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BackgroundThe Elecsys® Anti-SARS-CoV-2 electrochemiluminescence immunoassay (Roche Diagnostics International Ltd) was developed for the in vitro qualitative detection of antibodies to SARS-CoV-2. We evaluated the sensitivity of the Elecsys Anti-SARS-CoV-2 immunoassay in samples from a diverse cross-section of patients across multiple sites and compared results against commercially available comparators.MethodsSensitivity of the Elecsys Anti-SARS-CoV-2 immunoassay was evaluated using anonymised, frozen, residual single and sequential serum and plasma samples from patients with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection. Point estimates and 95% confidence intervals (CIs) were calculated and method comparisons performed versus the following comparator assays: Euroimmun Anti-SARS-CoV-2 IgG, Abbott ARCHITECT SARS-CoV-2 IgG, Siemens ADVIA Centaur SARS-CoV-2 Total, and YHLO iFlash SARS-CoV-2 IgG and IgM.ResultsOverall sensitivity for the Elecsys Anti-SARS-CoV-2 immunoassay in 219 samples drawn ≥14 days post-PCR confirmation was 93.6% (95% CI 89.5–96.5). Across the three study sites, sensitivity in samples drawn ≥14 days post-PCR confirmation ranged from 85.7–98.9%. Sensitivity was significantly higher for the Elecsys Anti-SARS-CoV-2 immunoassay compared with the YHLO iFlash SARS-CoV-2 IgM assay for samples drawn ≥14 days post-PCR confirmation (86.3% [95% CI 76.7–92.9] versus 33.8% [95% CI 23.6–45.2]). Both Siemens ADVIA Centaur SARS-CoV-2 Total and YHLO iFlash SARS-CoV-2 IgG assays had a significantly higher sensitivity compared with the Elecsys Anti-SARS-CoV-2 immunoassay for samples drawn ≥14 days post-PCR confirmation (95.1% [95% CI 87.8–98.6] versus 85.2% [95% CI 75.6–92.1]; 93.8% [95% CI 86.0–97.9] versus 86.3% [95% CI 76.7–92.9]). Differences in sensitivity between the Elecsys Anti-SARS-CoV-2 immunoassay and the Euroimmun Anti-SARS-CoV-2 IgG (90.3% [95% CI 83.7–94.9] versus 95.2% [95% CI 89.8–98.2]) and Abbott ARCHITECT SARS-CoV-2 IgG (84.8% [95% CI 75.0–91.9] versus 87.3% [95% CI 78.0–93.8]) assays for samples drawn ≥14 days post-PCR confirmation were not significant.ConclusionsThe Elecsys Anti-SARS-CoV-2 immunoassay demonstrated high sensitivity in samples collected ≥14 days post-PCR confirmation of SARS-CoV-2 infection, and comparable sensitivity to several commercially available comparator assays across multiple sites, supporting the use of this assay as a tool to aid in determination of previous exposure to SARS-CoV-2.Required information for submission systemEthical guidelinesThe study was conducted in accordance with the study protocol provided by Roche Diagnostics and in accordance with the principles of the Declaration of Helsinki. All human samples utilised at the three study sites in Germany (Augsburg, Heidelberg, Berlin) were anonymised, frozen, residual samples, therefore no ethical approval or waiver was required in accordance with local legislation from ZEKO (Central Ethics Commission at the German Medical Association). A statement was obtained from the Ethics Committee of the Landesärztekammer Bayern confirming that there are no objections to the coherent use of anonymised residual samples.Research reporting guidelinesPlease see separate STARD checklist.Data availability statementQualified researchers may request access to individual patient level data through the clinical study data request platform (https://vivli.org/). Further details on Roche’s criteria for eligible studies are available here: https://vivli.org/members/ourmembers/. For further details on Roche’s Global Policy on the Sharing of Clinical Information and how to request access to related clinical study documents, see here: https://www.roche.com/research_and_development/who_we_are_how_we_work/clinical_trials/our_commitment_to_data_sharing.htm

Liquid chromatography–mass spectrometry, the gold standard method for cortisol measurement, is expensive and not widely available in the developing countries. Chemiluminescent immunoassay, commonly used for cortisol measurement is prone to clinically meaningful inter-assay variability in some analysers. This occurs due to non-specific nature of anticortisol antibodies used in different platforms, having cross reactivity with structurally similar cortisol precursors like 17α-hydroxyprogesterone (17OHP), 11-deoxycortisol and 21-deoxycortisol. In patients with 21-hydroxylase deficiency, where 17OHP and 21-deoxycortisol are significantly elevated, older generation machines like Siemens Advia Centaur XP provide spuriously high cortisol concentration compared with values measured by Roche Cobas e 411 or Siemens Immulite 1000. Diagnosis of potentially life-threatening salt-wasting 21-hydroxylase deficiency may be missed and treatment may be delayed due to such interference. Two children with classic 21-hydroxylase deficiency are being reported here, in whom high cortisol values were observed in Siemens Advia Centaur XP system.

