National External Quality Assessment Scheme Research Articles

Estimating the parasitaemia of Plasmodium falciparum: experience from a national EQA scheme

BackgroundTo examine performance of the identification and estimation of percentage parasitaemia of Plasmodium falciparum in stained blood films distributed in the UK National External Quality Assessment Scheme (UKNEQAS) Blood Parasitology Scheme.MethodsAnalysis of performance for the diagnosis and estimation of the percentage parasitaemia of P. falciparum in Giemsa-stained thin blood films was made over a 15-year period to look for trends in performance.ResultsAn average of 25% of participants failed to estimate the percentage parasitaemia, 17% overestimated and 8% underestimated, whilst 5% misidentified the malaria species present.ConclusionsAlthough the results achieved by participants for other blood parasites have shown an overall improvement, the level of performance for estimation of the parasitaemia of P. falciparum remains unchanged over 15 years. Possible reasons include incorrect calculation, not examining the correct part of the film and not examining an adequate number of microscope fields.

Commutability Still Matters

Commutability is a property of a reference material such that values measured for that reference material and for representative clinical samples have the same relationship between 2, or more, measurement procedures for the same measurand (1, 2). Commutability is required when a reference material will be used as a common calibrator for clinical laboratory measurement procedures or will be used in an external quality assessment (proficiency testing) program to evaluate the agreement among measurement procedures for results from patient samples (3). Commutability is also required when a reference material will be used by an in vitro diagnostics manufacturer as part of their internal traceability procedures to value assign their product calibrators. In this issue of Clinical Chemistry , Zegers et al. (4) report the investigation and validation of commutability for a new reference material for ceruloplasmin, ERM-DA472/IFCC, which was prepared to replace ERM-DA470. The earlier reference material was a serum-based reference material for 15 proteins including ceruloplasmin that had not been validated for commutability but had been reported to improve the agreement among routine clinical laboratory measurement procedures for several proteins (5). However, ERM-DA470 did not lead to harmonization of patient sample results for ceruloplasmin, owing to its lack of commutability. The lack of agreement among results from routine procedures was identified by the United Kingdom National External Quality Assessment Scheme program that used commutable samples for performance assessment. The report by Zegers et al. emphasizes both the importance of validating the commutability of a reference material intended to be used as a common calibrator for routine measurement procedures and the responsibility that the reference material provider bears to evaluate commutability as part of the validation of a reference material. The laboratory medicine profession has recognized the importance of commutability of reference materials that are intended to be used …

Current practices of bleeding time in a developing country: an alert for noncompliance with the standard procedures

Bleeding time is still widely performed in many developing countries including Thailand. To generate an accurate result, the procedure should be complied with standard recommendations such as those from Clinical and Laboratory Standards Institute (CLSI) and World Federation of Hemophilia (WFH). The authors surveyed the current practices of bleeding time in Thailand in order to verify the practices that did not comply with the accepted standard. The questionnaires were sent to hospitals participating Thailand National External Quality Assessment Scheme (NEQAS) for blood coagulation. Items in the questionnaire comprised information about preanalytical, analytical, and postanalytical issues of bleeding time. From a dispatch of 201 questionnaires, 155 (77.1%) were returned. The common noncompliance with standards observed in this survey included inappropriateness of indication, e.g. use for preoperative screening (95 of 126, 75.4%), use of devices other than standard template (130 of 132, 98.5%), and inappropriate reference range (125 of 127, 98.4%). The noncompliance shown in this survey can affect the accuracy of bleeding time results. The authors would like to address these problems as an alert for other laboratories especially in the developing countries where the standard templates are not widely available.

Point of Care INR testing devices: performance of the Roche CoaguChek XS and XS Plus in the UK NEQAS BC external quality assessment programme for healthcare professionals: four years’ experience

BackgroundVitamin K antagonists have been used for many decades and have been traditionally monitored by the measurement of the International Normalised Ratio (INR) in the laboratory. Introduction of Point of...

