UK National External Quality Assessment Research Articles

Differences between multifibrin U and conventional Clauss fibrinogen assays: data from UK National External Quality Assessment Scheme surveys

The measurement of fibrinogen is an important part of a haemostatic investigation and has traditionally been performed in the majority of clinical laboratories using a Clauss fibrinogen method [1]. More recently, automated coagulometers using optical endpoint detection systems have been developed, allowing use of fibrinogen measurements derived from the clotting curve characteristics of the prothrombin time measurement (PTderived fibrinogen). Several reports [2,3] including data from the UK National External Quality Assessment Scheme (NEQAS; Blood Coagulation) EQA exercises demonstrated clinically important differences between Clauss and PT-derived fibrinogen measurements in subgroups of patients and led to a recommendation that the PT-derived method be not used as a primary method for fibrinogen estimation [4].

Digital Morphology Accessed by the Internet to Support Continuing Professional Development for Laboratory Staff

Between April 2005 and September 2007 the UK National External Quality Assessment Scheme for General Haematology (UK NEQAS (H)) trialled an internet based pilot scheme for Digital Morphology. The Scheme was registered with the Institute of Biomedical Science for Continuing Professional Development. Participating laboratories of the conventional glass slides Morphology External Quality Assessment Scheme were invited to register one individual to participate, in April 2006 registration was increased from 221 to 413 individuals from 14 countries (>85% UK). Following closure of the successful pilot scheme UK NEQAS (H) launched a full internet based Digital Morphology Scheme in April 2008. We report on the initial results from this novel digital morphology scheme.The scheme is aimed at providing educational feedback for the laboratory scientists who participate. Laboratory managers are invited to register their staff with UK NEQAS(H), participants are then instructed by email when surveys are available for analysis and access the cases by the internet. Cases are built from high quality images, blended and stitched, to give large scale fields of view, equal to an area of at least 60 separate fields at × 60 objective. The “virtual slides” are viewed using appropriate software to allow the participant to move across the image, alter viewer settings and change magnification of the image. Morphology comment assessment sheets are then accessed along with the image and participants complete and submit their findings on line. Once submission is completed the participant has immediate access to detailed educational information about the morphology of the case, including electronic links to relevant internet sites. Once the survey has closed participants receive an email allowing then to access overall completed case data including consensus data from the survey, statistical data and expert opinion. Furthermore they can print a reflective report of their findings against the consensus data.Since April 2008 two surveys have been fully completed and three more are due for release before the end of the year. For the last release (a case of TPLL), 552 individuals fully completed the survey, whilst a further 51 accessed the case but did not fully complete. Some 95 laboratory managers have registered laboratory staff for the scheme with 1102 individuals now registered for the next case release. Although this novel digital morphology scheme is an initial phase, the keen interest shown by laboratory managers in the UK to register the staff who routinely report morphology may reflect the requirement of laboratories to present evidence that staff are being educated and maintaining their skills in morphology. The system allows participants immediate access to relevant material and examples of morphological features using annotated quality images.The Scheme's aim is one of educatin rather than assessment, directed at individuals rather than laboratories or centres. With the key theme of personal professional development promoting improvement to the quality of heamatological morphology this novel internet based Scheme has potential for expansion internationally.

Platelet function testing: practice among UK National External Quality Assessment Scheme for Blood Coagulation participants, 2006

Aims:Platelet function testing forms an important part of the laboratory investigation of a bleeding tendency; however, little standardisation and quality control is available for these tests. A UK National External...

An assessment of the Ortho ELT-8

The Ortho ELT-8 is an automated blood counter which appears to be safe, precise and free from carry-over. Red and white cell results generally agree with those on the Coulter Counter, Model S, though discrepancies were noted with the WBC and PCV. Reference methods showed the Model S WBC results tended to be inaccurate on the discrepant samples though neither instrument was predominantly responsible for the PCV discrepancies. The ELT-8 platelet count tended to be higher than with the Thrombocounter/Thrombofuge system. When packed cells were diluted in autologous plasma serious variations in the red cell indices (MCV, MCH & MCHC) were first found due to incorrect voltage-frequency converter setting. Even after this setting had been corrected some variations in the MCH and MCHC were still apparent. In the UK National External Quality Assessment Scheme the ELT-8 results on animal bloods did not agree with those produced by Model S users; this discrepancy probably being due to differences between the light-scattering and aperture-impedance technology.

