External quality assessment in the measurement of haemoglobin by blood gas analysers in Belgium.

OBJECTIVE: The Belgian national External Quality Assessment Scheme (EQAS) for haematology organized a survey to assess the reliability of haemoglobin (Hb) measurements with the blood gas analysers (BGAs) currently available in Belgian hospitals. MATERIAL AND METHODS: All hospital laboratories received two specimens of fresh EDTA anticoagulated whole blood and were asked to determine the Hb concentration using both the conventional haematology analyser (HA) and all BGAs in the hospital. Ninety-seven hospital laboratories participated in the study and a total of 166 results were reported. The BGAs used (grouped according to technology) were Rapidlab 845, 855, 865 (Bayer 1, n = 41), Rapidlab 1245, 1265, Rapidpoint 405 (Bayer 2, n = 19), GEM Premier 3000 (Instrumentation Laboratory, IL, n = 13), ABL 500 and 600 series (Radiometer 1, n = 13), ABL 700 and 800 series (Radiometer 2, n = 35), Omni C, S5 (Roche 1, n = 7), Omni 3, 6, 9, S2, S4, S6 (Roche 2, n = 21). RESULTS: For the BGAs from Bayer, Radiometer and Roche, interlaboratory variation ranged from 0.6 % to 4.1 %, indicating good precision and close agreement between centres. A significant negative bias observed on the GEM Premier 3000 using the EDTA anticoagulated blood samples did not appear to be present in fresh heparinized whole blood samples. There was no significant difference in imprecision and bias between Hb measurements on BGA situated in and outside the central laboratory.

Role of external quality assurance schemes in assessing and improving quality in medical laboratories.

Medical laboratories have a long tradition of external quality assessment. Starting from pure quality control of laboratory performances, most external quality schemes in Europe evolved into a powerful tool for improving quality of clinical outcome of results. External quality assurance in medical laboratories not only includes laboratory performance evaluation, but also evaluation of method performance, post-market vigilance, training and help. In the future, the quality of programmes will further be improved by accreditation of schemes international collaboration and by using IT applications.

Effect of accreditation schemes on the setting of quality specifications by laboratories.

In the future, there will be a universal standard for quality management in medical laboratories: ISO 15189. This standard follows the basic principles of ISO 17025, the general standard for test laboratories, but also adds several specific aspects. A comparison between these standards is given. The language of ISO 15189 is designed to be understood by medical laboratory professionals. As this standard is applicable to all medical laboratory fields, requirements are given in general terms requiring the laboratory to implement them correctly. Because it is essential that information provided by laboratory results is useful for healthcare, the requirements covered by ISO 15189 are compared with those needed for providing good medical laboratory services. The capabilities of the personnel at the laboratory clinic interface are the most difficult to assess and evaluate in an adequate quality management system.

Concepts for a model of good medical laboratory services.

Several international standards and corresponding interpretation documents for quality management systems have been published. Although these standards are found useful to some extent, they are considered to be insufficient in several areas important for medical laboratories particularly in the pre- and post-examinational phases. The normative document for accreditation of laboratories (ISO/IEC Guide 25) is presently being revised and a document for medical laboratories (ISO/TC 212, CD 15189) is at draft stage. Both aim to include aspects of total quality management. The concept of total quality management is rather vague. Generally, its goal has been defined as "business excellence". This term, however, needs some explanation if applied to medical laboratories. Therefore, a project group of the European Confederation of Laboratory Medicine (ECLM) has developed a model for total quality management, which is based on a comprehensive management concept issued by the European Foundation for Quality Management. In the case of a medical laboratory, the term "business excellence" should be replaced by "good medical laboratory services". The proposed model could serve as a basis for future developments of total quality management standards in laboratory medicine. The goal of the "journey" should be clarified before it starts. To the best of our knowledge, this is the first attempt to develop a model of a good medical laboratory.

External quality assessment (EQA) of Belgian clinical laboratories. The telematics paradigm.