Public health emergency of SARS-CoV-2 has facilitated diagnostic testing as a related medical countermeasure against COVID-19 outbreak. Numerous serologic antibody tests have become available through an expedited federal emergency use only process. This paper highlights the analytical characteristic of an ELISA based assay by AnshLabs and three random access immunoassay (RAIA) by DiaSorin, Roche, and Abbott that have been approved for emergency use authorization (EUA), at a tertiary academic center in a low disease-prevalence area. The AnshLabs gave higher estimates of sero-prevalence, over the three RAIA methods. For positive results, AnshLabs had 93.3% and 100% concordance with DiaSorin or Abbott and Roche respectively. For negative results, AnshLabs had 69.7% and 73.0% concordance with DiaSorin and Roche or Abbott respectively. All discrepant samples that were positive by AnshLabs and negative by RAIA tested positive by all-in-one step SARS-CoV-2 Total (COV2T) assay performed on the automated Siemens Advia Centaur XPT analyzer. None of these methods, however, are useful in early diagnosis of SARS-CoV-2.

Objective In our laboratory, 2.36% (6626/280765) samples obtained for insulin evaluation have serum insulin concentrations higher than 300 mU/L, resulting in curves outside the linear range in the insulin release test (IRT). Accordingly, using appropriate dilution protocols to determine insulin concentration accurately is important. Here, we compared the effectiveness and economy of four different solutions for diluting high‐insulin serum in routine clinical measurements. Method Residual serum samples with high‐insulin concentrations ranging from 200 to 300 mU/L were collected in Peking Union Medical College Hospital from August to November 2017. Four different matrixes including a Siemens original diluent, pure water, 0.9% NaCl, and low‐insulin serum (labeled as A to D, respectively) were used to dilute the serum in the ratios of 1:2, 1:5, and 1:10. Results We found that the linear correlation coefficients of A to D were higher than 0.9. The recovery rates of A to D were 86.4%–104.0%, 73.2%–99.3%, 76.4%–101.3%, and 84.2%–99.7%, respectively. We conclude that the use of 0.9% NaCl, pure water, or low‐insulin serum to dilute high‐serum insulin (>300 mU/L) is feasible and cost‐effective. Conclusion We recommend a dilution factor of 1:5 on a Siemens ADVIA Centaur XP® instrument. The clinically reported range was 0.5‐1500 mU/L. For specific samples (>1500 mU/L), we recommended using low‐insulin serum samples for dilution.

Background Progesterone concentrations are routinely monitored during in vitro fertilization cycles. Immunoassay-based platforms are used most often in this setting because they are simple to use and amenable to same-day sample collection and result-reporting. However, immunoassay methods are subject to variation in specificity between different assay manufacturers. In this study, a set of unexpectedly high progesterone concentrations led to a method comparison between two in-house immunoassay platforms relative to the reference method. Methods Progesterone was measured in 28 serum samples from women undergoing IVF cycles using the Siemens ADVIA Centaur Immunoassay system and the Abbott Architect i1000SR analyzer. A subset of these samples was selected for progesterone measurement by liquid chromatography–tandem mass spectrometry to define the accuracy of each immunoassay. Results The Siemens ADVIA Centaur immunoassay system overestimated progesterone concentrations by 19% and the Abbott Architect overestimated progesterone concentrations by 5%. Conclusions The Abbott Architect progesterone immunoassay provides a more accurate measurement of serum progesterone than the Centaur immunoassay at concentrations relevant for monitoring in vitro fertilization populations.