The UK national external quality assessment scheme in blood group serology. Compatibility testing 1981-1982: performance and practice.

The design of exercises of compatibility testing was modified in 1981 in order better to accommodate participants' serological practices. Ten reference laboratories were also enrolled in order to determine the 'correct' results for each exercise. In 1981-1982 3.5 to 36% of participants missed incompatibilities in exercises in which undiluted antibodies were issued and this did not represent an improvement over performance obtained in 1979-1980. Surveys were undertaken of antiglobulin test procedures and revealed that serological practices continue to change, old techniques are being modified, new techniques are being employed but standardization shows little overall improvement. Surveys of quality control procedures and of cross-match procedures for agglutination in albumin and for agglutination of enzyme treated cells show equal lack of standardization.

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1979-1980: trends and performance in relation to practice in antiglobulin testing

Surveys of antiglobulin test procedures and reagents were undertaken in 1979-1980 as part of a national external quality assessment scheme in compatibility testing. An extraordinary lack of standardization was revealed. In addition, practices underwent considerable changes over this period. The use of tube and of low ionic strength solution (LISS) techniques increased whilst the use of tile and of albumin-antiglobulin techniques declined. Performance in compatibility test exercises was significantly better with tube techniques than with tile techniques in 9/22 incompatibilities. Performance with LISS techniques was occasionally significantly better than with normal ionic strength techniques. Performance with albumin-antiglobulin techniques was occasionally significantly worse than in the absence of albumin. To varying extents significant relationships were found between performance and cell concentration, serum/cell concentration ratio, antiglobulin reagent and method of reading the results.

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1979-1980: trends and performance in relation to practice in antiglobulin testing

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1979-1980: trends and performance in relation to practice in antiglobulin testing

The UK National External Quality Assessment Scheme in Blood Group Serology, Compatibility testing 1979-1980.

Seven proficiency tests in compatibility testing were issued in 1979 to 1980. In each exercise participants were required to test five sera, most of which contained alloantibodies, against three samples of red cells by three designated techniques, namely agglutination in saline at room temperature, agglutination in albumin at 37 degrees C and the antiglobulin test at 37 degrees C. Comparability was achieved by scoring of results. Incompatibilities were missed by 3.5 to 22% of participants in five exercises in which undiluted antibodies were issued. There was no significant improvement in performance over two years. Antibodies which were issued diluted, but detectable by antiglobulin test, were missed with high frequency.

Revision of national guidelines for cerebrospinal fluid analysis in suspected subarachnoid haemorrhage

