[Show abstract][Hide abstract] ABSTRACT: Laboratory medicine is amongst the fastest growing fields in medicine, crucial in diagnosis, support of prevention and in the monitoring of disease for individual patients and for the evaluation of treatment for populations of patients. Therefore, high quality and safety in laboratory testing has a prominent role in high-quality healthcare. Applied knowledge and competencies of professionals in laboratory medicine increases the clinical value of laboratory results by decreasing laboratory errors, increasing appropriate utilization of tests, and increasing cost effectiveness. This collective paper provides insights into how to validate the laboratory assays and assess the quality of methods. It is a synopsis of the lectures at the 15th European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Continuing Postgraduate Course in Clinical Chemistry and Laboratory Medicine entitled "How to assess the quality of your method?" (Zagreb, Croatia, 24-25 October 2015). The leading topics to be discussed include who, what and when to do in validation/verification of methods, verification of imprecision and bias, verification of reference intervals, verification of qualitative test procedures, verification of blood collection systems, comparability of results among methods and analytical systems, limit of detection, limit of quantification and limit of decision, how to assess the measurement uncertainty, the optimal use of Internal Quality Control and External Quality Assessment data, Six Sigma metrics, performance specifications, as well as biological variation. This article, which continues the annual tradition of collective papers from the EFLM continuing postgraduate courses in clinical chemistry and laboratory medicine, aims to provide further contributions by discussing the quality of laboratory methods and measurements and, at the same time, to offer continuing professional development to the attendees.
Clinical Chemistry and Laboratory Medicine 09/2015; DOI:10.1515/cclm-2015-0869 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives:
In this study, we evaluated the extent of inappropriate tumor marker (TM) ordering in a secondary care setting, approximately 6 years after the introduction of local guidelines, and we identified the main factors potentially influencing clinicians when performing an inappropriate TM request.
For this purpose, we regularly checked all requests containing more than two TMs. During the 21-month audit, the rate of rejected requests amounted to 3.6%. Several of those were performed for diagnostic purposes. The most frequent and inappropriately requested TMs were carcinoembryonic antigen and carbohydrate antigen 19.9.
The inappropriateness of requests appeared to be linked to the need for more education and knowledge on their clinical applicability and limitations. The clinical motivation was generally associated with patients displaying nonspecific signs/symptoms (ie, weight loss with worsening general conditions), having an incidentally positive result to some recently performed TM tests, or being tested by a TM to avoid more expensive diagnostic imaging procedures.
Our data show that real-time control and management of inappropriate requests by laboratory professionals may be relevant to increase the clinical efficacy of TM testing and useful in perspective to drive the introduction of new validated biomarkers.
American Journal of Clinical Pathology 09/2015; 144(4):649-58. DOI:10.1309/AJCPNZAPJRB3T6KK · 2.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Previous meta-analyses reported no significant or weak association between hyperuricemia (HU) and coronary heart disease (CHD). We updated the literature search, systematically reviewing retrieved papers. The peer-reviewed literature published from 1965 to December 2014 was searched using Medline and Embase. We included prospective cohort studies involving adults (sample size ≥100) with no cardiovascular disease (CVD) and a follow-up of at least 1 year. Studies were excluded if they considered as outcome the CVD incidence/mortality without separately reporting data on CHD, did not adjusted for major confounders and if the 95% confidence interval (CI) for risk ratio (RR) was not available. Relative risk or hazard ratio estimates, with the corresponding CIs, were obtained. For CHD incidence 12 populations were included (457,915 subjects [53.7% males]). For CHD mortality seven populations were included (237,433 subjects [66.3% males]). The overall combined RR were 1.206 (CI 1.066-1.364, p=0.003) for CHD incidence and 1.209 (CI 1.003-1.457, p=0.047) for CHD mortality, respectively. Subgroup analysis showed a marginal (incidence) and not significant (mortality) association between HU and CHD in men, but an increased risk for CHD incidence and mortality in hyperuricemic women (RR 1.446, CI 1.323-1.581, p<0.0001, and RR 1.830, CI 1.066-3.139, p=0.028, respectively). The risk markedly increases for urate concentrations >7.0 mg/dL. HU appears to increase the risk of CHD events in the general population, mainly in adult women. This finding requires, however, further investigation.
