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Le raccomandazioni SIPMeL per l'accreditamento ISO del monitoraggio di validità dei risultati degli esami --- SIPMeL recommendations for ISO accreditation of validity monitoring of examination results
Abstract
La norma ISO 15189 revisionata è stata pubblicata il 6 dicembre 2022, quasi un anno dopo il termine previsto. SIPMeL, dopo aver partecipato attivamente al processo di revisione, mette a disposizione una serie di documenti di Raccomandazioni, con i principali contenuti della norma ISO in lingua italiana, qualche riflessione critica, e le indicazioni per applicare i requisiti della norma. Le Raccomandazioni SIPMeL Q19 concernono i requisiti di UNI EN ISO 15189:2023 su validità dei risultati degli esami, con il controllo di qualità interno (CQI), la valutazione esterna della qualità (VEQ) e la comparabilità dei risultati degli esami. I requisiti di ISO 15189 per il CQI non scendono in dettagli, ma le Raccomandazioni Q19 richiamano almeno ISO 15198 (compiti dei produttori) e CLSI C24 (statistica del CQI), oltre al Vocabolario Internazionale di Metrologia (VIM). Pubblicando il documento ISO 20914, è stato stabilito che il CQI non serve solo per il monitoraggio dei risultati, ma fornisce la base per la stima dell’incertezza. Il documento Q19 raccoglie elementi da vari documenti CLSI, come le guide per l’immunometria, quelle per la microbiologia, quelle per i metodi molecolari e quelle per gli esami POCT. CLSI poi fornisce indicazioni sulle alternative per i materiali di controllo. Q19 introduce infine la tematica del monitoraggio dei risultati qualitativi. ISO 15189 fornisce più dettagli sulla partecipazione a VEQ, ma la Raccomandazione Q19 aggiunge i riferimenti a guide CLSI come QMS24 e MM14. I requisiti per VEQ di ISO 15189 hanno grande importanza per l’esito delle verifiche di accreditamento. ISO 15189 affianca infine nella stessa clausola CQI, VEQ e comparabilità dei risultati degli esami. Le Raccomandazioni Q19 correggono la terminologia in base al VIM, richiamano le guide CLSI EP31 e CLSI EP09, nonché le proprie Raccomandazioni sulla stessa materia del 2016. Secondo Q19, le procedure di comparazione hanno caratteristiche più vicine alle attività di validazione e verifica dei metodi, diverse da CQI e VEQ, da cui dovrebbero essere distinte. Q19 propone ai laboratori un approccio semplice, poco oneroso e con statistiche non troppo sofisticate.
----- The revised ISO 15189 standard was published on 6 December 2022, almost one year after the deadline. SIPMeL, having actively participated in the revision process, provides a series of Recommendations documents, with the main contents of the ISO standard in Italian language, some critical reflections, and indications for applying the requirements of the standard. The SIPMeL Recommendations Q19 concern the requirements of UNI EN ISO 15189:2023 on validity of examination results, with internal quality assurance (IQC), external quality assessment (EQA) and comparability of examination results. The requirements of ISO 15189 for CQI do not go into detail, but Recommendation Q19 at least recalls ISO 15198 (manufacturers' tasks) and CLSI C24 (CQI statistics), as well as the International Vocabulary of Metrology (VIM). By publishing ISO 20914, it was established that the IQC not only serves for monitoring results, but also provides the basis for estimating uncertainty.
Document Q19 collects elements from various CLSI documents, such as the guides for immunometry, those for microbiology, those for molecular methods and those for POCT examinations. CLSI then provides guidance on alternatives for control materials. Q19 finally introduces the topic of monitoring quality results. ISO 15189 provides more detail on participation in VEQ, but Recommendation Q19 adds references to CLSI guides such as QMS24 and MM14. The requirements for VEQ in ISO 15189 are of great importance for the outcome of accreditation audits. ISO 15189 finally combines IQC, VEQ and comparability of examination results in the same clause. The Q19 Recommendations correct the terminology according to VIM, recall the CLSI EP31 and CLSI EP09 guides as well as its own 2016 Recommendations on the same subject. According to Q19, comparison procedures have characteristics that are closer to method validation and verification activities, different from IQC and VEQ, from which they should be distinguished. Q19 proposes to the laboratories a simple, inexpensive approach with not too sophisticated statistics.
The revised ISO 15189 standard was published on December 6th; 2022. SIPMeL provides Italian medical laboratories with a series of Recommendation documents. In SIPMeL Recommendations Q20-1 the requirements in chapter 6 (resources), those in clause 6.2 (personnel) and clause 6.3 (space, physical and environmental facilities) are presented. In SIPMeL Recommendations Q20-2 the requirements in clauses 6.4 (Equipment), 6.6 (Reagents and consumables), 6.7 (Service agreements) and 6.8 (Externally purchased products and services) are presented. ISO 15189:2022 contains several references to other ISO documents, the requirements of which are to be fulfilled in laboratories and to be verified during accreditation visits. The Q20 Recommendations consider that other requirements should be added, such as those of ISO 22583 for instruments in POCT services, ISO 20658 for point-of-care spaces and ISO 15190 (health and safety at work). The Recommendations also deem it necessary to consider several CLSI documents, such as CLSI GP17 (health and safety), CLSI QMS03 (staff competence), CLSI QMS16 (job description), CLSI QMS04 (spaces), CLSI QMS05 (reference laboratories). --- La norma ISO 15189 revisionata è stata pubblicata il 6 dicembre 2022. SIPMeL mette a disposizione dei laboratori medici italiani una serie di documenti di Raccomandazioni. Nelle Raccomandazioni SIPMeL Q20-1 vengono presentati i requisiti nel capitolo 6 (risorse), quelli della clausola 6.2 (Personale) e della clausola 6.3 (spazi, strutture fisiche e ambientali). Nelle Raccomandazioni SIPMeL Q20-2 vengono presentati i requisiti delle clausole 6.4 (Attrezzature), 6.6 (Reagenti e materiali di consumo), 6.7 (Accordi di servizio) e 6.8 (Prodotti e servizi acquistati all’esterno). ISO 15189:2022 contiene diversi riferimenti ad altri documenti ISO, i cui requisiti sono da ottemperare nei laboratori e da verificare nelle visite di accreditamento. Le Raccomandazioni Q20 ritengono che vadano aggiunti altri requisiti, come quelli di ISO 22583 per gli strumenti dei servizi POCT, ISO 20658 per gli spazi dei punti di prelievo e ISO 15190 (salute e sicurezza nel lavoro). Le Raccomandazioni ritengono altresì necessario considerare diversi documenti CLSI, come CLSI GP17 (salute e sicurezza), CLSI QMS03 (competenza del personale), CLSI QMS16 (mansioni degli operatori), CLSI QMS04 (spazi), CLSI QMS05 (laboratori di referenza).
