Corrigendum to: Assessment of the degree of adherence of medical laboratories to KDIGO 2012 guideline for evaluation and management of CKD in Czechia and Slovakia.

[This corrects the article DOI: 10.11613/BM.2019.030704.].

[The common position of the Czech professional associations on the consensus of the European Atherosclerosis Society and the European Federation of Clinical Chemistry and Laboratory Medicine regarding investigation on blood lipids and interpretation of their levels]. / Spolecné stanovisko ceských odborných spolecností ke konsenzu European Atherosclerosis Society a European Federation of Clinical Chemistry and Laboratory Medicine k vysetrování krevních lipidu a k interpretaci jejich hodnot.

The aim of this opinion is to summarize and to comment the consensus of the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine, which covers two main areas: 1) whether it is necessary / required to be fasting or non-fasting before blood sampling for lipids measurement, and what are the changes in the concentration of blood lipids during the day; 2) What decision limits (cut off value) of lipids and lipoproteins should be reported from laboratories and what is the recommended procedure for people with extreme / critical blood lipid values. Following parameters are discused: total cholesterol, LDL cholesterol, HDL cholesterol, non-HDL cholesterol, triglycerides, apolipoprotein A1, apolipoprotein B, lipoprotein(a). This opinion should be the object of interest both for professionals in clinical laboratories and for physicians in hospitals and out-patients departments.Key words: apolipoproteins - blood collection - cholesterol - laboratory testing - lipoprotein(a) - cut off limits - triglycerides.

Interlaboratory study of free monoclonal immunoglobulin light chain quantification.

BACKGROUND: Quantification of monoclonal immunoglobulin free light chains (FLCs) in serum is used increasingly in clinical practice for the diagnosis, prognostic assessment, and treatment monitoring of monoclonal gammopathies. It is used as an adjunct to standard serum protein electrophoresis and immunofixation. However, methods for FLC quantification need further standardization and validation. METHODS: The Czech Myeloma Group and the Czech Society of Clinical Biochemistry have initiated an interlaboratory study where six laboratories collaborating with the primary myeloma treatment centres measured FLC concentrations in 12 serum samples from patients with monoclonal gammopathies. RESULTS: Repeatability of the measurements in five laboratories was calculated based on differences between the results of duplicate measurements. We found that repeatability depended more on the laboratory than on the device used for measurement. CONCLUSIONS: The study revealed several weak points in the methodology, including the need for a uniform sample dilution procedure. Interlaboratory reproducibility was comparable with values achieved in the NEQAS programme. Because the κ/λ ratio cannot be measured with high precision, κ and λ FLC concentrations should be used where possible. Due to its impact on the clinical management of patients with gammopathy, FLC quantification needs to become a part of the regular quality control cycle in myeloma centres.

Estimation of trueness of measurement results obtained in external quality assessment.

BACKGROUND: We demonstrated that lyophilised EQA/PT control materials, under certain circumstances, provide equal information about bias values as pools of native patient sera, and that in some cases, long-term reliable work with such materials is possible. METHODS: Bias values, estimated from results of routine surveys of EQA SEKK (Czech Republic) programmes for eight basic blood serum analytes using lyophilised control materials, were compared with bias values reached in the CAP (USA) programme where pools of native and lyophilised patient sera were used. RESULTS: Results for the components Na, K, Mg, Cl, P, urea, glucose, and uric acid were assessed. No significant differences were found between the bias values estimated by CAP using native sera, and those estimated by SEKK using lyophilised sera. CONCLUSIONS: It can be concluded that well-prepared lyophilised control materials may show the required commutability level. If so, they constitute a practical and cost-efficient alternative to native or fresh frozen sera when assessing bias.

Quality of serum creatinine measurement in light of EQA programs.

