scholarly journals PB2273 LABORATORY PERFORMANCE OF SERUM HOLOTRANSCOBALAMIN ASSAY IN THE UNITED KINGDOM (UK) AS ASSESSED BY THE UK NATIONAL EXTERNAL QUALITY ASSESSMENT SCHEME FOR HAEMATINICS

HemaSphere ◽  
2019 ◽  
Vol 3 (S1) ◽  
pp. 1016-1017
Author(s):  
V. Devalia ◽  
F. MacKenzie
Keyword(s):  
United Kingdom ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Laboratory Performance ◽  
The United Kingdom ◽  
The Uk

The UK National External Quality Assessment Scheme for Heritable Bleeding Disorders

2014 ◽  
Vol 40 (02) ◽  
pp. 261-268 ◽  
Author(s):  
David Perry ◽  
Tony Cumming ◽  
Anne Goodeve ◽  
Marian Hill ◽  
Ian Jennings ◽  
...  
Keyword(s):  
United Kingdom ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Wide Spectrum ◽  
Bleeding Disorders ◽  
The European Union ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
The United Kingdom ◽  
The Uk

Molecular genetic analysis of families with hemophilia and other heritable bleeding disorders is a frequently requested laboratory investigation. In the United Kingdom, laboratories undertaking genetic testing must participate in a recognized external quality assessment scheme for formal accreditation. The UK National External Quality Assessment Scheme (UK NEQAS) for heritable bleeding disorders was established in its current format in 2003, and currently has 27 registered participants in the United Kingdom, the European Union (EU), and the non-EU countries. Two exercises per annum are circulated to participants comprising either whole blood or DNA isolated from cell lines, and laboratories are allowed 6 weeks to analyze the samples and generate a report. Reports are assessed by a panel comprising clinicians and scientists with expertise in this area. Samples to date have involved analysis of the F8 gene (10 exercises), the F9 gene (4 exercises), and the VWF gene (3 exercises) and have comprised a wide spectrum of mutations representing the routine workload encountered in the molecular genetics laboratory. The majority of laboratories in each exercise passed, but a small number did not and reasons for failing included clerical errors, genotyping inaccuracies, and a failure to correctly interpret data. Overall we have seen an improvement in quality of reports submitted for assessment, with a more concise format that will be of value to referring clinicians and counsellors. Informal feedback from participants has been very positive.

scholarly journals Laboratory Performance of Serum Holotranscobalamin Assay in the United Kingdom (UK) As Assessed By the UK National External Quality Assessment Scheme for Haematinics

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5793-5793
Author(s):  
Vinod Devalia ◽  
Finlay Mackenzie
Keyword(s):  
United Kingdom ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
The Body ◽  
Serum Samples ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Target Value ◽  
The United Kingdom ◽  
The Uk