Aims
Next-generation sequencing (NGS) is integral to the delivery of personalised medicine for targeted cancer therapy. Average turnaround times (TAT) from reference laboratories with advanced expertise in sequencing are typically 2–3 weeks. Prolonged TAT for biomarker analysis can adversely affect patient outcomes. The project aim was to establish an accredited NGS service integrated within a routine clinical diagnostic laboratory, in a designated tertiary cancer centre with no previous experience in NGS or bioinformatics.
Methods
Platform selected was the novel Ion Torrent Genexus Sequencer with automated onboard library preparation, templating, sequencing and data analysis, with subsequent reporting using Oncomine Reporter software.
Entire workflow validation was performed with a targeted panel, the Oncomine Precision Assay, on formalin-fixed paraffin embedded clinical tumour samples. Oncomine Reporter software was used to report on variants including mutations, copy number variations and fusions across 50 key genes.
Samples included surgical resections, biopsies, cytology and commercial reference material. Assessment of criteria included analytical sensitivity, specificity, limit of detection, accuracy, repeatability and reproducibility, with the establishment of performance metrics and quality parameters.
Results
High sensitivity, specificity and reproducibility were achieved. DNA/RNA input requirements optimised to >10 ng, and sequencing performance established with a limit of detection of 5% when depth of coverage of 2500X was reached. This NGS service attained ISO15189 accreditation with no non-conformances and >56% reduction in TAT.
Conclusion
Successful implementation, clinical validation and accreditation of a novel NGS technology was achieved in this institution, with a significantly improved TAT of results to oncologists
Objectives
Moving average quality control (MA QC) is a patient-based real-time quality control system. Advantages compared to conventional periodic internal quality control (IQC) include absence of commutability problems and continuous monitoring of performance. We implemented MA QC for multiple routine hematology and chemistry parameters. We describe the evaluation process and provide practical tools to aid MA QC implementation.
Methods
Nine parameters (serum sodium, calcium, bicarbonate and free thyroxine, hemoglobin [Hb], mean corpuscular volume, mean corpuscular hemoglobin concentration [MCHC], reticulocyte count and erythrocyte sedimentation rate [ESR]) were chosen for initial consideration. Using data extractions from the laboratory information system (LIS; General Laboratory Information Management System), evaluation of usefulness and optimization of MA QC settings was performed using bias detection curves. After this, MA QC settings were incorporated in our LIS for further evaluation and implementation in routine care.
Results
Three out of nine parameters (Hb, ESR, and sodium) were excluded from MA QC implementation due to high variation and technical issues in the LIS. For the six remaining parameters, MA QC showed added value to IQC and was therefore implemented in the LIS. For three parameters a direct MA alarm work-up method was set up, including newly developed built-in features in the LIS. For the other parameters, we identified MA utilization beyond real-time monitoring.
Conclusions
Implementation of MA QC has added value for our laboratory setting. Additional utilization beyond real-time QC monitoring was identified. We find MA QC especially useful for trend monitoring, detection of small shifts after maintenance and inter-analyzer comparisons.
The revision of ISO 15189 retains the requirement for uncertainty estimation, referring to ISO/TS 20914 for implementation. [1] With document Q16 [2], SIPMeL collects the main ISO, literature, and CLSI guidance on the topic. Typical examples of application of the Q16 Recommendations are presented here to demonstrate their ease of use.
Methods:
The performance characteristics of an assay with quantitative results ( ALT EC 2.6.1.2) are derived from refs [3] and [4]. A test with "qualitative" results, Abbott BinaxNOW-19 COVID-19 Ag card [5] [6], is then described.
The SIPMeL Q16 recommendations provide for quantitative results, and for quantitative phases of examinations with nominal results, the calculation of type deviation (σ) from the long-term IQC data and the repeatability limit from type deviation (σ) in the series. For nominal qualitative results, and for the weakly positive result of a method that provides ordinal qualitative values, the CQI for a material near the detection limit or C95 provides a frequency value of positives (POD%), while the repeatability check uses the equality criterion between two repeated results.
Results:
The uncertainty component of the calibration, the prerogative of the manufacturers, is set to zero. The precision component results for ALT σ 2.94 U/L (CV 8.3%), extended uncertainty (U) 5.88 U/L (16.6%), while for COVID-19 Ag the precision of the chosen level is fixed at POD 95%. Results of duplicate testing are presented.
Conclusion:
In the medical laboratory, pressured by the amount of tests to be performed and turnaround times to be met, procedures for quality must be easily executable, simple, intuitively understandable, robust, and uncontroversial. This is what ISO 20914 and a long list of ISO and CLSI documents, collected in SIPMeL Q16, are for. Knowledge of uncertainty provides the laboratory with awareness of the reliability of results, information that is shared with users or third parties, for example, in accreditation inspections.
"Precision" requires repetitions of the measurement on the same material at a set level. For qualitative results, it is easy to determine how often observations differ from each other, rather than measuring by how much observations differ from the mean.
References:
1. Pradella M. Alcune certezze dell'incertezza di misura: nuova ISO 20914 e raccomandazioni SIPMeL. Riv Ital Med Lab 2021 Sep 15. DOI: 10.23736/S1825-859X.21.00112-22. SIPMeL Recommendations for estimating measurement uncertainty in medical laboratories (ISO 15189 and ISO 20914) http://dx.doi.org/10.13140/RG.2.2.31013.63207/2 https://www.sipmel.it/en/lineeguida/approvate/118096
3. Biswas SS et al. Evaluation of imprecision, bias and total error of clinical chemistry analysers. Indian J Clin Biochem. 2015 Jan;30(1):104-8.
4. Beckman Coulter. Alanine Aminotransferase (ALT). https://bit.ly/BeckmanALT
5. Perchetti GA et al. Analytical Sensitivity of the Abbott BinaxNOW COVID-19 Ag Card. J Clin Microbiol. 2021 Feb 18;59(3):e02880-20.