Pathology harmony moves on: progress on implementation in haematology

Pathology harmony moves on: progress on implementation in haematology

Implementation of External Quality Assessment Scheme in Clinical Chemistry for District Laboratories in Bhutan.

External Quality Assessment Scheme (EQAS) involves evaluation of a number of laboratories by an outside agency on the performance of a number of laboratories based on their analytical performance of tests on samples supplied by the external agency. In developing countries, establishment of national EQAS by preparing homemade quality control material is a useful scheme in terms of resources and time to monitor the laboratory performance. The objective of this study is to implement an EQAS to monitor the analytical performance of the district laboratories in Bhutan. Baseline information was collected through questionnaires. Lyophilized human serum including normal and abnormal levels were prepared and distributed to 19 participating laboratories. Nine routine analytes were included for the study. Their results were evaluated using Variance index scores (VIS) and Coefficient of variations (CV) was compared with Clinical Laboratory Improvement Act (CLIA) Proficiency Testing Criteria (PT) for each analyte. There was significant decrease in CV at the end of the study. The percentages of results in acceptable VIS as 'A' were 63, 60, 66, 69, 73 and 74, 75, 76 and 79% in November 2009-July 2010 respectively. From our results, we concluded that, establishment of EQAS through distribution of home-made quality control material could be the useful scheme to monitor the laboratory performance in clinical chemistry in Bhutan.

The Accuracy of Platelet Counting in Thrombocytopenic Blood Samples Distributed by the UK National External Quality Assessment Scheme for General Haematology

A knowledge of the limitations of automated platelet counting is essential for the effective care of thrombocytopenic patients and management of platelet stocks for transfusion. For this study, 29 external quality assessment specimen pools with platelet counts between 5 and 64 × 10(9)/L were distributed to more than 1,100 users of 23 different hematology analyzer models. The same specimen pools were analyzed by the international reference method (IRM) for platelet counting at 3 reference centers. The IRM values were on average lower than the all-methods median values returned by the automated analyzers. The majority (~67%) of the automated analyzer results overestimated the platelet count compared with the IRM, with significant differences in 16.5% of cases. Performance differed between analyzer models. The observed differences may depend in part on the nature of the survey material and analyzer technology, but the findings have implications for the interpretation of platelet counts at levels of clinical decision making.

Response to a commentary by Wiwanitkit (2011) on a report by

1. In our study, clinical specimens were examined by the national laboratory, Thailand Ministry of Public Health (urinary cadmium) and the laboratory of Mae Sot General Hospital (other measurements). The national laboratory has been certified for toxicological analyses in biological materials by the German External Quality Assessment Scheme. The laboratory of the hospital has been certified for clinical chemistry analysis by the National External Quality Assessment Scheme in Clinical Chemistry, Thailand Ministry of Public Health, and by the External Quality Assessment in Clinical Chemistry, Faculty of Medical Technology, Mahidol University. The hospital has also received the national laboratory accreditation. Quality control is mandatory for the measurements by both laboratories. 2. The cadmium-contaminated areas were discovered in the 12 rural villages of the district. We conducted population screening surveys consecutively to determine changes in cadmium exposure using urinary cadmium measurement among inhabitants living in these areas (Swaddiwudhipong et al., 2010). In our health management program, only those with high urinary cadmium levels (Z5 mg/g creatinine) were regularly followed up for chronic cadmium toxicity. Our study included all persons who had urinary cadmium levels Z5 mg/g creatinine and were screened for renal dysfunctions, hypertension, diabetes and urinary stone disease in 2005 (Swaddiwudhipong et al., 2011).

