IMEP-12: trace elements in water; objective evaluation of the performance of the laboratories when measuring quality parameters prescribed in the European Directive 98/83/EC

The International Measurement Evaluation Programme (IMEP) is an interlaboratory comparison scheme, founded, owned and co-ordinated by the Institute for Reference Materials and Measurements (IRMM) since 1988. IMEP-12, for the fourth time in the series, focused on trace elements in water and it was designed specifically to support European Commission directive 98/83/EC. Reference values for the concentration of ten elements were established with expanded uncertainties according to GUM. In total, 348 laboratories from 46 countries in five continents participated in the comparison and the degree of equivalence between the results of the laboratories and the reference values is presented graphically. Samples from the same batch were distributed to ten laboratories from European Countries, which represented their country in the framework of the EUROMET project 528. Participation in this comparison was offered to the European Co-operation for Accreditation (EA) for participation of accredited laboratories from all over Europe in the framework of the collaboration between IRMM and EA and to laboratories from the EU new member states and acceding countries in the frame of IRMM’s ‘Metrology in Chemistry support program for EU new member states and acceding countries.’     

Anti-HIV quality assurance programs in Australia and the southeast Asian and Western Pacific regions

Anti-HIV testing is the most regulated area of laboratory medicine in Australia. These regulations have placed the National Sero-logy Reference Laboratory, Australia (NRL) in a unique position to implement a comprehensive quality assurance (QA) program for HIV testing. The elements of our QA program include pre-market evaluation of assays, external quality assessment schemes (EQAS), quality control, specificity monitoring, consultations, and training workshops. The results of the NRL EQAS for Australian laboratories were compared with those of a program developed by the NRL for reference laboratories in the Southeast Asian and Western Pacific (SEAWP) regions. For laboratories authorized to use tests for HIV in Australia, participation in the entire QA program is mandatory, whereas the SEAWP EQAS program is voluntary. While the overall percentage of discrepant results for these programs are similar, the percentage of false negatives, variation in laboratory results, and choice of assay differ. These differences have decreased with time with improvements in assays and laboratory testing practices. The educational component of both EQAS, which comprises workshops, laboratory questionnaires, consultancies, and newsletters, has had a critical impact on the testing practices of laboratories. Received: 30 October 2000 Accepted: 9 December 2000     

Analytical performance is improved by regular participation in proficiency testing: an analysis of data from the Aquacheck proficiency testing scheme

Analysis of historical data from the Aquacheck proficiency testing scheme demonstrates improvement in the performance of participants correlated to the frequency of participation. Analysis of the spread of results returned by all participants, defined by the percentage relative standard deviation (RSD) and the performance (Z) scores awarded to the individual participants, indicates that the overall performance for the group of participants is consistent. However, when the frequency of participation is analysed, it can be clearly seen that those laboratories who participated in the majority of the distributions available reported 10–15% more acceptable (Z-scores between +2 and ?2) results than those labs who took part with a greatly reduced frequency. When ‘more difficult’ analytes are considered, those laboratories who participated in greater than 75% of available rounds reported up to 30% more acceptable results than those laboratories who participated in 25% or fewer, of the available rounds.     

A survey of workload, facilities and awareness of uncertainty of measurement among Italian laboratories performing analyses in occupational and environmental medicine

Biological monitoring is essential for risk assessment in the presence of exposure of workers or the general population to harmful chemical agents. Besides the choice of analytical methods which are fit for purpose and the skills of the analysts, the performance of laboratories, including those working in the field of environmental and occupational medicine, also depends on other technical factors such as frequency of testing, the use of well maintained and properly functioning equipment and the implementation of quality control procedures including the participation in External Quality Assessment Schemes (EQAS). Surveys of laboratory workload have been organized periodically since 1997 within the MeTos Project, an Italian national EQAS for biomarkers of environmental and occupational exposure to chemical agents. In 2001, a more extensive survey, including specific technical issues, was organized as part of the activities of the Thematic Network of European Organizers of External Quality Assessment/Proficiency Testing Schemes Related to Occupational and Environmental Medicine (Network survey). In addition, information on the awareness and implementation of the new requirement for laboratories to estimate the uncertainty of their measurements was collected since 2000. The results of these surveys are reported and compared here. In all surveys, Pb in blood was the biomarker most frequently determined. As for biomarkers of exposure to organic compounds, the data collected in the Network survey indicate that methylhippuric acid, hippuric acid and mandelic acid in urine were the assays most commonly performed. About a third of the participants stated that they estimate the uncertainty of at least some of their measurements. Preliminary analysis of data, limited to Pb in blood, showed that analytical performance improved with continuous participation in EQAS and was positively influenced by a high workload.     