6. Abbott. BinaxNOWTM COVID-19 Ag CARD https://www.fda.gov/media/141570/download ---
https://cattendee.abstractsonline.com/meeting/10594/Presentation/337 ---
https://www.abstractsonline.com/pp8/#!/10594/presentation/337
For diagnosing SARS-CoV-2 infection and for monitoring its spread, the implementation of external quality assessment (EQA) schemes is mandatory to assess and ensure a standard quality according to national and international guidelines. Here, we present the results of the 2020, 2021, 2022 EQA schemes in Lombardy region for assessing the quality of the diagnostic laboratories involved in SARS-CoV-2 diagnosis. In the framework of the Quality Assurance Programs (QAPs), the routinely EQA schemes are managed by the regional reference centre for diagnostic laboratories quality (RRC-EQA) of the Lombardy region and are carried out by all the diagnostic laboratories. Three EQA programs were organized: (1) EQA of SARS-CoV-2 nucleic acid detection; (2) EQA of anti-SARS-CoV-2-antibody testing; (3) EQA of SARS-CoV-2 direct antigens detection. The percentage of concordance of 1938 molecular tests carried out within the SARS-CoV-2 nucleic acid detection EQA was 97.7%. The overall concordance of 1875 tests carried out within the anti-SARS-CoV-2 antibody EQA was 93.9% (79.6% for IgM). The overall concordance of 1495 tests carried out within the SARS-CoV-2 direct antigens detection EQA was 85% and it was negatively impacted by the results obtained by the analysis of weak positive samples. In conclusion, the EQA schemes for assessing the accuracy of SARS-CoV-2 diagnosis in the Lombardy region highlighted a suitable reproducibility and reliability of diagnostic assays, despite the heterogeneous landscape of SARS-CoV-2 tests and methods. Laboratory testing based on the detection of viral RNA in respiratory samples can be considered the gold standard for SARS-CoV-2 diagnosis.
Objective
MALDI-TOF MS is a widely used method for bacterial species identification. Incomplete databases and mass spectral quality (MSQ) still represent major challenges. Important proxies for MSQ are: number of detected marker masses, reproducibility, and measurement precision. We aimed to assess MSQs across diagnostic laboratories and the potential of simple workflow adaptations to improve it.
Methods
For baseline MSQ assessment, 47 diverse bacterial strains which are challenging to identify by MALDI-TOF MS, were routinely measured in 36 laboratories from 12 countries, and well defined MSQ features were used. After an intervention consisting of detailed reported feedback and instructions on how to acquire MALDI-TOF mass spectra, measurements were repeated and MSQs were compared.
Results
At baseline, we observed heterogeneous MSQ between the devices, considering the median number of marker masses detected (range = [5, 25]), reproducibility between technical replicates (range = [55%, 86%]), and measurement error (range = [147 parts per million (ppm), 588ppm]). As a general trend, the spectral quality was improved after the intervention for devices which yielded low MSQs in the baseline assessment: for 4/5 devices with a high measurement error, the measurement precision was improved (p-values<0.001, paired Wilcoxon test); for 6/10 devices, which detected a low number of marker masses, the number of detected marker masses increased (p-values<0.001, paired Wilcoxon test).
Conclusion
We have identified simple workflow adaptations, which, to some extent, improve MSQ of poorly performing devices and should be considered by laboratories yielding a low MSQ. Improving MALDI-TOF MSQ in routine diagnostics is essential for increasing the resolution of bacterial identification by MALDI-TOF MS, which is dependent on the reproducible detection of marker masses. The heterogeneity identified in this EQA requires further study.
Objectives
Not many reports have covered large-scale point of care testing (POCT) blood glucose comparisons, and many interfering factors affect detection. This study aims to verify the performance of POCT blood glucose meters and discusses the factors that interfere with detection.
Methods
Accuracy and precision verification in five glucose concentration groups-high 1 (H1), High 2 (H2), medium 1 (M1), medium 2 (M2), and low (L); comparison of different test methods and specimens; and also the influence of iodophor was investigated in a dilution experiment.
Results
A total of 58 out of 64 Accu-Chek Inform II POCT blood glucose meters (ACI II) qualified for testing. A proportional significant difference in the relative bias was observed with the POCT instruments in the intermediate and high glucose concentration groups (H=15.364, p=0.02). There were significant differences among the five groups with compliance rates ( χ ² =21.03, p=0.00); Group L showed higher values than groups H1 and H2. The precision verification met the requirements issued by the Consensus. Significant differences were found between the three detection methods. The measurement of the Glucose Oxidase Method (Cobas B 123) was lower than that of the HITACHI Plasma Hexokinase Method and the Glucose Dehydrogenase Method on the ACI II (p=0.005 and 0.003) in the preliminary study. No differences were seen among the three types of specimens (p>0.05). The glucose results were incorrect in the presence of iodophor interference.
Conclusions
The ACI II and Cobas B123 (with a slightly negative bias) provide sufficiently accurate measurements, and all types of blood specimens can be applied. Iodophor, a disinfectant, interferes with glucose measurement.
Background:
Results from laboratories using multiple instruments should be standardized or harmonized and comparability-verified for consistent quality control. We developed a simple frequent comparability verification methodology applicable to large healthcare centers using multiple clinical chemistry instruments from different manufacturers.
Methods:
Comparability of five clinical chemistry instruments (Beckman Coulter AU5800, Abbott Architect Ci16000, two Siemens Vista 1500, and Ortho Vitros 5600) was evaluated from 2015 to 2019 for 12 clinical chemistry measurements. Pooled residual patient samples were used for weekly verifications. Results from any instrument exceeding the allowable verification range versus the results from the comparative instrument (AU5800) were reported to clinicians after being multiplied by conversion factors that were determined via a linear regression equation obtained from simplified comparison.
Results:
Over the five-year study period, 432 weekly inter-instrument comparability verification results were obtained. Approximately 58% of results were converted due to non-comparable verification. Expected average absolute percent bias and percentage of non-comparable results for non-converted and converted results after conversion action were much lower than those for data measured before conversion action. The inter-instrument CV for both non-converted and converted results after conversion action was much lower than that for measured data before conversion action for all analytes.
Conclusions:
We maintained within-laboratory comparability of clinical chemistry tests from multiple instruments for five years using frequent low-labor periodic comparability verification methods from pooled residual sera. This methodology is applicable to large testing facilities using multiple instruments.
Introduction:
It is unclear what is the best strategy for applying patient-based real-time quality control (PBRTQC) algorithm in the presence of multiple instruments. This simulation study compared the error detection capability of applying PBRTQC algorithms for instruments individually and in combination using serum sodium as an example.
