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@#Kidney function is commonly quantified using the glomerular filtration rate (GFR). However, the gold standard of measuring GFR, inulin clearance, is not practical for daily clinical use. This study compares different methods of GFR estimation based on serum creatinine, plasma levels of 99mTc-diethylenetriaminepentaacetic acid (DTPA), and camera acquisition of 99mTc-DTPA uptake. Seventy-five Filipino adults between ages 20 and 35 presumed to have normal kidneys were recruited. Each subject underwent gamma camera scintigraphy using the Gates and Inoue protocols after receiving a dose of 99mTc-DTPA. Blood samples were subsequently extracted at 1 hour and 3 hours after tracer injection, and GFRs were calculated based on single- and double-plasma sampling methods (SPSM and DPSM, respectively). Serum creatinine was also measured to derive GFR using the CKD-EPI, MDRD, and CockroftGault equations. Each method was correlated with a reference standard (DPSM) based on accuracy, linear regression, bias, and precision. SPSM tends to overestimate GFR unlike the other methods evaluated, but otherwise shows the most favorable diagnostic performance among the six methods when correlated with DPSM. The Inoue method appears modestly better than the routinely utilized Gates protocol, though both methods exhibit lack of precision. The CKD-EPI formula shows similar, if not slightly superior, diagnostic properties to the MDRD and Cockroft-Gault equations, thus confirming its validity for use in this Filipino population subset. Further studies are needed, particularly involving SPSM and CKD-EPI, to determine the applicability of our findings in Filipinos with varying degrees of kidney function. It is hoped that modifications to these methods can be made that are tailor-fit to derive more accurate and population-specific GFR values.
Subject(s)
Glomerular Filtration Rate , CreatinineABSTRACT
OBJECTIVE: To compare the advantages and disadvantages and application range of three methods for detection of urinary mercury. These methods include alkaline stannous chloride cold atomic absorption spectrometry, acid stannous chloride cold atomic absorption spectrometry and atomic fluorescence spectrometry. METHODS: The detection limits, accuracy and precision in these three methods were compared. RESULTS: The alkaline stannous chloride cold atomic absorption method and acidic stannous chloride cold atomic absorption method had a wide linear range(1.000-10.000 μg/L). The detection limit was high(0.265 and 0.556 μg/L, respectively). The atomic fluorescence spectrometry had the narrowest linear range(0.400-2.000 μg/L) and the lowest detection limit(0.048 μg/L). The average spiked recoveries of the above three methods were 95.93%-101.02%, 92.49%-98.72% and 95.96%-99.57%. The relative standard deviations within and between batches of these three methods were less than 5.00%. The addition recovery of organic mercury by alkaline cold chloride atomic absorption method was 80.91%. The recoveries of inorganic mercury and organic mercury by other methods were close to 100.00%. CONCLUSION: All three methods meet the daily needs of detecting urinary mercury. Among them, alkaline stannous chloride cold atomic absorption method is suitable for promotion in primary laboratories as a preliminary screening method. The atomic fluorescence spectrometry is suitable for the detection of microscale and trace amount of urinary mercury.
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Objective@#To investigate the consistency of plasma prothrombin time (PT) results detected by the STAGO STA-R Evolution and Mindray Precil C3510 automatic coagulation analyzers. @*Methods@#The PTs from 69 plasma samples were detected by the STA-R Evolution and Precil C3510 coagulation analyzers, respectively, and the obtained results were compared. Based on the CLSI EP9-A3 protocol, the ESD test was used to detect outliers, the scatter plot, difference plot, and frequency distribution plot were drawn, and the method comparison and bias evaluation were performed using the Passing-Bablok regression and Bland-Altman plot. @*Results@#The PTs (median \[P 25, P 75\]) detected by the STA-R Evolution and Precil C3510 analyzers were 19.00 (13.85, 25.65) s and 20.50 (13.83, 26.30) s, respectively, and there was no significant difference between them (P＞0.05). No outliers were detected by the ESD test, and the variation of PTs (CV) was constant. There were no systematic, random and proportional differences in PT results from two coagulation analyzers. The bias between two coagulation analyzers was within the acceptable range (1/2 CLIA′88 TEa). The predicted bias of PT at each medical decision point was also within the acceptable range. @*Conclusion@#The results of PT detected by the Precil C3510 and STA-R Evolution coagulation analyzers are comparable, and the bias is within the acceptable range, which can meet the needs of clinical diagnosis and treatment.
