scholarly journals Analytical quality assessment and method comparison of immunoassays for the measurement of serum cobalamin and folate in dogs and cats

2019 ◽  
Vol 31 (2) ◽  
pp. 164-174 ◽  
Author(s):  
Susan A. McLeish ◽  
Kay Burt ◽  
Kostas Papasouliotis
Keyword(s):  
Method Comparison ◽  
Reference Intervals ◽  
Specific Reference ◽  
Altman Analysis ◽  
Poor Agreement ◽  
Bland Altman Analysis ◽  
Intestinal Dysbiosis ◽  
Deming Regression ◽  
Small Intestinal ◽  
Very High

Serum cobalamin and folate are often measured in cats and dogs as part of laboratory testing for intestinal disease, small intestinal dysbiosis, or exocrine pancreatic deficiency. We performed an analytical validation of human immunoassays for cobalamin and folate measurement (AIA-900 analyzer, Tosoh Bioscience) and compared results with those obtained using chemiluminescence assays (Immulite 2000 analyzer, Siemens Medical Solutions Diagnostics). Accuracy, precision, total observable error (TEobs%), and σ values were calculated for the immunoassays. Correlation and agreement were evaluated with Deming regression, Passing–Bablok regression, and Bland–Altman analysis. Cobalamin intra-assay and inter-assay CVs were 1.8–9.3% and 2.6–6.8%, respectively. Folate intra-assay and inter-assay CVs were 1.5–9.1% and 3.4–8.1%, respectively. TEobs (%) were ≤19 and ≤31 for cobalamin and folate, respectively. Sigma values were 3.60–11.50 for cobalamin and 2.90–7.50 for folate. Regression analysis demonstrated very high or high correlations for cobalamin [ r = 0.98 (dogs), 0.97 (cats)] and folate [ r = 0.88 (dogs), 0.92 (cats)] but Bland–Altman analysis revealed poor agreement for both. The immunoassays had good analytical performance for measuring cobalamin and folate in both species. Results obtained by the 2 analyzers cannot be used interchangeably and should be interpreted using instrument-specific reference intervals. Further studies are required to establish immunoassay-specific reference intervals and to evaluate the diagnostic performance and clinical utility of the analyzer for these analytes.

Performance of Automated Telemetry in Diagnosing QT Prolongation in Critically Ill Patients

2021 ◽  
Vol 30 (6) ◽  
pp. 466-470
Author(s):  
Enrique Calvo-Ayala ◽  
Vince Procopio ◽  
Hayk Papukhyan ◽  
Girish B. Nair
Keyword(s):  
Critically Ill ◽  
Critically Ill Patients ◽  
Demographic Data ◽  
Area Under The Curve ◽  
Qt Prolongation ◽  
Altman Analysis ◽  
Poor Agreement ◽  
Bland Altman Analysis ◽  
Prolonged Qt ◽  
Definition Of

Background QT prolongation increases the risk of ventricular arrhythmia and is common among critically ill patients. The gold standard for QT measurement is electrocardiography. Automated measurement of corrected QT (QTc) by cardiac telemetry has been developed, but this method has not been compared with electrocardiography in critically ill patients. Objective To compare the diagnostic performance of QTc values obtained with cardiac telemetry versus electrocardiography. Methods This prospective observational study included patients admitted to intensive care who had an electrocardiogram ordered simultaneously with cardiac telemetry. Demographic data and QTc determined by electrocardiography and telemetry were recorded. Bland-Altman analysis was done, and correlation coefficient and receiver operating characteristic (ROC) coefficient were calculated. Results Fifty-one data points were obtained from 43 patients (65% men). Bland-Altman analysis revealed poor agreement between telemetry and electrocardiography and evidence of fixed and proportional bias. Area under the ROC curve for QTc determined by telemetry was 0.9 (P < .001) for a definition of prolonged QT as QTc ≥ 450 milliseconds in electrocardiography (sensitivity, 88.89%; specificity, 83.33%; cutoff of 464 milliseconds used). Correlation between the 2 methods was only moderate (r = 0.6, P < .001). Conclusions QTc determination by telemetry has poor agreement and moderate correlation with electrocardiography. However, telemetry has an acceptable area under the curve in ROC analysis with tolerable sensitivity and specificity depending on the cutoff used to define prolonged QT. Cardiac telemetry should be used with caution in critically ill patients.

scholarly journals Performance of StatSensor Point-of-Care Device for Measuring Creatinine in Patients With Chronic Kidney Disease and Postkidney Transplantation