Comparison of evaluation procedures used by European external quality assessment scheme organizers for haemoglobin concentration and leukocyte concentration

This study aimed to assess currently used evaluation procedures for haemoglobin concentration and leukocyte concentration in European external quality assessment schemes (EQAS). Participating EQAS organizers were asked to complete a questionnaire gathering information on the statistical procedures used to assess the performance of participants, and to analyse an Excel file with 262 results for haemoglobin concentration and leukocyte concentration. Responses were received from the New York State Proficiency Testing programme in the US and from 11 European EQAS: Belgium, Croatia, Finland, France, Germany, Hungary, Russia, Slovenia, Spain (two organizers), and Switzerland. Five of the 11 European EQAS use fixed limits based upon experience, biological variation, state of the art, or professional consensus. The other EQAS use variable limits based upon statistical analysis of the performance attained. With the exception of the German, Hungarian, and Slovenian schemes, all European EQAS use consensus target values. The percentage of unsatisfactory results obtained by the European EQAS organizers for the given set of data varied between 0.4 and 15.6% for haemoglobin concentration and between 0 and 19.8% for leukocyte concentration.     

Quality assurance in biological monitoring of environmental exposure to pollutants: from reference materials to external quality assessment schemes

The presence of chemicals in the environment is a matter of concern in that it poses potential health risks. At present, exposure to toxic chemicals and their biological and biochemical effects can be better estimated by biological monitoring, through the systematic collection of specimens from potentially exposed humans. Biological monitoring of human exposure to environmental pollutants is hampered by the difficulty to assess data reliability. As a consequence, the validity of biological monitoring should depend on the strict implementation of a quality assurance (QA) program, which includes a series of procedures aiming to ensure that laboratory results meet defined standards of quality and are reliable. For the validation and monitoring of methods’ performance, to ensure the trueness of measurements and to warrant the traceability to international standards, reference materials (RMs) and certified reference materials should be used. Internal quality control and external quality assessment (EQA) are part of overall QA and are carried out to verify that analytical errors are compatible with the specific requirements or needs of the user. In particular EQA schemes (EQAS) allow to test independently the analytical performance of participating laboratories. In the last decades, increasing concern has been raised by urban air pollution; lead and benzene, two gasoline components released by motor vehicle exhausts, are known to be toxic to humans. For biological monitoring of lead exposure of the general population, screening campaigns, utilizing lead in blood as a biomarker, have been carried out since the 1970s. Strict strategies were adopted to ensure data comparability, including the preparation of RMs, the organization of EQAS and the cross-exchange and analysis of blood samples between laboratories. Biological monitoring of benzene exposure could be carried out by means of various biomarkers such as benzene in blood and benzene, trans,trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA) in urine. At present, few RMs and EQAS are available for these biomarkers. A pilot EQAS for t,t-MA in urine, adopted to assess the reliability of data regarding benzene exposure, has been organized and carried out between 1996 and 1997 in Italy. From the accrued experience, it clearly emerges the importance of strategies designed to guarantee the quality of biological monitoring data. The use of RMs and the participation in EQAS are highly recommended in order to improve the global performance of methods and laboratories involved in biological monitoring.     

