A Multicenter Evaluation of a Point-of-Care Blood Glucose Meter System in Critically Ill Patients.

BACKGROUND: Our purpose was to evaluate the performance of the ACCU-CHEK® Inform II blood glucose monitoring system (Roche Diagnostics GmbH) compared with the perchloric acid hexokinase (PCA-HK) comparator method on the cobas® 6000 analyzer (Roche Diagnostics International Ltd) in critically ill patients. METHODS: Overall, 476 arterial (376 pediatric/adult, 100 neonate), 375 venous, and 100 neonatal heel-stick whole-blood samples were collected and evaluated from critical care settings at 10 US hospitals, including the emergency department, medical and surgical intensive care units (ICUs), and neonatal and pediatric ICUs. The ACCU-CHEK Inform II system was evaluated at 2 cutoff boundaries: boundary 1 was ≥95% of results within ±12 mg/dL of the reference (samples with blood glucose <75 mg/dL) or ±12% of the reference (glucose ≥75 mg/dL), and boundary 2 was ≥98% of results within ±15 mg/dL or ±15% of the reference. Clinical performance was assessed by evaluating sample data using Parkes error grid, Monte Carlo simulation, and sensitivity and specificity analyses to estimate clinical accuracy and implications for insulin dosing when using the ACCU-CHEK Inform II system. RESULTS: Proportions of results within evaluation boundaries 1 and 2, respectively, were 96% and 98% for venous samples, 94% and 97% for pediatric and adult arterial samples, 84% and 98% for neonatal arterial samples, and 96% and 100% for neonatal heel-stick samples. Clinical evaluation demonstrated high specificity and sensitivity, with low risk of potential insulin-dosing errors. CONCLUSIONS: The ACCU-CHEK Inform II system demonstrated clinically acceptable performance against the PCA-HK reference method for blood glucose monitoring in a diverse population of critically ill patients in US care settings.

Evaluation of the Elecsys Syphilis Immunoassay for Detection of Syphilis in Populations at Risk of Disease in the US and Argentina.

BACKGROUND: The Elecsys® syphilis immunoassay is an automated, qualitative immunoassay that uses a double-antigen sandwich format to detect antibodies to Treponema pallidum in human serum and plasma. We aimed to validate performance of the immunoassay in various populations at risk for syphilis infection in the US and Argentina. METHODS: Samples were obtained for a number of study cohorts, including participants from routine syphilis testing at high or low risk for syphilis, HIV-positive patients, pregnant women, and patients in various stages of syphilis infection. The primary objective was to validate the Elecsys syphilis immunoassay by comparing it with a composite testing algorithm using US Food and Drug Administration (FDA)-approved tests, including the predicate IMMULITE 2000 syphilis screening assay, the rapid plasma reagin, and the T. pallidum particle agglutination assay. RESULTS: Complete algorithm testing was performed on all 2660 collected samples. Acceptable precision was demonstrated in all samples. Comparison of the Elecsys syphilis immunoassay with the final syphilis status for all samples yielded a diagnostic sensitivity of 99.5% (95% CI, 98.21-99.94) and a diagnostic specificity of 99.2% (95% CI, 98.69-99.49). Overall, the lower limit of the 95% CIs for sensitivity and specificity met the expected performance of ≥95%. CONCLUSION: This is the first study that confirms the high sensitivity and specificity of the Elecsys syphilis immunoassay in US and Argentinian cohorts and highlights the assay's usefulness as an alternative to current tests for the diagnosis of syphilis infection in a broad range of participant cohorts.

Evaluating the analytical performance of four new coagulation assays for the measurement of fibrinogen, D-dimer and thrombin time.

INTRODUCTION: New laboratory methods to measure haemostatic function require careful assessment before routine use. We evaluated the analytical performance of four new coagulation assays for the measurement of fibrinogen by Clauss assay, prothrombin time-derived fibrinogen, thrombin time and D-dimer levels. METHODS: The four assays were evaluated on the cobas t 711 and cobas t 511 analysers at four centres in Europe. Analytical performance and method comparisons with other commercially available assays were performed according to Clinical and Laboratory Standards Institute guidelines (EP09-A3, EP05-A3) using residual anonymized human sodium citrate (3.2% [0.109M]) plasma samples. Lot-to-lot variability and the equivalency of each assay on the cobas t 711 and cobas t 511 analysers were also assessed. RESULTS: Overall, coefficients of variance were ≤4.1% and ≤8.6% for within-run precision and total reproducibility, respectively. Method comparison experiments showed good or acceptable agreement for each assay compared with their respective comparator method, and equivalency was demonstrated for the two cobas t platforms (Pearson's correlation coefficient ≥0.991). A high level of consistency was observed between lots for all four assays (Pearson's correlation coefficient ≥0.994). CONCLUSION: This multicentre study demonstrates excellent analytical performance for four new coagulation assays on the cobas t 711 and cobas t 511 analysers.