Background Although serum B12 assay is the most commonly used routine test for assessing cobalamin status in the body, it has its limitations (Mackenzie F and Devalia V (2018) Laboratory performance of serum B12 assay in the United Kingdom (UK) as assessed by the UK National External Quality Assessment Scheme for haematinics: implications for clinical interpretation. BLOOD, 132, suppl 1, 2230). Holotranscobalamin assay(HoloTC), also known as 'Active B12' assay, is an alternative test which is increasingly used as a first line test since it is felt to represent the assessment of the functional component of the cobalamin status of the body, and possibly a more relevant assessment clinically. However, its technical performance in terms of reliability and suitability in a routine diagnostic laboratory for clinical assessment has not been published. In the United Kingdom, there are over 30 laboratories performing the assay using five different platforms. The numerical value obtained of any sample can vary considerably between the different methodologies used.. External quality assessment of the assays is organised by UK NEQAS for Haematinics by sending three serum samples every 3 months. An 'all participants' consensus mean is calculated and used as the target value and the results analysed with respect to intra-group variation. The percentage bias from the target value is used to assess performance. Aim We present data on one such assessment to demonstrate the performance of the serum holotranscobalamin assay (Survey number 248, April 2018) and also how it is interpreted by the laboratory for clinical use. Method Three serum samples with a HoloTC target value of approximately 7.98 (low/indeterminate), 35.7 (normal/indeterminate) and 53.2 (normal) pmol/L were sent to participating laboratories for analysis (labelled as 248A, B and C respectively: see figure 1). Laboratories were also asked for an interpretation of their result which would be reported to the requesting clinician, namely from low to high (see figure 2). Results Fig 1 shows an individual laboratory's result in relation to all laboratories using the same technology (shaded histogram) or all methods (open histogram). There is a significant variation with an overall co-efficient of variation of around 10% within all the three different samples. Fig 2 shows the distribution of results in the different methodologies used and how each laboratory interpreted its result. It demonstrates the bias of results obtained by the different methods.The vast majority use the Abbot Architect (AB13) platform, and there is a suggestion of a trend of the results obtained to lie on the lower side than the other platforms used. For sample 248A, all laboratories reported it as 'low' or deficient. For sample 248B, there is a significant variation is reporting the sample as 'low', 'normal' or 'indeterminate' within the same platform used, clearly seen in the Abbot Architecture group. Indeed, the interpretation provided by the laboratory varies even with the same numerical value of the result. Discussion These data demonstrate that serum HoloTC assay has an overall co-efficient of variation around 10%. The numerical value obtained of any sample can vary considerably according to the technology used, and the clinical interpretation provided by the laboratory can be variable and not entirely concordant with the numerical result of the assay used. This is particularly evident around the 30-40 pmol/L range. This may be partly explained by the fact that it is not quite clear what would be regarded as the normal or reference range, which has been previously taken as 40 - 200 pmol/L (according to previous publications). Conclusion The UK NEQAS Haematinics Programme is unique in providing external quality assessment for laboratories using HoloTC assays for determining body cobalamin status in a style that is also unique across EQA/ PT schemes. Laboratories need to assess their performance in analysis of serum HoloTC levels in order to provide appropriate clinical advice. Ideally clinicians should be aware of the limitations of the HoloTC assay as demonstrated in this external quality assessment scheme exercise. Disclosures No relevant conflicts of interest to declare.

External quality assessment of assays of lead in blood.

1986 ◽  
Vol 32 (10) ◽  
pp. 1884-1889 ◽  
Author(s):  
D G Bullock ◽  
N J Smith ◽  
T P Whitehead
Keyword(s):  
United Kingdom ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Lead In Blood ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Scheme Design ◽  
The United Kingdom ◽  
Consensus Values ◽  
Variance Index

Abstract The operation and results of the United Kingdom External Quality Assessment Scheme for Lead in Blood, which currently has about 140 participants within and outside the U.K. are described. The choice of specimens, scheme design, and scoring of performance are discussed, as is the validity of the consensus values used as a basis for the scoring. There has been a continued improvement in performance as assessed by this program, some of which appears to have been stimulated by the introduction of Variance Index scoring. The relative performance of the methods for assaying lead in blood is also examined.

scholarly journals Quality of Performance of Assays for Maternal Serum Alphafetoprotein in the United Kingdom: Evidence from the UK External Quality Assessment Scheme 1980–87

1988 ◽  
Vol 25 (3) ◽  
pp. 310-318 ◽  
Author(s):  
J Seth ◽  
I Hanning ◽  
R R A Bacon ◽  
W M Hunter
Keyword(s):  
Neural Tube ◽  
External Quality Assessment ◽  
Maternal Serum ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Laboratory Performance ◽  
The United Kingdom ◽  
Assay Performance ◽  
The Uk

Between-laboratory agreement in the UK EQAS for maternal serum alphafetoprotein has improved steadily since 1976 and the geometric coefficient of variation is now 8 to 9% at levels of 50 to 150 kU/L. The use of a common standard and commercial assay kits appear to have contributed to this trend. Within-laboratory performance is also generally good, about 50% of participants maintain a bias of less than 5%, together with a scatter of the bias of less than 10%. These data indicate that the quality of assay performance is adequate for the requirements of screening programmes for open neural tube effects. The improvement in laboratory performance is such that between-laboratory agreement is better expressed in kU/L than as multiples of the median. Errors in interpretation of clearly normal or abnormal results appear to be rare (0·4%), and contribute little to overall false positive and negative rates. However. they assume significance as most arc due to avoidable errors.