Occupational and environmental laboratory medicine: A network of EQAS organisers

Most people in any community come into contact with chemicals that are potentially harmful to their health. Some elements are essential to health and inadequate amounts in food may also lead to ill health. Measurement of chemicals in blood, urine or other specimens is a fundamental feature of studies undertaken in the field of Occupational and Environmental Laboratory Medicine (OELM). Results are used to assess the risk for either overexposure or deficiency of essential nutrients. External Quality Assessment Schemes (EQAS) aid laboratories to achieve accurate and consistent data and 11 organisers of EQAS in Europe and North America are working to improve the effectiveness of their activities.The aims of the Network of EQAS Organisers in OELM are to stimulate improvements in analytical results, establish equivalence of assessment among Schemes, collaborate to enhance the practice of EQA including whenever possible to warrant traceability of EQAS to primary standards.Presented at the Eurachem PT Workshop September 2005, Portorož, Slovenia.     

The current status and future of medical laboratory quality regulation and accreditation in Ghana

High-quality and reliable laboratory services are important components of effective and well-functioning health systems. Accurate, reliable and timely medical laboratory testing is crucial to patient care and disease surveillance. Unfortunately, in many sub-Saharan African countries, medical laboratory systems are adversely affected by the unavailability of medical laboratories, poor laboratory infrastructure and lack of well-trained personnel [1]. Quality in the laboratory is only achieved in a systematic way through the implementation of a quality management system. The results of the study showed that approximately 60?% of the 78 respondents were unaware of the requirements of ISO 15189:2007. A trial of proficiency testing, termed ??blind proficiency testing??, was carried out in which 19 laboratories determined the concentrations of urea and cholesterol in a proficiency testing material. Of the 19 laboratories that determined the concentration of urea, 63?% produced satisfactory results with scores between ?2 and +2. Similarly, 63?% of the participating laboratories obtained satisfactory z scores for cholesterol determination. Some of the laboratories that obtained satisfactory scores for urea determination had unsatisfactory scores for cholesterol determination and vice versa. It is recommended that the Ghanaian government pass a law and establish a standard to regulate medical laboratories in Ghana in order to improve quality in a significant way.     

Pathology laboratory accreditation: the Australian experience

 The National Associating of Testing Authorities, Australia (NATA) is a laboratory accreditation company that has been involved in the accreditation of pathology laboratories since 1982. This role is carried out in conjunction with the Royal College of Pathologists of Australasia (RCPA). The accreditation process is known as the NATA/RCPA scheme. The NATA/RCPA accreditation scheme originated from the desire to raise professionalstandards in pathology. The scheme aimed to achieve this through a peer review process in which education and voluntary participation were stressed. In 1986, the Australian Federal Government adopted the scheme as its measure of the competence of testing by pathology laboratories seeking payment from the Commonwealth Department of Human Services and Health reimbursement scheme, Medicare. This meant that NATA/RCPA accreditation became mandatory for such laboratories. The benefits of peer review as a means for establishing professional competence and the challenges a mandatory accreditation program poses to such a scheme will be discussed. Received: 6 May 1996 Accepted: 29 May 1996     

Blood lead monitoring in Italy: Assessment of the quality of results obtained between 1992 and 1994

Between 1992 and 1994, a new screening campaign for blood Pb monitoring in the Italian general population was carried out. Since the first campaign (started in 1978, in accomplishment of the European Community Directive 77/312/EEC) a working group of the Laboratory of Clinical Biochemistry at the Italian National Institute of Health (Istituto Superiore di Sanità), as the Reference Centre (RC), has coordinated the activity of various laboratories spread over the national territory. Appropriate quality assurance procedures, including an external quality assessment scheme (EQAS), were elaborated. Within the EQAS, three or four trials were carried out every year. Each laboratory participating in the trial analyzed eight control samples prepared from cow blood at different Pb concentrations. The results obtained by each peripheral laboratory and the RC between 1992 and 1994 have been compared by regression analysis. The same statistical method was adopted to compare the results obtained by each peripheral laboratory and the RC in the duplicate analysis of about 10 per cent of the human samples collected during the 1992–1994 monitoring campaign. There was no evidence of systematic differences between the regression lines obtained on control and human samples. In spite of the lower Pb concentration in the control samples analyzed during the 1992–1994 campaign, the analytical performance of the laboratories was better than that obtained in the previous screening campaign (1985–1986). Blood Pb levels observed in human samples collected between 1992 and 1994, confirm the downward time trend observed in the campaigns carried out in 1978–1979, 1980–1981 and 1985–1986. This study confirms that the results obtained in an EQAS are representative of the actual performance in the analysis of real (human) samples.     

