The final part of the CRESS trilogy - how to evaluate the quality of stability studies.

High quality laboratory results are critical for patient management. However, poor sample quality can impact these results and patient safety. To ensure reliable and accurate results laboratories must be aware of each analyte's stability under various storage conditions and matrices to guarantee correct and dependable outcomes. This knowledge allows laboratories to define the allowable delay between sample collection and centrifugation/analysis for all analytes to guarantee appropriate results quality and interpretation. The EFLM WG-PRE therefore established a 4-step plan to tackle this issue, aiming to standardize and harmonize stability studies for improved comparison and meta-analysis. The plan included the development of checklists and how-to guides for performing and reporting stability studies as well as a central resource of stability data. This manuscript deals with the issue of evaluating publications and incorporating them into a central resource. To evaluate stability studies, the CRESS checklist was used to structure 20 sections used to judge the quality of studies. Each section has 4 levels of quality, with scores converted to numerical values and weighted based on expert opinion. Based on this, a final score ranging from A to D was determined. The procedure was then tested on six manuscripts and checked for agreement between expert judgements. The results demonstrated that the proposed evaluation process is a useful tool to distinguish between best in class manuscripts and those of lower quality. The EFLM WG-PRE strongly believes that the provided recommendations and checklists will help improving stability studies both in quality and standardisation.

Recommendation for the design of stability studies on clinical specimens.

OBJECTIVES: Knowledge of the stability of analytes in clinical specimens is a prerequisite for proper transport and preservation of samples to avoid laboratory errors. The new version of ISO 15189:2022 and the European directive 2017/746 increase the requirements on this topic for manufacturers and laboratories. Within the project to generate a stability database of European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group Preanalytical Phase (WG-PRE), the need to standardise and improve the quality of published stability studies has been detected, being a manifest deficit the absence of international guidelines for the performance of stability studies on clinical specimens. METHODS: These recommendations have been developed and summarised by consensus of the WG-PRE and are intended primarily to improve the quality of sample stability claims included in information for users provided by assay supplier companies, according to the requirements of the new European regulations and standards for accreditation. RESULTS: This document provides general recommendations for the performance of stability studies, oriented to the estimation of instability equations in the usual working conditions, allowing flexible adaptation of the maximum permissible error specifications to obtain stability limits adapted to the intended use. CONCLUSIONS: We present this recommendation based on the opinions of the EFLM WG-PRE group for the standardisation and improvement of stability studies, with the intention to improve the quality of the studies and the transferability of their results to laboratories.

External quality assessment of serum indices: Spanish SEQC-ML program.

OBJECTIVES: Serum indices included in clinical chemistry instruments are widely used by laboratories to assess the quality of samples. Instruments that report quantitative results allow an evaluation of their diagnostic performance in a similar way to other biochemical tests. The Spanish Society of Laboratory Medicine (SEQC-ML) launched a monthly External Quality program of serum indices in 2018 using three lyophilized materials of simultaneous annual distribution. We present the results of the first three years of the program. METHODS: The use of four different quality control materials with different concentrations in three alternate months allows an annual evaluation of the participant's accuracy. Assigned values are established by consensus among homogeneous groups, considering necessary at least 10 participants for a comparison at instrument level. The average percentage difference results per instrument allow the assessment of bias among groups. RESULTS: The imprecision of the three indices ranges between 3 and 9%, with no major differences among instruments. Significant differences were observed in all indices among instruments with more than 10 participants (Roche Cobas, Abbott Architect, Abbott Alinity and Siemens Advia). The 90th percentile of the distribution of percentage differences was used as the analytical performance specification (APS). An improvement in performance was observed in the first three years of the program, probably due to the learning curve effect. In 2020, APS of 7.8, 12.2 and 9.7% were proposed for hemolytic, icteric and lipemic indices, respectively. CONCLUSIONS: Serum indices have a great impact on the quality and the reliability of laboratory test results. Participation in proficiency testing programs for serum indices is helpful to encourage harmonization among providers and laboratories.