2020 ◽  
Vol 7 ◽  
pp. 205435812097071
Author(s):  
Melissa Nataatmadja ◽  
Angela W. S. Fung ◽  
Beryl Jacobson ◽  
Jack Ferera ◽  
Eva Bernstein ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Whole Blood ◽  
Point Of Care ◽  
Reference Method ◽  
Plasma Creatinine ◽  
Altman Analysis ◽  
Bland Altman Analysis ◽  
Deming Regression ◽  
Ckd Stage

Background: The StatSensor is a point-of-care device which measures creatinine in capillary whole blood. Previous studies reported an underestimation of the creatinine measurements at high creatinine concentrations and were performed in the prestandardization era for creatinine. Objective: This accuracy-based study evaluates the use of this device in kidney-transplanted patients and those with chronic kidney disease (CKD). Design: Cross-sectional diagnostic accuracy study. Setting: Nephrology outpatient clinic in an urban tertiary center. Participants: Adults with CKD or a functioning kidney transplant. Measurements: Duplicate StatSensor creatinine measurements were performed on capillary whole blood samples collected by direct fingerstick and SAFE-T-FILL collection device. Results were compared with simultaneous venous blood sampling for serum and plasma creatinine measured by an enzymatic method on the Roche Integra 400 mainframe analyzer with traceability to the ID-GC-MS (isotope dilution gas chromatography mass spectrometry) reference method. Methods: Deming regression, Pearson correlation coefficient, and Bland-Altman analysis were used to assess accuracy and comparability between capillary whole blood measured by StatSensor and plasma creatinine measured by routine analyzer with traceability to the reference method. Estimated glomerular filtration (eGFR) rates were calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and concordance with Kidney Disease Improving Global Outcomes (KDIGO) CKD stage classification was evaluated. Results: There were 60 participants (mean age = 61.9 ± 15.0 years, 55% men, 33% transplant, mean plasma creatinine = 137 ± 59 µmol/L). Bland-Altman analysis indicated a positive mean bias of 12.7 µmol/L between StatSensor fingerstick creatinine measurement and plasma creatinine. Comparison of eGFR (CKD-EPI) calculated from the StatSensor fingerstick creatinine versus plasma creatinine showed misclassification across all KDIGO CKD stages. Postanalytical correction of the bias did not improve misclassifications. The use of mean of duplicate StatSensor creatinine results did not improve performance compared with the use of singlet results. Limitations: Single center, limited participant numbers. Conclusions: The results of our study suggest that the limiting characteristics of the StatSensor device are not only bias, but also imprecision. The level of imprecision observed may influence clinical decision-making and limit the usefulness of StatSensor as a CKD screening tool. If choosing to utilize it for either screening for or monitoring CKD, it is essential that clinicians understand the limitations of point-of-care devices and apply this knowledge to test interpretation.

scholarly journals Comparison of two methods for measurement of equine adrenocorticotropin

2017 ◽  
Vol 30 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Heidi E. Banse ◽  
Nichol Schultz ◽  
Molly McCue ◽  
Ray Geor ◽  
Dianne McFarlane
Keyword(s):  
Pars Intermedia ◽  
Plasma Samples ◽  
Altman Analysis ◽  
Poor Agreement ◽  
Limits Of Agreement ◽  
Cutoff Value ◽  
Bland Altman Analysis ◽  
Acth Concentration

Accurate measurement of equine adrenocorticotropin (ACTH) is important for the diagnosis of equine pituitary pars intermedia dysfunction (PPID). Several radioimmunoassays (RIAs) and chemiluminescent immunoassays (CIAs) are used for measurement of ACTH concentration in horses; whether these methods yield similar results across a range of concentrations is not determined. We evaluated agreement between a commercial RIA and CIA. Archived plasma samples ( n = 633) were measured with both assays. Correlation between the 2 methods was moderate ( r = 0.49, p < 0.001). Bland–Altman analysis revealed poor agreement, with a proportional bias and widening limits of agreement with increasing values. Poor agreement between assays was also observed when evaluating plasma samples with concentrations at or below the recommended diagnostic cutoff value for PPID testing. The lack of agreement suggests that measurements obtained should not be considered interchangeable between methods.

scholarly journals Better Performance of Flow-FISH in Comparison to qPCR As a Diagnostic Test for Telomere Diseases