Background Thyroid-stimulating hormone (TSH) is used as the first-line test of thyroid function. Siemens Healthcare Diagnostics recommend that Siemens Centaur reagents must be protected from light in the assay information and on reagent packaging. We have compared the effect of light exposure on results using Siemens TSH-3Ultra and follicle-stimulating hormone reagents. The thyroid-stimulating hormone reagent includes fluoroscein thiocyanate whereas the follicle-stimulating hormone reagent does not. Methods Three levels of quality controls were analysed using SiemensTSH-3Ultra and follicle-stimulating hormone reagent packs that had been kept protected from light or exposed to light at 6-h intervals for 48 h and then at 96 h. Results Thyroid-stimulating hormone results were significantly lower after exposure of TSH-3Ultra reagent packs to light. Results were >15% lower at all three levels of quality control following 18 h of light exposure and continued to decrease until 96 h. There was no significant difference in follicle-stimulating hormone results whether reagents had been exposed to or protected from light. Conclusions Thyroid-stimulating hormone results but not follicle-stimulating hormone results are lowered after exposure of reagent packs to light. Laboratories must ensure that TSH-3Ultra reagents are not exposed to light and analyse quality control samples on every reagent pack to check that there has not been light exposure prior to delivery. The labelling on TSH-3Ultra reagent packs should reflect the significant effect of light exposure compared with the follicle-stimulating hormone reagent. We propose that the effect of light exposure on binding of fluoroscein thiocyanate to the solid phase antibody causes the falsely low results.

About 15–40% India is Vitamin B12 deficient (commonly diagnosed by total Vitamin B12) but, as only holoTC (active form) is taken up by body cells, thus measuring holoTC is more reflective of Vitamin B12 status than the former. We aimed to assess diagnostic accuracy of serum holoTC in comparison with total Vitamin B12 and total Homocysteine (HCY) as indicator of serum Vitamin B12 status. 217 human subjects (99 males and 118 females) ranging from 17 to 83 years were divided into Vitamin B12 deficient (n = 70), borderline (n = 100) and sufficient groups (n = 47) who were further assessed for markers of Vitamin B12 deficiency—holoTC, HCY, Mean Corpuscular Volume (MCV), Folate, heamoglobin and creatinine. Samples were analysed using Siemens Advia Centaur Xpi. Total Vitamin B12 deficient group had − 84.3% holoTC deficient; 15.7% holoTC sufficient; 72.9% with elevated HCY; 27.1% with normal HCY; 11.4% with megaloblastic anaemia. Borderline group had − 34% holoTC deficient; 28% elevated HCY. A strong positive correlation was found between Total Vitamin B12 and holoTC (r = 0.754, p =

Although immunoassays in measuring 25-hydroxyvitamin D [25(OH)D] have been improved recently, relatively large differences are still seen between results of 25(OH)D measured by immunoassays and by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the present studies, we compared two immunoassays with LC-MS/MS for measuring 25(OH)D concentrations. Concentrations of 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] in serum samples from 59 healthy subjects were measured by two immunoassays including Siemens ADVIA Centaur Vitamin D Total (Centaur) and Roche Elecsys Vitamin D Total (Elecsys) and LC-MS/MS. To determine the cross reactivity of Elecsys and Centaur toward 25(OH)D2, a dosage of 200,000 IU vitamin D2 was given after first sampling. Serum samples were obtained 30 days later and concentrations of 25(OH)D2 and 25(OH)D3 were measured again. The results showed poor agreement between the immunoassays and LC-MS/MS in 25(OH)D2 and 25(OH)D3 measurements. The percentage of 25(OH)D2 cross-reactivity was 45.3% for Centaur and 41.2% for Elecsys and there was no significant difference between Centaur and Elecsys. In conclusion, Centaur and Elecsys perform unsatisfactorily in measuring 25(OH)D levels, especially for 25(OH)D2 cross-reactivity. Therefore, clinicians need to be aware of the underestimation of vitamin D status when using these immunoassays for measuring individuals supplemented with vitamin D2.

