scholarly journals An approach for estimating measurement uncertainty in medical laboratories using data from long-term quality control and external quality assessment schemes

2017 ◽  
Vol 55 (11) ◽  
Author(s):  
Andrea Padoan ◽  
Giorgia Antonelli ◽  
Ada Aita ◽  
Laura Sciacovelli ◽  
Mario Plebani
Keyword(s):  
Quality Control ◽  
Measurement Uncertainty ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Internal Quality ◽  
Test Results ◽  
External Quality ◽  
Iso 15189 ◽  
Medical Laboratories

AbstractBackground:The present study was prompted by the ISO 15189 requirements that medical laboratories should estimate measurement uncertainty (MU).Methods:The method used to estimate MU included the: a) identification of quantitative tests, b) classification of tests in relation to their clinical purpose, and c) identification of criteria to estimate the different MU components. Imprecision was estimated using long-term internal quality control (IQC) results of the year 2016, while external quality assessment schemes (EQAs) results obtained in the period 2015–2016 were used to estimate bias and bias uncertainty.Results:A total of 263 measurement procedures (MPs) were analyzed. On the basis of test purpose, in 51 MPs imprecision only was used to estimate MU; in the remaining MPs, the bias component was not estimable for 22 MPs because EQAs results did not provide reliable statistics. For a total of 28 MPs, two or more MU values were calculated on the basis of analyte concentration levels. Overall, results showed that uncertainty of bias is a minor factor contributing to MU, the bias component being the most relevant contributor to all the studied sample matrices.Conclusions:The model chosen for MU estimation allowed us to derive a standardized approach for bias calculation, with respect to the fitness-for-purpose of test results. Measurement uncertainty estimation could readily be implemented in medical laboratories as a useful tool in monitoring the analytical quality of test results since they are calculated using a combination of both the long-term imprecision IQC results and bias, on the basis of EQAs results.

Applicability of various quality-control sera to assay of high-density lipoprotein cholesterol.

1980 ◽  
Vol 26 (7) ◽  
pp. 903-907
Author(s):  
D G Bullock ◽  
T J Carter ◽  
S V Hughes
Keyword(s):  
Quality Control ◽  
High Density Lipoprotein ◽  
Quality Assessment ◽  
High Density Lipoprotein Cholesterol ◽  
External Quality Assessment ◽  
Density Lipoprotein ◽  
High Density ◽  
Lipoprotein Cholesterol ◽  
Internal Quality ◽  
External Quality

Abstract Effective internal quality control and external quality assessment of high-density lipoprotein cholesterol assay is made difficult by analyte instability, and the suitability of quality-control sera for this purpose has not been studied. We have therefore investigated the properties of 25 different control sera from 15 suppliers by estimating within-batch precision for the two precipitation procedures used most widely (phosphotungstate/Mg2+ and heparin/Mn2+ with enzymic measurement of cholesterol. Some sera had properties similar to those of fresh human serum, but others demonstrated poor precision for one or both procedures or contained apparent high-density lipoprotein cholesterol in unphysiological concentrations. A study of six sera indicated that between-batch precision was consistent with the within-batch findings. We found that eight of the 25 batches of quality-control serum we investigated may be used for internal quality control and external quality assessment of high-density lipoprotein cholesterol assay.

The application of Six Sigma to perform quality analyses of plasma proteins

2019 ◽  
Vol 57 (2) ◽  
pp. 121-127
Author(s):  
Fumeng Yang ◽  
Wenjun Wang ◽  
Qian Liu ◽  
Xizhen Wang ◽  
Guangrong Bian ◽  
...  
Keyword(s):  
Quality Control ◽  
Quality Assessment ◽  
Six Sigma ◽  
Plasma Proteins ◽  
External Quality Assessment ◽  
Internal Quality ◽  
C Reactive Protein ◽  
External Quality ◽  
Reactive Protein ◽  
Assessment Standards