scholarly journals Laboratory Performance of Serum B12 Assay in the United Kingdom (UK) As Assessed By the UK National External Quality Assessment Scheme for Haematinics: Implications for Clinical Interpretation

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2230-2230 ◽  
Author(s):  
Finlay Mackenzie ◽  
Vinod Devalia
Keyword(s):  
United Kingdom ◽  
Quality Assessment ◽  
Serum Sample ◽  
External Quality Assessment ◽  
British Society ◽  
External Quality ◽  
Clinical Interpretation ◽  
Target Value ◽  
The United Kingdom ◽  
The Uk

Abstract Serum B12 assay is the most commonly used routine test for assessing cobalamin status in the body. In the United Kingdom, there are around 350 laboratories performing the assay using seven different platforms. External quality assessment of the assays is organised by UK NEQAS for Haematinics by sending a serum sample every 3 months. An 'all participants' consensus mean is calculated and used as the target value and the results analysed with respect to intra- and inter- group variation. The percentage bias from the target value is used to assess performance. We present data on one such assessment to demonstrate the problems of the serum B12 assay (Survey number 248, April 2018) and also how it is interpreted by the laboratory for clinical use. Method A serum sample with a B12 target value of approximately 173 ng/L was sent to participating laboratories for analysis. Laboratories were also asked for an interpretation of their result which would be reported to the requesting clinician, namely from low to high. Results Fig 1 shows an individual laboratory's result (indicated by the arrow) in relation to all laboratories using the same technology (shaded histogram) or all methods (open histogram). There is a significant variation ranging from 86 to 258 ng/L depending on the assay used, with an overall standard deviation of 28 and co-efficient of variation of 16%. Fig 2 shows the distribution of results in the different methodologies used and how each laboratory interpreted its result. It demonstrates the bias of results obtained by the different methods. The assays using Beckman Coulter Access/Dxl (SF5 and SF6) gave much lower results than other methods. In the group SF5, three laboratories interpreted the result as 'normal' and one as 'indeterminate'. In the groups Abbot Architect (AB13) and Roche Cobas/Modular (BO5), although having higher results than other groups, there is a significant number of laboratories interpreting the result as 'low' and also 'normal' or 'indeterminate'. Fig 3 shows a graphical representation of an individual laboratory's performance bias and the consistency of its individual and group bias over a period of 6 months. The Bias score (B score on y axis) is how far the result obtained deviated from the target value. The C score (on x axis) informs on consistency of the bias over the past 6 months. Hence, ideally both B score and C score should be as low as possible, and therefore all methodologies would harmonise towards similar results. Discussion These data demonstrate the limitations of the serum B12 assay in assessing body B12 status. The numerical value obtained of any sample can vary considerably between the different methodologies used. In addition, the interpretation provided by the laboratory can also be highly variable. This may have profound implications for clinical assessment and management. In addition, this is compounded by the fact that it is not quite clear what would be regarded as the normal or reference range. Laboratories in the United Kingdom use the manufacturers ranges and clinicians may consult the British Society for Haematology Guidelines (Devalia V et al (2014) BCSH Guidelines for the diagnosis and treatment of cobalamin and folate disorders. British Journal of Haematology, 166, 496-513) for help in clinical interpretation. Our data shows that the different reference ranges quoted by the kit manufacturers do not correspond to their assay bias, ie there is no simple direct correlation between the ranges provided against the bias of their particular assay. Conclusion The UK NEQAS Haematinics Programme demonstrates problems associated with the serum B12 assay with data on variation of results obtained, bias and interpretation of results in a style that is unique across currently available Proficiency Testing/ External Quality Assessment schemes. Laboratories need to be aware of their performance in assessing serum B12 level in order to provide appropriate clinical advice. This needs collection of feedback and audit of data of the clinical situation for which the request was made. Clinicians need to be aware of the performance of their laboratories in order that they can interpret the result provided in a meaningful way in relation to the clinical picture. Disclosures No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document