An important requirement for a state-of-the-art hepatitis B surface antigen (HBsAg) screening assay is reliable detection of mutated HBsAg. Currently, there is a striking shortage of data regarding the detection rates of in vivo HBsAg mutations for these clinically important assays. Therefore, we compared the detection rates of four commercial HBsAg screening assays using a global cohort of 1553 patients from four continents with known HBV genotypes. These samples, which represent the broadest spectrum of known and novel HBsAg major hydrophilic region (MHR) mutations to date, were analyzed for the presence of HBsAg using the Roche Elecsys® HBsAg II Qualitative, Siemens ADVIA Centaur XP HBsAg II, Abbott Architect HBsAg Qualitative II and DiaSorin Liaison® HBsAg Qualitative assays, respectively. Of the 1553 samples, 1391 samples could be sequenced; of these, 1013 (72.8%) carried at least one of the 345 currently known amino acid substitutions (distinct HBsAg mutation) in the HBsAg MHR. All 1553 patient samples were positive for HBsAg using the Elecsys® HBsAg II Qual assay, with a sensitivity (95% confidence interval) of 99.94% (99.64%-100%), followed by the Abbott Architect 99.81% (99.44%-99.96%), Siemens ADVIA 99.81% (99.44%-99.96%) and DiaSorin Liaison® 99.36% (98.82%-99.69%) assays, respectively. Our results indicate that the Elecsys® HBsAg II Qual assay exhibits the highest sensitivity among the commercial HBsAg screening assays, and demonstrate that its capacity to detect HBV infection is not compromised by HBsAg MHR mutants.

SummaryBackground: The measurement of 25OH vitamin D continues to grow in clinical laboratories. The aim of this multicenter study was to compare the results of seven automated commercial immunoassays with a reference HPLC technique.Methods: One hundred and twenty consecutive outpatient serum samples were centrifuged, divided in aliquots, frozen and shipped to the participating laboratories. 25OH Vita - min D was measured with a reference HPLC system and with seven automated commercial immunoassays (Roche Cobas E601, Beckman Coulter Unicel DXI 800, Ortho Vitros ES, DiaSorin Liaison, Siemens Advia Centaur, Abbott Architect i System and IDS iSYS).Results: Compared to the reference method, the regression coefficients ranged from 0.923 to 0.961 (all pConclusions:The excellent correlation with the reference HPLC technique attests that all seven automated immuno - assays may be reliably used for routine assessment of 25OH-D in clinical laboratories. The significant bias among the different methods seems mostly attributable to the lack of standardization and calls for additional efforts for improving harmonization of 25OH-D immunoassays.

Background With a 10-year sustained increase in 25-hydroxyvitamin D [25(OH)D] testing, laboratories have swapped their LC-MS/MS methods for high-throughput automated immunoassays. Although it is generally well-known that immunoassays have poor recoveries for 25-hydroxyvitamin D2 [25(OH)D2], the frequency and extent to which this impacts total 25(OH)D have not been previously demonstrated. We evaluated 3 automated immunoassays against the first FDA-cleared CDC/NIST-traceable LC-MS/MS method. Methods Method comparison was performed for the Siemens ADVIA Centaur, Roche Elecsys Cobas, and Abbott Architect 25(OH)D immunoassay methods in real patient samples (n = 105). We calculated the mean bias in samples containing >20 ng/mL 25(OH)D2 and estimated the percent 25(OH)D2 cross-reactivities. We determined the prevalence of appreciable concentrations of 25(OH)D2 in our patient population through random sampling (n = 120) and projected the frequency of inaccurate 25(OH)D immunoassay results. Results Linear regression for 25(OH)D was y = 1.09x − 4.44 (Centaur), y = 0.84 + 0.43 (Cobas), and y = 0.83x − 0.48 (Architect). The mean biases of 25(OH)D concentrations were 5.6 (11.0) ng/mL (Centaur), −17.5 (7.2) ng/mL (Cobas), and −20.3 (9.8) ng/mL (Architect) in samples containing >20 ng/mL 25(OH)D2. The observed percent cross-reactivities for 25(OH)D2 were 115% (Centaur), 52% (Cobas), and 44% (Architect). We estimate that 8% of our population has >20 ng/mL 25(OH)D2, thereby compromising the accuracy of 25(OH)D results in >3000 samples annually. Conclusions We demonstrate that immunoassay manufacturer package inserts indicate much better recoveries of 25(OH)D2 than what is observed in unadulterated real patient samples. We estimate the frequency of inaccurate total 25(OH)D determination by these immunoassay methods to be largely dependent on the concentration of 25(OH)D2 in each sample.