Isotope Dilution–LC-MS/MS Reference Method Assessment of Serum Folate Assay Accuracy and Proficiency Testing Consensus Mean

Current methods for measuring folates in clinical laboratories are competitive folate binding protein assays. These assays show a considerable lack of agreement that has implications for the comparability of data across studies as well as for long-term population studies. The development of isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) reference methods permitted the evaluation of method accuracy and consistency over time. We measured 3 pools of human serum by ID-LC-MS/MS, calculated values for total folate, and distributed the same pools to participants in a national External Quality Assessment scheme. We used linear regression to compare the all-laboratory and method data with reference method values. The exercise was repeated after 18 months to assess the stability of the all-laboratory and method data. The distributed serum pools had mass spectrometry values for folate species typical of those found in healthy individuals from populations not receiving dietary folic acid fortification. There was good agreement of the all-laboratory data set with the reference method (y =0.86x + 0.91 μg/L) at both time points. Linear regression demonstrated that the Abbott Architect showed the closest agreement with the reference method. The Roche Elecsys method was nonlinear and showed a calibration offset of 2.6 μg/L (4.57 nmol/L). Calibration of serum folate assays traceable to higher-order reference methods increases method accuracy and improves consistency. The all-laboratory consensus mean proved sufficiently accurate and stable to be used as the target for monitoring laboratory performance.

Falsely Reported Malaria Parasites in Otherwise Normal Peripheral Blood Smears

In Iraq the diagnosis of malaria relies only on detection of the parasite in thick blood film and later on determination of its species using thin blood film. Almost always there are no other auxiliary tests. Moreover, the incidence of malaria in Iraq nowadays is very low that no routine training for its morphological detection is available. In Iraq the incidence of false positive reporting of the presence of malaria parasites in peripheral blood smear of normal people or febrile patients as part of routine diagnosis process or as a quality control check for the hematology laboratory morphology work is a well known phenomenon but no real statistics are available for the local work. However, problems with this false positive diagnosis of malaria are not only confined to Iraq, as there are 6.0% of 2,744 laboratory reported malaria parasites when none were present by United Kingdom National External Quality Assessment Scheme (NEQAS) surveys [1]. Moreover, as far as we know no explanation can be found in the published literature. Myeloid cell cytoplasm fragments are perfectly normal findings that have very variable shapes, sizes and granular contents without a specific clinical significance. It is seen mainly in bone marrow smears and less frequently in peripheral blood smears. Unfortunately, in many occasions these fragments were erroneously mixed with the morphological diagnosis of malaria by junior hematologists who are usually performing the routine work [2]. This can be an important explanation for the falsely reported malaria parasites in otherwise normal peripheral blood smears.

Development of a United Kingdom National External Quality Assessment Scheme (UK NEQAS) for HIV point of care testing

The use of HIV point of care tests (POCTs) is increasing rapidly in both laboratory and other settings. These tests are often performed by non-laboratory trained staff. At the present time there are no external quality assessment (EQA) providers in the UK offering proficiency testing schemes for HIV point of care testing. The aim of this study is to develop such an EQA scheme. Firstly, a selection of the most widely used POCTs was selected and their performance assessed using existing HIV-positive serology EQA specimens. All assays produced the correct results however intensity of results observed for the same specimen differed greatly between POCT devices. In addition the effect of various sub-groups of HIV-1 serum samples on the HIV POCT assays was investigated and no difference between the results on the POCTs was observed. Ultimately four serum specimens, two HIV-1 and one HIV-2 positive, one HIV negative, were chosen and sent to NHS laboratories and sexual health clinics for testing as part of a pilot EQA scheme for HIV POCT. Results were excellent with 97% of participants reporting correct results (n= 20). The study highlighted a lack of awareness of EQA particularly in non-laboratory settings, although recommendations (ISO 22870:2006) are in place for the users of such devices. In conclusion, the need for EQA for providers of point of care testing is an integral part of ensuring reliability of results and quality of care for the patient.

The United Kingdom National External Quality Assessment Service for parasitology: toxoplasma serology scheme

AimTo examine performance in the UK National External Quality Assessment Scheme (UKNEQAS) for toxoplasma serology for evidence of discrepant results as compared with the predistribution and postdistribution results supplied by...