Materials and methods:
Four sets of random serum sodium measurements were generated with differing means and standard deviations to represent four simulated instruments. Moving median with winsorization was selected as the PBRTQC algorithm. The PBRTQC parameters (block size and control limits) were optimized and applied to the four simulated laboratory data sets individually and in combination.
Results:
When the PBRTQC algorithm were individually optimized and applied to the data of the individual simulated instruments, it was able to detect bias several folds faster than when they were combined. Similarly, the individually applied algorithms had perfect error detection rates across different magnitudes of bias, whereas the error detection rates of the algorithm applied on the combined data missed smaller biases. The performance of the individually applied PBRTQC algorithm performed more consistently among the simulated instruments compared to when the data were combined.
Discussion:
While combining data from different instruments can increase the data stream and hence, increase the speed of error detection, it may widen the control limits and compromising the probability of error detection. The presence of multiple instruments in the data stream may dilute the effect of the error when it only affects a selected instrument.
The Italian Society of Clinical Pathology and Laboratory Medicine (SIPMeL) Quality and Accreditations Commission produced its recommendations on this matter [3] acknowledging ISO 15198:2004 [4] document, confirmed for the first time in 2008 and revised with a positive result in December 2018. Key points are shared responsibility between the laboratory and the manufacturer, specific terms and definitions and validation and re-validation of updated quality-control procedures.
Enhancing the task of the diagnostic manufacturer has several advantages. It adds material and knowledge resources to those of medical laboratories, not always sufficient for these activities, which are often complex and expensive. It favors the harmonization of procedures between different laboratories and the comparability of the quality of the services provide, the emergence of specific critical issues, which reported at the manufacturer’s site and subjected to comparison with other laboratories, can find an adequate solution. SIPMeL therefore recommends that all diagnostic manufacturers provide the laboratory with appropriate internal quality-control instructions.
Special conditions associated with laboratory autoimmune testing are not well compatible with recent developments in regulatory frameworks such as EN/ISO 15189 accreditation or in vitro diagnostic medical device regulation (IVD-R). In addition, international recommendations, guidelines and disease criteria are poorly defined with respect to requirements on autoantibody testing. Laboratory specialists from Austria, Belgium, Croatia, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Norway, Poland, Portugal, South Africa, Spain, Sweden, Switzerland, and The Netherlands collected information, reported national experience, and identified quality issues in relation to autoantibody testing that require consensus on interpretation of the regulatory frameworks and guidelines. This process has been organized by the European Autoimmunity Standardisation Initiative (EASI). By identifying the critical items and looking for a consensus, our objective was to define a framework for, in particular, EN/ISO accreditation purposes. Here, we present a review of current publications and guidelines in this field to unify national guidelines and deliver in this way a European handout on quality control and accreditation for laboratories involved in autoantibody testing. We focus on quality items that can be checked during accreditation visits. Despite various local varieties, we encountered an overwhelming dedication to quality assurance in all contributing countries.
dalla presentazione al Corso Residenziale: Statistica del controllo di qualità interno per
l'accreditamento ISO 15189, 11 maggio 2018 - Santorso (VI), Sala Convegni Bolla Rossa Ulss 7, Pedemontana, Ospedale Alto Vicentino e dalla presentazione al seminario Informatica e statistica del controllo di qualita' interno nel laboratorio medico per l'accreditamento ISO 15189, 12 ottobre 2017, Ore 8.30 – 09.45, 3° Congresso Nazionale SIPMeL - Da Medicina di Laboratorio a Medicina in Laboratorio dal 10 al 12 ottobre 2017 a Riva del Garda (TN) presso il Centro Congressi di Riva del Garda - Parco Lido ------------------------
La Commissione SIPMeL Qualità e Accreditamenti ha recentemente prodotto le sue raccomandazioni su questa materia. Le raccomandazioni costituiscono il recepimento del documento ISO 15198:2004, confermato una prima volta nel 2008 e sottoposto a revisione con esito per ora positivo nel dicembre 2018.
ISO 15198 vien ripresa e rilanciata in documenti ISO correnti o addirittura in preparazione, come ISO/DIS 20391-2, in documenti del Clinical Laboratory Standard Institute CLSI (QMS01, QMS11, EP05) ed in documenti della Organizzazione mondiale della sanità WHO (TSS-6, TSS7, TSS-8).
Correct measurement of autoantibodies is essential for the diagnosis of autoimmune diseases. However, due to the variability of autoantibody results and the heterogeneity of testing, wrong diagnosis is a reality. For this and more reasons, harmonization of testing is of the outmost importance. In this review we have summarized the factors contributing to this variability. The ways with which the working group on harmonization of autoantibody testing of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has been trying to tackle the issue with the production and correct use of certified reference materials (CRMs), is discussed. Finally the advantages and the limitations of the use of CRMs are presented.
The Critical Success Factors (CSFs) are “those few things that must go well to ensure success” and allow strategic choosing. A non-systematic review identified as CSFs for Laboratory Medicine quality and continuous quality improvement, innovation, and strategy.
“Quality” is the answer to the clinical request that fits the implicit/explicit needs/requests of the complex “client” of the Laboratory Medicine, and “quality improvement” is the better outcomes and experience of the patient, achieved through systematic change of behavior and procedures, that overcome the barriers of the “silo” in which Laboratory Medicine is often confined.
“Innovation” is diffusion of new technologic and diagnostic interventions, and its validation, establishing evidences by structured methodologies as Evidence-based Laboratory Medicine. Moreover, knowledge management and translation to complex stakeholders are duties of Clinical Laboratory.
“Strategic planning and management” is not “something that organizations have”, but “something that people do” in a vision of strategy-as-practice or “strategizing”, in which organizational innovation is the core of changing challenges. Converging technologies, i.e. miniaturization and information technology, determined the new context of relationship between patients and laboratory with the amplification of clinic-laboratory interface and consequential issues of safety, communication, and reorganization of service around the patient.
Using the above CSFs, the Clinical Laboratory should become a High-Reliability Organization and a High-value Organization.
There is little confidence in the consistency of estimation of DNA concentrations when samples move between laboratories. Evidence on this consistency is largely anecdotal. Therefore there is a need first to measure this consistency among different laboratories and then identify and implement remedies. A pilot experiment to test logistics and provide initial data on consistency was therefore conceived.
DNA aliquots at nominal concentrations between 10 and 300 ng/mul were dispensed into the wells of 96-well plates by one participant - the coordinating centre. Participants estimated the concentration in each well and returned estimates to the coordinating centre.