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1605-1605
Author(s):  
Fernanda Gutierrez-Rodrigues ◽  
Bárbara A Santana-Lemos ◽  
Priscila Santos Scheucher ◽  
Raquel M Alves-Paiva ◽  
Rodrigo T. Calado
Keyword(s):  
Telomere Length ◽  
Diagnostic Test ◽  
Quantitative Pcr ◽  
Measurement Techniques ◽  
Healthy Individuals ◽  
Altman Analysis ◽  
Poor Agreement ◽  
Limits Of Agreement ◽  
Gold Standard Method ◽  
Bland Altman Analysis

Abstract Excessive telomere erosion is the molecular etiology of a group of disorders (dyskeratosis congenita, aplastic anemia, idiopathic pulmonary fibrosis) collectively called telomeropathies. Telomere length measurement is an essential diagnostic test for these diseases. The most commonly used methods are terminal restriction fragment (TRF) analysis by Southern blotting (the gold-standard method), flow cytometry combined with fluorescence in situ hybridization (flow-FISH), and quantitative PCR (qPCR). Although the clinical use of these methods has been reported, their utility and characteristics have not been widely compared. Measurement techniques and coefficients of variations often differ among diagnostic services. Here, we directly compared the accuracy, reproducibility, sensitivity, and specificity of flow-FISH and qPCR in comparison to TRF to measure peripheral blood leukocyte’s telomere length in healthy individuals and patients with telomeropathies. TRF analyses and flow-FISH showed good correlation in the analysis of samples from healthy subjects (R2=0.60; p<0.0001) and patients (R2=0.51; p<0.0001). Bland-Altman analyses also displayed a very good agreement between these methods for both healthy individuals (bias±SD = 0.17±1.03; limits of agreement ranging from 2.24 to -1.88) and patients (bias±SD = 0.0±1.21; limits of agreement ranging from 2.41 to -2.41). In contrast, the comparison between TRF and qPCR yielded modest correlation for the analysis of samples of healthy individuals (R2=0.35; p<0.0001) and low correlation for patients (R2=0.20; p=0.001). Bland-Altman analysis indicated poor agreement between the two methods for both patients and controls. The differences averages were very different from zero and standard deviation was wide. For patients, the bias±SD was 0.78±1.34 with limits of agreement ranging from 3.47 to -1.90, and for controls, the bias±SD was 1.15±1.49 with limits of agreement ranging from 4.14 to -1.84. Finally, qPCR and flow-FISH also modestly correlated in the analysis of healthy individual samples (R2=0.33; p<0.0001) and did not correlate in the comparison of patients’ samples (R2=0.1, p=0.08). Bland-Altman analysis corroborate this finding. For controls, the bias±SD were very similar to the one found by comparison between qPCR and TRF analysis (-0.6±1.27; limits of agreement ranging from 1.94 to -3.16). For patients, bias ± SD were -1.15 ± 1.65 with limits of agreement ranging from 2.15 to -4.45, which evidenced a poor agreement between flow-FISH and qPCR in these samples. Intra-assay coefficient of variation (CV) was 10.8±7.1% for flow-FISH and 9.5±7.4% for qPCR (p=0.35). The inter-assay CV was lower for flow-FISH (9.6±7.6%) in comparison to qPCR (16±19.5%; p=0.02). Flow-FISH and qPCR were sensitive (both 100%) and specific (93% and 89%, respectively) to distinguish very short telomeres. However, qPCR sensitivity (40%) and specificity (63%) to detect telomere length below tenth percentile were lower in comparison to flow-FISH (80% sensitivity and 85% specificity). Taken together, these findings indicate that, in the clinical setting, flow-FISH is more accurate and reproducible in the measurement of human leukocyte’s telomere length in comparison to qPCR. Quantitative PCR exhibited low accuracy in the analysis of samples of patients with short telomeres. In conclusion, flow-FISH appears to be a more appropriate method for diagnostic purposes. Studies that compare methodologies are helpful in the selection of standard methods and to narrow the differences among laboratories. Disclosures No relevant conflicts of interest to declare.

scholarly journals Cross-Method Comparison of Serum Androstenedione Measurement Using Three Different Assays: The Siemens Immulite Immunoassay, the Roche Elecsys Immunoassay, and an LC/MS-MS Assay

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A730-A731
Author(s):  
Ruhan Wei ◽  
Kathleen Bowers ◽  
Grace M Kroner ◽  
Drew Payto ◽  
Jessica Colon Franco
Keyword(s):  
Clinical Performance ◽  
Polycystic Ovary ◽  
Pediatric Population ◽  
Method Comparison ◽  
Reference Intervals ◽  
Healthy Children ◽  
Healthy Male ◽  
Serum Samples ◽  
Female Sex Hormones ◽  
Deming Regression