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The reliability of clinical measurements is critical to medical research and clinical practice. Newly proposed methods are assessed in terms of their reliability, which includes their repeatability, intra- and interobserver reproducibility. In general, new methods that provide repeatable and reproducible results are compared with established methods used clinically. This paper describes common statistical methods for assessing reliability and agreement between methods, including the intraclass correlation coefficient, coefficient of variation, Bland-Altman plot, limits of agreement, percent agreement, and the kappa statistic. These methods are more appropriate for estimating reliability than hypothesis testing or simple correlation methods. However, some methods of reliability, especially unscaled ones, do not clearly define the acceptable level of error in real size and unit. The Bland-Altman plot is more useful for method comparison studies as it assesses the relationship between the differences and the magnitude of paired measurements, bias (as mean difference), and degree of agreement (as limits of agreement) between two methods or conditions (e.g., observers). Caution should be used when handling heteroscedasticity of difference between two measurements, employing the means of repeated measurements by method in methods comparison studies, and comparing reliability between different studies. Additionally, independence in the measuring processes, the combined use of different forms of estimating, clear descriptions of the calculations used to produce indices, and clinical acceptability should be emphasized when assessing reliability and method comparison studies.
Subject(s)
Bias , Methods , Reproducibility of ResultsABSTRACT
Introducción: la elevada prevalencia mundial de la enfermedad renal crónica (ERC) y sus implicancias para la salud pública son ampliamente reconocidas pero existen pocos estudios relacionados a los valores de tasa de filtrado glomerular (TFG) y su estadificación en jóvenes. Se buscó describir los valores de TFG estimada por clearance de creatinina (ClCr) y por fórmulas, totales, por categoría G de TFG y por sexo y evaluar concordancia entre métodos de estimación en una muestra de estudiantes argentinos. Material y métodos: Estudio descriptivo en 75 estudiantes. Período mayo 2014-setiembre 2015. Se estimó TFG por Cockcroft-Gault (CG), MDRD-4 y ClCr usando creatinina no trazable a IDMS y por MDRD-4 IDMS y CKD-EPI con creatinina trazable. Resultados: Medias y frecuencias variables según método de estimación. Acuerdo moderado a bueno entre CKDEPI y CG y entre ClCr y CG. Conclusiones: Si bien estos hallazgos son preliminares y deben confirmarse en una muestra mayor, aportan a la descripción de los estadios superiores de TFG en jóvenes y a visualizar diferencias de comportamiento de los estimadores utilizados. El acuerdo moderado a bueno hallado entre la ecuación recomendada, CKD-EPI y CG constituye un avance exploratorio dentro de este rango poco estudiado de G en este grupo etario.
Introduction: the high global prevalence of Chronic Kidney Disease (CKD) and its implications for public health are well recognized. There are few studies related to the values of glomerular filtration rate (GFR) and its staging in young people. GFR was estimated by creatinine clearance (CrCl) by formulas, totals, by category G of GFR and sex on a sample of Argentine students. Agreement between estimation methods was also evaluated. Methods: Descriptive study of 75 students during the period May 2014-September 2015. GFR was estimated by Cockcroft-Gault (CG), MDRD-4 and CrCl using creatinine not traceable by IDMS and MDRD-4 IDMS and CKD-EPI with traceable creatinine. Results: Mean values and frequencies depending on the estimation method. Moderate to good agreement between CKD-EPI and CG and between CrCl and CGwas found. Conclusions: Although these findings are preliminary and should be confirmed in a larger sample, they help to describe higher GFR stages in a young population and to visualize differences between estimators used.