Background Cancer antigens 125, 27.29, and 15-3 (CA125, CA27.29, and CA15-3) are markers of ovarian and breast cancer. Comparing tumor marker results across methods is challenging because of the lack of harmonization. Documenting comparability of results is important. Methods Siemens Advia Centaur CA125 and CA27.29 assays were compared to their corresponding Beckman Coulter DxI CA125 and CA15-3 assays. The interassay bias was determined and the manufacturer-recommended reference intervals were evaluated. Results The DxI CA125 assay demonstrated an overall positive 29% bias relative to the Centaur CA125 assay. The DxI CA15-3 assay demonstrated an overall negative 65% bias relative to the Centaur CA27.29 assay. For patients with multiple comparisons during the study period, the trend of results over time was similar across both sets of assays. Implementing the manufacturer-recommended reference interval for the DxI CA125 assay increased the abnormal flagging rate by 4.5%. In contrast, implementing the manufacturer-recommended reference interval for the DxI CA15-3 assay decreased the abnormal flagging rate by 13.0%. Conclusions The overall trends for the majority of patients were similar. Therefore, despite the overall biases, transitioning tumor marker assays should not affect clinical interpretation of results.

Background Treponemal tests for detecting syphilis should be sufficiently sensitive and specific, especially when used as the first-line method in reverse-algorithm testing. We compared the Siemens ADVIA Centaur® Syphilis assay to 2 other commercial assays in use by the Star-MDC laboratory to evaluate its performance and usability. Methods Agreement between the Siemens ADVIA Centaur Syphilis assay, Siemens IMMULITE® 2000 Syphilis Screen, and Biokit bioelisa Syphilis 3.0 assay was evaluated using 1251 patient samples (50 from known positives, 701 from patients referred for syphilis testing, and 500 from pregnant women). Reactive samples (i.e., reactive according to at least two of the three treponemal methods) were further evaluated using Western blot IgG and IgM, and Venereal Disease Research Laboratory (VDRL) testing. Results Overall, positive and negative agreement was 100% between the Centaur and IMMULITE assays. In this study, overall agreement was 99.92% between either of the Siemens assays and the Biokit assay; positive agreement was 99%, and negative agreement was 100%. Overall, 0.88% (11/1251) of the samples were interpreted as positive/reactive based on the combined positive results by the ADVIA Centaur, IMMULITE 2000, and bioelisa assays; a positive Euroline anti- Treponema pallidum IgM blot; and a VDRL result of ≥ 1:8. In this study, no false-reactive samples were identified using this method. Conclusion The Centaur Syphilis assay performance is comparable to the other 2 commercial assays.

IntroductionRecent advances in troponin sensitivity enabled early and accurate judgement of ruling-out myocardial infarction, especially non-ST elevation myocardial infarction (NSTEMI) in emergency departments (EDs) with development of various prediction-rules and high-sensitive-troponin-based strategies (hs-troponin). Reliance on clinical impression, however, is still common, and it remains unknown which of these strategies is superior. Therefore, our objective in this prospective cohort study is to comprehensively validate the diagnostic accuracy of clinical impression-based strategies, prediction-rules and hs-troponin-based strategies for ruling-out NSTEMIs.Methods and analysisIn total, 1500 consecutive adult patients with symptoms suggestive of acute coronary syndrome will be prospectively recruited from five EDs in two tertiary-level, two secondary-level community hospitals and one university hospital in Japan. The study has begun in July 2018, and recruitment period will be about 1 year. A board-certified emergency physician will complete standardised case report forms, and independently perform a clinical impression-based risk estimation of NSTEMI. Index strategies to be compared will include the clinical impression-based strategy; prediction rules and hs-troponin-based strategies for the following types of troponin (Roche Elecsys hs-troponin T; Abbott ARCHITECT hs-troponin I; Siemens ADVIA Centaur hs-troponin I; Siemens ADVIA Centaur sensitive-troponin I). The reference standard will be the composite of type 1 MI and cardiac death within 30 days after admission to the ED. Outcome measures will be negative predictive value, sensitivity and effectiveness, defined as the proportion of patients categorised as low risk for NSTEMI. We will also evaluate inter-rater reliability of the clinical impression-based risk estimation.Ethics and disseminationThe study is approved by the Ethics Committees of the Kyoto University Graduate School and Faculty of Medicine and of the five hospitals where we will recruit patients. We will disseminate the study results through conference presentations and peer-reviewed journals.