Abstract Introduction: Androstenedione is a common precursor of male and female sex hormones produced by the adrenal glands and gonads. Serum androstenedione is a helpful biomarker in the diagnostic workup of a subset of patients with polycystic ovary syndrome (PCOS), the investigation of virilizing endocrinopathies, and for monitoring pediatric patients with congenital adrenal hyperplasia. The gold standard for the measurement of androstenedione is LC-MS/MS. A newly developed androstenedione competitive immunoassay is now available in the US, the Roche Elecsys Androstenedione (ASD) immunoassay. Until recently, the Siemens Immulite assay was the only non-radioimmunologic immunoassay available. We characterized the analytical and clinical performance of the ASD across different patient populations and in comparison to the Immulite and an LC-MS/MS assay. Methods and materials: The experiments performed were: linearity and analytical measuring range (AMR), precision (intra- and inter-assay), and accuracy. Androstenedione was measured on de-identified residual serum samples (n=40) using the ASD and Immulite immunoassays and an LC-MS/MS assay. The reference intervals (RIs) provided by Roche for healthy male (0.280-1.52 ng/mL), healthy female (0.490-1.31 ng/mL), postmenopausal women (0.187-1.07 ng/mL), healthy children (&lt;0.519 ng/mL), and patients with PCOS (0.645-3.47 ng/mL) were verified with at least 20 specimens, according to CLSI C28A3. Statistical analysis was performed using EP Evaluator and R program. Results: The ASD had a linear response across the AMR of 0.3 to 10.0 ng/mL. The inter- and intra-assay coefficients of variation were 4.5% and 2.0% or lower, at concentrations 0.5-6.7 ng/mL, respectively. The ASD and LC-MS/MS assays had a mean bias of -0.0542 ng/mL (-2%), Deming regression of y = 1.000 [0.961; 1.039] x - 0.0548 [-0.1806; 0.0709], and r = 0.9930. The Immulite assay had a mean bias of 1.15 ng/mL (44%) and 1.22 ng/mL (32%) compared to the LC-MS/MS and ASD assays, respectively. The recommended RIs from Roche for healthy male, female, and postmenopausal female groups were successfully verified in our patient population. However, the androstenedione concentrations for the healthy children and PCOS groups were outside of the suggested RIs, with concentrations up to 1.41 ng/mL and 0.527-2.24 ng/mL, respectively. Unlike published elsewhere, hormone therapies such as contraceptive pills and steroid treatments did not significantly affect serum androstenedione concentrations in healthy females and patients with PCOS. Conclusion: The ASD is superior to the Immulite immunoassay, and it has excellent comparability with the LC-MS/MS for serum androstenedione measurement. The RIs published by Roche may not be universally transferable; verification is recommended, and establishing RIs for the pediatric population may be necessary.

scholarly journals Multicenter comparison of the Cobas 6800 system with the RealStar RT-PCR kit for the detection of SARS-CoV-2

2020 ◽  
Author(s):  
Marc Wirden ◽  
Linda Feghoul ◽  
Mélanie Bertine ◽  
Marie-Laure Nere ◽  
Quentin Le Hingrat ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Linear Regression Analysis ◽  
Regression Line ◽  
Clinical Samples ◽  
Altman Analysis ◽  
Rt Pcr ◽  
Bland Altman Analysis ◽  
Deming Regression ◽  
The Mean ◽  
Pcr Assays

ABSTRACTBackgroundRT-PCR testing is crucial in the diagnostic of SARS-CoV-2 infection. The use of reliable and comparable PCR assays is a cornerstone to allow use of different PCR assays depending on the local equipment. In this work, we provide a comparison of the Cobas® (Roche) and the RealStar® assay (Altona).MethodsAssessment of the two assays was performed prospectively in three reference Parisians hospitals, using 170 clinical samples. They were tested with the Cobas® assay, selected to obtain a distribution of cycle threshold (Ct) as large as possible, and tested with the RealStar assay with three largely available extraction platforms: QIAsymphony (Qiagen), MagNAPure (Roche) and NucliSENS-easyMag (BioMérieux).ResultsOverall, the agreement (positive for at least one gene) was 76%. This rate differed considerably depending on the Cobas Ct values for gene E: below 35 (n = 91), the concordance was 99%. Regarding the positive Ct values, linear regression analysis showed a determination correlation (R2) of 0.88 and the Deming regression line revealed a strong correlation with a slope of 1.023 and an intercept of -3.9. Bland-Altman analysis showed that the mean difference (Cobas® minus RealStar®) was + 3.3 Ct, with a SD of + 2.3 Ct.ConclusionsIn this comparison, both RealStar® and Cobas® assays provided comparable qualitative results and a high correlation when both tests were positive. Discrepancies exist after 35 Ct and varied depending on the extraction system used for the RealStar® assay, probably due to a low viral load close to the detection limit of both assays.