Quality Assurance and Quality Control of Thrombelastography and Rotational Thromboelastometry: The UK NEQAS for Blood Coagulation Experience

Global hemostasis devices are currently being employed in operating rooms to assess the bleeding risk and outcomes for patients undergoing surgery. Two devices currently available are the TEG (Thromboelastograph; Haemoscope Corp., Niles, IL) and the ROTEM (Rotation Thromboelastometer; Pentapharm GmbH, Munich, Germany). Both measure the speed of clot formation, the strength of the clot when formed, and clot fibrinolysis kinetics. The two devices use different parameters so no cross comparisons of results can be made. The devices are usually operated by a member of the operating team and not a laboratory scientist; thus their testing and performance is generally not laboratory controlled, despite quality control being required to ensure reliable results. The UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation has undertaken a series of exercises evaluating the provision of External Quality Assessment (EQA) material for these devices. A series of four studies have taken place using lyophilized plasmas as the test material. Up to 18 TEG users and 10 ROTEM users have been involved in testing two samples per study, for a total of eight samples tested. The samples were normal plasmas, factor VIII or XI deficient samples, or normal plasmas spiked with heparin. The precision of the tests varied greatly for both devices, with coefficients of variances ranging from 7.1 to 39.9% for TEG and 7.0 to 83.6% for ROTEM. Some centers returned results that were sufficiently different from those obtained by other participants to predict alterations in patient management decisions. Our data indicate that regular EQA/proficiency testing is needed for these devices.

Improvement of Coagulation Laboratory Practice in Thailand: The First-Year Experience of the National External Quality Assessment Scheme for Blood Coagulation

Improvement of Coagulation Laboratory Practice in Thailand: The First-Year Experience of the National External Quality Assessment Scheme for Blood Coagulation

Interlaboratory Variation in Factor VIII:C Inhibitor Assay Results Is Sufficient to Influence Patient Management: Data from the UK National Quality External Assessment Scheme for Blood Coagulation

We report the results of external quality assessment exercises in which 60 to 120 centers performed factor VIII (FVIII) inhibitor testing on a series of samples over a 13-year period. Samples from seven different subjects were distributed for analysis comprising the following: four different subjects with severe hemophilia A with antibodies following replacement therapy, one subject with acquired hemophilia A and antibodies to FVIII, one subject with normal FVIII and an easily detected lupus anticoagulant, and one subject with mild hemophilia A and a difficult-to-detect lupus anticoagulant but without antibodies to FVIII. In all of the surveys the results obtained in different centers analyzing the same sample varied to an extent that would influence patient management decisions. In the UK National External Quality Assessment Scheme surveys reported here, there was considerable interlaboratory variation in the results of FVIII inhibitor testing that did not improve over the survey period. The coefficient of variation of results in different centers was between 33% and 106% in samples from patients with severe congenital hemophilia A. In some cases, results were affected by assay components. For one plasma, the mean FVIII inhibitor results in centers using one source of normal plasma was 3.9 Bethesda unit (BU)/mL compared with a mean of 5.7 BU/mL in centers using a different normal plasma source ( P = 0.04). Our data indicate that the detection of FVIII inhibitors is not the same in different centers, and the degree of variability noted makes it likely that assay variability has contributed to the lack of international consensus in relation to the real incidence of FVIII inhibitors in different clinical settings. Improvements in assay standardization are urgently needed.

Improvement of Coagulation Laboratory Practice in Thailand: The First-Year Experience of the National External Quality Assessment Scheme for Blood Coagulation

Abstract Context.—In Thailand until 2005 there had been no external quality assessment scheme at the national level for blood coagulation tests. Only a few laboratories had an external quality assessment for these tests. In the year 2005, the Thailand National External Quality Assessment Scheme for Blood Coagulation was founded. Objectives.—To describe the establishment of the Thailand National External Quality Assessment Scheme for Blood Coagulation (including problems encountered and solutions), its progression and expansion, and the improvement of coagulation laboratory practice in Thailand during 2 trial surveys and 4 formal surveys conducted in the first 1;h1 years. Design.—Between 2005 and 2006, the external quality assessment samples for prothrombin time/international normalized ratio and activated partial thromboplastin time were distributed to the participants as well as the instructions and suggestions for the improvement of laboratory practice. From the data collected, the all-method coefficien...

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].