To evaluate the newly developed Roche MODULAR Analytics E170 Total Vitamin D and the Siemens ADVIA Centaur Vitamin D Total assays.Assays were evaluated using the Clinical and Laboratory Standards Institute protocols. Split patient samples were compared with LC-MS/MS and DiaSorin LIAISON assays (n=79 including 15 specimens with detectable endogenous 25-OH vitamin D(2)). Assay accuracy was also evaluated using the Vitamin D External Quality Assessment Scheme (DEQAS) samples.The ADVIA Centaur and E170 assays demonstrated maximum total CVs of 14.1% and 5.9%, respectively. Both showed excellent linearity (R(2)0.99). The ADVIA Centaur assay demonstrated interference with bilirubin at 800 μmol/L, hemolysis at 1.25 g/L, and triglycerides at 2.8 mmol/L. Compared to LC-MS/MS, the ADVIA Centaur assay demonstrated a R(2) value of 0.893, average bias of -8.8%; the E170 assay an R(2) value of 0.872, average bias of 14.3% with underestimation of 25-OH vitamin D(2). Compared to the LIAISON assay, the ADVIA Centaur assay demonstrated an R(2) value of 0.781, average bias of -17.3%; the E170 assay an R(2) value of 0.823, average bias of 11.4%. The ADVIA Centaur and E170 assays demonstrated a biases of20% in 10/10 and 8/10 DEQAS samples, respectively.The ADVIA Centaur and E170 vitamin D assays demonstrated acceptable linearity, imprecision, and accuracy. The E170 assay demonstrated consistent underestimation of 25-OH vitamin D(2) levels. Compared with LC-MS/MS, the ADVIA Centaur assay demonstrated a higher R(2) value and a smaller average bias than the E170 assay.

BACKGROUND Data to standardize and harmonize the differences between cardiac troponin assays are needed to support their universal status in diagnosis of myocardial infarction. We characterized the variation between methods, the comparability of the 99th-percentile cutoff thresholds, and the occurrence of outliers in 4 cardiac troponin assays. METHODS Cardiac troponin was measured in duplicate in 2358 patient samples on 4 platforms: Abbott Architect i2000SR, Beckman Coulter Access2, Roche Cobas e601, and Siemens ADVIA Centaur XP. RESULTS The observed total variances between the 3 cardiac troponin I (cTnI) methods and between the cTnI and cardiac troponin T (cTnT) methods were larger than expected from the analytical imprecision (3.0%–3.7%). The between-method variations of 26% between cTnI assays and 127% between cTnI and cTnT assays were the dominant contributors to total variances. The misclassification of results according to the 99th percentile was 3%–4% between cTnI assays and 15%–17% between cTnI and cTnT. The Roche cTnT assay identified 49% more samples as positive than the Abbott cTnI. Outliers between methods were detected in 1 patient (0.06%) with Abbott, 8 (0.45%) with Beckman Coulter, 10 (0.56%) with Roche, and 3 (0.17%) with Siemens. CONCLUSIONS The universal definition of myocardial infarction should not depend on the choice of analyte or analyzer, and the between- and within-method differences described here need to be considered in the application of cardiac troponin in this respect. The variation between methods that cannot be explained by analytical imprecision and the discordant classification of results according to the respective 99th percentiles should be addressed.

BACKGROUND It is important that cardiac troponin be measured accurately with a robust method to limit false results with potentially adverse clinical outcomes. In this study, we characterized the robustness of 4 analytical platforms by measuring the outlier rate between duplicate results. METHODS We measured cardiac troponin concurrently in duplicate with 4 analyzers on 2391 samples. The outliers were detected from the difference between duplicate results and by calculating a z value: z = (result 1 − result 2) ÷ √(SD1est2 + SD2est2), with z > 3.48 identifying outliers with a probability of 0.0005. RESULTS The outlier rates were as follows: Abbott Architect i2000SR STAT Troponin-I, 0.10% (0.01%–0.19%); Beckman Coulter Access2 Enhanced AccuTnI, 0.44% (0.25%–0.63%); Roche Cobas e601 TroponinT hs, 0.06% (0.00%–0.13%); and Siemens ADVIA Centaur XP TnI-Ultra, 0.10% (0.01%–0.19%). The occurrence of outliers was higher than statistically expected on all platforms except the Cobas e601 (χ2 = 2.7; P = 0.10). A conservative approach with a constant 10% CV and z > 5.0 identified outliers with clear clinical impact and resulted in outlier rates of 0.11% (0.02%–0.20%) with the Architect i2000SR STAT Troponin-I, 0.36% (0.19%–0.53%) with the Access2 Enhanced AccuTnI, 0.02% (0.00%–0.06%) with the Cobas e601 TroponinT hs, and 0.06% (0.00%–0.13%) with the ADVIA Centaur XP TnI-Ultra. CONCLUSIONS Outliers occurred on all analytical platforms, at different rates. Clinicians should be made aware by their laboratory colleagues of the existence of outliers and the rate at which they occur.