National guidelines for analysis of cerebrospinal fluid (CSF) in suspected subarachnoid haemorrhage (SAH) were published by a UK National External Quality Assessment Scheme (NEQAS) Immunochemistry Working Group in 2003. These guidelines provided recommendations on sampling requirements, spectrophotometric analysis and interpretation of results. The same group, having evolved into the UK NEQAS Specialist Advisory Group for External Quality Assessment (EQA) of CSF Proteins and Biochemistry, published in 2007 the results of the audit it conducted into current UK laboratory practice for the biochemical investigation of CSF. As a result of the findings of this audit and in the light of experience in the use of the 2003 guidelines, amendments have been made to the original guidelines and the revised guidelines are published in this journal. The main aims of the revision are threefold: to ensure that CSF is always analysed spectrophotometrically if sufficient sample is received; to downgrade the clinical significance of detecting small amounts of haemoglobin with no increase in bilirubin; and to emphasize the clinical significance of increased bilirubin with a visible oxyhaemoglobin absorbance peak irrespective of CSF protein or serum bilirubin concentrations. The National Audit of CSF Testing identified 78 laboratories which offered spectrophotometric analysis of CSF either on site or elsewhere. Twenty-one of these 78 laboratories rejected samples delivered by pneumatic tube, 17 rejected heavily blood-stained samples and 14 rejected samples taken outwith sample timing guidelines. These sample rejection policies are indefensible because useful information may be gained from spectrophotometry in all of these circumstances. CSF usually will be blood-stained following SAH – blood staining does not necessarily reflect a traumatic tap. The detection of increased bilirubin is significant irrespective of the mode of sample delivery or sample timing. Use of pneumatic tube would not be expected to cause false-negative bilirubin results. CSF is precious. Repeat sampling is invasive and interpretation of any positive results highly problematic. Laboratories are duty bound to analyse any CSF sample if sufficient is received and to interpret the results in the light of all the available information. It is the combined experience of the group over several years that the probability of SAH in a patient whose correctly timed CSF sample contains only small amounts of oxyhaemoglobin is vanishingly small. We know of one patient with a posterior communicating artery aneurysm whose CSF sample had a borderline net bilirubin absorbance (0.0067 AU) with a net oxyhaemoglobin absorbance of 0.067 AU. We are aware of no other cases of SAH where the CSF sample had a net oxyhaemoglobin absorbance ,0.1 AU and a net bilirubin absorbance 0.007 AU. The reporting comment recommended in the original guidelines for such samples ‘oxyhaemoglobin on its own has a low predictive value for SAH but does not exclude’ confuses and frustrates clinicians. We recommend that it be replaced by the less ambiguous comment ‘no evidence to support SAH’. In the original guidelines, the recommended interpretation effectively downgrades the likelihood of SAH when net bilirubin absorbance .0.007 AU but CSF protein concentration is .1 g/L. The 1 g/L cut-off is an arbitrary figure selected in recognition of the fact that high CSF protein concentrations (and therefore bilirubin absorbances) may reflect alternative pathology such as meningitis. However, it is important that biochemists realize that by its nature SAH usually results in a raised CSF protein concentration, sometimes .1 g/L. A blood-stained CSF sample with increased oxyhaemoglobin and bilirubin absorbances and CSF protein concentration .1 g/L is entirely consistent with SAH. For example, of 18 cases of SAH

National audit of cerebrospinal fluid testing

UK National External Quality Assessment Service (NEQAS) Specialist Advisory Group for EQA of CSF Proteins and Biochemistry was interested in current practice for the biochemical investigation of cerebrospinal fluid (CSF) in the UK. A questionnaire was sent to laboratories via regional audit committees and the results collated. Most laboratories were analysing CSF in a satisfactory manner. There was some variation in the reference ranges used for glucose, protein and lactate. There was concern about the rejection policies of some laboratories on these unrepeatable samples and the wavelengths used to measure bilirubin. The survey revealed the lack of spectrophotometric scanning for haem pigments and bilirubin in some hospitals. The current practice for the measurement of CSF samples in the UK is satisfactory in most laboratories responding to the questionnaire. National agreement on reference ranges for glucose, protein and lactate should be achievable. Those performing spectrophotometric scanning of the CSF were doing so in concordance with the national guidelines. Some hospitals in the UK may not have responded to the questionnaire because they did not offer spectrophotometric scanning.

International Lecture: Standardization of Immunohistochemistry: Is It Achievable?

Today, the use of immunohistochemistry (IHC) is widespread. It sometimes seems that no tumor diagnosis is complete without it. (Of course, many cases do not need IHC to support the pathology or indeed to predict whether subsequent treatment may be effective.) Although IHC is now a large part of diagnostic pathology today, it seems quite incredible to think that standardization across the globe is still a long way off. UK National External Quality Assessment Service (UK EQAS) is in the privileged position to see large numbers of “in-house” control sections. Many are both well processed and stained. However, an increasing number are poorly fixed and, as a consequence, are poorly stained. Within the United Kingdom, we are able to provide advice and help when laboratories get into difficulty. When participants beyond our boundaries have problems, and especially within Europe, it is not so easy to help without being seen as intrusive. So what is the solution? Ideally, we need a consortium of external quality assessment services that work hand-in-hand. Funding is, of course, an issue but within Europe Framework 7, monies are possibly available to start-up such a program.

Should Spectrophotometry Be Used to Identify Xanthochromia in the Cerebrospinal Fluid of Alert Patients Suspected of Having Subarachnoid Hemorrhage?

