Reagent Lots Research Articles

Analytical Validation of AmpliChip p53 Research Test for Archival Human Ovarian FFPE Sections.

The p53 tumor suppressor gene (TP53) is reported to be mutated in nearly half of all tumors and plays a central role in genome integrity. Detection of mutations in p53 can be accomplished by many assays, including the AmpliChip p53 Research Test. The AmpliChip p53 Research Test has been successfully used to determine p53 status in hematologic malignancies and fresh frozen solid tissues but there are few reports of using the assay with formalin fixed, paraffin-embedded (FFPE) tissue. The objective of this study was to describe analytical performance characterization of the AmpliChip p53 Research Test to detect p53 mutations in genomic DNA isolated from archival FFPE human ovarian tumor tissues. Method correlation with sequencing showed 96% mutation-wise agreement and 99% chip-wise agreement. We furthermore observed 100% agreement (113/113) of the most prevalent TP53 mutations. Workflow reproducibility was 96.8% across 8 samples, with 2 operators, 2 reagent lots and 2 instruments. Section-to-section reproducibility was 100% for each sample across a 60 μm region of the FFPE block from ovarian tumors. These data indicate that the AmpliChip p53 Research Test is an accurate and reproducible method for detecting mutations in TP53 from archival FFPE human ovarian specimens.

Development of the molecular diagnostic (MDx) DLBCL Lymphoma Subtyping Test (LST) on the nCounter Analysis System.

8536 Background: Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin’s lymphoma with two distinct molecular cell-of-origin (COO) subtypes known as germinal center B-cell (GCB) or activated B-cell (ABC). DLBCL subtypes have been reported to be prognostic and potentially predictive of treatment benefit, underscoring the need for a precise and accurate MDx test. NanoString’s LST is based on the Lymph2Cx gene expression profile (GEP). These studies describe the development of the LST and analytical robustness and clinical accuracy of the Linear Predictor Score (LPS) and DLBCL subtypes (ABC and GCB). Methods: 51 banked formalin fixed, paraffin embedded (FFPE) DLBCL specimens were used to recalibrate the algorithm using a clinical grade assay. The subtype accuracy of the final locked algorithm was verified by testing 68 independent specimens with gold standard (GS) GEP results. Analytical precision was measured across 2 operators and 3 reagent lots by testing 10 FFPE DLBCL RNA samples. Reproducib...

55: Evaluation of the Clinical and Laboratory Standards Institute EP26-A Guideline: A Protocol for Reagent Lot-to-Lot Verification

Verification of reagent lot performance prior to clinical use is not only good laboratory practice, but a regulatory requirement. Recently, the Clinical and Laboratory Standards Institute (CLSI) published the EP26-A guideline, User Evaluation of Between-Reagent Lot Variation, which provides a protocol for lot-to-lot verification aiming to limit the number of samples required to detect significant changes in test performance due to reagent lot variability. The aim of this study was to compare the performance of EP26-A with our institution’s reagent …

Assessment of Reproducibility of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Bacterial and Yeast Identification.

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has revolutionized the identification of clinical bacterial and yeast isolates. However, data describing the reproducibility of MALDI-TOF MS for microbial identification are scarce. In this study, we show that MALDI-TOF MS-based microbial identification is highly reproducible and can tolerate numerous variables, including differences in testing environments, instruments, operators, reagent lots, and sample positioning patterns. Finally, we reveal that samples of bacterial and yeast isolates prepared for MALDI-TOF MS identification can be repeatedly analyzed without compromising organism identification.