Clinical Chemistry and Laboratory Medicine 09/2015; DOI:10.1515/cclm-2015-0523 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The measurement uncertainty budget should combine the uncertainty of higher order references, the uncertainty of commercial system calibration, the system imprecision and individual laboratory performance in terms of variability. Here we recommend that no more than one third of the total uncertainty budget, established by appropriate analytical performance specifications, is consumed by the uncertainty of references and approximately 50% of the total budget consumed by the manufacturer's calibration and value transfer protocol. The remaining 50% should be available for the commercial system imprecision (including the batch to batch variation of the reagents) and individual laboratory performance in order to fulfil the uncertainty goal. For commercial systems to work properly, in vitro diagnostics (IVD) manufacturers will need to take more responsibility and ensure the traceability of the combination of platform, reagents, calibrators and control materials for system alignment verification that only as such (as a whole) are certified ("CE marked") by the manufacturer itself in terms of traceability to the selected reference measurement system. Particularly, IVD manufacturers should report the combined (expanded) uncertainty associated with their calibrators when used in conjunction with other components of their analytical system (platform and reagents). This is more than what they are currently providing as traceability and uncertainty information.
Clinical Chemistry and Laboratory Medicine 04/2015; 53(6). DOI:10.1515/cclm-2014-1240 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: As a part of an International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) project to prepare a commutable reference material for cardiac troponin I (cTnI), a pilot study evaluated current cTnI assays for measurement equivalence and their standardization capability.
cTnI-positive samples collected from 90 patients with suspected acute myocardial infarction were assessed for method comparison by 16 cTnI commercial assays according to predefined testing protocols. Seven serum pools prepared from these samples were also assessed.
Each assay was assessed against median cTnI concentrations measured by 16 cTnI assays using Passing-Bablok regression analysis of 79 patient samples with values above each assay's declared detection limit. We observed a 10-fold difference in cTnI concentrations for lowest to highest measurement results. After mathematical recalibration of assays, the between-assay variation for patient samples reduced on average from 40% to 22% at low cTnI concentration, 37%-20% at medium concentration, and 29%-14% at high concentration. The average reduction for pools was larger at 16%, 13% and 7% for low, medium and high cTnI concentrations, respectively. Overall, assays demonstrated negligible bias after recalibration (y-intercept: -1.4 to 0.3 ng/L); however, a few samples showed substantial positive and/or negative differences for individual cTnI assays.
All of the 16 commercial cTnI assays evaluated in the study demonstrated a significantly higher degree of measurement equivalence after mathematical recalibration, indicating that measurement harmonization or standardization would be effective at reducing inter-assay bias. Pooled sera behaved similarly to individual samples in most assays.
Clinical Chemistry and Laboratory Medicine 04/2015; 53(5):677-690. DOI:10.1515/cclm-2014-1197 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To be accurate and equivalent, laboratory results should be traceable to higher-order references. Furthermore, their quality should fulfill acceptable measurement uncertainty as defined to fit the intended clinical use. With this aim, in vitro diagnostics (IVD) manufacturers should define a calibration hierarchy to assign traceable values to their system calibrators and to fulfill during this process uncertainty limits for calibrators, which should represent a proportion of the uncertainty budget allowed for clinical laboratory results. It is therefore important that, on one hand, the laboratory profession clearly defines the clinically acceptable uncertainty for relevant tests and, on the other hand, endusers may know and verify how manufacturers have implemented the traceability of their calibrators and estimated the corresponding uncertainty. Important tools for IVD traceability surveillance are quality control programmes through the daily verification by clinical laboratories that control materials of analytical systems are in the manufacturer’s declared validation range [Internal Quality Control (IQC) component I] and the organization of Exter nal Quality Assessment Schemes meeting metrological criteria. In a separate way, clinical laboratories should also monitor the reliability of employed commercial systems through the IQC component II, devoted to estimation of the measurement uncertainty due to random effects, which includes analytical system imprecision together with individual laboratory performance in terms of variability.
