The UK National External Quality Assessment Scheme in Blood Group Serology. ABO and D grouping, antibody screening, direct antiglobulin test and antibody identification 1984-1985

In seven exercises of blood grouping the overall rates of major error were 0.19% and 0.25% in ABO and D grouping respectively. In ABO grouping this represents an increase in error rate over that observed in 1982-1983 but the increase was due to an unusually high error rate with one particular group A2B cell. An improvement in performance was observed in simple D grouping and was largely due to a lower incidence of false positive grouping of D-negative cells in the antiglobulin test. An improvement in performance observed in D grouping IgG-coated D-negative cells appeared to be due to a better understanding of the problem rather than to any change in serological practice. Error rates in antibody screening were somewhat lower than in 1982-1983 but this may or may not represent an improvement in performance as the test materials were not the same in the two periods. The direct antiglobulin test with IgG-coated cells was reliably performed with polyspecific and with anti-IgG reagents but an excess of false positive results was obtained with anti-C3d. Error rates in antibody identification varied from 0.6% for anti-D to 74% for anti-c + E.     

The UK National External Quality Assessment Scheme in Blood Group Serology. ABO and D grouping,antibody screening,direct antiglobulin test and antibody identification 1984–1985

Summary In seven exercises of blood grouping the overall rates of major error were 0.19% and 0.25% in ABO and D grouping respectively. In ABO grouping this represents an increase in error rate over that observed in 1982–1983 but the increase was due to an unusually high error rate with one particular group A₂B cell. An improvement in performance was observed in simple D grouping and was largely due to a lower incidence of false positive grouping of D-negative cells in the antiglobulin test. An improvement in performance observed in D grouping IgG-coated D-negative cells appeared to be due to a better understanding of the problem rather than to any change in serological practice. Error rates in antibody screening were somewhat lower than in 1982–1983 but this may or may not represent an improvement in performance as the test materials were not the same in the two periods. The direct antiglobulin test with IgG-coated cells was reliably performed with polyspccific and with anti-IgG reagents but an excess of false positive results was obtained with anti-C3d. Error rates in antibody identification varied from 0.6% for anti-D to 74% for anti-c + E.     

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1981–1982: performance and practice

Summary. 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

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°C and the antiglobulin test at 37°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.     

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1983-1984: the influence of variables in test procedures on detection of incomplete antibodies

Error rates in exercises in compatibility testing varied between 3% and 36% over the six years 1979-1984. Evolution of serological procedures was continuous through this period but without clear evidence of improvement in performance of antibody detection although performance in the UK appears to be comparable with that elsewhere. Relationships have been established between a number of variables of reagents and techniques, and their performance. The influence of some variables is reasonably clear but there appear to be interactions between certain variables in their effects on performance, and interpretation is less straightforward. A test for agglutination of enzyme treated cells together with an antiglobulin test appears to be the most reliable combination for detection of incomplete antibodies in compatibility testing although one stage enzyme techniques are an inevitable compromise between reliability and convenience. Compatibility testing should not be considered in isolation from antibody screening in determining the optimum combination of tests for pretransfusion antibody detection.     

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1983–1984: the influence of variables in test procedures on detection of incomplete antibodies

Summary Error rates in exercises in compatibility testing varied between 3% and 36% over the six years 1979–1984. Evolution of serological procedures was continuous through this period but without clear evidence of improvement in performance of antibody detection although performance in the UK appears to be comparable with that elsewhere. Relationships have been established between a number of variables of reagents and techniques, and their performance. The influence of some variables is reasonably clear but there appear to be interactions between certain variables in their effects on performance, and interpretation is less straightforward. A test for agglutination of enzyme treated cells together with an antiglobulin test appears to be the most reliable combination for detection of incomplete antibodies in compatibility testing although one stage enzyme techniques are an inevitable compromise between reliability and convenience. Compatibility testing should not be considered in isolation from antibody screening in determining the optimum combination of tests for pre-transfusion antibody detection.     

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

Summary 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

Summary 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.     