To the Editor: We read with interest the article by Perry and colleagues.1 There appears to be a reluctance in North America to embrace what we believe to be the most sensitive method for demonstrating bilirubin in cerebrospinal fluid (CSF), spectrophotometry, on the basis that it is not requested, that the equipment does not exist and that it is difficult to interpret.1,2 It is then somewhat disingenuous to criticize spectrophotometry by using 4 methods, the first of which (‘traditional’) has many deficiencies which have been well documented3,4; the second of which (‘Chalmers and Kiley’)5 has been superseded by the third (‘Chalmers revised’) …

The authors of the article cited above respond:

The European Concerted Action on Anticoagulation (ECAA) includes the founder and former long-term organizer of the UK National External Quality Assessment Scheme (NEQAS) and the WHO International External Quality Assessment Scheme in blood coagulation as well as current European national external quality assessment (EQA) organizers. We strongly endorse the 2 main points made by Kitchen and his UK NEQAS colleagues, that EQA for point-of-care international normalized ratio (INR) devices should be mandatory and caution is required when interpreting data from lyophilized plasma samples analyzed with whole blood prothrombin time (PT) monitors. During the past several years, the ECAA and its successor, European Action on Anticoagulation (EAA), have published data on both of these concerns in more than 60 reports, including 4 in Clinical Chemistry . With regard to plasma/whole blood differences, the ECAA initially studied the reliability of use of plasma samples in calibrating the CoaguChek monitor (1) with an international sensitivity index (ISI). An optimum formulation of …

Thyroid guidelines - are thyroid-stimulating hormone assays fit for purpose?

Most thyroid-stimulating hormone (TSH) assays now have the sensitivity required by thyroid guidelines and allow the reliable identification of patients with both overt and subclinical hyperthyroidism. Clinical guidelines usually quote decision limits for TSH, but often ignore the issue of whether variability in bias between assays should be considered when such decision limits are implemented. Clinicians and laboratories should appreciate that these decision limits arise largely from historical data that used TSH assays with poorly defined bias. It is thus unlikely that laboratories will be able to apply an appropriate method-related bias adjustment to these TSH cut-offs. Clinicians should appreciate that TSH decision limits should thus be regarded as typical target figures rather than an absolute cut-off and thus can be applied with some degree of flexibility. There is currently insufficient evidence to justify a significant lowering of the upper reference limit for TSH, but fine-tuning of current reference ranges is required since there appears to be no association between the ranking of the assay bias in the UK National External Quality Assessment Service scheme and the manufacturers' quoted reference ranges. There is room for further improvement in TSH assays and this can best be achieved if manufacturers, laboratories and clinicians work together to produce TSH assays and reference ranges that show closer agreement between methods. Until this is achieved, future studies that examine the relationship of TSH with symptoms and treatment should ensure that sufficient information is included in the publication to allow the method related bias of the TSH assay to be clearly described.

Variation in GH and IGF‐I assays limits the applicability of international consensus criteria to local practice

There is increasing reliance on consensus criteria for decision making. Recent criteria state that acromegaly is excluded by a nadir GH during an oral glucose tolerance test (OGTT) of < 1 microg/l and a normal level of IGF-I. To study GH and IGF-I assay performance close to cut-off values for active acromegaly. Two serum samples known to give borderline results were sent to all centres participating in the UK National External Quality Assessment Service (NEQAS). Sample A was assigned to be a nadir during an OGTT and sent for GH assessment to 104 centres. Sample B, with a clinical scenario, was sent to 23 centres that measure IGF-I, and these centres were asked to measure IGF-I, interpret the result and provide the source of their reference ranges (RRs). For sample A, the median GH was 2.6 mU/l (range 1.04-3.5 mU/l). Applying a conversion factor (CF) of 2.0 (1 microg/l = 2 mU/l), the most negatively biased method classified 10% of the values consistent with acromegaly, while the most positively biased method classified all values as consistent with the diagnosis. Applying a CF of 3.0 (1 microg/l = 3 mU/l), only 11% of results were consistent with acromegaly. For sample B, the median IGF-I was 50.8 nmol/l (range 24.3-60.9 nmol/l). All centres used age-related RRs. There was a 50% variation in the upper limit of the RRs between centres. Overall, 30% of the IGF-I results were against the diagnosis. There was little agreement in the RRs quoted by centres using the same method. Variability in assay performance, coupled with use of inappropriate CFs and RRs, undermines the applicability of international consensus criteria to local practice.