A1c Gear: Laboratory quality HbA1c measurement at the point of care

IntroductionHbA1c is an important part of assessing the diabetic control and since the use of point-of-care devices for monitoring HbA1c is increasing, it is important to determine how these devices compare to the central laboratory. MethodsOne hundred and twenty patient samples were analyzed on the Bio-Rad Variant™II and one POC analyzer (Sakae A1c Gear). Three patient sample pools containing ~5%, ~7%, and ~10% HbA1c levels were run over 20days. Three reagent lots and three instruments were evaluated for the A1c Gear. ResultsThe 120 patient samples showed strong correlation (R2>0.989) when compared to the Variant™II with means=8.06% and 7.81%, for Variant IIand A1c Gear, respectively. Changing reagent lots or instruments had no impact for the A1c Gear. The ~5%, ~7%, and ~10% pools within-run and between-run imprecision was between 0.87–1.33% and 1.03–1.32%, and 1.41–2.35% and 1.24–1.89% with total imprecision of 1.67–2.35% and 1.61–2.31% for the A1c Gear and Variant II, respectively. The A1c Gear showed a small negative bias (0.25% HbA1c) across HbA1c measurement ranges of <11.5%. This bias was, however, acceptable and not considered to be clinically significant. ConclusionsThe A1c Gear meets the criteria of total CV <3% leading us to the conclusion that the A1c Gear can give results as precise as the laboratory at the POC.

In vitro diagnostic company recalls and medical laboratory practices: an Italian case.

IntroductionIn vitro human diagnostic (IVD) company recalls are a common practice aimed to either minimize a potential error or eliminate an existing failure. In this case report, we aim to provide a critical analysis of a recent IVD recall and to provide a practical framework about what to do when an IVD company recalls product(s) based on the International Organization for Standardization - ISO 15189:2012 standard.Case reportIn 2014, Abbott Laboratories® (Green Oaks, IL) published an urgent field safety notice regarding a product recall (Architect Intact parathyroid hormone (PTH) Assay List Number 8K25) with immediate action required. The IVD company explained the reasons for the recall as follows: i) Abbott has confirmed that a performance shift in the Architect Intact PTH assay has the potential to generate falsely elevated results on patient samples; ii) results generated with impacted lots may demonstrate a positive shift relative to those generated with previous reagent and/or calibrator lots. This issue may also impact established Architect Intact PTH reference ranges; iii) the magnitude of shift averages approximately 13% to 45%; iv) Abbott Architect Intact PTH controls do not detect the shift; and v) all current reagent, calibrator, and control inventory are impacted. The recall could have resulted in ~40,000 inaccurate laboratory tests reported by 18 laboratories from Italy (Lombardy region).ConclusionIVD company recalls have a serious impact on the patient safety and require a thorough investigation and responsible approach to minimize the possible damage. Medical laboratories accredited according to the ISO 15189 standard have procedures in place to manage such situations and ensure that patient safety is maintained when such recalls are issued.

Performance Characteristics of a PCR Assay for the Detection of KRAS Mutations in Formalin-Fixed Paraffin-Embedded Tissue Samples of Non-Small Cell Lung Cancer

Abstract Introduction: Approximately 25% of non-small cell lung cancer (NSCLC) tumors contain mutations in KRAS. These tumors are insensitive to therapy directed against the epidermal growth factor receptor and appear to be resistant to adjuvant chemotherapy. The current study demonstrates the performance of the cobas® KRAS Mutation Test (cobas test), a TaqMelt polymerase chain reaction (PCR) assay designed to detect 19 mutations in codons 12, 13, and 61. Methods: To reflect real-world testing conditions, the study used formalin-fixed, paraffin-embedded tissue (FFPET) NSCLC samples for the predominant mutations. DNA blends of cell lines and plasmids were used where FFPET samples were not available. Results: In the limit of detection study, a correct mutation call rate of ≥95% was obtained with approximately 5% mutant sequences using 3.1-50.0 ng DNA per PCR reaction. Mutation levels as low as 2.4% consistently yielded correct mutation calls when 50.0 ng DNA was used for testing. The cobas test performance was compared to Sanger sequencing in a method correlation using two cobas reagent lots and 194 specimens. After resolution of discordant results using 454 sequencing, the positive, negative, and overall percent agreement for mutations in codons 12/13 and 61 between the cobas test and sequencing ranged from 97.0% to 100%. Mutation detection was 100% reproducible and showed greater specificity than Sanger sequencing. Test performance was not impaired by the presence of interfering substances or clinically relevant microbes, and inclusivity testing demonstrated the kit’s ability to detect rare mutations. Conclusions: The cobas test is a robust, sensitive, and reproducible method for detecting KRAS mutations in FFPET tumor samples from NSCLC patients.