Multilaboratory testing in thrombophilia through the United Kingdom National External Quality Assessment Scheme (Blood Coagulation) Quality Assurance Program

We describe here results from the United Kingdom National External Quality Assessment Scheme (UK NEQAS) Thrombophilia Screening Program, in which an average of 21% of 280 centers reported an incorrect diagnosis for a series of plasma samples. Three case studies are described, showing causes of error in individual laboratories, related to the source of reference plasma or reagents. Methodological bias is also described. For protein C (PC) assays 18% of centers reported PC deficiency in a patient homozygous for factor V Leiden. Studies in the NEQAS laboratory confirmed the effect of activated protein C resistance (APCR) on clot-based PC activity assays. Differences in results obtained for PS-deficient subjects with different protein S (PS) activity kits are reported; several subjects would be misdiagnosed as normal with one kit if the manufacturer's reported reference range was adopted instead of a locally determined reference range. Antithrombin (AT) assays were shown to vary in their sensitivity to different molecular defects in the antithrombin gene; 77% of centers employing human thrombin-based activity assays reported a normal AT level in a patient with antithrombin Cambridge II. Sensitivity of the APC resistance test in the absence of factor V-deficient plasma was shown to be improved through normalization of results, and errors in the genetic diagnosis of factor V Leiden and the P20210A prothrombin gene mutation are described. Errors in the diagnosis of thrombophilic defects can therefore be identified through participation in EQA programs, and following dissemination of information, improvements in diagnosis can be demonstrated.     

POSEIDON数字血型仪在ABO正反定型及 Rh(D)不规则抗体筛选中的应用

目的:评价数字血型仪在血液系统中进行自动化血型定型的准确性和可靠性.方法:使用POSEIDON数字血型仪、U型板法和试管法进行血型正反血型判定比较.结果:试管法和POSEIDON数字血型仪的符合率达100%,且特异性和灵敏度均优于U型板,在本站应用正反血型定型符达100%.结论:数字血型仪在血液系统中进行自动化血型定型的具有准确性和可靠性,有效节约试剂,提高血型定型的自动化水平.     

Country report: the Indonesian NEQAS on hematology. National External Quality Assessment Scheme

Around six hundred clinical laboratories in all the province of Indonesia participated the Indonesian National External Quality Assessment Scheme (NEQAS) on Hematology (Program Nasional Pemantapan Kualitas Laboratorium Klinik bidang Hematologi). Automated analyzer gave better results compared to the manual method. For hemoglobin, the CV of automated analyzer and manual method were 2.8% and 9.1%, respectively. The CV of automated analyzer and manual method for leukocyte count were 8.3% and 32.3%; for erythrocyte count were 9.7% and 80.8%; and for thrombocyte count were 10.3% and 45.9%. We observe no significant improvement of the overall performance from 1986 to 1998. Quality control material for NEQAS on hematology is still a problem. The artificial particles seem not behave exactly like the human cells (leukocytes, thrombocytes).     

A pilot External Quality Assessment Scheme for haemocytometry in Italy.

BACKGROUND. An Italian EQA scheme for haemocytometry, organized by the Istituto Superiore di Sanità, has been active for about five years (1984-1989). The aims of this programme were to evaluate the state of the art and to introduce in Italy a scheme recommended by ICSH. N. 126 public laboratories from different provinces joined voluntarily the programme and trials for haemoglobinometry (A01, A02), full blood count (B01-B08) and platelet count (D01-D03) were performed. METHODS. Materials for testing consisted of blood lysate, preserved blood preparation containing native red cells and pseudoleukocytes, suspension of fixed platelets. The performances of laboratories was evaluated by consensus values (median, mean and standard deviation) and individual deviation index. RESULTS. The instrument survey demonstrated that fully automated systems had the highest frequency. Non Gaussian distributions of results were often obtained and this was particularly true for WBC, PLT and MCV. The overall variability was lower than 5.5% for Hb, RBC and MCH and lower than 9.3% for other erythrocyte parameters; WBC and PLT counts displayed a higher dispersion (CV* = 9.8% and 25.4%); the spreading of results was strongly reduced in the homogeneous group of Coulter counters. In the course of the programme CV*s didn't show any relevant modification, a steady state performance being apparent. As regards the nature of variability, the random component was prevalent for all parameters, with the exception of MCV. CONCLUSIONS. This pilot programme allowed to demonstrate the practicability of a national EQAS for haemocytometry according to the ICSH guidelines. Materials for testing showed acceptable stability, homogeneity and commutability. As regards analytical equipment as well as analytical variability, hospital centers participating in these EQA trials were comparable with laboratories taking part in similar EQAS of other European countries.     

Variability in factor V:C assays in UK National External Quality Assessment Scheme surveys: there is a need for an international standard.