The CRESS checklist for reporting stability studies: on behalf of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group for the Preanalytical Phase (WG-PRE).

To ensure that clinical laboratories produce results that are both accurate and of clinical utility it is essential that only samples of adequate quality are analysed. Although various studies and databases assessing the stability of analytes in different settings do exist, guidance on how to perform and report stability studies is lacking. This results in studies that often do not report essential information, thus compromising transferability of the data. The aim of this manuscript is to describe the Checklist for Reporting Stability Studies (CRESS) against which future studies should be reported to ensure standardisation of reporting and easy assessment of transferability of studies to other healthcare settings. The EFLM WG-PRE (European Federation of Clinical Chemistry and Laboratory Medicine Working Group for the Preanalytical Phase) produced the CRESS checklist following a detailed literature review and extensive discussions resulting in consensus agreement. The checklist consists of 20 items covering all the aspects that should be considered when producing a report on a stability study including details of what should be included for each item and a rationale as to why. Adherence to the CRESS checklist will ensure that studies are reported in a transparent and replicable way. This will allow other laboratories to assess whether published data meet the stability criteria required in their own particular healthcare scenario. The EFLM WG-PRE encourage researchers and authors to use the CRESS checklist as a guide to planning stability studies and to produce standardised reporting of future stability studies.

A protocol for testing the stability of biochemical analytes. Technical document.

Stability of a measurand in a specimen is a function of the property variation over time in specific storage conditions, which can be expressed as a stability equation, and is usually simplified to stability limits (SLs). Stability studies show differences or even inconsistent results due to the lack of standardized experimental designs and heterogeneity of the chosen specifications. Although guidelines for the validation of sample collection tubes have been published recently, the measurand stability evaluation is not addressed. This document provides an easy guideline for the development of a stability test protocol based on a two-step process. A preliminary test is proposed to evaluate the stability under laboratory habitual conditions. The loss of stability is assessed by comparing measurement values of two samples obtained from the same patient and analyzed at different time points. One of them is analyzed under optimal conditions (basal sample). The other is stored under specific stability conditions for a time set by the laboratory (test sample). Differences are expressed using percentage deviation (PD%) to facilitate comparison with specifications. When the preliminary test demonstrates instability, a comprehensive test is proposed in order to define the stability equation and to specify SLs. Several samples are collected from a set of patients. The basal sample is analyzed under optimal conditions, whereas analysis of test samples is delayed at time intervals. For each patient PD% is calculated as the difference between measurements for every test sample and its basal one and represented in a coordinate graph versus time.

Laboratory sample stability. Is it possible to define a consensus stability function? An example of five blood magnitudes.

BACKGROUND: The stability limit of an analyte in a biological sample can be defined as the time required until a measured property acquires a bias higher than a defined specification. Many studies assessing stability and presenting recommendations of stability limits are available, but differences among them are frequent. The aim of this study was to classify and to grade a set of bibliographic studies on the stability of five common blood measurands and subsequently generate a consensus stability function. METHODS: First, a bibliographic search was made for stability studies for five analytes in blood: alanine aminotransferase (ALT), glucose, phosphorus, potassium and prostate specific antigen (PSA). The quality of every study was evaluated using an in-house grading tool. Second, the different conditions of stability were uniformly defined and the percent deviation (PD%) over time for each analyte and condition were scattered while unifying studies with similar conditions. RESULTS: From the 37 articles considered as valid, up to 130 experiments were evaluated and 629 PD% data were included (106 for ALT, 180 for glucose, 113 for phosphorus, 145 for potassium and 85 for PSA). Consensus stability equations were established for glucose, potassium, phosphorus and PSA, but not for ALT. CONCLUSIONS: Time is the main variable affecting stability in medical laboratory samples. Bibliographic studies differ in recommedations of stability limits mainly because of different specifications for maximum allowable error. Definition of a consensus stability function in specific conditions can help laboratories define stability limits using their own quality specifications.