BACKGROUND: The aim of our study was to identify the role of External Quality Assessment (EQA) programs in improving the quality of serum creatinine measurement and glomerular filtration rate (GFR) estimation. Comparison of results achieved during EQA with National Kidney Disease Education Program and College of American Pathologists guidelines identified an urgent need for an improvement in measurement quality. We compared actual results for serum creatinine measurement within the Czech Republic EQA with the requirements of EC Directive 98/79. METHODS: We used the results for 2005-2006 EQA programs. There were seven surveys involved with two samples each, and a 2006 questionnaire on the post-analytical phase survey. RESULTS: Bias depended strongly on the creatinine concentration. However, this dependence varied for different in vitro diagnostic manufacturers, although they should all follow the same directive. We chose biological variation as the significance rate for bias and a resulting overall error of 6.9%. The proportion of results with total error <6.9% ranged from 11% to 80%. The total error for a reference sample of 94.8 mumol/L also showed significant dependence on the working calibrator used and ranged from 1% to 17%. CONCLUSIONS: The main role of EQA programs in improving the quality of creatinine measurement results and GFR calculation should be in monitoring the quality of IVD products, enabling users to adapt their use of these products accordingly. EQA programs can also educate on performing GFR estimation in a unified way. Highly commutable control materials with certified creatinine values or, alternatively, lyophilized materials with sufficient commutability proved by comparison with native frozen human sera, should become an important EQA tool.

Comparability of eight immunoassay procedures for the determination of CA 15-3 and related markers.

MUC1 mucins are tumour markers that are frequently indicated and examined, particularly as part of the treatment of breast cancer. Relatively large differences were observed in external quality assessment (EQA) between the results that were obtained by different immunoassay technologies. Thus, we compared eight routinely employed immunoassay sets for the determination of MUC1 mucins in the serum: six closed automated systems (AxSYM, Centaur, ECi Vitros, Elecsys 2010, Immulite 2000 and Kryptor), and two IRMA kits (ELSA CIS and IRMA-mat Byk-Sangtec). Using all analytical systems, we measured identical groups of clinical samples complete with selected calibrator and control samples. The repeatability of measurements (presented as coefficients of variation) ranged from 0.7% (Kryptor) to 6.9% (Immulite 2000). Even though the cut-off values differ among various systems, no similar clinical efficacy appears to be attained. In the region of cut-off values, the highest specificity that was set as a standard was found for the AxSYM analyser, while the sensitivity was highest for the Elecsys 2010. Data from Bland-Altman differential plots suggest the presence of significant individual differences among individual samples, mainly in the region of high concentrations of MUC1 mucins. The parameters of Passing-Bablok regression show significant systematic differences between some of the analytical systems as well as an increase of the differences with increasing MUC1 mucin concentrations. The effect of the combination of antibodies used on the extent of differences among results obtained with individual systems is more obvious than the effect of the matrix of analysed materials.

Pilot external quality assessment survey for post-market vigilance of in vitro diagnostic medical devices and investigation of trueness of participants' results.

The Czech External Quality Assessment Scheme organized a survey using 14 fresh-frozen sera targeted for cholesterol and glucose by reference measurement procedures. The objective was to investigate whether it could fulfil a post-market vigilance function for in vitro diagnostic medical devices and assess trueness of participants' results. It revealed a mean bias of +5.1% for cholesterol and +3.7% for glucose (n approximately 150). However, the bias source (manufacturer or laboratory) could not be identified unequivocally because of the lack of homogeneous groups. This was due to the fact that laboratories mainly used reagents from manufacturers that do not market instruments or combined calibrators and reagents from different sources. Consequently, these habits did not allow the survey to fulfil the vigilance function. On the other hand, we were able to show the individual participants results for patient samples deviating from the true value (deviations >10% in approximately 20% of the laboratories). However, again, the survey failed in problem-solving via peer-group evaluation, even for participants that applied homogeneous tests. If other European schemes confirm this outcome, cooperation and/or participation of manufacturers may be the solution. The survey pointed out to the other participants, interchanging instrument, reagent and calibrator, that they are themselves responsible for the problems shown and hence also for problem-solving.