Subject(s)
Male , Female , Humans , Adult , Glomerular Filtration Rate , Kidney Function Tests , Argentina , CreatinineABSTRACT
Objective To develop improved enzymatic creatinine(Cr)assay reagents (self-R&D),and to investigate their appli-cation on serum detection by comparing with imported commercial Cr reagents(enzymatic Cr reagents from Toyobo)Methods En-zymatic method was used to evaluate the effect of every component and different concentrations of reagents on Cr assay by detecting the alteration of absorbance of Cr before or after the reaction.Meanwhile,the blank absorbance and analysis sensitivity of self-R&D and imported reagents,the technical indicators of precision,linearity,as well as method comparison of self-R&D reagents,were de-tected on the same automatic biochemical analyzer.Results The blank absorbance of self-R&D reagents was 0.009,and the detec-tion sensitivity was 0.13,better than that of imported Cr reagents.The coefficient of variation (CV)of high and low values of ser-um of self-R&D reagents were 1.5%,and 1.1%,respectively.The linear range was 0-2 850 μmol/L and the method comparison result was Y =0.98X +1.15 (r =0.999).The expected bias was less than the allowable error region.Using relative deviation≥10% as an index to evaluate the existence of significant interference,it shows that 35 mmol/L of creatine,3.42 mmol/L of biliru-bin,0.03 g/L of vitamin C,5 g/L of hemoglobin and 1450 FTU chyle in both low and high concentration serum samples did not interfere with the test result.Conclusion The quality of self-R&D reagents was good,and there was a good relativity between self-R&D reagents and imported Cr reagents with excellent quality.This indicates the self-R&D reagents could satisfy the application requirements of the clinics.
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Objective To improve EP9-A2 for Bias estimation among multiple quantitative detection systems within full range of AMR.Methods 40 patients specimens were determined twice for serum total cholesterol by four detection systems(A,B,C and D).With system A served as comparative method,Bias between A and the other three was evaluated according to CLSI EP9-A2 separately.Furthermore,DD(distance from deviation to tolerable error)and its average confidence intervals between every two sys-tem were calculated and compared with zero.The confidence interval of greater than zero was served as criteria for accepting bias between every two system.Results Bias between A and the other three meet the analytical quality specification according to EP9-A2,although that of D system was positive,and those of B and C system were negative.DD between every two system obeyed nor-mality distribution.All biases between every two system wes acceptable except that between B and D,causing of their interval con-taining zero.After correcting of results from system D,Biases between every two system were all acceptable.Plots of confidence in-terval could provide a full range bias assessment within AMR.Conclusion Comparability and Bias estimation in full range of AMR for results between every two system among 3 or more systems could be evaluated by confidence intervals.
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Objective To analyze the comparability of potassium results detected by blood-gas analyzer and dry chemical analy-zer .Methods Dry chemical detection system was used as comparison method (X) ,and blood gas analyzer systems was used as the experimental method (Y ) .Arterial blood samples collected from ICU newborns were detected respectively by the two methods .If SE of medical decision level was less than or equal to 1/2 TEa decided by CLIA′88 ,the results was acceptable .Results There was a linear correlation in potassium concentrations of the two detection systems(r=0 .976 ,P<0 .01) .But among three medical decision levels ,the SE of the two detection systems only acceptable at 3 .0 mmol/L .Conclusion The potassium concentration of blood gas analyzer is lower than that of dry chemistry analyzer .The potassium concentration of dry chemistry analyzer should be taken as a reference to diagnose and clinical treatment .
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OBJECTIVE: To get the present information of potency assay Methods of adsorbed tetanus vaccine, latest research and developmental trend. METHODS: Induction, summary and analyses were used, mainly according to the Chinese Pharmacopoeia, European Pharmacopoeia, British Pharmacopoeia, Japanese Pharmacopoeia, Indian Pharmacopoeia, the manual for quality control of diphtheria, tetanus, and pertussis vaccines, adopted Methods of FDA and literatures in the field. RESULTS and CONCLUSION: In the near future, complete in vitro potency assay Methods of adsorbed tetanus vaccine can be used instead of in vivo assay, so it is important and urgent that related research should be made in China.