Background The Six Sigma theory is an important tool for laboratory quality management. It has been widely used in clinical chemistry, haematology and other disciplines. The aim of our study was to evaluate the analytical performance of plasma proteins by application of Sigma metric and to compare the differences among three different allowable total errors in evaluating the analytical performance of plasma proteins. Methods Three different allowable total error values were used as quality goals. Data from an external quality assessment were used as bias, and the cumulative coefficient of variation in internal quality control data was used to represent the amount of imprecision during the same period. Sigma metric of analytes was calculated using the above data. The quality goal index was calculated to provide corrected measures for continuous improvements in analytical quality. Results The Sigma metric was highest using the external quality assessment standards of China: it was sigma ≥6 or higher in 57.1% of plasma proteins. But Sigma metric was lower by using RiliBÄK or biological variation standards. IgG, C3 and C-reactive protein all required quality improvements in imprecision. A single-rule 13s for internal quality control was recommended for IgA, IgM, C4 and rheumatoid factor, whereas multiple rules (13s/22s/R4s) were recommended for IgG, C3 and C-reactive protein, according to the external quality assessment standards of China. Conclusions Different quality goals can lead to different Sigma metric for the same analyte. As the lowest acceptable standard in clinical practice, the external quality assessment standard of China can guide laboratories to formulate reasonable quality improvement programmes.

Quality assurance in laboratory haematology

1993 ◽  
Vol 101 ◽  
pp. 283-310
Author(s):  
S. M. Lewis
Keyword(s):  
Quality Control ◽  
Quality Assurance ◽  
Quality Assessment ◽  
Blood Count ◽  
External Quality Assessment ◽  
Blood Film ◽  
Test Reliability ◽  
Internal Quality ◽  
External Quality ◽  
External Quality Assessment Scheme

SynopsisQuality assurance in laboratory haematology includes (a) constant checking of test reliability by internal quality control, (b) external quality assessment by an independent agency to check performance of a number of laboratories at intervals in order to obtain a retrospective indication of their ability and (c) proficiency control by supervision of the pre-test and post-test phases of laboratory work, from specimen collection to delivery of the report to the clinician.The procedures which comprise quality control are described; these include use of control preparations with control charts, CUSUM analysis, constancy of daily means of the blood count indices of ‘absolute values’, duplicate testing, clinical correlation and the important role of the blood film to check the instrument-derived blood count measurements.A description of the functions of an external quality assessment scheme is based on the UK National Scheme (UK NEQAS). The blood count and other tests of general haematology have been used as models to describe the procedures for qualitative and quantitative tests, low results are analysed and performance is assessed. The tribulations and triumphs of NEQAS are described and it is concluded that NEQAS has a vital role in ensuring good laboratory practice in general, and the reliability of the individual laboratories who participate in the scheme. NEQAS, in turn, must ensure its own ability to provide stable materials which are suitable for each test in the programme, and to analyse data correctly. There is also need to take account of the continued expansion of laboratory services as new techniques are introduced and to develop appropriate EQA procedures and materials in order to incorporate these in a comprehensive scheme.

External Quality Assessment of Serum Alpha-Fetoprotein Assays

1980 ◽  
Vol 17 (6) ◽  
pp. 332-333 ◽  
Author(s):  
J S Woodhead ◽  
Heather A Kemp ◽  
A B J Nix ◽  
R J Rowlands
Keyword(s):  
Quality Control ◽  
Quality Assessment ◽  
Neural Tube ◽  
External Quality Assessment ◽  
Maternal Serum ◽  
Alpha Fetoprotein ◽  
Internal Quality ◽  
External Quality ◽  
Individual Laboratory ◽  
Serum Alpha Fetoprotein

Adequate control of performance in immunoassays of maternal serum alpha-fetoprotein is an essential part of screening for neural tube defects. Information derived from external quality assessment schemes may be of limited value in monitoring individual laboratory performance and stresses the need for proper internal quality control.

