scholarly journals Analytical Bias Exceeding Desirable Quality Goal in 4 out of 5 Common Immunoassays: Results of a Native Single Serum Sample External Quality Assessment Program for Cobalamin, Folate, Ferritin, Thyroid-Stimulating Hormone, and Free T4 Analyses

2016 ◽  
Vol 62 (9) ◽  
pp. 1255-1263 ◽  
Author(s):  
Gunn B B Kristensen ◽  
Pål Rustad ◽  
Jens P Berg ◽  
Kristin M Aakre
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Measurement Procedure ◽  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Free T4 ◽  
External Quality ◽  
Reference Measurement ◽  
Serum Pool ◽  
Reference Measurement Procedure

Abstract BACKGROUND We undertook this study to evaluate method differences for 5 components analyzed by immunoassays, to explore whether the use of method-dependent reference intervals may compensate for method differences, and to investigate commutability of external quality assessment (EQA) materials. METHODS Twenty fresh native single serum samples, a fresh native serum pool, Nordic Federation of Clinical Chemistry Reference Serum X (serum X) (serum pool), and 2 EQA materials were sent to 38 laboratories for measurement of cobalamin, folate, ferritin, free T4, and thyroid-stimulating hormone (TSH) by 5 different measurement procedures [Roche Cobas (n = 15), Roche Modular (n = 4), Abbott Architect (n = 8), Beckman Coulter Unicel (n = 2), and Siemens ADVIA Centaur (n = 9)]. The target value for each component was calculated based on the mean of method means or measured by a reference measurement procedure (free T4). Quality specifications were based on biological variation. Local reference intervals were reported from all laboratories. RESULTS Method differences that exceeded acceptable bias were found for all components except folate. Free T4 differences from the uncommonly used reference measurement procedure were large. Reference intervals differed between measurement procedures but also within 1 measurement procedure. The serum X material was commutable for all components and measurement procedures, whereas the EQA materials were noncommutable in 13 of 50 occasions (5 components, 5 methods, 2 EQA materials). CONCLUSIONS The bias between the measurement procedures was unacceptably large in 4/5 tested components. Traceability to reference materials as claimed by the manufacturers did not lead to acceptable harmonization. Adjustment of reference intervals in accordance with method differences and use of commutable EQA samples are not implemented commonly.

Establishing an Accuracy Basis for the Vitamin D External Quality Assessment Scheme (DEQAS)

2017 ◽  
Vol 100 (5) ◽  
pp. 1277-1287 ◽  
Author(s):  
Carolyn Q Burdette ◽  
Johanna E Camara ◽  
Federica Nalin ◽  
Jeanita Pritchett ◽  
Lane C Sander ◽  
...  
Keyword(s):  
Vitamin D ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Measurement Procedure ◽  
Binding Assays ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Hydroxyvitamin D ◽  
Target Values ◽  
High Concentrations

Abstract Until recently, the Vitamin D External Quality Assessment Scheme (DEQAS) assessed the performance of various assays for the determination of serum total 25-hydroxyvitamin D [25(OH)D] by using a consensus mean based on the all-laboratory trimmed mean (ALTM) of the approximately 1000 participants' results. Since October 2012, the National Institute of Standardsand Technology (NIST), as part of the Vitamin D Standardization Program, has participated in DEQAS by analyzing the quarterly serum sample sets using an isotope dilution LC-tandem MS (ID LC-MS/MS) reference measurement procedure to assign an accuracy-based target value for serum total 25(OH)D. NIST has analyzed90 DEQAS samples (18 exercises × 5 samples/exercise) to assign target values. The NIST-assigned values are compared with the ALTM and the biases assessed for various assays used by the participants, e.g., LC-MS/MS, HPLC, and several ligand-binding assays. The NIST-value assignment process and the resultsof the analyses of the 90 DEQAS samples are summarized. The absolute mean bias between the NIST-assignedvalues and the ALTM was 5.6%, with 10% of the samples having biases >10%. Benefits of the accuracy-based target values are presented, including for sample sets with high concentrations of 25(OH)D2 and 3-epi-25(OH)D3.

scholarly journals Proficiency Testing/External Quality Assessment: Current Challenges and Future Directions