Application of patient samples in verifying results consistency after biochemistry reagent lot change

Objective To study the role of clinical patient samples in verifying consistency of clinical results between different reagent lots.Methods The results of 5 clinical samples,Roche quality control materials and Biorad quality control materials for 13 clinical routine biochemical tests were obtained by using both old and new reagent lot,and performed the statistics.The bias of 13 measurands were computed after changing reagent lots,and also were judged according to the 1/3 limits of CLIA' 88 defined acceptable error,whether the bias was conform to clinical requirements or not.Results QC material results had no significant difference between two reagent lots (P ＞ 0.05).The results of ALT,UA,TC and ApoA for patient samples had significant difference (P ＜ 0.05),but the bias of these items were within the 1/3 limits of CLIA' 88 defined acceptable error,which were 2.57％,4.41％,1.81％ and 3.84％ respectively,in accordance with clinical requirement.Conclusions As there is matrix effect of quality control materials,the results for QC materials should not be used to verify the consistency of results for patient samples when changing reagent lots.To overcome this situation,we should use quality control materials together with clinical samples to compare consistency of results after changing reagent lots. Key words: Lots of reagents; Clinical samples; Quality control materials; Matrix effect

The chronic injury glucose error grid: a tool to reduce diabetes complications.

Traditional glucose error grids provide error limits for glucose meters. These criteria help to assess the meter's suitability to prevent acute injury. We present a rationale for an error grid that provides a different set of error limits to help prevent chronic injury in diabetes. For example, glucose values in the no treatment zone of a traditional error grid could be harmful in diabetic retinopathy. The same method comparison data informs both the acute and chronic injury error grids. All of the data are used in an acute injury error grid, whereas only long-term biases populate a chronic injury error grid. These biases can be due to reagent lots and patient specific interferences. An example of a chronic injury glucose error grid is provided using simulated data.

Performance characteristics of the Beckman Coulter total βhCG (5th IS) assay

BackgroundBeckman Coulter recently released the first commercially available hCG reagent calibrated against the 5th International Standard (IS) for hCG (total βhCG (5th IS)). We performed a comprehensive analytical validation of this reagent. MethodsPrecision experiments were completed using 3 concentrations of commercial quality control material. Linearity, sample stability, and analytical sensitivity were evaluated using pools of human serum. Reportable range was assessed by comparing manual dilutions to those performed by the instrument. Male and female reference intervals were established using residual serum specimens submitted for routine testing. Inter-lot variability of hCG assay reagent was assessed by analyzing serum specimens with detectable hCG using 2 different reagent lots. Inter-assay variability was established using 203 serum specimens analyzed for hCG on 6 different reagent platforms. ResultsInter-day precision showed a CV of <6.0% for all concentrations of QC material. LOB, LOD, and LOQ were determined to be 0.3, 0.4, and 0.6U/l, respectively. The Access (5th IS) reagent has an average positive bias of approximately 20% when compared to most platforms and the previous generation Beckman hCG assay. Results were consistent between lots. Female reference intervals varied by age: <1.0U/l (<41y), <6.0U/l (41–50y), and <8.0U/l (>50y). Male reference intervals were <2.0U/l. ConclusionsThe analytical performance of the total βhCG (5th IS) was established. Care should be taken to re-baseline patients needing serial monitoring and/or notify physicians when transitioning to the total βhCG (5th IS) reagent.