Objectives: A multicenter study to compare results of BRAHMS Kryptor PCT with those obtained using four BRAHMS-partnered procalcitonin (PCT) automated immunoassays (DiaSorin Liaison, BioMérieux Vidas, Roche Cobas E601 and Siemens Advia Centaur) and the Diazyme immunotubidimetric assay implemented on four clinical chemistry platforms (Abbott Architect c16000, Siemens Advia 2400, Roche Cobas C501 and Beckman Coulter AU5800). Design and methods: One hundred serum samples from in-patients with PCT values between 0.10 and 58.7 ng/mL were divided into aliquots and tested with the nine different reagents and analyzers. BRAHMS PCT Kryptor results were used as reference. Results: Compared to BRAHMS PCT Kryptor, significant differences in results were observed on Vidas, Advia Centaur, Architect, Cobas C501 and AU5800. However, the correlation coeffiecients (r) with BRAHMS PCT Kryptor were between 0.899 and 0.988. The mean bias was less than ±1.02 ng/mL, except for Vidas (2.70 ng/mL). The agreement at three clinically relevant cut-offs was optimal: between 83–98% at 0.50 ng/mL, 90–97% at 2.0 ng/mL, and 98% at 10 ng/mL. The comparison of Diazyme PCT across the four clinical chemistry analyzers yielded high correlation coefficients (r between 0.952 and 0.976), a mean bias less than ±0.9 ng/mL, acceptable agreement at 0.5 ng/mL (>82%), and high concordance at the 2.0 ng/mL (>97%) and 10 ng/mL (>98%) cut-offs. Conclusions: The methods and applications evaluated in this multicenter study are aligned with BRAHMS PCT Kryptor and can be used for predicting the risk of progression to systemic inflammation in patients with bacterial infections using the conventional PCT diagnostic thresholds. Keywords: Procalcitonin, Sepsis, Bacterial infections, Immunoassay, Multicenter study

A significant bias was found when using the Siemens ADVIA Centaur XP system for measurement of 25-hydroxyvitamin D (25OHD) with VACUETTE® tubes with Serum Clot Activator and Gel. Here, we examined whether other commonly used tubes or temperatures affected 25OHD results obtained with the Siemens ADVIA Centaur XP system. Serum was collected into five types of vacuum blood collection tubes from three manufacturers, and 25OHD was analyzed using the Siemens ADVIA Centaur XP system and liquid chromatography tandem mass spectrometry (LC-MS/MS) immediately or after storage at 4°C or -80°C for 48 h. Significantly higher 25OHD values were found when using the Siemens ADVIA Centaur XP system with VACUETTE® tubes with serum clot activator and gel and VACUETTE® tubes with clot activator but no gel compared with VACUETTE® tubes with no additives. The 25OHD values in all of these tubes were not significantly different from those obtained by LC-MS/MS. Moreover, after storage at -80°C for 48 h, the values obtained in IMPROVEVACUTER® tubes with serum clot activator and gel significantly increased, with a mean bias of 74.6% compared with the values before storage, on analysis with the Siemens ADVIA Centaur XP system. VACUETTE® tubes containing additives significantly affect the accuracy of 25OHD results obtained using the Siemens ADVIA Centaur XP system. Additionally, the composition of serum collected in IMPROVEVACUTER® tubes was affected by freezing, resulting in different measurements when using the Siemens 25OHD assay platform.