Considerable overall variability was observed among estimates. There were statistically significant differences between participants' measurements and between fluorescence emission and absorption spectroscopy.
Anecdotal evidence of variability in DNA concentration estimation has been substantiated. Reduction in variability between participants will require the identification of major sources of variation, specification of effective remedies and their implementation.
The objectives of this study were 1) to construct new error grids (EGs) for blood glucose (BG) self-monitoring by using the expertise of a large panel of clinicians and 2) to use the new EGs to evaluate the accuracy of BG measurements made by patients.
To construct new EGs for type 1 and type 2 diabetic patients, a total of 100 experts of diabetes were asked to assign any error in BG measurement to 1 of 5 risk categories. We used these EGs to evaluate the accuracy of self-monitoring of blood glucose (SMBG) levels in 152 diabetic patients. The SMBG data were used to compare the new type 1 diabetes EG with a traditional EG.
Both the type 1 and type 2 diabetes EGs divide the risk plane into 8 concentric zones with no discontinuities. The new EGs are similar to each other, but they differ from the traditional EG in several significant ways. When used to evaluate a data set of measurements made by a sample of patients experienced in SMBG, the new type 1 diabetes EG rated 98.6% of their measurements as clinically acceptable, compared with 95% for the traditional EG.
The consensus EGs furnish a new tool for evaluating errors in the measurement of BG for patients with type 1 and type 2 diabetes.
External quality assurance (EQA) programs for diagnostic tests based on nucleic acid amplification have not been widely implemented in clinical laboratories and remain limited to few tests. Development of specific EQA programs based on application-based proficiency testing for any diagnostic molecular target is challenging. Development of EQA trials based on methodologic proficiency testing and directed to the evaluation of analytical aspects common to the majority of PCR-based tests may be valuable.
We developed an EQA program for evaluation of DNA extraction and amplification and analysis of products after PCR. Participants received a package containing primers and reference materials to evaluate three specific controls for, respectively, DNA extraction (quality and quantity), PCR performance (specificity and efficiency), and interpretation of results after electrophoresis. Each participant was asked to return to the organizers a form with their numerical results and an aliquot of all amplified samples for joint evaluation.
Results varied in all phases of the experimental procedure: preamplification, amplification, and post-PCR interpretation. To give a general estimation on the quality of performances for each laboratory, we designed a score scheme in which the results of any specific action were evaluated on the basis of the distribution around the median consensus values. The maximum possible score was 84. On the basis of total score obtained by each laboratory, we created a qualitative ranking list that provided the final interpretation of results as excellent (>63 points; n = 4 laboratories), good (53-63 points; n = 13), sufficient (42-52 points; n = 15), poor (31-41 points; n = 3), and not acceptable (<31 points; n = 4).
This survey demonstrates the importance of EQA trials based on methodologic proficiency testing directed to evaluation of analytical aspects common to the majority of PCR-based tests.
In the past 15 years, clinical laboratory science has been transformed by the use of technologies that cross the traditional boundaries between laboratory disciplines. However, during this period, issues of quality have not always been given adequate attention. The European Molecular Genetics Quality Network (EMQN) has developed a novel external quality assessment scheme for evaluation of DNA sequencing. We report the results of an international survey of the quality of DNA sequencing among 64 laboratories from 21 countries.
Current practice for DNA sequence analysis was established by use of an online questionnaire. Participating laboratories were provided with 4 DNA samples of validated genotype. Evaluation of the results included assessing the quality of sequence data, variant genotypes, and mutation nomenclature. To accommodate variations in mutation nomenclature, variants indicated by participants were scored for compliance with 3 acceptable marking schemes.
A total of 346 genotypes were analyzed. Of these, 19 (5%) genotyping errors were made. Of these, 10 (53%) were false-negative and 9 (47%) were false-positive results. A further 27 (8%) errors were made in naming mutations. Results were analyzed for 3 indicators of data quality: PHRED quality scores, Quality Read Length, and Quality Read Overlap. Most laboratories produced results of acceptable diagnostic quality as judged by these indicators. The results were used to calculate a consensus benchmark for DNA sequencing against which individual laboratories could rank their performance.
We propose that the consensus benchmark can be used as a baseline against which the aggregate and individual laboratory standard of DNA sequencing may be tracked from year to year.
Quantitative gene expression analysis by real-time PCR is important in several diagnostic areas, such as the detection of minimum residual disease in leukemia and the prognostic assessment of cancer patients. To address quality assurance in this technically challenging area, the European Union (EU) has funded the EQUAL project to develop methodologic external quality assessment (EQA) relevant to diagnostic and research laboratories among the EU member states. We report here the results of the EQUAL-quant program, which assesses standards in the use of TaqMan probes, one of the most widely used assays in the implementation of real-time PCR.
The EQUAL-quant reagent set was developed to assess the technical execution of a standard TaqMan assay, including RNA extraction, reverse transcription, and real-time PCR quantification of target DNA copy number.
The multidisciplinary EQA scheme included 137 participating laboratories from 29 countries. We demonstrated significant differences in performance among laboratories, with 20% of laboratories reporting at least one result lacking in precision and/or accuracy according to the statistical procedures described. No differences in performance were observed for the >10 different testing platforms used by the study participants.
This EQA scheme demonstrated both the requirement and demand for external assessment of technical standards in real-time PCR. The reagent design and the statistical tools developed within this project will provide a benchmark for defining acceptable working standards in this emerging technology.
The new SIPMeL Recommendations for IT address some specific requirements for ISO accreditation, they do not replace the previous Recommendations, which were developed for a broader range of topics, such as the presentation of examination results. ISO 15189 states the validity of the requirements for both computerised and paper-based systems, but in reality they are all addressed to digital systems. Some rules on the management of traditional paper-based media can be found in chapter 4 (confidentiality), in sections 7.2.3 (examination requests) and 7.4.1 (presentation of results), in chapter 8 (management).
In general, the requirements of the revision of ISO 15189 are viewed positively in the Recommendations, so much so that they are recommended as good practice even regardless of the possible accreditation pathway, despite the residual presence of individual contradictory elements or ambiguities. The Recommendations highlight the topic of IT security, a solid chain of responsibility management between laboratory and manufacturer, and the completion and development of requirements with the ISO 27000 family and CLSI AUTO11 documents.