2011 ◽  
Vol 57 (12) ◽  
pp. 1670-1680 ◽  
Author(s):  
W Greg Miller ◽  
Graham RD Jones ◽  
Gary L Horowitz ◽  
Cas Weykamp
Keyword(s):  
Quality Assessment ◽  
Proficiency Testing ◽  
External Quality Assessment ◽  
Peer Group ◽  
Measurement Procedure ◽  
Comparison Method ◽  
External Quality ◽  
Group Evaluation ◽  
The Status ◽  
Relationship Of

BACKGROUND Proficiency testing (PT), or external quality assessment (EQA), is intended to verify on a recurring basis that laboratory results conform to expectations for the quality required for patient care. CONTENT Key factors for interpreting PT/EQA results are knowledge of the commutability of the samples used and the process used for target value assignment. A commutable PT/EQA sample demonstrates the same numeric relationship between different measurement procedures as that expected for patients' samples. Noncommutable PT/EQA samples frequently have a matrix-related bias of unknown magnitude that limits interpretation of results. PT/EQA results for commutable samples can be used to assess accuracy against a reference measurement procedure or a designated comparison method. In addition, the agreement of the results between different measurement procedures for commutable samples reflects that which would be seen for patients' samples. PT/EQA results for noncommutable samples must be compared to a peer group mean/median of results from participants who use measurement procedures that are expected to have the same or very similar matrix-related bias. Peer group evaluation is used to asses whether a laboratory is using a measurement procedure in conformance to the manufacturer's specifications and/or in conformance to other laboratories using the same technology. A noncommutable PT/EQA sample does not give meaningful information about the relationship of results for patients' samples between different measurement procedures. SUMMARY PT/EQA provides substantial value to the practice of laboratory medicine by assessing the performance of individual laboratories and, when commutable samples are used, the status of standardization or harmonization among different measurement procedures.

scholarly journals Interassay Variability of Immunometric Methods for Thyrotropin in an External Quality Assessment Survey: Evidence that Functional Sensitivity is not Always Adequate for Clinical Decisions

1992 ◽  
Vol 38 (7) ◽  
pp. 1345-1349 ◽  
Author(s):  
A Pilo ◽  
G C Zucchelli ◽  
R Malvano ◽  
A Clerico ◽  
G Iervasi ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Control Period ◽  
Thyroid Stimulating Hormone ◽  
The Other ◽  
External Quality ◽  
Diagnostic Reliability ◽  
Assessment Survey ◽  
One Year ◽  
Interassay Precision

Abstract We investigated the ability of current immunometric methods for thyrotropin (TSH; thyroid-stimulating hormone) to distinguish between low-normal and subnormal hormone concentrations by using the data from an external quality assessment (EQA) survey in 1990. We computed the interassay (between-run) precision profiles from results from 101 laboratories, which used the five most popular kits in the survey; during the control period (one year) each laboratory assayed 4 EQA pools distributed (as hidden replicates) in five occasions. The interassay CV was relatively low (9-13%) for three pools in the normal TSH range (greater than 0.8 milli-int. unit/L) but markedly higher (30-40%, except for one more precise kit) in the subnormal range (0.2 milli-int. unit/L). We calculated the effect of the between-run variability on the diagnostic accuracy (discrimination between normal and subnormal values) for three representative TSH concentrations: 0.2, 0.4, and 0.5 milli-int. unit/L (0.3 milli-int. unit/L was considered the lower normal limit). The three concentrations were reasonably discriminated (P less than or equal to 5%), and only one kit showed a between-run CV less than 18% at 0.2 milli-int. unit/L. For the other four less-precise kits, only the higher TSH value (0.5 milli-int. unit/L) could be classified with an acceptable diagnostic reliability. With the most precise kit, one can distinguish two TSH concentrations in the 0.3-0.5 milli-int. unit/L range that differ by at least 30%; with the other kits, differences greater than 50-60% are needed for reliable discrimination. Thus many laboratories fail to achieve the functional sensitivity of a second-generation assay, even if they use immunometric methods. TSH assays with a better interassay precision in the low concentration range are needed.