Journal of Medical Biochemistry 01/2015; 34(3). DOI:10.1515/jomb-2015-0004 · 1.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Laboratory diagnostics develop through different phases that span from test ordering (pre-preanalytical phase), collection of diagnostic specimens (preanalytical phase), sample analysis (analytical phase), results reporting (postanalytical phase) and interpretation (post-postanalytical phase). Although laboratory medicine seems less vulnerable than other clinical and diagnostic areas, the chance of errors is not negligible and may adversely impact on quality of testing and patient safety. This article, which continues a biennial tradition of collective papers on preanalytical quality improvement, is aimed to provide further contributions for pursuing quality and harmony in the preanalytical phase, and is a synopsis of lectures of the third European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)-Becton Dickinson (BD) European Conference on Preanalytical Phase meeting entitled ‘Preanalytical quality improvement. In pursuit of harmony’ (Porto, 20–21 March 2015). The leading topics that will be discussed include unnecessary laboratory testing, management of test request, implementation of the European Union (EU) Directive on needlestick injury prevention, harmonization of fasting requirements for blood sampling, influence of physical activity and medical contrast media on in vitro diagnostic testing, recent evidence about the possible lack of necessity of the order of draw, the best practice for monitoring conditions of time and temperature during sample transportation, along with description of problems emerging from inappropriate sample centrifugation. In the final part, the article includes recent updates about preanalytical quality indicators, the feasibility of an External Quality Assessment Scheme (EQAS) for the preanalytical phase, the results of the 2nd EFLM WG-PRE survey, as well as specific notions about the evidence-based quality management of the preanalytical phase.
Clinical Chemistry and Laboratory Medicine 12/2014; DOI:10.1515/cclm-2014-1051 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: At least one in 10 patients experience adverse events while receiving hospital care. Many of the errors are related to laboratory diagnostics. Efforts to reduce laboratory errors over recent decades have primarily focused on the measurement process while pre- and post-analytical errors including errors in sampling, reporting and decision-making have received much less attention. Proper sampling and additives to the samples are essential. Tubes and additives are identified not only in writing on the tubes but also by the colour of the tube closures. Unfortunately these colours have not been standardised, running the risk of error when tubes from one manufacturer are replaced by the tubes from another manufacturer that use different colour coding. EFLM therefore supports the worldwide harmonisation of the colour coding for blood collection tube closures and labels in order to reduce the risk of pre-analytical errors and improve the patient safety.
Clinical Chemistry and Laboratory Medicine 10/2014; 53(3). DOI:10.1515/cclm-2014-0927 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract The availability of so-called high-sensitivity troponin assays (hsTn) has scored a compelling goal for laboratory medicine, allowing the safe clinical application of international recommendations for the definition of acute myocardial infarction (AMI). However, the introduction of hsTn has not been welcomed by clinicians, claiming an increase in false-positive results. Here we critically trace back the steps following the introduction of hsTn by referring to the 5-year practical experience in our academic hospital and to suitable information available in the literature. In agreement with published data, we found that hsTn introduction was associated with an increased number of AMI diagnoses, whereas the test volume, the revascularization rate, and the proportion of cases with negative angiography findings remained virtually unchanged. Fast-track protocols for ruling out AMI have been further optimized to recommend sampling at presentation and after 3 h only. We focus on a cost-effective use of hsTn that can account for all clinical variables increasing the pre-test probability in order to ensure that tests are ordered only for patients at medium to high risk for acute coronary syndrome (ACS). To guide interpretation of results, hsTn typical release patterns suggestive for AMI should be identified by evaluating the significance of concentration changes. hsTn have markedly shortened the time to rule out or rule in AMI and has the potential to improve the prognostic assessment of critical patients in clinical contexts different from ACS.