Quality counts: new parameters in blood cell counting

Recently several parameters have been introduced to the complete blood count such as nucleated red blood cells, immature granulocytes; immature reticulocyte fraction, immature platelet fraction and red cell fragments as well as new parameters for detection of functional iron deficiency. Leucocyte positional parameters, which may diagnose specific diseases (e.g. differentiate between abnormal lymphocytes in leukaemia and viral conditions and may also detect malarial infection) are now available. At this time they are only used for research; however, generally such parameters later become reportable. One manufacturer's routine analyser allows measurement of cells by flow cytometry using monoclonal antibodies. Currently, there are no accredited external quality assessment schemes (EQAS) for these parameters. For a number of parameters, on some instruments, there is no internal quality control, which brings into question whether these parameters should be used for clinical decision making. Other more established parameters, such as mean platelet volume, red cell distribution width and the erythrocyte sedimentation rate do not have EQAS available. The UK National EQAS for General Haematology held a workshop earlier this year in 2008 to discuss these parameters. Participants were asked to provide a consensus opinion on which parameters are the most important for inclusion in future haematology EQAS.

Laboratory performance in the World Federation of Hemophilia EQA programme, 2003–2008

External quality assessment (EQA) has been shown to improve laboratory performance and diagnosis in haemostasis. We report here findings from the World Federation of Haemophilia (WFH) EQA programme during the period 2004-2007. Samples for PT, APTT, FVIII:C, FIX:C and VWF assays were distributed to centres in both established and emerging countries, and results were compared with results obtained by United Kingdom National External Quality Assessment Scheme (UK NEQAS) participants on the same samples. In general, good agreement was seen throughout between WFH and UK NEQAS for screening tests, and it was possible to identify an improvement in WFH centre agreement for results for VWF assays during the period of study. Agreement between emerging and established WFH centres was comparable for screening tests, possibly indicative of the relative simplicity of these tests and the degree of automation now employed in almost all haemostasis laboratories. However, CVs and performance compared with UK NEQAS participant results for factor assays amongst established centres was better than between emerging centres. Distribution of a questionnaire revealed different application of methodology for these assays, which may contribute to the observed difference in performance. Several centres participated in supplementary exercises, with comparable results obtained by emerging and established centres performing FVIII and fibrinogen measurement on cryoprecipitate, and all centres performing FVIII inhibitor assays correctly identifying the presence of an inhibitor. Participation in EQA programmes should continue to encourage improvement in laboratory performance and therefore improvements in the diagnosis and care of patients with haemophilia.

Reduced estimated glomerular filtration rate in Alzheimer's disease

Renal disease is increasingly regarded as an independent risk factor for vascular disease which in itself is believed to influence risk of AD. Alterations in amyloid homeostasis via reduced renal clearance of peripheral beta-amyloid (A|*beta*|) may represent another potential role for variation in renal function leading to increased risk of AD. We sought to examine estimates of glomerular filtration rate in AD and control groups. AD patients were randomly recruited from the Memory Clinic of the Belfast City Hospital (n = 83). Genomic DNA was extracted from peripheral leucocytes and was genotyped for Apolipoprotein E using standard methods. Using creatinine values, age and gender, estimated Glomerular Filtration Rates (eGFR) were calculated using the isotope dilution mass spectrometry (IDMS)-traceable Modification of Diet in Renal Disease (MDRD) Study equation (using the United Kingdom National External Quality Assessment Scheme (UKNEQAS) correction factor). IDMS eGFR values were then compared between AD and control groups. Significant baseline differences in age, diastolic blood pressure, education level attained and APOE |*epsilon*|4 carriage were noted between cases and controls. The AD group had a significantly lower eGFR versus controls (69 vs 77 ml/min) which persisted after adjustment for possible confounders (p = 0.045). This case-control analysis suggests that using a relatively accurate estimate of renal function, patients with AD have greater renal impairment than cognitively normal controls. This may reflect impaired renal clearance of peripheral A|*beta*| or be a marker of shared vascular processes altering cerebral and renal functioning.