Technology that enables communication between information systems has recently become cheaper and more powerful. It is therefore timely to consider the effects of the introduction of such techniques in external quality assessment (EQA) schemes on both users and organizers. Traditionally, results are returned to EQA organizers as hand-written numbers on structured forms. These data are then manually entered into a computer. The process is time-consuming, slow (as it depends on the postal service), prone to error at every transcription stage, and expensive, as clerical staff must be employed to input the data. Computer-to-computer communication allows this process to be improved. A telematics system for electronic data interchange has been developed for the Belgian EQA programme and it offers several advantages, such as the use of standardized semantics, expression of results in laboratory familiar units, possible interface with the Laboratory Information System, faster data analysis, shorter report time and long-term performance evaluation.

Characterisation and evaluation of external quality assessment scheme serum. Discussion paper from the European External Quality Assessment (EQA) Organisers Working Group C.

This work reviews the procurement, specification and manufacture of serum for external quality assessment (EQA) and provides a checklist for scheme organisers. Guidance on the assessment of commutability and notes on the use of EQA materials to assess assay problems are provided. The importance of the appropriateness of materials in respect of scheme design and objectives, and the essential nature of a detailed specification prior to manufacture are emphasised.

Total quality management for clinical laboratories: a need or a new fashion?

In most European countries, concepts of quality management in medical laboratories have been proposed. These concepts are based on general standards for test laboratories (EN 45001, ISO 25) or specific adapted standards. Improvement of quality lays on the foundation of the implementation of quality systems in medical laboratories. This new approach will have consequences on management style and on working conditions. Efficacy on the implementation can only be tested by external audits. During this audit, not only the quality system and analytical competence must be examined, but also if there is a real contact between pathologists and clinicians and if laboratory results are clinically validated (clinical audit). This new vision on quality in medical laboratories will ask a reconsideration of the tasks, duties and knowledge of clinical pathologists.

Proposed guidelines for the internal quality control of analytical results in the medical laboratory.

The factors involved in analytical quality relate to definition of quality, creation of quality, and control of quality, and errors arise from external and internal sources as well as from permanent and variable factors. Further, the two main types of error are classified as systematic and random errors. Internal quality control (IQC) systems can only operate on the variable factors which are related to batch-to-batch variations (external factors) and to the performance in the laboratory (internal factors). In creating an adequate internal control system, several problems are faced: (i) quality of control materials, (ii) types and frequency of possible errors, (iii) number and types of control materials, (iv) number of replicates of the control, (v) probability of error detection, (vi) probability of false rejection, (vii) consequences of reject signals, (viii) trouble-shooting systems, and (ix) prevention of errors among many other conditions. Gaussian distributions of control results are assumed and the statistical control rules are evaluated in relation to probability of false rejections, Pfr, and probability of error detection, Ped, for the different rules. Combinations of low Pfr and high Ped are obtained by combining results from e.g. four measurements of the same control sample by use of mean and range rules. Further, it is not possible to establish a common control system which can be used for all quantities and analytical procedures; on the contrary, each procedure should have its particular efficient IQC system. These aspects are discussed and a number of guidelines for statistical control rules and problem related internal quality control are presented.

Characterization and classification of external quality assessment schemes (EQA) according to objectives such as evaluation of method and participant bias and standard deviation. External Quality Assessment (EQA) Working Group A on Analytical Goals in Laboratory Medicine.

Within the scope of this paper, the Working Group has attempted to place external quality assessment (EQA) within the whole context of quality management in laboratory medicine. First, the objectives of EQA schemes are defined and current EQA schemes evaluated. In most schemes, the objectives are not defined a priori and do not allow the definition of the origin of unacceptable individual results from participants. There is an ongoing trend for making traditional EQA schemes more interesting for the participants. Analysis of the factors involved in analytical quality allow the definition of the essential analytical tasks of educational EQA schemes. Beside these quality control tasks, educational EQA also includes quality assurance elements. EQA today has not only an important role to play in the assessment of each participant's performance but also in the assessment of the method. Efficiency of the schemes and educational impact can be improved by appropriate scheme designs according to objectives. After this theoretical approach, some practical examples of problem related EQA designs are given.

Desirable routine analytical goals for quantities assayed in serum. Discussion paper from the members of the external quality assessment (EQA) Working Group A on analytical goals in laboratory medicine.