Severe familial factor V:C deficiency is a rare, recessively inherited coagulation disorder but there is little information in respect of the accuracy and reliability of factor V:C assays that are required for diagnosis and treatment monitoring. We present here the results of three External Quality Assessment exercises in respect of factor V:C assays undertaken by 192--225 participating laboratories performed over a 2-year period. Consistent significant differences were observed between results obtained using different reference plasmas and different thromboplastins. The relationship between results obtained with different reference plasmas was not constant and varied between the surveys. In-house studies confirmed the observation derived from the External Quality Assessment surveys that the choice of commercial reference plasma significantly affects the results of factor V:C assays. These results clearly indicate the necessity for an international standard for factor V:C.     

Emerging technologies and quality assurance: the United Kingdom National External Quality Assessment Scheme perspective

The pattern of tests employed and technologies developed within hemostasis laboratories has changed considerably within the last 10 years. These changes have presented challenges to external quality assessment (EQA) providers, including the United Kingdom National External Quality Assessment Scheme (NEQAS). EQA for point-of-care devices used for monitoring oral anticoagulant therapy has focused on provision of suitable material to assess performance of devices designed for capillary blood testing, and on education of a user group not usually trained in laboratory quality control procedures. Development of novel therapeutic agents for hemophilia has presented challenges regarding standardization of assays for monitoring treatment, whereas advances related to laboratory testing and automation have not always been accompanied by improved accuracy and precision. EQA provision has also been shown to be of value in molecular genetic screening tests for thrombophilia, and in highlighting standardization issues related to D-dimer measurement in the exclusion of deep vein thrombosis. The increasing prevalence of screening tests of global hemostasis, such as thrombin generation tests and thromboelastography, presents additional challenges to EQA providers in the attempt to standardize these new and potentially beneficial technologies.     

The Czech National External Quality Assessment of monoclonal immunoglobulin in the period of 1996 - 2005

The aim of the presented study was to evaluate the results of SEKK "Gammopathy" (GP) control cycle (Czech National External Quality Assessment) that assessed the success rate of monoclonal immunoglobulin determination by clinical laboratories for the 1996 - 2005 period. The study summarizes the results of 20 "Gammopathy" control cycles during the ten-year period. Control cycles were repeated every 6 months. Patients who provided samples for individual SEKK "Gammopathy" control cycles were selected during routine diagnostic process in the University Hospital Hradec Kralove. Correct paraprotein typing in both A and B control samples (plasma, serum or urine) is required prior to certification. Assessment of paraprotein concentration is optional. The number of participating laboratories was gradually increasing from 26 in 1996 to 79 in 2005 (including 6 Slovak laboratories). The majority of laboratories used immunofixation electrophoresis as the method of paraprotein typing. In 2005, only one laboratory was still using immunoelectrophoresis. Typing was successful in approximately 70% of cases during the first 3 cycles and the success rate gradually increased to almost 96% by 2005. The only exception was GP 1/02 cycle with a sample of relatively rare IgD-lambda paraprotein and the success rate of 38% only. A sample of plasma without paraprotein was distributed 4 times. Several laboratories falsely identified fibrinogen as paraprotein each time. Results of "Gammopathy" control cycle for the past 10 years confirmed the value and legitimacy of this control cycle in the system of external quality control of SEKK laboratories.     

Laboratory tests for measurement of von Willebrand factor show poor agreement among different centers: results from the United Kingdom National External Quality Assessment Scheme for Blood Coagulation

In recognition of the importance of von Willebrand factor (vWF) testing in the diagnosis of von Willebrand disease (vWD), the United Kingdom National External Quality Assessment Scheme for Blood Coagulation regularly distributes samples for determination of vWF:antigen (vWF:Ag). Data from 10 separate surveys performed between 2001 and 2005 are reviewed. These include results from ~200 different centers, of which 55% are within the United Kingdom and the remainder are from other countries. During the period of the surveys, the use of immunoelectrophoresis for determination of vWF:Ag practically disappeared and was largely replaced by latex agglutination assays. The coefficient of variation (CV) of results in different centers was approximately 15 to 20% for most vWF:Ag techniques, with CVs of approximately 7% for a fluorescence-based assay. Several different techniques were used for determination of vWF ristocetin cofactor activity (vWF:RCo), all of which were associated with poor agreement among centers as indicated by CVs of 40 to 50%. Several centers calculated the ratio of vWF:Ag/vWF:RCo but with variable success. Ratios compatible with either type 1 or type 2 vWD were obtained on samples from subjects with type 1 vWD, as well as on samples from subjects with genetically confirmed type 2 vWD. Overall, our data show that laboratory testing for vWD remains problematic. It remains to be seen whether newer techniques will offer consistently improved precision.