Development of reference intervals for serum alkaline phosphatase among adults in Southern China traced to the new IFCC reference measurement procedure

2016 ◽  
Vol 54 (4) ◽  
Author(s):  
Liqiao Han ◽  
Jianbing Wang ◽  
Qiaoxuan Zhang ◽  
Peifeng Ke ◽  
Xiaobin Wu ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Serum Alkaline Phosphatase ◽  
Southern China ◽  
Critical Role ◽  
Measurement Procedure ◽  
Reference Intervals ◽  
Modular System ◽  
Chinese Han ◽  
Reference Measurement ◽  
Reference Measurement Procedure

Abstract: Serum alkaline phosphatase (ALP) plays a critical role in the diagnosis of various diseases, and the establishment of relevant, reliable reference intervals (RI) is key to avoiding misdiagnoses. In 2011, IFCC published the new reference measurement procedure (RMP) for the determination of serum ALP in which one of the main modifications was the measuring temperature of the assay. Here, the new RMP was used to help establish RIs for serum ALP concentrations in healthy Chinese Han.Volunteer individuals in Guangdong province, China (n=1622) were screened by questionnaire and laboratory testing for eligibility as a reference. Blood (20 mL) was collected and samples were measured by the Roche Modular system using the new RMP for the serum ALP compatible method. Partitioning of values by gender and/or age was evaluated with a standard normal deviate test after removing outliers. A simple non-parametric method for a two-sided 95% distribution of reference values was calculated.Serum ALP concentrations were obtained from the cohort of eligible reference individuals (n=658). The RI for serum ALP in males age 18–79 years was 48–131 U/L. Females were partitioned into two age groups based on statistical analysis, 18–49 years and 50–79 years, and the RIs derived were 40–106 U/L and 57–159 U/L, respectively.RIs for serum ALP for Chinese Han individuals in between the ages of 18 and 79 years were determined and required partitioning due to the higher ALP values of females age 50–79 years.

Systematic differences between commercial immunoassays for free thyroxine and free triiodothyronine in an external quality assessment program

1994 ◽  
Vol 40 (10) ◽  
pp. 1956-1961 ◽  
Author(s):  
G C Zucchelli ◽  
A Pilo ◽  
M R Chiesa ◽  
S Masini
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
External Quality ◽  
Assessment Program ◽  
Serum Pool ◽  
Back Titration ◽  
Control Samples

Abstract Data collected in a national external quality assessment program for free thyroxine (fT4) and free triiodothyronine (fT3) were analyzed to evaluate the performance of 10 method/kits with 26 control samples distributed to approximately 170 laboratories. The control materials were normal serum pools, pooled sera supplemented with thyroid hormones, a pregnancy serum pool, serum pooled from patients with familial dysalbuminemic hyperthyroxinemia (FDH), and a normal serum pool progressively diluted. The between-laboratory variability (CV) was approximately constant in normal and supplemented pools for fT4 (15.3%) and fT3 (24.0%) but markedly increased in diluted, pregnancy, and FDH pools (21.9-35.2% for fT4 and 28.6-66.5% for fT3) because of increases in systematic between-kit differences in control samples with altered binding-protein capacity. Moreover, free hormone concentrations measured in progressively diluted sera averaged lower than in undiluted samples. This decrease of concentration was less for back-titration or labeled-antibody techniques and greater for labeled-analog methods; only the method involving adsorption to cross-linked dextran (Sephadex) was unaffected by dilution. Evaluation of the reproducibility of the method/kits showed between-assay, between-laboratory precision ranging from 7.8% to 17.0% for fT4 and from 9.8% to 20.3% for fT3.

scholarly journals Comparability of thyroid-stimulating hormone immunoassays using fresh frozen human sera and external quality assessment data

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253324
Author(s):  
Shunli Zhang ◽  
Fei Cheng ◽  
Hua Wang ◽  
Jiangping Wen ◽  
Jie Zeng ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Human Serum ◽  
External Quality Assessment ◽  
Thyroid Stimulating Hormone ◽  
Clinical Samples ◽  
Systematic Bias ◽  
Serum Samples ◽  
Bias Analysis ◽  
External Quality ◽  
Human Sera

Background This study aimed to assess the comparability among assays using freshly frozen human sera and external quality assessment (EQA) data in China. Methods Twenty-nine serum samples and two commercial EQA materials, obtained from the National Center for Clinical Laboratories (NCCL), were analyzed in triplicate using eight routine TSH assays. The commutability of commercial EQA materials (NCCL materials) was evaluated in accordance with the CLSI EP30-A and IFCC bias analysis. Median values obtained for the NCCL EQA materials were used to determine the systematic and commutability-related biases among immunoassays through back-calculation. The comparability of TSH measurements from a panel of clinical samples and NCCL EQA data was determined on the basis of Passing–Bablok regression. Furthermore, human serum pools were used to perform commutable EQA. Results NCCL EQA materials displayed commutability among three or five of seven assay combinations according CLSI or IFCC approach, respectively. The mean of systematic bias ranged from -13.78% to 9.85% for the eight routine TSH assays. After correcting for systematic bias, averaged commutability-related biases ranged between -42.26% and 12.19%. After correction for systematic and commutability -related biases, the slopes indicating interassay relatedness ranged from 0.801 to 1.299 using individual human sera, from 0.735 to 1.254 using NCCL EQA data, and from 0.729 to 1.115 using pooled human serum EQA(the commutable EQA). Conclusions The harmonization of TSH measurement is challenging; hence, systematic and commutability-related biases should be determined and corrected for accurate comparisons among assays when using human individual serum and the commercial EQA materials.