1. The requirements of UNI EN ISO 15189:2023 as good laboratory practice
2. Sampling points and point-of-care testing services (POCT) included in the ISO requirements, regardless of formal ownership
3. Compliance with ISO 9001 makes compliance with ISO 15189 easier
4. Laboratory documents, including ISO standards to be consulted, written in Italian language
5. Measurement uncertainty estimated and used in medical laboratories in specific ways
6. Sampling points and "Network laboratories" held to the requirements of ISO 15189, ISO 20658 and related standards.
7. Pre-examination processes in POCTs subject to the requirements of ISO 15189 and ISO 22583.
8. Detailed lists of ISO 15189 to be balanced with actual clinical risk.
9. Informed consent: ISO requirements harmonised with current legislation.
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1. I requisiti di UNI EN ISO 15189:2023 come buona pratica di laboratorio
2. Punti di prelievo e i servizi di esami vicino al punto di cura (POCT) inclusi nei requisiti ISO, qualunque sia la titolarità formale
3. La conformità a ISO 9001 rende più facile quella a ISO 15189
4. Documenti dei laboratori, comprese le norme ISO da consultare, redatti in lingua italiana.
5. Incertezza di misurazione stimata e usata nei laboratori medici con modalità specifiche
6. Punti di prelievo e “Laboratori in rete” tenuti ai requisiti di ISO 15189, di ISO 20658 e norme collegate.
7. Processi preesame nei POCT soggetti ai requisiti ISO 15189 e ISO 22583.
8. Liste dettagliate di ISO 15189 da bilanciare con il reale rischio clinico.
9. Consenso informato: requisiti ISO armonizzati con le norme di legge vigenti.
Repeat-patient testing quality control (RPT-QC) is a version of statistical quality control (SQC) in which individual patient samples, rather than commercial control materials, are used. Whereas conventional SQC assumes control material stability and repeatedly measures the same lot of control material over time, RPT-QC uses a unique patient sample for each QC event and exploits the labile nature of patient samples under prescribed storage conditions for QC purposes. Advantages of RPT-QC include commutability, lower cost, and QC at concentrations of medical interest. Challenges include sample procurement and the establishment of control limits. The objective of this review is to compare and contrast the principles and procedures of RPT-QC and conventional SQC and to provide an overview of RPT-QC control limit establishment.
ISO's concern about the neglected quality of MPS/NGS is
more than well-founded. Laboratory operations are considered analogous to a manufacturing process where the industrial process is replaced by the measurement process, the output of which is the results of examinations. Process control is therefore an essential element of the quality management system. The complexity of the MPS/NGS process is obviously daunting for some medical laboratories. The expression of the final result in nominal format is misleading. The ISO 20397-2 document provides many indicators and useful examples for doing laboratory estimation of result uncertainty for MPS/NGS.
In the last few decades, quality in laboratory medicine has evolved in concert with the transformation and the changes (technological, scientific and organizational) in this sector. Laboratory professionals have faced great challenges, at times being overwhelmed, yet also involved in this progress. Worldwide, laboratory professionals and scientific societies involved in laboratory medicine have raised awareness concerning the need to identify new quality assurance tools that are effective in reducing the error rate and enhancing patient safety, in addition to Internal Quality Control (IQC) procedures and the participation in the External Quality Assessment Schemes (EQAS). The use of Quality Indicators (QIs), specifically designed for laboratory medicine are effective in assessing and monitoring all critical events occurring in the different phases of Total Testing Process (TTP), in particular, in the extra-analytical phases. The Model of Quality Indicators (MQI), proposed by the Working Group “Laboratory Errors and Patient Safety” (WG-LEPS) of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and validated by experts in consensus conferences, is an important window of opportunity for the medical laboratory to demonstrate the use of an effective quality assurance tool fit for this purpose. Aim of this paper is to provide an update of the state-of-the-art concerning the most used QIs data collected in 2021 and the Quality Specifications (QSs) proposed for their evaluation. Moreover, a strategy for the future is proposed in order to improve the MQI and encourage its use in medical laboratories throughout the world.
To the Editor
Most test results in medical laboratories are numbers, known as “quantitative results” if they have linearity (a ratio or interval scale) and are related to the international/national reference standard. Results consisting of nouns or adjectives (known as “qualitative results”) are less frequent but no less important to service quality.
The Eurachem/Cooperation on International Traceability in Analytical Chemistry (CITAC) guide “Evaluating Performance and Uncertainty in Qualitative Chemical Analysis” has recently been published (1). However, the Eurachem/CITAC guide states that it does not address all available tools for evaluating the performance of qualitative methods and the uncertainty of qualitative results. It is limited to comparison of results to a reference and does not consider, for example, concordance between qualitative methods or the classification on ordinal scales. In fact, a number of criticisms of the guide have recently been reported, including the lack of the repeatability and reproducibility components for the accuracy of the methods (2).
ISO published the draft for final approval of the revision of ISO 15189 standard. Following ISO directives, ISO 15189 must be aligned with ISO/IEC 17025:2017 and should be less prescriptive. Draft ISO/DIS 15189 deviates in some points from ISO 17025 and the ISO indications to limit prescriptiveness: equipment, uncertainty, quality control. This do not seem to be justified by medical specificities and could complicate the understanding of the new requirements in medical laboratories.
Technical quality assurance (QA) and quality control (QA/QC) are important activities within medical laboratories to ensure the adequate quality of obtained test results. QA/QC tools available at medical laboratories include external QC and internal QC, patient-based real-time quality control (PBRTQC) tools such as moving average quality control (MAQC), limit checks, delta checks, and multivariate checks, and finally, analyzer flagging. Recently, for PBRTQC tools, new optimization and validation methods based on error detection simulation have been developed to obtain laboratory-specific insights into PBRTQC error detection. These developments have enabled implementation and application of these individual tools in routine clinical practice. As a next step, they also enable performance comparison of the individual QA/QC tools and integration of all the individual QA/QC tools in order to obtain the most powerful and efficient QA/QC plans. In this review, a brief overview of the individual QA/QC tools and their characteristics is provided and the error detection simulation approaches are explained. Finally, a new concept entitled integrated quality assurance and control (IQAC) is presented. To enable IQAC, a conceptual framework is suggested and demonstrated for sodium, based on available published data. The proposed IQAC framework provides ways and tools by which the performance of different QA/QC tools can be compared in a so-called QA/QC error detection table to enable optimization and validation of the overall QA/QC plan in terms of alarm rate as well as pre-analytical, analytical, and post-analytical error detection performance.