International Measurement Evaluation Programme (IMEP); IMEP-14: Picturing the performance of analytical laboratories measuring trace elements in sediment

The International Measurement Evaluation Programme (IMEP) is an interlaboratory comparison scheme founded, owned and co-ordinated by the Institute for Reference Materials and Measurements (IRMM) since 1988. IMEP-14, for the first time in the series, is focusing on trace elements in sediment. Reference values for ten elements stating total concentrations and expanded uncertainties according to GUM were established. In total, 239 laboratories from 43 countries in five continents participated in the comparison, and the degree of equivalence between the results from the laboratories and the reference values is presented graphically. Identical samples were distributed to nine National Measurement Institutes within the frame of the CCQM-P15 pilot study. Participation in the IMEP-14 interlaboratory comparison was offered to laboratories in the EU new member states and acceding countries according to the IRMMs Metrology in Chemistry support programme for EU new member states and acceding countries.This revised version was published online in August 2004 with corrections to text especially to the Discussion section.     

Blood lead and cadmium determination: Results of the Italian external quality assessment scheme

The procedures adopted in the Italian external quality assessment scheme (EQAS) for blood Pb (B-Pb) and Cd (B-Cd) determination, including the preparation of control materials, are described. Each scheme involves the use of internal quality control materials and the participation in periodical external quality assessment trials. All control materials are prepared at the Laboratory of Clinical Biochemistry, Italian National Institute of Health (Istituto Superiore di Sanità, ISS), as the reference centre. Computerized procedures have been adopted whenever possible, i.e. sample randomization, data transfer and treatment. The analytical performance of the participating laboratories, evaluated from the results obtained in ten years of activity, is reported. A total of eight phases has been carried out between 1983 and 1993. Over the course of these ten years, a positive trend was observed for B-Pb towards a smaller bias and a lower percentage of laboratories with poor performance. In the eighth phase, taking into account the results from all participants, the mean absolute inaccuracy for B-Pb was 32 g/l (mean Pb concentration in control samples, 165 g/l). The percentage of laboratories providing results within established acceptability limits for at least 80% of the examined samples (good performers) increased with time from 28% in the first phase to 48% in the last phase. The laboratories providing less than 50% of acceptable results (poor performers) decreased from 35% in the first phase to 22% in the last phase. As regards B-Cd, mean absolute inaccuracy decreased from 0.96 g/l to 0.55 g/l between the first phase and the sixth phase. The percentage of good performers increased from 45% to 62% and that of poor performers decreased from 31% to 5%. From the seventh phase a large group of new laboratories agreed to participate in the EQAS for B-Cd and the inaccuracy rose to 0.75 g/l (mean concentration: 2.7 g/l) and the percentage of poor performers rose to 24%, whereas the percentage of good performers remained almost unchanged.     

Estimates of uncertainty of measurement from proficiency testing data: a case study

The results obtained by a laboratory over a number of proficiency testing/external quality assessment schemes (PT/EQAS) rounds can give information on the uncertainty of its measurements for a given test, provided that conditions such as full coverage of the routine analytical range, traceability, and small uncertainty of the assigned values (compared to the spread of the results) are met and provided that systematic deviations and any other sources of uncertainty are considered. As organisers of the Italian EQAS (ITEQAS) in occupational and environmental laboratory medicine, we tested this hypothesis using as model data from well-performing laboratories taking part in ITEQAS for lead in blood over the last 2 years. We also investigated how different PT/EQAS features (frequency of trials and number of samples) would affect a laboratory estimate of its uncertainty. Such information can be helpful in improving PT/EQAS organisation and define, for a given test: (a) the state of the art of the uncertainty of current measurement procedures, (b) identify needs for improvement of analytical methodologies and (c) set targets for acceptable uncertainty values.Presented at the Eurachem PT Workshop September 2005, Portorož, Slovenia.Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher.     