The aim of the Working Group was to describe guidelines for deriving desirable analytical goals in laboratory medicine. First, a literature review is given of the different approaches used until now, and some of the most important studies are presented in detail. These approaches are then discussed critically, and the analytical goals proposed by the group are outlined with respect to monitoring and diagnostic testing. The group recommends that, most realistically, analytical quality specifications be biologically based. For diagnostic testing, the aim is achievement of accuracy, allowing the use of common reference intervals when populations are homogeneous for a given quantity. For monitoring (within an individual laboratory and performed with the same instrument), analytical performance should aim at stable operation and low imprecision compared with the within-subject biological variation. Method accuracy is also very important for the comparability of results from different laboratories or instruments.

Quality assurance in Belgium.

Clinical laboratories in Belgium working within the social security system require to be licensed. Internal quality control and participation in external quality assessment (EQA) belong to the licensing conditions. The evolution of the Belgian EQAs is outlined, including a performance evolution over the last ten years. Halving of interlaboratory CVs is observed for most clinical chemistry and immunoassay analytes. Improvement is less spectacular for haematological analytes and is missing for coagulation analytes. Using the results of EQAs 1989-1991 the mean overall method interlaboratory CVs could be estimated. Using data from a commercial internal quality control program for clinical chemistry and a request in 145 laboratories, current intralaboratory CVs are estimated.

Positive interference of merthiolate in the TDx digoxin assay in control samples used in the Belgian External Quality Assessment (EQA) Scheme.

We investigated the possible origin of the spuriously high results observed with the Abbott TDx Immunoassay in the 1991 Belgian external quality assessment scheme for digoxin. The present work ascribes this discrepancy to a matrix effect induced by the addition of merthiolate as preservative to the control samples. It consequently stresses the importance of avoiding the use of this compound for preparing such samples.

Factors influencing between-laboratory variability of C-reactive protein results as evidenced by the Belgian External Quality Assessment(EQA) Scheme.

Based on results from the Belgian External Quality Assessment (EQA) Scheme, we studied the main factors affecting the between-laboratory variation of C-reactive protein determination. Participants using homogeneous systems with several calibration points generally achieved better performance. Working temperatures influenced the results to a lesser extent. The present study stresses the importance for EQA organizers to collect more detailed information about CRP analytical methods used by the participants. It also suggests that manufacturers should be more involved in the management of quality, in particular by striving for standardization of the material (kit and calibrator) they produce for CRP assay.

Factitiously low urate recoveries in control sera with the Beckman Synchron Systems.

In the Belgian national external quality assessment scheme, we observed significantly lowered recoveries for urate in the group of Beckman Synchron users in comparison with the overall median values of the uricase/peroxidase colorimetric methods. These effects were linked to control sera of some manufacturers and we could demonstrate that these sera contained large amounts of pyridoxal-5-phosphate (PLP) as activator for transaminases. By spiking normal human serum with increasing PLP concentrations from 62.5 to 1000 mumol l-1, we observed a decrease in the urate recovery from 125 mumol l-1 (-11%). At 1000 mumol l-1 PLP, only 40% of the urate concentration was measured. An explanation for this effect was found in the polychromatic corrections of the Beckman Sychron system only applied with the Beckman urate method. This study demonstrates that EQAS organizers must carefully distinguish in their peer groups, not only the analytical principle and the measurement equipment, but also the reagent origin. Finally, the use of EQA control sera without PLP addition is strongly recommended if these sera are intended to be used as accuracy controls in EQA schemes including Beckman Synchron users.

Inter-laboratory external quality assessment schemes for specific IgE antibodies. The results of a European scheme for 1992.

External quality assessment programmes for specific IgE have been organised for some years in the United Kingdom, Belgium and the Netherlands but independently. This paper describes a co-operation scheme whereby the same samples were circulated simultaneously from each of the three countries and subsequent results combined to produce a single "EURO EQAS" report. Serum pools were prepared each containing antibodies, at differing concentrations, to 4 different allergens. The allergens surveyed represented the 10 most commonly encountered in Northern Europe. Results were submitted in grades (or classes) and in quantitative units and they showed some similarity by grade regardless of method used but differed greatly in units probably due to method differences. This paper shows how results could be treated to produce statistical data for the participants to help them be aware of their performance internally and also in comparison to other users.