External Quality Assessment/Proficiency Testing and Internal Quality Control for the PFA-100 and PFA-200: An Update

2014 ◽  
Vol 40 (02) ◽  
pp. 239-253 ◽  
Author(s):  
Emmanuel Favaloro ◽  
Roslyn Bonar
Keyword(s):  
Quality Control ◽  
Quality Assessment ◽  
Platelet Function ◽  
Whole Blood ◽  
External Quality Assessment ◽  
Internal Quality ◽  
External Quality ◽  
Platelet Function Testing ◽  
Primary Hemostasis ◽  
Function Testing

Platelet function testing is an essential component of comprehensive hemostasis evaluation within the framework of bleeding and/or bruising investigations, and it may also be performed to evaluate antiplatelet medication effects. Globally, the platelet function analyzer (PFA)-100 (Siemens Healthcare, Marburg, Germany) is the most used primary hemostasis-screening instrument and has also been recently remodeled/upgraded to the PFA-200. The PFA-100 is sensitive to a wide range of associated disorders, including platelet function defects and von Willebrand disease (VWD), as well as to various antiplatelet medications. The PFA-100 is also useful in therapy monitoring, especially in VWD. External quality assessment (EQA) (or proficiency testing) and internal quality control (IQC) are critical to ensuring quality of test practice, inclusive of all hemostasis tests. However, both EQA and IQC for platelet function testing, including the PFA-100, is logistically challenging, given theoretical requirements for production, storage, and shipment of large volumes of “stabilized” normal and pathological blood/platelets covering both normal function plus a wide variety of potential defects. We accordingly describe the development and testing of novel feasible approaches to both EQA and IQC of PFA-100/PFA-200 instruments, whereby a range of formulated “platelet function antagonist” materials are utilized. For EQA purposes, these are distributed to participants, and citrated normal whole blood collected on site is then added locally, thereby creating test material that can be locally evaluated. Several exercises have been conducted by the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) over the past 6 years. A total of 26 challenges, with most designed to mimic moderate to severe primary hemostasis defects, have been tested in 26 to 50 laboratories depending on the year of dispatch. Numerical results for PFA-100/PFA-200 closure times (CTs) and interpretive comments supplied by participants are analyzed by the RCPAQAP. During this period, reported CTs for each challenge were within limits of expectation and good reproducibility was evidenced by repeated challenges. Coefficients of variation (CVs) generated for challenges using the two major PFA-100/PFA-200 cartridge types (collagen/adenosine diphosphate and collagen/epinephrine) are always similar to those obtained using native whole blood, and in general range from 15 to 25%. Interpretations are also in general consistent with expectations and test data provided by laboratories. The EQA created material has also been assessed within the context of possible IQC material. In conclusion, EQA and IQC processes for the PFA-100/PFA-200 have been developed that include highly reproducible test challenge processes, not only supporting the concept that EQA/IQC is possible for platelet function testing but also providing a valuable mechanism for monitoring and improving laboratory performance in this area.

Applicability of various quality-control sera to assay of high-density lipoprotein cholesterol.

1980 ◽  
Vol 26 (7) ◽  
pp. 903-907 ◽  
Author(s):  
D G Bullock ◽  
T J Carter ◽  
S V Hughes
Keyword(s):  
Quality Control ◽  
High Density Lipoprotein ◽  
Quality Assessment ◽  
High Density Lipoprotein Cholesterol ◽  
External Quality Assessment ◽  
Density Lipoprotein ◽  
High Density ◽  
Lipoprotein Cholesterol ◽  
Internal Quality ◽  
External Quality

Abstract Effective internal quality control and external quality assessment of high-density lipoprotein cholesterol assay is made difficult by analyte instability, and the suitability of quality-control sera for this purpose has not been studied. We have therefore investigated the properties of 25 different control sera from 15 suppliers by estimating within-batch precision for the two precipitation procedures used most widely (phosphotungstate/Mg2+ and heparin/Mn2+ with enzymic measurement of cholesterol. Some sera had properties similar to those of fresh human serum, but others demonstrated poor precision for one or both procedures or contained apparent high-density lipoprotein cholesterol in unphysiological concentrations. A study of six sera indicated that between-batch precision was consistent with the within-batch findings. We found that eight of the 25 batches of quality-control serum we investigated may be used for internal quality control and external quality assessment of high-density lipoprotein cholesterol assay.

