25 (OH) D concentrations <50.0 nmol/L (< 30 ng/ml) indicate vitamin D deficiency; thus, inaccuracies at low concentrations have a limited impact on treatment decisions. These results are consistent with the findings of previous studies (Madenci et al, 2017;Kocak et al, 2015).…”

“…In a study by Kocak et al, (2015) the Roche Cobas vitamin D total assay method showed a bias of (-14.1%), but in our study it is (-4.22%) observed for the Cobas e601. Madenci et al, (2017) had examined Access 2 25 OH vitamin D assay by Bland-Altman analysis and a negative bias with the reference LC-MS/MS was seen (-19.2%).…”

“…This may explain the lower bias in the case of Roche and Acess 2 method compared to Abbott method. I n s p i t e o f t h e s a m e S t a n d a r d i n b o t h , the methodology of Access2 25(OH)D assay is a competitive chemiluminescence enzyme immune assay, while Cobas 25 (OH)D total assay is a competitive electrochemiluminescence immunoassay, explains bias between them (Madenci et al, in 2017).…”

“…Ultra performance liquid chromatography (UPLC) is considered a candidate reference method for accurate quantification of 25 (OH) D. However, HLPC technique has several drawbacks compared to automated immunoassays, including higher complexity, longer turnaround time and the need for skilled personnel, which make it virtually unavailable to some laboratories. Therefore, automated assays are typically regarded as the best choice for a number of laboratory services, provided that these methods display satisfactory analytical performance and optimal agreement with the reference techniques (Madenci et al, 2017).…”

An evaluation of total 25-hydroxyvitamin D assay standardization: Where are we today?

“…Several studies have evaluated and compared 25(OH)D assays. Though the methods overall correlated well, substantial variability between assays was found [12][13][14][15][16]. Some of these studies were performed early after the initiation of the VDSP initiative where standardization of assays…”