Spanish Preanalytical Quality Monitoring Program (SEQC), an overview of 12 years' experience.

BACKGROUND: Preanalytical variables, such as sample collection, handling and transport, may affect patient results. Preanalytical phase quality monitoring should be established in order to minimize laboratory errors and improve patient safety. METHODS: A retrospective study (2001-2013) of the results obtained through the Spanish Society of Clinical Biochemistry and Molecular Pathology (SEQC) External quality assessment (preanalytical phase) was performed to summarize data regarding the main factors affecting preanalytical phase quality. Our aim was to compare data from 2006 to 2013 with a previously published manuscript assessing the 2001-2005 period. RESULTS: A significant decrease in rejection rates was observed both for blood and urine samples. For serum samples, the most frequent rejection causes in the first period were non-received samples (37.5%), hemolysis (29.3%) and clotted samples (14.4%). Conversely, in the second period, hemolysis was the main rejection cause (36.2%), followed by non-received samples (34.5%) and clotted samples (11.1%). For urine samples, the main rejection cause overall was a non-received sample (up to 86.1% of cases in the second period, and 81.6% in the first). For blood samples with anticoagulant, the number of rejections also decreased. While plasma-citrate-ESR still showed the highest percentages of rejections (0.980% vs. 1.473%, p<0.001), the lowest corresponded to whole-blood EDTA (0.296% vs. 0.381%, p<0.001). CONCLUSIONS: For the majority of sample types, a decrease in preanalytical errors was confirmed. Improvements in organization, implementation of standardized procedures in the preanalytical phase, and participation in a Spanish external quality assessment scheme may have notably contributed to error reduction in this phase.

The Laboratory Medicine and the care of patients infected by the Ebola virus. Experience in a reference hospital of Madrid, Spain.

The ongoing Ebola virus outbreak in several countries in West Africa was considered by the World Health Organisation (WHO) as a public health emergency of international concern. Healthcare providers must be prepared by organising specific procedures in our hospitals based on recommendations from national and international healthcare organisations. Two aims should be considered: appropriate medical care for patients with suspected or confirmed disease must be ensured, as must measures to prevent transmission to healthcare workers. The clinical laboratory plays an important role and must define and establish its own procedures in accordance with clinicians and integrated into those of the institution, starting with the definition of the organisation model in the laboratory to achieve those goals. In this review we present our experience based on the care of three patients with confirmed cases. We hope it will help other colleagues to plan for Ebola.

Current status of verification practices in clinical biochemistry in Spain.

BACKGROUND: Verification uses logical algorithms to detect potential errors before laboratory results are released to the clinician. Even though verification is one of the main processes in all laboratories, there is a lack of standardization mainly in the algorithms used and the criteria and verification limits applied. A survey in clinical laboratories in Spain was conducted in order to assess the verification process, particularly the use of autoverification. METHODS: Questionnaires were sent to the laboratories involved in the External Quality Assurance Program organized by the Spanish Society of Clinical Biochemistry and Molecular Pathology. Seven common biochemical parameters were included (glucose, cholesterol, triglycerides, creatinine, potassium, calcium, and alanine aminotransferase). RESULTS: Completed questionnaires were received from 85 laboratories. Nearly all the laboratories reported using the following seven verification criteria: internal quality control, instrument warnings, sample deterioration, reference limits, clinical data, concordance between parameters, and verification of results. The use of all verification criteria varied according to the type of verification (automatic, technical, or medical). Verification limits for these parameters are similar to biological reference ranges. Delta Check was used in 24% of laboratories. Most laboratories (64%) reported using autoverification systems. Autoverification use was related to laboratory size, ownership, and type of laboratory information system, but amount of use (percentage of test autoverified) was not related to laboratory size. CONCLUSIONS: A total of 36% of Spanish laboratories do not use autoverification, despite the general implementation of laboratory information systems, most of them, with autoverification ability. Criteria and rules for seven routine biochemical tests were obtained.