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Most of important variables measured in medicine are in numerical forms or continuous in nature. New instruments and tests are constantly being developed for the purpose of measuring various variables, with the aim of providing cheaper, non-invasive, more convenient and safe methods. When a new method of measurement or instrument is invented, the quality of the instrument has to be assessed. Agreement and reliability are both important parameters in determining the quality of an instrument. This article will discuss some issues related to methods comparison study in medicine for the benefit of medical professional and researcher. METHOD: This is a narrative review and this article review the most common statistical methods used to assess agreement and reliability of medical instruments that measure the same continuous outcome. The two methods discussed in detail were the Bland-Altman Limits of Agreement, and Intra-class Correlation Coefficient (ICC). This article also discussed some issues related to method comparison studies including the application of inappropriate statistical methods, multiple statistical methods, and the strengths and weaknesses of each method. The importance of appropriate statistical method in the analysis of agreement and reliability in medicine is also highlighted in this article. CONCLUSION: There is no single perfect method to assess agreement and reliability; however researchers should be aware of the inappropriate methods that they should avoid when analysing data in method comparison studies. Inappropriate analysis will lead to invalid conclusions and thus validated instrument might not be accurate or reliable. Consequently this will affect the quality of care given to a patient.
Subject(s)
Costs and Cost AnalysisABSTRACT
BACKGROUND: The Samsung LABGEO PT Hepatic Test 9 (Samsung electronics, Korea) was developed as a point-of-care (POC) testing device. The levels of 9 analytes, namely, albumin, AST, ALT, alkaline phosphatase, gamma-glutamyl transferase, glucose, total bilirubin, direct bilirubin, and total protein, could be evaluated simultaneously by using 70 microL of whole blood, plasma, or serum samples. In this study, we assessed the performance of the Samsung LABGEO PT Hepatic Test 9. METHODS: The precision and linearity of the test were evaluated according to the CLSI EP5-A2 and CLSI EP6-A guidelines, respectively. Correlational analyses between Samsung LABGEO PT Hepatic Test 9 and Cobas 8000 modular analyzer (Roche, Switzerland) were carried out as per the CLSI EP9-A2 guidelines. Additionally, the results between 3 different specimen types, whole blood, plasma, and serum samples obtained from the same individual were compared to evaluate the matrix effect. RESULTS: The total imprecision at both low and high levels of the 9 analytes was within 10% and in the clinically important concentration range for all test items, all obtained results were linear. We compared the above results with those obtained using Cobas 8000 and a good correlation was observed with a correlation coefficient of more than 0.975 for all 9 analytes. Simple linear regression analyses between the 3 different specimen types indicated that there was no statistically significant difference (P<0.001). CONCLUSIONS: The Samsung LABGEO PT Hepatic Test 9 showed good precision and linearity when compared to established assays for 9 clinical test items and could be useful in cases where the POC testing is required.
Subject(s)
Alkaline Phosphatase , Bilirubin , Electronics , Electrons , Glucose , Linear Models , Plasma , TransferasesABSTRACT
BACKGROUND: Tumor markers are used for diagnosing cancers and monitoring responses to cancer therapy. In this study, we evaluated the performance of Lumipulse G1200 (Fujirebio, Japan), a fully automated serum analyzer, for immunoassays of tumor markers. METHODS: We determined the precision and linearity of assays performed using Lumipulse G1200 and the correlation between the results of this and other analyzers used for tumor markers according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). We used 9 tumor markers, namely, carcinoembryonic antigen, alpha-fetoprotein, cancer antigen 125, cancer antigen 15-3 (CA 15-3), cancer antigen 19-9, prostate specific antigen, protein induced by vitamin K absence or antagonist-II, and pepsinogens I and II. Further, we validated reference intervals using 20 serum samples of healthy individuals. RESULTS: Lumipulse G1200 yielded acceptable precision with total CV0.975 for all markers, except pepsinogen I (0.9569). The reference intervals provided by the manufacturer met the criteria mentioned in the CLSI guideline. CONCLUSIONS: Assays using Lumipulse G1200 had high precision, clinically acceptable linearity, and good correlation with the established assays. This indicates that Lumipulse G1200 can be potentially used in routine laboratories.