Abstract 3678: An immunoassay for measurement of methotrexate on ARCHITECT i system

Abstract Methotrexate (MTX) is a cancer therapeutic drug for leukemia, osteosarcoma, non-Hodgkin's lymphoma and others. MTX levels in blood are monitored in patients to avoid toxic effects caused by the excessive dosage of this drug, and to determine when to intervene with the counter-acting ‘rescue’ therapy. An assay for serum and plasma MTX measurement on ARCHITECT i System (ARCHITECT Methotrexate) is being developed and the analytical feasibility of this assay is presented. METHODS: The ARCHITECT Methotrexate is a competitive immunoassay. First, the instrument mixes and incubates a sample (calibrators, controls, sera or plasma) with anti-methotrexate antibody-coated magnetic microparticles, biotinylated anti-methotrexate antibody and acridinium-conjugated MTX. Then, the instrument washes the microparticles and adds pre-trigger and trigger solutions to initiate the chemiluminescence reaction. Signals obtained as relative luminescent units are inversely proportional to the amount of MTX in the sample. RESULTS: The limit of quantitation was ≤ 0.040 µmol/L MTX. The 20-day imprecision study showed a total CV ≤ 7.1% within the range of 0.056 to 1705.433 µmol/L MTX with 6 controls and 5 panels on 4 instruments using 3 lots of reagents (n = 80). Dilution linearity showed the deviations from linearity were -4.1% to 7.2% within the range of 1.881 to 0.012 µmol/L MTX. Spike recovery revealed a mean recovery of 92% - 94% for samples at 0.045, 0.909 and 9.090 µmol/L of MTX. In the interference studies, the average levels of MTX in the individual interfering substance-spiked samples (10 endogenous substances including human anti-mouse antibody and rheumatoid factor, and 21 therapeutic drugs) were within 90% - 110% of that in the unspiked control samples. Method comparison of ARCHITECT Methotrexate to TDx/TDxFLx Methotrexate II (TDx) generated a Passing Bablok correlation as [ARCHITECT] = 0.00 + 1.01 [TDx] for samples within the range of 0.040 to 1.415 µmol/L (n = 92) and [ARCHITECT] = 0.00 + 1.04 [TDx] for samples within the range of 0.040 to 1624.760 µmol/L MTX , n = 142). Specimen storage study denoted that specimens could be stored at room temperature for 24 hours or at 2-8oC for 48 hours since the MTX values of the stored specimens described above were within 10% deviation from that of the baseline control specimens. Specimen Tube type study demonstrated that specimens collected in K2-EDTA, sodium heparin, and lithium heparin tubes was within ± 10% deviation from that collected in serum tubes across the range of 0.040 to 10.00 μmol/L MTX. Reagent on-board stability showed that the ARCHITECT Methotrexate reagents could remain on the analyzer for a minimum of 30 days with no more than 10% shift from baseline. CONCLUSION: The ARCHITECT Methotrexate under development was demonstrated to be an accurate, precise, sensitive and robust assay for the measurement of Methotrexate in human serum and plasma. Citation Format: Robert J. Smalley, Raymond E. Picard, Beth A. Burkhart, Robert L. Frescatore, Curtis L. Glover, Lisa C. Zhu, Elizabeth A. Roessner, Karin MajnesjÖ, Anders Öhrvik, Kuanglin He, Zhong Qian Li, Timothy R. Kettlety. An immunoassay for measurement of methotrexate on ARCHITECT i system. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3678. doi:10.1158/1538-7445.AM2014-3678

Evaluation of Beckman Coulter DxI 800 immunoassay system using clinically oriented performance goals