Evaluation of 18 quality indicators from the external quality assurance preanalytical programme of the Spanish Society of Laboratory Medicine (SEQCML).

Objectives: Most errors in laboratory medicine occur in the pre- and post-analytical phases of the total testing process (TTP). In 2014, the Spanish Society of Laboratory Medicine (SEQCML) started the current Preanalytical Phase EQA Programme, with the objective of providing a tool for the improvement of the preanalytical phase. The aim of this study was to review the evolution of quality indicators (QI) and the comparability of established performance specifications (PS) with other EQA programmes. Methods: In the SEQCML programme, participants were asked to register rejections of the main specimens and the causes for rejections. Data collected from 2014 to 2017, and then reviewed biennially (2018-2019), was used to calculate the percentiles; p25, p50, p75, and p90 for every round, and their means were set as PS. These PS were compared with the results of other programmes. Results: The evolution of QI results for 2018-2019 period showed general maintenance or improvement, e.g., a significant decrease in the number of serum samples with a haemolytic index ≥0.5 g/L, except for EDTA and citrate samples handle, maybe for an improvement in detection. The comparison with PS for the QI of the IFCC Working Group "Laboratory Errors and Patient Safety" and the Key Incident Management and Monitoring System (KIMMS) programme of the RCPA showed comparable results, supporting the validity of the established specifications. Conclusions: The PS obtained are a helpful tool for benchmarking and to identify processes of the preanalytical phase whose improvement should be set as a priority.

Bilateral inferior petrosal sinus sampling in the diagnosis of ACTH-dependent Cushing's syndrome: experience in a tertiary hospital.

Objectives: Bilateral inferior petrosal sinus sampling (BIPSS) is a useful test for differential diagnosis of central vs. ectopic adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome (CS). We provide a description of the protocol used in our Center and an analysis of its diagnostic accuracy. Methods: A retrospective study was conducted of 28 patients who underwent BIPSS combined with corticotropin-releasing hormone (CRH) stimulation. The procedure is performed in an interventional neuroradiology suite, involving a multidisciplinary team of neuroradiologists, endocrinologists and laboratory professionals. The two petrosal sinuses are catheterized and a peripheral blood sample is obtained simultaneously, at baseline and at 3, 6 and 10 min following stimulation. ACTH and prolactin are determined by immunochemiluminescence. Results: A total of 19 cases of Cushing's disease (CD) and 1 case of ectopic CS were confirmed. In all cases, BIPSS provided accurate diagnostic guidance, with a sensitivity and specificity of 100%. In 8 patients, remission was not achieved after surgery. In 84% of catheterizations, ACTH ratio peaked at 3-6 min following stimulation. Patients with histologically-confirmed CD exhibited higher sinus ACTH ratios and values. Prolactin ratio helped us identify and exclude 28.6% of the samples with inconsistent results. Conclusions: In our series, BIPSS combined with CRH stimulation demonstrated to be a safe, effective procedure. Prolactin emerges as a useful marker of correct catheterization. The participation of a multidisciplinary team is essential.

Influence of study model, baseline catalytic concentrations and analytical system on the stability of serum alanine aminotransferase.

Objectives: The stability of the analytes most commonly used in routine clinical practice has been the subject of intensive research, with varying and even conflicting results. Such is the case of alanine aminotransferase (ALT). The purpose of this study was to determine the stability of serum ALT according to different variables. Methods: A multicentric study was conducted in eight laboratories using serum samples with known initial catalytic concentrations of ALT within four different ranges, namely: <50 U/L (<0.83 µkat/L), 50-200 U/L (0.83-3.33 µkat/L), 200-400 U/L (3.33-6.67 µkat/L) and >400 U/L (>6.67 µkat/L). Samples were stored for seven days at two different temperatures using four experimental models and four laboratory analytical platforms. The respective stability equations were calculated by linear regression. A multivariate model was used to assess the influence of different variables. Results: Catalytic concentrations of ALT decreased gradually over time. Temperature (-4%/day at room temperature vs. -1%/day under refrigeration) and the analytical platform had a significant impact, with Architect (Abbott) showing the greatest instability. Initial catalytic concentrations of ALT only had a slight impact on stability, whereas the experimental model had no impact at all. Conclusions: The constant decrease in serum ALT is reduced when refrigerated. Scarcely studied variables were found to have a significant impact on ALT stability. This observation, added to a considerable inter-individual variability, makes larger studies necessary for the definition of stability equations.