scholarly journals Reliability and Validity of an Ultrasonic Device for Measuring Height in Adults

2021 ◽  
Vol 42 (5) ◽  
pp. 376-381
Author(s):  
Seon Hwa Cho ◽  
Young Gyu Cho ◽  
Hyun Ah Park ◽  
A Ra Bong
Keyword(s):  
Correlation Coefficient ◽  
Health Surveys ◽  
Intraclass Correlation ◽  
Reliability And Validity ◽  
Altman Analysis ◽  
Bland Altman Analysis ◽  
Community Health Survey ◽  
Measurement Devices ◽  
The Difference ◽  
Very High

Background: The ultrasonic stadiometer was originally developed as a device to measure and monitor children’s height. However, an ultrasonic stadiometer (InLab S50; InBody Co., Seoul, Korea) was used to measure adults’ height in the 2018 Korea Community Health Survey (KCHS). This study was conducted to assess the reliability and validity of the InLab S50 in adults. Methods: The study subjects were 120 adults (reliability test, n=20; validity test, n=100) who had visited a health screening center. The intra- and inter-rater reliabilities of InLab S50 were assessed using the intraclass correlation coefficient (ICC). The agreement between InLab S50 and an automatic stadiometer (HM-201; Fanics, Busan, Korea) was assessed using Pearson’s correlation coefficient and Bland-Altman analysis. Results: The intra- and inter-rater reliabilities of the InLab S50 were excellent (ICC=0.9999 and 0.9998, respectively). The correlation coefficient of the height measured by the two measurement devices was very high (r=0.996). The difference (Δheight [HM-201-InLab S50]) was -0.15±0.78 cm (95% limit of agreement [LOA], -1.69 to 1.38). After excluding the values outside 95% LOA, the difference was further reduced to -0.05±0.59 cm (95% LOA, -1.20 to 1.10). Conclusion: This study showed that the InLab S50 is a reliable and valid device for the measurement of adults’ height. Therefore, we think that InLab S50 could be used to measure adults’ height in household health surveys such as the KCHS.

scholarly journals Agreement of Measurement between Arterial and Venous Electrolyte Levels in Neonates in a Tertiary Care Hospital

2020 ◽  
Vol 12 (01) ◽  
pp. 20-26
Author(s):  
Parveen Doddamani ◽  
Kusuma Kasapura Shivashankar ◽  
Shobha Chikkavaddaragudi Ramachandra ◽  
Insha Aman ◽  
Suma Maduvanahalli Nataraj
Keyword(s):  
Venous Blood ◽  
Tertiary Care ◽  
Prediction Equation ◽  
Sample Type ◽  
Strong Positive Correlation ◽  
Care Hospital ◽  
Altman Analysis ◽  
Bland Altman Analysis ◽  
Arterial Blood ◽  
Deming Regression

Abstract Context Venous or arterial blood is used for the estimation of electrolytes in neonates in neonatal intensive care unit (NICU). In addition to the measurement of blood gases and bicarbonate in the arterial blood, arterial blood gas analysis also estimates electrolytes thus circumventing the need to collect a venous sample for electrolytes. The literature survey revealed studies comparing the electrolyte levels in arterial and venous blood in adults and older children, but to our knowledge none were found in neonates, hence the study. Aims The aim of the study is to compare the electrolytes in arterial and venous samples in neonates in a critical care set up and derive in-house prediction equation to correlate the arterial and venous electrolytes. Settings and Design Hospital-based, retrospective cross-sectional study done in critically ill neonates. Materials and Methods All the newborns (age ≤28 days) admitted in NICU from July 2016 to June 2018 were selected for the study and data collected with the help of Hospital Information System. Statistical Analysis MedCalc and NCSS 12 (trial version) software was used. Deming Regression and Bland Altman analysis were performed. Results A strong positive correlation between the arterial and venous blood electrolytes observed. An in-house prediction equation was derived for the venous electrolytes. Deming regression analysis showed that only potassium levels are statistically equivalent between the instruments and the sample type. Bland Altman Analysis between the arterial and venous electrolytes showed a mean difference which was well within the accepted Clinical Laboratory Improvement Amendment guidelines. Conclusion The electrolyte levels estimated by arterial blood in neonates can be used in an interchangeable manner only for potassium levels, whereas sodium and chloride estimation necessitates one to be cautious.

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