Background Currently, 24 out of 39 laboratories in Quebec use the AxSYM HIV Ag/Ab Combo for HIV screening. This kit will be discontinued December 2013 and three novel 4th generation screening HIV assays (Architect, Roche Elecsys HIV Combi and ADVIA CENTAUR), approved by Health Canada, represent the alternative to AxSYM. Objective and Methods: To investigate the performance of these 3 novel screening HIV Combo assays, in 6 clinical sites from Quebec. A total of 150 samples from patients with documented acute infection, a panel of 25 Seracare HIV-1 specimens, 3 quality control specimens (HIV-1.2 Ab POS, p24Ag POS, HIV-1.2 NEG), and 5577 sera from routine diagnostic patients were tested. Results Sensitivity assessment- The 3 novel combos demonstrated comparable 100% sensitivity. Confirmed positive samples on the Architect and Roche Elecsys presented much greater S/CO values than AxSYM. Specificity assessment- Each novel combo was compared separately to the AxSYM. Discordant results were confirmed using supplemental confirmatory assays. The specificity of Architect was evaluated using 1099 specimens: 1095/1099 were non reactive, 3/1099 were reactive and 1/1099 was discordant. For Roche Combo, 3282 specimens were tested: 3222/3282 were non reactive, 41/3282 were reactive, and 19/3282 were discordant. The Advia Centaur was evaluated using 1196 specimens, 1177/1196 were non reactive, 12/1196 were reactive and 7 were discordant. Amongst the 66 specimens that were reactive with novel and AxSYM combos, 52 (79%) were confirmed positive. All discordant results were confirmed negative. The 5494 specimens that were negative with both kits (novel and AxSYM) demonstrated lower S/CO values on Architect and Roche than on AxSym. Conclusions The 3 novel HIV Ag/Ab Combo demonstrated good performance (sensitivity, specificity and concordance) with better segregation of positive and negative samples than AxSYM. All 3 kits represent a good alternative to the AxSYM.

Objectives The ability of current immunoassays to accurately measure equimolar amounts of 25(OH)D 2 and 25(OH)D 3 has been recently questioned. This study determined serum 25(OH)D 2 , 25(OH)D 3 and total serum 25(OH)D concentrations in healthy vitamin D 2 -supplemented subjects by isotope dilution liquid chromatography mass spectrometry (ID-LC-MS/MS); and, evaluated the ability of the Siemens, DiaSorin, Roche, and Abbott Vitamin D Total assays to monitor total serum 25(OH)D concentrations compared to an ID-LC-MS/MS method traceable to the National Institute of Standards and Technology (NIST), and that has achieved certification from the Centers for Disease Control and Prevention (CDC) Vitamin D Standardization Certification Program (VDSCP). Design and methods Twenty (20) healthy adults, with no history of prior vitamin D supplementation were administered oral vitamin D 2 (2400 IU/day for 6 months). Serum samples (140) from baseline and monthly blood draws were tested. Results After one month, the mean serum 25(OH)D 2 concentrations rose from 0.8 to 43.6 nmol/L, whereas 25(OH)D 3 concentrations declined from 84.0 to 63.4 nmol/L; total serum 25(OH)D concentrations rose from 86.6 to 107.0 nmol/L. The overall mean bias to ID-LC-MS/MS was − 7.1% for the Siemens ADVIA Centaur assay, − 15.3% for the DiaSorin LIAISON assay; − 8.4% for the Roche ELECSYS assay and − 16.3% for the Abbott ARCHITECT assay. Correlation coefficients (r) were 0.94, 0.79, 0.74, and 0.73; the mean bias for baseline [25(OH) D 3 -containing] versus six-month [25(OH)D 2 - and 25(OH)D 3 -containing] samples was − 13.4% and − 5.7%; − 3.5% and 20.3%, 9.6% and − 12.1%, and 0.2% and − 17.8%, respectively. Conclusions The bias results obtained for the Siemens ADVIA Centaur assay and Roche ELECSYS assay were slightly lower than those for the DiaSorin LIAISON assay and the Abbott ARCHITECT assay, but all 25(OH)D assays demonstrated acceptable performance.

Measurement of cardiac troponin I (cTnI) should be feasible for point-of-care testing (POCT) to diagnose acute myocardial infarction (AMI). Lateral flow immunoassays (LFIAs) have been long implemented in POCT and clinical settings. However, sensitivity, matrix effect and quantitation in lateral flow immunoassays (LFIAs) have been major limiting factors. The performance of LFIAs can be improved with upconverting nanoparticle (UCNP) reporters. Here we report a new methodological approach to quantify cTnI using UCNP-LFIA technology with minimized plasma interference. The performance of the developed UCNP-LFIA was evaluated using clinical plasma samples (n = 262). The developed UCNP-LFIA was compared to two reference assays, the Siemens Advia Centaur assay and an in-house well-based cTnI assay. By introducing an anti-IgM scrub line and dried EDTA in the LFIA strip, the detection of cTnI in plasma samples was fully recovered. The UCNP-LFIA was able to quantify cTnI concentrations in patient samples within the range of 30–10,000 ng/L. The LoB and LoD of the UCNP-LFIA were 8.4 ng/L and 30 ng/L. The method comparisons showed good correlation (Spearman’s correlation 0.956 and 0.949, p