Corrigendum to: Preanalytical issues related to routine and diagnostic glucose tests: Results from a survey in Spain.

[This corrects the article DOI: 10.11613/BM.2020.010704.].

Preanalytical issues related to routine and diagnostic glucose tests: Results from a survey in Spain.

INTRODUCTION: Diabetes mellitus (DM) is one of the most prevalent diseases worldwide. The objective of this study was to find out under what preanalytical conditions routine and diagnostic glucose tests are performed across Spanish laboratories; and also what criteria are used for DM diagnosis. MATERIALS AND METHODS: An online survey was performed by the Commission on Quality Assurance in the Extra-Analytical Phase of the Spanish Society of Laboratory Medicine (SEQC-ML). Access to the questionnaire was available on the home page of the SEQC-ML website during the period April-July 2018. Data analysis was conducted with the IBM SPSS© Statistics (version 20.0) program. RESULTS: A total of 96 valid surveys were obtained. Most laboratories were in public ownership, serving hospital and primary care patients, with high and medium workloads, and a predominance of mixed routine-urgent glucose testing. Serum tubes were the most used for routine glucose analysis (92%) and DM diagnosis (54%); followed by lithium-heparin plasma tubes (62%), intended primarily for urgent glucose testing; point-of-care testing devices were used by 37%; and plasma tubes with a glycolysis inhibitor, mainly sodium fluoride, by 19%. Laboratories used the cut-off values and criteria recognized worldwide for DM diagnosis in adults and glucose-impaired tolerance, but diverged in terms of fasting plasma glucose and gestational DM criteria. CONCLUSION: Preanalytical processing of routine and DM diagnostic glucose testing in Spain does not allow a significant, non-quantified influence of glycolysis on the results to be ruled out. Possible adverse consequences include a delay in diagnosis and possible under-treatment.

Spanish society of laboratory medicine external quality assurance programmes: evolution of the analytical performance of clinical laboratories over 30 years and comparison with other programmes.

The purpose of this study is to understand the evolution of the analytical performance of the laboratories participating in the Spanish society of laboratory medicine (SEQCML) external quality assurance (EQA) programmes during its 30 years of operation and to compare it with the performance of other EQA programmes to establish whether the results are similar. The results obtained during this period are evaluated by applying the biological variability (BV) and state of the art-derived quality specifications. In addition, the results are compared with those obtained by other EQA programme organisations. It is noted that the laboratories participating in the EQA-SEQCML programmes have improved their performance over 30 years of experience and that the specifications derived from biological variation are achievable. It is difficult to compare EQA programmes, due to lack of accessibility and the differences in the design of these programmes (control materials, calculations used and analytical specifications established). The data from this study show that for some biological magnitudes the results obtained by the programmes are not yet harmonised, although efforts are being made to achieve this. Organisers of EQA programmes should also join the harmonisation effort by providing information on their results to enable comparison.

Impact of implementing a category 1 external quality assurance scheme for monitoring harmonization of clinical laboratories in Spain.

Background: The objective of the present study was to examine the evolution of the analytical performance specifications (APS) used in External Quality Assurance (EQA) schemes, as well as the efficacy of a category 1 EQA scheme in monitoring the harmonization of clinical laboratory results in Spain. Methods: A review of the literature on the types of quality specifications used in schemes in other countries and their evolution was performed. In addition, a comparative analysis of the potential impact that different APS from eight countries had on clinical decision-making was made based on three measurands: sodium, thyroid-stimulating hormone (TSH), and activated partial thromboplastin time (aPTT). Results: Harmonization of analytical methods was demonstrated by assessing whether average results deviated from the certified reference value of control materials within the APS derived from biological variation (BV). The APS used in EQA have evolved from state-of-the-art models to BV. Poor clinical decision-making would occur if the results accepted by some APS were applied. Conclusions: In Spain, only 2 of the 18 measurands studied are considered to be well harmonized. Closer collaboration between laboratories and analytical system providers would be required to resolve discrepancies.