Subject(s)
alpha-Fetoproteins , Carcinoembryonic Antigen , Immunoassay , Pepsinogen A , Pepsinogens , Prostate-Specific Antigen , Biomarkers, Tumor , Vitamin KABSTRACT
BACKGROUND: Tumor markers are used for diagnosing cancers and monitoring responses to cancer therapy. In this study, we evaluated the performance of Lumipulse G1200 (Fujirebio, Japan), a fully automated serum analyzer, for immunoassays of tumor markers. METHODS: We determined the precision and linearity of assays performed using Lumipulse G1200 and the correlation between the results of this and other analyzers used for tumor markers according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). We used 9 tumor markers, namely, carcinoembryonic antigen, alpha-fetoprotein, cancer antigen 125, cancer antigen 15-3 (CA 15-3), cancer antigen 19-9, prostate specific antigen, protein induced by vitamin K absence or antagonist-II, and pepsinogens I and II. Further, we validated reference intervals using 20 serum samples of healthy individuals. RESULTS: Lumipulse G1200 yielded acceptable precision with total CV0.975 for all markers, except pepsinogen I (0.9569). The reference intervals provided by the manufacturer met the criteria mentioned in the CLSI guideline. CONCLUSIONS: Assays using Lumipulse G1200 had high precision, clinically acceptable linearity, and good correlation with the established assays. This indicates that Lumipulse G1200 can be potentially used in routine laboratories.
Subject(s)
alpha-Fetoproteins , Carcinoembryonic Antigen , Immunoassay , Pepsinogen A , Pepsinogens , Prostate-Specific Antigen , Biomarkers, Tumor , Vitamin KABSTRACT
BACKGROUND: We evaluated the HbA1c assay on COBAS INTEGRA 800 Closed Tube System (Roche Diagnostics, USA). METHODS: Precision was determined following Clinical and Laboratory Standards Institute (CLSI) EP5-A2 using the Lyphochek Diabetes Control (Bio-Rad Laboratories, Canada). Two levels of QC materials were assayed in duplicates at two separate times per day for 20 days. The within-run, between-run and between-day precisions were evaluated. We compared the HbA1c of COBAS INTEGRA 800 Closed tube system using Tina quant Hemoglobin A1c Gen.2 (Roche Diagnostics, Germany) reagent with Variant II Turbo (Bio-Rad Laboratories, USA). Bias was determined following CLSI EP9-A2. RESULT: The HbA1c assay on COBAS INTEGRA 800 Closed Tube System showed excellent precision performance: at a level of 5.9%, total, between run, and between day CVs were 1.8%, 0.5%, and 1.6%, respectively. At a level of 9.6%, total, between run, and between day CVs were 1.4%, 0.3%, and 1.1%, respectively. The assay correlated well with the Variant II Turbo (y=0.9x+0.53, r2=0.9857). Mean bias against Variant II Turbo was -0.2%. Compared with Variant II Turbo, the estimate of the predicted bias at a given medical decision level (HbA1c at 6% and 9%) was -0.1% and -0.31%, respectively. CONCLUSIONS: The COBAS INTEGRA 800 Closed Tube System HbA1C assay was precise and equivalent to Variant II Turbo.
Subject(s)
Bias , HemoglobinsABSTRACT
DNA microarray is currently the most prominent tool for investigating large-scale gene expression data. Different algorithms for measuring gene expression levels from scanned images of microarray experiments may significantly impact the following steps of functional genomic analyses. Affymetrix(R) recently introduced high-density microarrays and new statistical algorithms in Microarray Suit (MAS) version 5.0(R). Very high correlations (0.92 - 0.97) between the new algorithms and the old algorithms (MAS 4.0) across several species and conditions were reported. We found that the column-wise array correlations had a tendency to be much higher than the row-wise gene correlations, which may be much more meaningful in the following higher-order data analyses including clustering and pattern analyses. In this paper, not only the detailed comparison of the two sets of algorithms is illustrated, but the impact of the introducing new algorithms on the further clustering analysis of microarray data and of possible pitfalls in mixing the old and the new algorithms were also described.