Multi-center Performance Evaluations of Tacrolimus and Cyclosporine Electrochemiluminescence Immunoassays in the Asia-Pacific Region.

BACKGROUND: The immunosuppressant drugs (ISDs), tacrolimus and cyclosporine, are vital for solid organ transplant patients to prevent rejection. However, toxicity is a concern, and absorption is highly variable across patients; therefore, ISD levels need to be precisely monitored. In the Asia-Pacific (APAC) region, tacrolimus and cyclosporine concentrations are typically measured using immunoassays. The objective of this study was to assess the analytical performance of Roche Elecsystacrolimus and cyclosporinee electrochemiluminescence immunoassays (ECLIAs). METHODS: This evaluation was performed in seven centers across China, South Korea, and Malaysia. Imprecision (repeatability and reproducibility), assay accuracy, and lot-to-lot reagent variability were tested. The Elecsys ECLIAs were compared with commercially available immunoassays (Architect, Dimension, and Viva-E systems) using whole blood samples from patients with various transplant types (kidney, liver, heart, and bone marrow). RESULTS: Coefficients of variation for repeatability and reproducibility were ≤5.4% and ≤12.4%, respectively, for the tacrolimus ECLIA, and ≤5.1% and ≤7.3%, respectively, for the cyclosporine ECLIA. Method comparisons of the tacrolimus ECLIA with Architect, Dimension, and Viva-E systems yielded slope values of 1.01, 1.14, and 0.897, respectively. The cyclosporine ECLIA showed even closer agreements with the Architect, Dimension, and Viva-E systems (slope values of 1.04, 1.04, and 1.09, respectively). No major differences were observed among the different transplant types. CONCLUSIONS: The tacrolimus and cyclosporine ECLIAs demonstrated excellent precision and close agreement with other immunoassays tested. These results show that both assays are suitable for ISD monitoring in an APAC population across a range of different transplant types.

Evaluating the analytical performance of five new coagulation assays for the measurement of prothrombin time and activated thromboplastin time.

INTRODUCTION: New methods for coagulation tests require careful assessment before routine use. We evaluated the analytical performance of five new coagulation assays for measuring prothrombin time (PT) and activated partial thromboplastin time (aPTT). METHODS: PT Rec, PT Owren, aPTT, aPTT Lupus and aPTT Screen assays (Roche Diagnostics) were evaluated on cobas t 711 and cobas t 511 analysers (Roche Diagnostics) at four European centres. Analytical performance and method comparisons with relevant commercially available assays were performed to Clinical Laboratory Standards Institute guidelines using residual anonymized samples. Lot-to-lot comparison and equivalency of the cobas t analysers were also assessed; reference ranges were determined using samples from apparently healthy volunteers. RESULTS: Overall, coefficients of variation were ≤1.3% for within-run precision and ≤6.3% for total reproducibility across all sites. Deming regression analyses showed good agreement between each assay (cobas t 711) and respective comparator method (Pearson's r: 0.964-0.999, n > 120 samples/assay/site). Passing-Bablok regression analyses demonstrated equivalence of the two cobas t platforms for use with each assay (Pearson's r ≥ 0.995). Lot-to-lot consistency was high for all assays and comparisons (Pearson's r ≥ 0.998). Reference ranges (2.5th-97.5th percentiles; n = 200 samples/assay) in seconds were 8.4-10.6 (PT Rec), 18.2-27.2 (PT Owren), 23.6-30.6 (aPTT), 24.1-31.7 (aPTT Lupus) and 23.9-33.2 (aPTT Screen). CONCLUSION: Based on the excellent analytical performance and good agreement with relevant comparator methods, the five coagulation assays on the novel cobas t 711 and cobas t 511 analysers are suitable for routine use in core laboratories.