Advances for proficiency testing for genetic laboratory science

Nucleic acid based clinical genetic testing has undergone explosive growth in recent years due in large part to the human genome project. Characterization of the human genome has led to a molecular understanding of the pathogenesis of many human diseases, and ultimately to clinical molecular tests becoming routinely used to diagnose a wide diversity of diseases. This rapid growth in clinical molecular genetic testing coupled with the complexity of the analytical procedures underscores the necessity for proficiency testing (i.e. external quality assessment) to allow laboratories offering such services the ability to evaluate their analytical procedures via inter-laboratory comparisons. The American College of Medical Genetics (ACMG) in partnership with the College of American Pathologists (CAP) have been offering proficiency testing for clinical molecular genetics laboratories since 1995, and presently have more than 230 laboratories from 11 countries enrolled in this program. This paper describes the evolution of this program and several challenges encountered in the delivery of a proficiency testing program for laboratories offering clinical molecular genetic services. Received: 13 April 2002 Accepted: 18 July 2002     

Interlaboratory comparison for the determination of five residual organochlorine pesticides in ginseng root samples by gas chromatography

An interlaboratory comparison study for the determination of 5 residual organochlorine pesticides (hexachlorobenzene and 4 hexachlorocyclohexane isomers) in ginseng root was performed. This program [Asia Pacific Laboratory Accreditation Cooperation (APLAC) T049] was the first of its kind for an herbal matrix and involved the participation of 70 laboratories from 26 countries worldwide. Consensus mean values were computed statistically from the reported results, which were eventually used to assess the performance of individual laboratories in terms of the z-scores. The distribution of analytical data was found to be widespread, with standard deviation ranging from 43.9 to 55.9%, and the result patterns obtained were similar to those residue pesticide programs using other matrixes. Although the estimation of measurement uncertainty is a crucial requirement for all quantitative tests for laboratories that meet the requirements of International Organization for Standardization/International Electrotechnical Commisssion (ISO/IEC) 17025, some laboratories in this program had difficulties and showed unfamiliarity with respect to that quality criterion. It was recommended that laboratories review and rectify the situation promptly so that they would have a better understanding of measurement uncertainty or the test service provided.     

The Swiss External Quality Assessment Scheme in Bacteriology and Mycology 1992–1996

 The Swiss External Quality Assessment Scheme in Bacteriology and Mycology was created in 1980 and has been organised since 1983 by the Department of Medical Microbiology in Zurich. The number of Swiss participants has steadily risen from 66 in 1989 to 92 in 1996. Twelve bacterial and fungal strains are sent to the participants in four despatches, each containing three specimens, per year. Scores are allocated per specimen and range between 0 and 1. Participants with mean scores of ≤0.75 are considered poor performers. The mean scores increased from 0.85 in 1992 to 0.91 in 1996. This improvement can be attributed to the educational effect of the external quality control scheme, since all participants receive a detailed discussion for each specimen together with their individual results. On average, both large University and Cantonal (state) laboratories as well as private laboratories show satisfactory performance. In particular, laboratories officially recognised by the Swiss Federal Office of Public Health (SFOPH) rate better than non-recognised participants. Many small regional hospital laboratories, most of them not SFOPH-recognised, are often among the poor performers. They are often managed by technical staff and lack a trained microbiologist. The recently introduced legislation in Switzerland renders participation in external quality assessment schemes compulsory, and all clinical microbiology laboratories are required to employ qualified microbiologists. This will certainly help to improve the quality standards of all laboratories performing microbiological tests. Received: 13 November 1997 · Accepted: 28 December 1997     

