Performance of the IDEXX Catalyst DxÂ® Chemistry ... - NetNews

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MethodsSamples: All patient samples were canine, feline, or equine serum or plasma that wasremaining after primary diagnostic testing at either the Purdue University Veterinary TeachingHospital (PUVTH) or at the North Grafton IDEXX Reference Laboratory (IDEXX). InitialC for1 week after initial diagnostic analysis, thawed, and then reanalyzed for the analyte ofinterest within 4 hours on both the Catalyst Dx and the Vitros 5,1 FS system. After theinitial assessment, characterized clinical specimens from the PUVTH and IDEXX wereobtained to assure that sufficient spread over the complete dynamic range of each analytedays prior to analysis on both instruments, which was performed in the same manner. Allsamples were analyzed in the PUVTH by one author (W.D.S.) or an experienced laboratorytechnician, according to manufacturer instructions.Method comparison: Analytes for which method comparison was performed includedglucose (GLU), blood urea nitrogen (BUN), creatinine (CREA), phosphorus (PHOS), calcium(Ca), magnesium (Mg), total protein (TP), albumin (ALB), alanine aminotransferase (ALT),aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alkaline phosphatase(ALKP), gamma glutamyltransferase (GGT), total bilirubin (TB), cholesterol (CHOL),triglycerides (TRIG), amylase (AMYL), lipase (LIPA), and creatine kinase (CK). For eachwhich included a broad range of results similar to those that might be routinely encounteredin healthy and ill veterinary patients. For each analyte, correlation plots were constructed,with calculation of the R 2 value and root mean square error.Precision analysis:multiple target concentrations of each analyte were selected in advance to represent low,“normal,” and high values for that test. For most analytes, two patient samples with resultsin close proximity to each target concentration for the analyte were selected, with10 replicates of the assay run on the Catalyst Dx analyzer. Mean, standard deviation, andcoefficients of variation (CV) were calculated for each precision run.ResultsMethod comparison: Correlation and bias plots for selected analytes that are commonlyevaluated using the Catalyst Dx analyzer are shown in Figure 1. These analytes and theirrespective R 2 ALKP (0.95), AST (0.99), GGT (0.96), BUN (0.99), LIPA (0.93), AMYL (0.94) and CK (0.96).PHOS (0.99), CA (0.94), Mg (0.91), LDH (0.96), TBIL (0.99), CHOL (0.99), and TRIG (0.95).Precision analysis: In order to determine the precision for each assay, means, standardcorrespond to results for each analyte expected to fall in a typical reference interval areshown in Table 2. CVs were also calculated for precision runs with target concentrationsexpected to be significantly outside a typical reference interval to ensure acceptablereproducibility at concentrations likely to occur in disease states. The majority of %CVs wereless than 1% and nearly all were 2.5% or less, which included all runs for ALB, ALKP, AMYL,AST, BUN, CA, CHOL, CK, CREA, GLU, LIPA, MG, PHOS, TP, and TRIG. Of those remaining
Results (cont.)Table 1. Comparison of results from theCatalyst Dx analyzer and Vitros system.Table 2. Results from the Catalyst Dxprecision analysis.Test N R2 MSE Test Mean SD %CVALB 0.95 0.2 ALB 3.0 0.04 1.2ALKP 0.95 94 ALKP 2.0 1.2ALT 59 0.98 31 ALT 5.4 AMYL 51 0.94 98 AMYL 1239 25.3 2.0AST 65 0.99 24 AST 135 0.9 BUN 55 0.99 1.1 BUN 20 0.2 1.0CA 45 0.94 0.4 CA 10.0 0.06 0.6CHOL 39 0.99 6.6 CHOL 223 1.9 0.9CK 53 0.96 90 CK 194 1.1 0.6CREA 0.98 0.4 CREA 1.2 0.01 0.9GGT 44 0.96 GGT 39 1.8 4.3GLU 69 0.99 6.6 GLU 115 0.4 0.4LDH 48 0.96 103 LDH 400 15.4 3.9LIPA 32 0.93 126 LIPA 4.0 0.6MG 48 0.91 0.1 MG 2.0 0.045 2.3PHOS 0.99 0.2 PHOS 4.6 0.03 TBIL 50 0.99 0.4 TBIL 0.5 0.04 TP 48 0.2 TP 0.04 0.6TRIG 88 0.95 TRIG 132 0.5Discussionpreventive screening of healthy patients and evaluation of ill patients. Therefore, results fromsuch instruments must be consistent and reliable, and ideally should offer rapid sampleindustry standard aids in the assessment of an analyzer’s accuracy, while precision analysisis essential to demonstrate reproducibility of results. In this study, results from the Catalyst DxChemistry Analyzer correlated well with results from the Vitros 5,1 FS Chemistry System.Precision was shown to be high for most analytes, with %CVs typically less than 5%, even foranalyte concentrations at high and low ends of the possible clinical results spectrum.Based on the findings of this study, the Catalyst Dx provides consistent results for the analytesevaluated in this study and these results correlate well with an established veterinary teachinghospital analyzer.*
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Performance of the IDEXX Catalyst DxÂ® Chemistry ... - NetNews

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