The estimation of measurement uncertainty is required for accreditation of medical laboratories, according to the International Organization for Standardization (ISO). ISO provides adequate indications to obtain uncertainty and above all precision and repeatability with simplicity in laboratories of any type and size, both for numerical quantitative and nominal qualitative results. Other consistent guidelines are contained in various documents of the Clinical & Laboratory Standards Institute (CLSI). The Recommendations of the Italian Society of Clinical Pathology and Laboratory Medicine (SIPMeL) with document Q16 bring together the sources and provide a clear and simple description of how they should be applied.
Effective management of clinical laboratories relies upon an understanding of Quality Control and External Quality Assurance principles. These processes, when applied effectively, reduce patient risk and drive quality improvement. In this Review, we will describe the purpose of QC and EQA and their role in identifying analytical and process error. The two concepts are linked, and we will illustrate that linkage. Some EQA providers offer far more than analytical surveillance. They facilitate training and education and extend quality improvement and identify areas where there is potential for patient harm into the pre-and post-analytical phases of the total testing process.
Agreement between two methods of clinical measurement can be quantified using the differences between observations made using the two methods on the same subjects. The 95% limits of agreement, estimated by mean difference 1.96 standard deviation of the differences, provide an interval within which 95% of differences between measurements by the two methods are expected to lie. We describe how graphical methods can be used to investigate the assumptions of the method and we also give confidence intervals. We extend the basic approach to data where there is a relationship between difference and magnitude, both with a simple logarithmic transformation approach and a new, more general, regression approach. We discuss the importance of the repeatability of each method separately and compare an estimate of this to the limits of agreement. We extend the limits of agreement approach to data with repeated measurements, proposing new estimates for equal numbers of replicates by each method on each subject, for unequal numbers of replicates, and for replicated data collected in pairs, where the underlying value of the quantity being measured is changing. Finally, we describe a nonparametric approach to comparing methods.
These notes can serve both for labs to set purchasing specifications and for manufacturers who have to meet these specifications. ISO 15189 accreditation of medical laboratories requires comparability of results between different laboratories, preferably by means of metrological traceability to the SI. The twin standards ISO 17511 and ISO 21151 draw a finally robust framework to provide laboratory methods with calibration, harmonization and standardization, even when it cannot reach SI. We find the meanings of words used in metrology and the correct use of "higher" and "highest".
ISO, the International Organization for Standardization, is preparing document ISO/TS 17822-2 on the quality control of nucleic acid amplification techniques (NAAT). ISO 17822-2 takes into consideration many aspects that affect quality. ISO 17822 prescribes the use of control materials and describes different types of them. ISO 17822-2 states that the laboratory shall decide the appropriate type and frequency of use of internal and external controls, but says however that the results must remain within the pre-established limits, without saying how the limits should be fixed. Worldwide quality control in medical laboratories is often not performed correctly. Quality costs represent 22% of the laboratory’s direct costs. The SIPMeL Quality and Accreditation Commission has therefore produced its recommendations on quality control, with the transposition of ISO 15198: 2004, reconfirmed also in 2018. Diagnostic system manufacturers have a primary role in this activity. The guidelines for quality control are in the document Clinical Laboratory Standards Institute (CLSI) C24.
The ongoing revision of ISO 15189, the standard for accreditation of medical laboratories that will be launched in 2022, shall use ISO/IEC 17025:2017 as a model. The most significant changes of ISO 17025 are introduced in the management system, now aligned with that of the ISO 9001:2015 standard. The ISO 9001:2015 standard introduced several innovations, which other ISO standards must take into account, such as the risk-based thinking. In the new ISO 17025, some issues such as impartiality, confidentiality, complaint handling and management systems have been imposed. In the new ISO 15189 a number of requirements will be transferred from ISO 17025. Discussion in the ISO working groups is intensively developing point by point to maintain the ISO 17025 standard structure without losing the specific characteristics of the medical laboratories regulated by ISO 15189.
Background
New moving average quality control (MA QC) optimization methods have been developed and are available for laboratories. Having these methods will require a strategy to integrate MA QC and routine internal QC.
Methods
MA QC was considered only when the performance of the internal QC was limited. A flowchart was applied to determine, per test, whether MA QC should be considered. Next, MA QC was examined using the MA Generator (www.huvaros.com), and optimized MA QC procedures and corresponding MA validation charts were obtained. When a relevant systematic error was detectable within an average daily run, the MA QC was added to the QC plan. For further implementation of MA QC for continuous QC, MA QC management software was configured based on earlier proposed requirements. Also, protocols for the MA QC alarm work-up were designed to allow the detection of temporary assay failure based on previously described experiences.
Results
Based on the flowchart, 10 chemistry, two immunochemistry and six hematological tests were considered for MA QC. After obtaining optimal MA QC settings and the corresponding MA validation charts, the MA QC of albumin, bicarbonate, calcium, chloride, creatinine, glucose, magnesium, potassium, sodium, total protein, hematocrit, hemoglobin, MCH, MCHC, MCV and platelets were added to the QC plans.
Conclusions
The presented method allows the design and implementation of QC plans integrating MA QC for continuous QC when internal QC has limited performance.
Once an in-vitro diagnostic (IVD) measuring system has been marketed and introduced into daily practice, the possible sources of degradation of its performance are numerous. It is therefore essential to put in place a continuous post-market surveillance of the quality of performance of the IVD system and of the laboratories that perform measurements in clinical setting. The participation to external quality assessment (EQA) schemes that meet specific metrological criteria is central to the evaluation of performance of clinical laboratories in terms of standardization and clinical suitability of their measurements. In addition to the use of commutable materials, in this type of EQA it is necessary to assign values (and uncertainty) to them with reference procedures and to define and apply clinically permissible analytical performance specifications to substantiate the suitability of laboratory measurements in the clinical setting. Unfortunately, there are still few permanent EQA programs fully covering these requirements because some practical constraints, including technical and economic aspects, which limit their introduction. It is, however, clear that these issues should be quickly overcome, since EQA schemes are in a unique position to add substantial value to the practice of laboratory medicine, by identifying analytes that need improved harmonization and by stimulating and sustaining standardization initiatives that are needed to support clinical practice. Importantly, this will definitively help those manufacturers that produce superior products to demonstrate the superiority of those products and oblige end users (and consequently industry) to abandon assays with demonstrated insufficient quality.
Background:
Diabetes mellitus is a metabolic disease that is characterized by hyperglycemia. Blood glucose (BG) is helpful for the diagnosis and treatment of diabetes and an important part of the management of diabetes. Point-of-care testing (POCT) is generally used by patients themselves or medical personnel to monitor BG. The objective of this article was to evaluate the accuracy and consistency of POCT on venous blood samples and compare it with the central laboratory system to determine the reliability of POCT measurement results as diagnostic criteria.