ObjectivesWe evaluated the analytical performance of 24 immunoassays using the Beckman Coulter DxI 800 immunoassay systems at Mayo Clinic, Rochester, MN for trueness, precision, detection limits, linearity, and consistency (across instruments and reagent lots). MethodsClinically oriented performance goals were defined using the following methods: trueness-published desirable accuracy limits, precision-published desirable biologic variation; detection limits — 0.1 percentile of patient test values, linearity — 50% of total error, and consistency-percentage test values crossing key decision points. Local data were collected for precision, linearity, and consistency. Data were provided by Beckman Coulter, Inc. for trueness and detection limits. ResultsAll evaluated assays except total thyroxine were within the proposed goals for trueness. Most of the assays met the proposed goals for precision (86% of intra-assay results and 75% of inter-assay results). Five assays had more than 15% of the test results below the minimum detection limits. Carcinoembryonic antigen, total thyroxine and free triiodothyronine exceeded the proposed goals of ±6.3%, ±5% and ±5.7% for dilution linearity. All evaluated assays were within the proposed goals for instrument consistency. Lot-to-lot consistency results for cortisol, ferritin and total thyroxine exceeded the proposed goals of 3.3%, 11.4% and 7% at one medical decision level, while vitamin B12 exceeded the proposed goals of 5.2% and 3.8% at two decision levels. ConclusionsThe Beckman Coulter DxI 800 immunoassay system meets most of these proposed goals, even though these clinically focused performance goals represent relatively stringent limits.

The Flotation Process with High Intensity Conditioning and Cleaning for Fine Coal

The properties analyzing of flotation feed sample told that this fine coal sample is high-ash and hard-to-float coal slime. The ash reduction comparison of the step-by-step release flotation test with high intensity conditioning (HIC) or not, and the comparison of flotation test with HIC and adding depressant were made. The results showed that HIC can significantly improve the flotation effect for high-ash and hard-to-float coal slime. Comparing with the traditional step-by-step flotation process, if it meets the demand of ash content is 10.00% and 8.00%, the clean coal yield with HIC will increase 18 and 29 percentage points respectively; comparing with the effect of floatation adding depressant, HIC has more help to reduce the ash content and increase the yield of clean coal. In addition, HIC will save a lot of flotation reagents.

Three of 7 hemoglobin A1c point-of-care instruments do not meet generally accepted analytical performance criteria.

In 2009, we investigated the conformance of 8 hemoglobin A(1c) (Hb A(1c)) point-of-care (POC) instruments. Since then, instruments have improved and new devices are available on the market. In this second study, we evaluated the performance of DCA Vantage, Afinion, InnovaStar, Quo-Lab, Quo-Test, Cobas B101, and B-analyst Hb A(1c) POC instruments. Clinical and Laboratory Standards Institute protocols EP-5 and EP-9 were applied to investigate imprecision, accuracy, and bias. We assessed bias using the mean of 3 certified secondary reference measurement procedures (SRMPs). Assay conformance with the National Glycohemoglobin Standardization Program (NGSP) certification criteria was also evaluated. Interference of common Hb variants was investigated for methods that could work with hemolysed material. The total CVs for all instruments, except for the DCA Vantage at a high Hb A(1c) value, were ≤3.1% in SI units and ≤2.1% in Diabetes Control and Complications Trial (DCCT) units. Afinion, DCA Vantage, B-analyst, and Cobas B101 instruments passed the NGSP criteria with 2 different reagent lot numbers. Quo-Test, Quo-Lab, and InnovaStar instruments had a negative bias compared to the mean of the 3 SRMPs and failed NGSP criteria. Most of the common Hb variants did not interfere with the investigated instruments, except Hb AE for the Cobas B101. Afinion, DCA Vantage, Cobas B101, and B-analyst instruments met the generally accepted performance criteria for Hb A(1c). Quo-Test, Quo-Lab, and InnovaStar met the criteria for precision but not for bias. Proficiency testing should be mandated for users of Hb A1c POC assays to ensure quality.

Interlaboratory Comparison of Single Antigen Bead Based Assay for HLA Antibody Detection.