Clinical Chemistry and Laboratory Medicine 10/2014; 53(5). DOI:10.1515/cclm-2014-0812 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Amongst the newly proposed biomarkers for ovarian cancer, serum human epididymis protein 4 (HE4) shows the greatest potential for clinical use. However, systematic appraisals of its biological characteristics are not available. This study sought to critically revise the available literature on biological and lifestyle factors affecting HE4 concentrations in serum to understand their possible influence on the marker interpretation.
A literature search was undertaken on electronic databases and references from retrieved articles. Article results were analyzed by evaluating study design, sample size, statistical approach, employed assay and, when available, by collecting similar information for carbohydrate antigen 125 (CA-125).
Several factors may influence serum HE4 concentrations. In contrast to CA-125, higher HE4 concentrations are reported in the elderly. Although no variations in HE4 concentrations can be clearly associated to menopausal status, a strong difference in biomarker biological intra-individual variation according to the fertility status is reported. Smoking and renal function can also significantly influence HE4 results.
The knowledge of factors influencing HE4 concentrations is relevant to promote more adequate interpretative criteria for use of this biomarker in the clinical setting.
[Show abstract][Hide abstract] ABSTRACT: Background:
An increased focus on the biological behaviour of serum biomarkers for ovarian cancer, i.e., carbohydrate antigen 125 (CA-125) and human epididymis protein 4 (HE4), has been advocated to improve their clinical use. Due to the paucity and poor design of available studies evaluating biological variation (BV) of CA-125 and the lack of BV data for HE4, in this study we evaluated BV of both biomarkers.
Monthly we obtained serum samples from 14 pre- (PreM) and 14 post-menopausal (PostM) healthy women for 4 consecutive months. Once all samples were available, they were analysed in a single run in duplicate for CA-125 and HE4 on Roche Modular system. Data were analysed by ANOVA.
For both biomarkers no difference in median concentrations was found between PreM and PostM. For CA-125 the intra-individual CV (CVI) was not different between groups (9.1% in both). For HE4 CVI was higher in PreM (12.1%) than in PostM (6.5%) (p<0.001). Between-subject CVs were 10.6% for CA-125 and 16.4% for HE4, with no influence by the fertility status. Both biomarkers showed high individuality meaning that the use of population-based reference limits may have limited value for their interpretation. Reference change values were 26% for CA-125 (all), 34% for HE4 PreM and 18% for HE4 PostM.
Monitoring longitudinal changes in serum concentrations of ovarian cancer biomarkers over time is probably better than using single threshold rules. According to differences in BV due to the hormonal status, one should differently interpret HE4 changes in PreM and PostM.
Clinical Chemistry and Laboratory Medicine 05/2014; 52(11). DOI:10.1515/cclm-2014-0097 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Glycated hemoglobin (HbA1c) plays a key role in diagnosing diabetes and monitoring the glycemic state. To guarantee the reliability of its measurement at the global level, the IFCC has defined a reference measurement system, based on the definition of the measurand as hemoglobin molecules having a special hexapeptide in common, which is the stable adduct of glucose to the N-terminal valine of the hemoglobin β-chain. In addition to the traceability of HbA1c results to the reference system, the establishment of analytical goals to make HbA1c measurements clinically reliable becomes crucial. However, allowable goals will depend on the assay specificity (i.e., selectivity) and, consequently, on units in which HbA1c results are expressed [mmol/mol for IFCC-aligned systems or % for National Glycohemoglobin Standardization Program (NGSP) converted numbers]. In this regard, analytical goals derived from biological variability studies in which the determination of HbA1c has been carried out by an assay providing the same selectivity for the measurand as defined by the IFCC are recommended. Only these targets should be used for evaluating the performance of commercial assays traceable to the IFCC system and of clinical laboratories using them through appropriately structured quality assessment schemes. Analytical systems following different calibration hierarchies (e.g., the NGSP-aligned assays) will require different analytical goals, possibly derived from clinical outcome data.
Clinical Chemistry and Laboratory Medicine 05/2014; 52(5):759. DOI:10.1515/cclm-2014-5001 · 2.71 Impact Factor