Method:
A total of 162 venous whole blood samples were pooled in this study, which included different concentrations and were determined by three POCT systems randomly. The results were compared with the central laboratory system, which uses the Glucose GOD-PAP method (HITACHI 7600-120). The accuracy was evaluated by the International Organization for Standardization (ISO) 15197:2013.
Result:
Bland-Altman and Passing-Bablok regression analysis showed three POCT systems that were comparable with the reference method (0.65, 95% CI: -0.57 to 1.86, Y = -0.11 + 0.95X for ACCU-CHEK® Performa; 0.40, 95% CI: -1.3 to 2.1, Y = 0.036 + 0.96X for ACCU-CHEK® Active; 0.70, 95% CI: -0.44 to 1.83, Y = -0.073 + 0.95X for OneTouch ® UltraVue). According to ISO 15197:2013, all POCT systems showed 100% of the results within 0.83 mmol/l (15 mg/dl) at BG concentrations <5.55 mmol/l (100 mg/dl); 92%, 89.2%, and 95.7% of the measurement results within 15% at BG concentrations ≥5.55 mmol/l (100 mg/dl) for ACCU-CHEK® Performa, ACCU-CHEK® Active, and OneTouch® UltraVue, respectively.
Conclusions:
The POCT system cannot replace the central laboratory system as a provider of a standard result in clinical diagnosis. It can only be used as a screening test.
Background.
Accreditation standards (ISO 15189 and ISO 22870) require both the medical laboratory and the manufacturer of systems and reagents to compare methods that provide results for the same examination. CLSI guideline EP09 and EP31 provide some operational tools and statistics.
Methods.
The text of the CLSI guidelines EP09 and EP31 has been critically analyzed and linked to key literature references. Was also considered the guideline CLSI EP30 for the particular case of commutable calibrators.
Results.
The guidelines provide very different indications to the medical Laboratory and the manufacturer of diagnostic systems. Fundamental is a graphical representation of the results. The tables for interpretation of CLSI EP31 appear quite complex.
Conclusions.
The comparison of methods of esaminations is one of the main managerial commitments of medical Laboratory, to which are devoted considerable human resources and mainly cultural. CLSI guidelines EP09 and EP31 provide different tools for the laboratory and for the manufacturer of diagnostic systems, sometimes complex.
This article discusses how specific patient data algorithms can be used and optimized for laboratory quality control. These algorithms include delta checks, patient averages, and multivariate checks. With the increasing emphasis on cost containment, the intelligent use of these algorithms should become widespread.
Kappa coefficients are measures of correlation between categorical variables often used as reliability or validity coefficients. We recapitulate development and definitions of the K (categories) by M (ratings) kappas (K x M), discuss what they are well- or ill-designed to do, and summarize where kappas now stand with regard to their application in medical research. The 2 x M(M>/=2) intraclass kappa seems the ideal measure of binary reliability; a 2 x 2 weighted kappa is an excellent choice, though not a unique one, as a validity measure. For both the intraclass and weighted kappas, we address continuing problems with kappas. There are serious problems with using the K x M intraclass (K>2) or the various K x M weighted kappas for K>2 or M>2 in any context, either because they convey incomplete and possibly misleading information, or because other approaches are preferable to their use. We illustrate the use of the recommended kappas with applications in medical research.
The exponentially moving average (EWMA) rule for internal quality control is a well-known type of control rule in industry. Here, the power of the EWMA rule is evaluated to outline the potential of this type of control rule in clinical chemistry.
Using simulations, the power of the EWMA rule was explicitly compared with that of commonly used rules in clinical chemistry. The type I error levels were standardized to common values to achieve unbiased comparisons.
For small to moderately large errors (systematic errors up to 2-3 standard deviations), the EWMA rule outperforms simple rules (N=1) and multi-rules (N=2-6). For example, for a systematic error of 2s, the EWMA rule equivalent to the 1(3s) rule has a power of 0.30, whereas the 1(3s) rule only displays a power of approximately 0.15. For N=4, comparison was carried out with the 1(3s)/2(2s)/R(4s)/4(1s) rule. Here the common type I error level is 0.017. At all error levels, the EWMA rule is superior to the multi-rule. For example, given a 1s systematic error, the EWMA rule has a power (0.4) of twice the value of the multi-rule (0.2).
The EWMA rule is an efficient control rule with regard to systematic errors that should be considered for general application in the field of clinical chemistry.
Point of care (POC) glucose meters are routinely used to monitor glucose levels for patients on tight glycemic control therapy. We determined if glucose values were different for a POC glucose meter as compared to the main clinical laboratory for medical intensive care unit patients on a tight glycemic protocol and whether the site of blood sampling had a significant impact on glucose values.
Eighty-four patients (114 paired samples) who were on a tight glycemic protocol in the period November 2005 through August 2006 were enrolled. After simultaneous blood draws, we compared the glucose levels for the glucose meter (arterial/venous/capillary), blood gas (arterial/venous), and central clinical laboratory (serum/plasma from arterial/venous samples).
The mean glucose levels of all arterial/venous/fingerstick samples using the glucose meter demonstrated a positive bias of 0.7-0.9 mmol/l (12.6-16.2 mg/dl) (p<0.001) relative to central laboratory venous plasma. There was also a smaller positive (0.1-0.3 mmol/l or 1.8-5.4 mg/dl, p<0.05) bias for arterial/venous blood gas samples and laboratory arterial serum/plasma glucose samples. Using Parkes error grid analysis we were able to show that the bias for arterial or venous POC glucose results would have not impacted clinical care. This was not the case, however, for fingerstick sampling where a high bias could have significantly impacted clinical care. Additionally, in 3 fingerstick samples a severe underestimation (<46% of the central laboratory plasma result) was found.
Glucose meters using arterial/venous whole blood may be utilized in the MICU; however, due to the increased variability of results we do not recommend the routine use of capillary blood sampling for monitoring glucose levels in the MICU setting.
La visione olistica della qualità
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Q11P1 Raccomandazioni per il controllo di qualità interno: compiti del produttore di diagnostici in vitro
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Produttore di diagnostici e laboratorio medico alleati per il controllo di qualità dei risultati: ritardi e novità
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per il controllo di qualità dei risultati: ritardi e novità. Riv Ital Med Lab
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Six Sigma Quality Design & Control: Desirable Precision and Requisite QC for Laboratory Measurement Processes
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