Introduction. The results of single antigen bead based assays (SAB) provided as mean fluorescence intensity (MFI) are frequently used with quantitative significances, although they were approved as qualitative tests. We assessed interlaboratory variability caused by laboratory condition in testing the SAB with same reagents and standardized protocol. Methods. Six HLA-antibodies-positive sera were tested at five laboratories according to the manufacturer's recommendation using the same lot of SAB kits (Genprobe, CT). Concordances of qualitative results according to the different MFI cutoffs (1000, 3000, 5000 and 10,000) and correlation of quantitative MFI values were analyzed. Results. For detection of HLA class I and class II antibodies, overall concordance between laboratories was 96.0% and 97.2% at all cutoffs, respectively. Pair-wise Pearson correlations between laboratories were 0.947-0.991 and 0.992-0.997 for MFI values of class I and class II antibodies. For both HLA class I and class II, CVs of the discordant results at the MFI = 1000 cutoff (median: 29.2, 28.2, respectively) were higher than CVs at other cutoff values (P < 0.01, P < 0.001, respectively). Variance components analysis found that the interlaboratory variation (SD = 37.3, 79.2, respectively) represented 0.01% and 0.03% of the total variation for class I and class II, respectively. Conclusion. SAB using same protocol and same lot of reagents showed good concordances and correlations between laboratories.

Ligand Binding Assay Critical Reagents and Their Stability: Recommendations and Best Practices from the Global Bioanalysis Consortium Harmonization Team

The L4 Global Harmonization Team on reagents and their stability focused on the management of critical reagents for pharmacokinetic, immunogenicity, and biomarker ligand binding assays. Regulatory guidance recognizes that reagents are important for ligand binding assays but do not address numerous aspects of critical reagent life cycle management. Reagents can be obtained from external vendors or developed internally, but regardless of their source, there are numerous considerations for their reliable long-term use. The authors have identified current best practices and provided recommendations for critical reagent lot changes, stability management, and documentation.

Statistical validation of reagent lot change in the clinical chemistry laboratory can confer insights on good clinical laboratory practice

Verification of new lot reagent's suitability is necessary to ensure that results for patients' samples are consistent before and after reagent lot changes. A typical procedure is to measure results of some patients' samples along with quality control (QC) materials. In this study, the results of patients' samples and QC materials in reagent lot changes were analysed. In addition, the opinion regarding QC target range adjustment along with reagent lot changes was proposed. Patients' sample and QC material results of 360 reagent lot change events involving 61 analytes and eight instrument platforms were analysed. The between-lot differences for the patients' samples (ΔP) and the QC materials (ΔQC) were tested by Mann-Whitney U tests. The size of the between-lot differences in the QC data was calculated as multiples of standard deviation (SD). The ΔP and ΔQC values only differed significantly in 7.8% of the reagent lot change events. This frequency was not affected by the assay principle or the QC material source. One SD was proposed for the cutoff for maintaining pre-existing target range after reagent lot change. While non-commutable QC material results were infrequent in the present study, our data confirmed that QC materials have limited usefulness when assessing new reagent lots. Also a 1 SD standard for establishing a new QC target range after reagent lot change event was proposed.

More on Lot-to-Lot Changes

To the Editor: Shifts in patient results due to reagent lot changes are a major issue for laboratories, and their investigation is both time-consuming and expensive. In a recent article, Algeciras-Schimnich et al. (1) point out the effect that reagent lot-to-lot changes over time can have on patient results and how these shifts, if large enough, could lead to misdiagnosis and inappropriate treatment. As was the case in this article, on insulin-like growth factor 1, it is often clinicians who alert the laboratory to changes in patient results. We have had similar experiences for a number of analytes, including creatinine. For this analyte, clinicians monitoring renal transplantation patients have asked whether changes as small as from 1.13 mg/dL (100 μmol/L) to 1.24 mg/dL (110 μmol/L) are real or due to shifts in the assay. In the laboratory, shifts in patient results can be caused by a number of assay system components, but the most likely are reagent …