Technical aspects of predictive and prognostic markers in breast cancer: What UK NEQAS data shows

Predictive and prognostic testing for breast cancer is now an important part of cellular pathology. The UK National External Quality Assessment Scheme (NEQAS) for immunocytochemistry and fluorescent in situ hybridization plays a significant role in ensuring that the quality of testing meets the clinical standards required, by assessing the performance of each participant laboratory every 3 months. Besides receiving a confidential performance report, data on the methods used are collected, analysed against the scores and published in the UK NEQAS journal. This information is intended to help those who are not achieving the best scores to improve their performance.

Dehydroepiandrostenedione sulphate interferes in many direct immunoassays for testosterone

In response to a report that the Abbott Architect direct testosterone immunoassay was affected by dehydroepiandrostenedione sulphate (DHEAS) cross-reactivity, this study investigated the effect of DHEAS on other testosterone methods using a UK National External Quality Assessment Scheme (UK NEQAS) for steroid hormones special distribution. Separate male and female matrix pools of normal human serum were prepared and divided into three portions. Two portions from each matrix were spiked with 10.07 and 20.14. micromol/L DHEAS, respectively. Aliquots of these pools were distributed to participants in UK NEQAS for male and female testosterone at distribution 319 (July 2006). Median testosterone results for each method group were examined for an increase in testosterone concentration. In the female matrix, the effect on Abbott Architect was confirmed and shown also for Roche Elecsys, Roche E170 Modular and Beckman Access (includes some Beckman DxI users). In the male matrix, the effect on Abbott Architect, Roche Elecsys and Roche E170 Modular was similar in magnitude to that in the female matrix, but was smaller for Beckman Access/DxI. However, the effect on Immulite 2000 (includes some Immulite 2500 users) was greater in the male matrix. Indications of interference in other methods, used by only a few laboratories (notably Tosoh AIA and Wallac Delfia), were also observed. DHEAS interference in testosterone assays is a feature of many routine testosterone methods, and occurs in both male and female matrices.

Difficult diagnoses in renal pathology: Evidence from EQA schemes

Summary The UK National External Quality Assessment Schemes in renal pathology and renal transplant pathology have accumulated evidence on the problems encountered by diagnostic histopathologists in routine practice. These can be subdivided into qualitative (getting the diagnosis right) and quantitative (achieving consistency in assessing the severity of a process). Some cases simply present difficult diagnostic problems. But in the qualitative group, problems often arise because descriptive terms (such as focal segmental glomerulosclerosis (FSGS) or interstitial nephritis) are accepted as a ‘diagnosis' without further thought to explaining the underlying cause of the pattern. This often demands clinical, biochemical and serological information; the renal pathologist should be capable of discussing such evidence with nephrologists. There is sometimes a tendency to overdiagnose recently described or ‘fashionable' diseases. In transplant pathology, early (and potentially catastrophic) antibody-mediated rejection is particularly easily missed, as is polyoma virus infection. In transplant pathology, the main quantitative problem is the evaluation of acute rejection and chronic allograft nephropathy, in which, despite the development of the Banff classification, interobserver variation remains high. Quantitation is an obvious problem in native renal biopsies in evaluating lupus nephritis, but an assessment of disease ‘grade and stage' is likely to be important when reporting most biopsies.

External quality assurance of HER2 fluorescence in situ hybridisation testing: results of a UK NEQAS pilot scheme

Background and Aims: Trastuzumab provides clinical benefit for advanced and early breast cancer patients whose tumours over-express or have gene amplification of the HER2 oncogene. The UK National External Quality...

Most commercial insulin assays fail to detect recombinant insulin analogues

Insulin assays are utilized in various clinical scenarios, including the assessment of insulin therapy compliance or of suspected insulin overdose. In an interpretative exercise carried out by UK National External Quality Assessment Service (NEQAS), serum sent to the participating laboratories was spiked with 30 pmol/L of the short-acting insulin analogue Human Actrapid. Only two out of 24 participant laboratories had sufficient assay cross-reactivity with Actrapid to interpret the results as suggestive of insulin administration. The development of specific insulin assays has led to deterioration in the ability to detect non-compliance or overdose with recombinant insulin treatment. Clinicians should be aware of this significant limitation, which could lead to misdiagnosis.