Sample transportation - an overview.

Transportation of blood samples is a major part of the preanalytical pathway and can be crucial in delaying laboratory results to the clinicians. A variety of aspects however makes sample transportation a complex, challenging and often overlooked task that needs thorough planning and dedicated resources. The purpose of this review is to outline the options available for this task and to emphasize the preanalytical aspects that need consideration in this process, e.g. performance specifications for sample transportation as stated in ISO standards 15189 and 20658, quality control of automated transportation systems, monitoring of sample integrity parameters and temperature surveillance in general and for external samplers in particular. All these are tasks that the laboratory must assure on a daily basis in terms of continuous quality control, and simultaneously the laboratory must remain alert to alterations in clinical demands (sample frequency, turn-around-times) and new regulations within this area (e.g. the recent General Data Protection Regulation from the EU).

Functional proteomics outlines the complexity of breast cancer molecular subtypes.

Breast cancer is a heterogeneous disease comprising a variety of entities with various genetic backgrounds. Estrogen receptor-positive, human epidermal growth factor receptor 2-negative tumors typically have a favorable outcome; however, some patients eventually relapse, which suggests some heterogeneity within this category. In the present study, we used proteomics and miRNA profiling techniques to characterize a set of 102 either estrogen receptor-positive (ER+)/progesterone receptor-positive (PR+) or triple-negative formalin-fixed, paraffin-embedded breast tumors. Protein expression-based probabilistic graphical models and flux balance analyses revealed that some ER+/PR+ samples had a protein expression profile similar to that of triple-negative samples and had a clinical outcome similar to those with triple-negative disease. This probabilistic graphical model-based classification had prognostic value in patients with luminal A breast cancer. This prognostic information was independent of that provided by standard genomic tests for breast cancer, such as MammaPrint, OncoType Dx and the 8-gene Score.

Maternal plasma antioxidant status in the first trimester of pregnancy and development of obstetric complications.

INTRODUCTION: Oxidative stress is present in pregnancy complications. However, it is unknown if early maternal antioxidant status could influence later development of complications. The use of assisted reproduction techniques (ART) is rising due to the delay of first pregnancy and there is scarce information on its influence on oxidative balance. OBJECTIVE: To assess the possible relationship between maternal plasma antioxidant status in first trimester of gestation with later development of pregnancy complications, evaluating the influence of ART and nutrition. METHODS: Plasma from 98 healthy pregnant women was obtained at week 10, nutrition questionnaires filled and women were followed until delivery. We evaluated biomarkers of oxidative damage (carbonyls, malondialdehyde-MDA), antioxidants (thiols, reduced glutathione, phenolic compounds, catalase and superoxide dismutase activities) by spectrophotometry/fluorimetry and melatonin (ELISA). Antioxidant status score (Antiox-S) was calculated as the computation of antioxidants. Diet-antioxidants relationship was evaluated through multiple correspondence analysis. RESULTS: Melatonin and carbonyls exhibited a negative correlation. No difference in oxidative damage was found between groups, but Antiox-S was significantly lower in women who developed complications. No differences in oxidative damage or Antiox-S were found between ART and no-ART pregnancies. High consumption of foods of vegetable origin cluster with high plasma levels of phenolic compounds and with high Antiox-S. CONCLUSIONS: In early normal gestation, low plasma antioxidant status, assessed through a global score, associates with later development of pregnancy complications. Larger population studies could help to determine the value of Antiox-S as predictive tool and the relevance of nutrition on maternal antioxidant status.