Effect of recalibration of the hs-TnT assay on diagnostic performance

To the Editor,Apple and Jaffe [1] recently reported on an adjustment to the high-sensitivity cardiac troponin T (hs-TnT) assay and questioned the consequent clinical implications. We report further on the effect of restandardisation of the assay on diagnostic performance. In our study between November 2008 and February 2011 (Trial registration ACTRN12610000053022) the diagnostic accuracy of the hs-TnT assay for acute myocardial infarction (AMI) was determined in a well-characterised but unselected cohort of patients presenting to the emergency department with chest pain suggestive of acute coronary syndrome (ACS) in whom blood was drawn for assay at presentation and after 2 h [2]. Serum was stored at −80C for later cTnT °analysis in 2012 using the Roche cobas e601 hs-TnT assay (Roche Diagnostics, Sydney, Australia; reagent lot no. 00163704; calibrator lot no. 00165094). Clinical endpoint adjudication was performed by one of two cardiologists using all clinical information available up to at least 30 days following presentation including results of the hospital’s usual troponin assay performed at presenta-tion and after 6–8 h (Beckman Coulter AccuTnI, deci-sion cut-off 40 ng/L cTnI). The outcome for the analysis of diagnostic accuracy was AMI at presentation and was diagnosed according to the Universal Definition of Myo-cardial Infarction published at the time of adjudication [3]. Briefly, this was defined as evidence of myocardial necrosis together with clinical evidence of myocar-dial ischaemia (ischaemic symptoms, ECG changes, or imaging evidence). Necrosis was diagnosed on the basis of a rising or falling pattern of the laboratory cTnI concentrations, with at least one value above the 99th percentile.Following completion of the hs-TnT analysis in 2012 a technical bulletin (No: 12–023) was published by Roche Diagnostics (Penzberg, Germany) calling for adjustment to the calibration of the hs-TnT assay when performed with certain reagent lots [1]. All study samples were found to require adjustment. This was performed according to the manufacturer’s method in which a new value assignment of the calibrator set used in this study was required. The result was that following recalibration the number of values that were below the limit of detection (5 ng/L) decreased from 1178 (71.0%) to 560 (33.8%). Eighty-six of 1659 values were in the cTnT concentration range 8.71–13.94 ng/L, and when recalcu-lated were on average 5 ng/L above the decision cut-off of 14 ng/L in the range 14.04–18.93 ng/L. The difference between recalculated and original values was +38% at the decision limit of 14 ng/L compared with +15.3% at 30 ng/L cTnT (Figure 1).Seven hundred and thirty-seven patients were included in the clinical analysis and an adjudicated diagnosis of AMI at presentation was made in 50 (6.8%)

Analytical Performance of the Axis-Shield Afinion® for Hemoglobin A1c Measurement: Impact of Lot Number

As the implementation of POC analyzers in clinical department is growing and HbA1c has been included in diagnostics, it appears mandatory to evaluate the accuracy of the POC method to be used. The aim of our study is to evaluate the analytical performance and usefulness of the Afinion analyzer, and the impact of HbF, hemoglobin variants, and changes of reagent lots. The Afinion analyzer (Axis-Shield, Oslo, Norway) is based on affinity separation methodology. Analytical performances including imprecision studies and correlation with currently used HPLC were performed on Biochemistry laboratory. We evaluated the effects of presence of variants on the results of HbA1c. Two reagent lots were evaluated on samples without variant as well as on samples with in the presence of hemoglobin variants HbA/S. The practicability of the system was also tested installing the instrument on pediatric consultation. Imprecision studies of Afinion were acceptable. Linear regression analysis indicated good correlation between HbA1c values with Afinion (r > 0.97) in comparison with HPLC method. Overall, the Afinion overestimated the HbA1 compared to the MenariniHA8140. These differences were confirmed when the estimated average glucose was calculated. In addition, the variance of cartridge lots requires its use with caution and the problem of lot number instability must be resolved, requiring an adjustment of the calibration by the manufacturer. The Afinion analyzer met the acceptance criteria of analytical performance, requires minimal operator interaction and presents good correlation with the laboratory method. Beyond the analytical performance, the different regression lines for different lots is a matter of concern. The reproductibility of the production of the different reagent lots for POC devices appears inadequate for its use in a clinical department.