scholarly journals Harmonization of units and reference intervals of plasma proteins: state of the art from an External Quality Assessment Scheme

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Sandra Secchiero ◽  
Laura Sciacovelli ◽  
Mario Plebani
Keyword(s):  
Quality Assessment ◽  
Plasma Proteins ◽  
External Quality Assessment ◽  
Reference Intervals ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Wide Variability ◽  
The Face ◽  
Assessment And Monitoring ◽  
Coordination And Collaboration

Abstract Background: The need to harmonize laboratory information is particularly intense in the field of plasma proteins, considering their clinical impact and relevance in monitoring diseases. Methods: We evaluated units and reference intervals (RIs) utilized by participants of the External Quality Assessment Scheme (EQAS) for plasma proteins of the Centre of Biomedical Research. Moreover, we evaluated inter-laboratory analytical variability from 2001 to 2017. Results: The census of participants’ units employed in 2017 showed that for albumin (ALB), ~66% of laboratories still used dL instead of L, and for most other proteins, ~70% still expressed the results in mg/dL. Laboratories primarily used the RIs reported in the packaging inserts of their analytical systems, but for each protein, there was a wide variability of RIs, also among laboratories using the same analytical method. Mean CVs% of the 13 certified proteins in the last five EQA cycles ranged from 3.8% of haptoglobin (HPT) to 12.4% of α1-antitrypsin (AAT) and decreased from 2001 to 2017 for most of them, in particular for C3, ALB, α2-macroglobulin (A2M), HPT and transferrin (TRF). Conclusions: In the face of a reduction in inter-laboratory variability for a lot of proteins, there has not been a substantial change in the units and in the RIs used by the participants. To change old habits is difficult and requires coordination and collaboration. The EQAS plays an important role in the assessment and monitoring of all elements that contribute to the formulation of laboratory information and may be useful to contribute to their harmonization.

scholarly journals National Program for External Quality Assessment of Chinese Newborn Screening Laboratories

2020 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Yuxuan Du ◽  
Wei Wang ◽  
Jiali Liu ◽  
Zhixin Zhang ◽  
Zhen Zhao ◽  
...  
Keyword(s):  
Newborn Screening ◽  
Quality Assessment ◽  
Evaluation System ◽  
External Quality Assessment ◽  
Fold Increase ◽  
Thyroid Stimulating Hormone ◽  
External Quality ◽  
Quantitative Results ◽  
Hydroxy Progesterone ◽  
Glucose 6 Phosphate Dehydrogenase

Objectives: To analyze the coefficient of variation (CV) of external quality assessment (EQA) in Chinese newborn screening (NBS) laboratories. Method: EQA’s robust CV was analyzed by the Clinet-EQA evaluation system. Results: Participating laboratories of the EQA program increased annually. There was more than a 11-fold increase in phenylalanine (Phe) and thyroid stimulating hormone (TSH). It has shown a declining robust CV, which has tended to level off in recent years. The interquartile range (IQR) of Phe and TSH’s robust CV has decreased from 15.5% to 1.5% and from 22.8% to 1.8%, respectively. Compared to bacterial inhibition assay (BIA), the robust CV of Phe has been shown to be relatively reduced in the fluorescence assay and quantitative enzymatic assay (QEA). The robust CV by ELISA was relatively unstable compared to DELFIA and FEIA. In addition, the robust CVs of glucose-6-phosphate dehydrogenase (G6PD) and 17-alpha-hydroxy progesterone (17-OHP) by Genetic Screening Processor (GSP) were lower than other systems. The median of robust CV by non-derivatized MS/MS (Fenghua) in Phe and free carnitine were around 2.2–4.7% and 2.6–5.2%. Conclusion: Neonatal screening has developed rapidly in China and the majority of participant laboratories had satisfactory performance for the quantitative results.

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