External quality assessment (EQA) and alternative assessment procedures (AAPs) in molecular diagnostics: findings of an international survey

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Deborah A. Payne ◽  
Graciela Russomando ◽  
Mark W. Linder ◽  
Katarina Baluchova ◽  
Tester Ashavaid ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Molecular Diagnostics ◽  
Alternative Assessment ◽  
External Quality Assessment ◽  
Clinical Chemistry ◽  
Molecular Diagnostic ◽  
Internal Quality ◽  
External Quality ◽  
Iso 15189 ◽  
Eqa Schemes

AbstractObjectivesQuality management for clinical laboratories requires the establishment of internal procedures including standard operating procedures (SOPs), internal quality control (QC), validation of test results and quality assessment. External quality assessment (EQA) and alternativeassessment procedures (AAPs) are part of the quality hierarchy required for diagnostic testing. The International Organization for Standardization (ISO) document with requirements for conformance ISO 15189 and the Clinical and Laboratory Standards Institute document (CLSI) QMS24 require participation in EQA schemes and AAPs where applicable. The purpose of this study was to perform a global survey of EQA and AAPs for key procedures in molecular diagnostic laboratories.MethodsThe Committee for Molecular Diagnostics of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC C-MD) conducted a survey of international molecular laboratories that covered specific topics of molecular diagnostic services as well as methods for EQA and AAPs. The survey addressed the following aspects: (1) usage of laboratory-developed test (LDT), (2) participation in EQA schemes and (3) performance of AAPs.ResultsA total of 93 responses from laboratories located in Asia, Europe, the Middle East, North America and South America were received. The majority of the participating laboratories (65.9%) use LDTs and 81.3% stated that it is mandatory for them to participate in EQA programs, while 22% of the laboratories reported not performing AAPs. Thirty-one percent of the laboratories use EQAs for fewer than 50.0% of their reported parameters/analytes.ConclusionsWhile the majority of laboratories perform EQA and AAPs to improve their quality in molecular diagnostics, the amount of AAPs as quality procedures differs within the laboratories. Further surveys are necessary to clarify the existing needs in additional EQAs and standardized AAPs. The survey will also guide future efforts of the IFCC C-MD for identifying quality practices in need to improve harmonization and standardization within molecular diagnostics.

Combi scheme: new combined internal/external quality-assessment scheme in The Netherlands

1991 ◽  
Vol 37 (7) ◽  
pp. 1196-1204 ◽  
Author(s):  
Herman Steigstra ◽  
Rob T Jansen ◽  
Henk Baadenhuijsen
Keyword(s):  
The Netherlands ◽  
Quality Assessment ◽  
Internal Control ◽  
External Quality Assessment ◽  
Clinical Chemistry ◽  
Laboratory Data ◽  
Data Communication ◽  
Professional Organization ◽  
Internal Quality ◽  
External Quality

Abstract The Dutch Foundation for Quality Assessment in Clinical Chemistry (SKZL) is the professional organization that conducts external quality-assessment schemes in The Netherlands. However, such schemes in fact assess the performance of the internal quality-control systems of the participating laboratories. In this paper we describe a new concept, relating the data for internal control materials with those for external samples and thereby leading to a combined external/internal scheme (Combi). The statistical principles underlying the Combi scheme are discussed and examples of the graphical presentation of the results are shown. Because the laboratory data are transmitted over the public telephone system to the computers of the SKZL, we also describe the principles of the data communication. At two-month intervals a statistical presentation is sent to all participants. The central database is updated daily with the received results, making possible an on-line consultation regarding the statistics of the accumulated findings of the control materials in use.

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