EAL interlaboratory comparison Wa1 – Testing of potable water

 The accreditation of laboratories has emphasized the use of interlaboratory comparisons as a tool to monitor the comparability and accuracy of results laboratories produce. An interlaboratory comparison for water laboratories was organized among European Cooperation for Accreditation (EA) member countries; 30 laboratories, 7 of which were not accredited, from 14 European countries participated in this intercomparison. All the laboratories were chosen by the appropriate national accreditation bodies, with the instruction to select as participants those laboratories which act as national reference laboratories in this field. About 90% of the data collected was considered satisfactory after statistical treatment. Non-accredited laboratories performed as well as accredited laboratories. The laboratories were asked to take corrective action and report the corrections to the accreditation bodies. A great variation in the reported uncertainties of the results was observed. There seems to be a need to organize EA interlaboratory comparisons for national reference laboratories analysing water. It is obvious that even reference laboratories need training in how to estimate the uncertainty of results. Received: 22 July 1998 · Accepted: 21 September 1998     

Acceptability limits based on biology goals in haematology EQAS

The current situation in defining and setting criteria used to determine acceptability limits in haematology external quality assessment schemes (EQAS) is discussed. This report also addresses the control materials and experiences used when determining the suitability of home-made material for complete blood count (CBC), which involves testing a small scheme of about 100 participants with different analytical systems based on a single principle for the attainment of quality specifications. By studying the biological variation in haemocytometry using home-made EQA control blood in a controlled study that employed only haematological analysers based on the electrical impedance (Coulter) principle, we have assessed whether total error goals are achieved for the following parameters: white blood cell (WBC), red blood cell (RBC), and platelet (Plt) counts, concentration of haemoglobin (Hb), and mean cell volume (MCV) in a simple single challenge external quality assessment scheme. We found that we could not attain the biological goals for MCV, RBC and Plt in a haematology EQAS that uses the single analytical principle; even minimum performance based upon the calculation of 1.65[0.75CV_I] + 0.375[CV_I² + CV_G²]^1/2 (p<0.05) is not achievable. For the other two parameters, the minimum (Hb) required for desirable performance (Lkci), given by 1.65[0.50CV_I] + 0.25[CV_I² + CV_G²]^1/2 (p<0.05), is achievable, but the optimum performance of 1.65[0.25CV_I] + 0.125[CV_I² + CV_G²]^1/2 (p<0.05) is not attainable for all five basic haemocitometry parameters. Besides acceptability limits, the control materials used for CBC and the target values used in haematology EQAS are discussed from a practical point of view in order to improve quality.     

Uncertainty estimation in organic elemental analysis using information from proficiency tests

We evaluate the uncertainty in organic elemental analysis of C, H, N, and S. We use data from six proficiency tests (PTs), in which some 35 Spanish laboratories participated. The uncertainty of the technique is estimated from the relative within-laboratory and between-laboratory variances for pure substances and samples with complex matrices (soil, powdered milk, oil, ash, and petroleum coke). We also calculate the relative standard uncertainties for individual laboratories when analysing pure substances using historical data from the participation of each laboratory in different editions of PTs. The uncertainty values obtained for the individual laboratories are comparable with the uncertainty of the technique and correlate with the combined z-scores. The evolution over time of those laboratories participating in common editions of PTs is also evaluated.     

International Measurement Evaluation Programme: IMEP-9, trace elements in water

The International Measurement Evaluation Programme (IMEP) is an interlaboratory comparison scheme, founded, owned and coordinated by the Institute for Reference Materials and Measurements (IRMM) since 1988. IMEP-9 is the third round of trace elements in water evaluation following IMEP-3 and IMEP-6. Reference values for 15 elements stating total concentrations and combined uncertainties (according to GUM) were established. The reference values were established mainly by isotope dilution mass spectrometry (IDMS) as a primary method of measurement, and values traceable to the SI were obtained. The four elements that could not be certified by IDMS were assigned values by means of other measurement techniques. Results from 201 laboratories from 35 countries and four continents were evaluated against the reference values and the comparability between the laboratories is presented graphically.