Periodic verification of results' comparability between several analyzers: experience in the application of the EP31-A-IR guideline.

OBJECTIVES: To assess the usefulness of the EP31-A-IR guideline published by the Clinical and Laboratory Standards Institute (CLSI) to perform the periodic verification of results' comparability between several analyzers. METHODS: Twenty-four biochemistry parameters that could be measured in different analyzers were included: albumin, alkaline phosphatase, alanine aminotransferase, amylase, aspartate aminotransferase, calcium, chloride, C-reactive protein, creatine kinase, creatinine, direct bilirubin, gamma glutamyl transferase, glucose, lactate dehydrogenase, magnesium, phosphate, potassium, sodium, total bilirubin, total cholesterol, total protein, triglycerides, urea and uric acid. In accordance with the EP31-A-IR guideline: (1) Patient samples were selected considering the concentration or activity of interest. (2) Acceptance criteria were established specifically for each concentration or activity level. A quality specification based on biological variation or on state of the art was selected, considering the analytical performance of the available technology. (3) Maximum allowable differences (MAD) between analyzers were calculated. (4) Measurements were performed as stated in appendix B of the guideline. (5) Maximum differences between analyzers were calculated. Results were considered comparable when the maximum difference was less than or equal to the MAD. RESULTS: For the 24 parameters evaluated, any difference between analyzers exceeded the MAD. CONCLUSIONS: The EP31-A-IR guideline proved to be useful for periodic verification of results' comparability. However, it must be considered that, to be practicable, it may require to adjust the acceptance criteria in accordance to the analytical performance of the available technology; as well as the number of analytical measurements conforming to the laboratory resources.

Cost-effectiveness of a high-sensitivity cardiac troponin T systematic screening strategy compared with usual care to identify patients with peri-operative myocardial injury after major noncardiac surgery.

BACKGROUND: About 300 million surgeries are performed worldwide annually and this figure is increasing constantly. Peri-operative myocardial injury (PMI), detected by cardiac troponin (cTn) elevation, is a common cardiac complication of noncardiac surgery, strongly associated with short- and long-term mortality. Without systematic peri-operative cTn screening, most cases of PMI may go undetected. However, little is known about cost effectiveness of a systematic PMI screening strategy with high-sensitivity cardiac troponin T (hs-cTnT) after noncardiac surgery. OBJECTIVE: To assess, in patients with high cardiovascular risk, the cost-effectiveness of a systematic screening strategy using a hs-cTnT assay, to identify patients with PMI after major noncardiac surgery, compared with usual care. DESIGN: Cost-effectiveness analysis; single centre prospective cohort study. SETTING: Spanish University Hospital. PATIENTS: From July 2016 to March 2019, we included 1477 consecutive surgical patients aged ≥65 or if <65, with documented history of cardiovascular disease or impaired renal function, who underwent major noncardiac surgery and required at least an overnight hospital stay. We excluded patients aged <65 years without cardiovascular disease, undergoing minor surgery, or with an expected <24 h hospital stays. INTERVENTIONS: We conducted a decision-tree analysis, comparing a systematic screening strategy measuring hs-cTnT before surgery, and at the 2nd and 3rd days after surgery vs. a usual care strategy. We considered a third-party payer perspective and the outcomes of both strategies in the short-term (30 days follow-up). Information about costs was expressed in Euros-2021. We calculated the incremental cost-effectiveness ratio (ICER) of the systematic hs-cTnT strategy, defined as the expected cost per any additional PMI detected, and explored the robustness of the model using deterministic and probabilistic sensitivity analysis. MAIN OUTCOME MEASURES: ICER of the systematic hs-cTnT screening strategy. RESULTS: The ICER was €425 per any additionally detected PMI. The deterministic sensitivity analysis showed that a 15% variation in costs, and a 1% variation in the predictive values, had a minor impact over the ICER, except in case of the negative predictive value of the systematic hs-cTnT screening strategy. Monte Carlo simulations (probabilistic sensitivity analysis) showed that systematic hs-cTnT screening would be cost-effective in 100% of cases with a 'willingness to pay' of €780. CONCLUSIONS: Our results suggest that systematic peri-operative PMI screening with hs-cTnT may be cost-effective in the short-term in patients undergoing major noncardiac surgery. Economic evaluations, with a long-term horizon, are still needed. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT03438448.

Quality assurance of add-on testing in plasma samples: stability limit for 29 biochemical analytes.

Introduction: Clinical laboratories should guarantee sample stability in specific storage conditions for further analysis. The aim of this study is to evaluate the stability of plasma samples under refrigeration for 29 common biochemical analytes usually ordered within an emergency context, in order to determine the maximum allowable period for conducting add-on testing. Materials and methods: A total of 20 patient samples were collected in lithium heparin tubes without gel separator. All analyses were performed using Alinity systems (Abbott Laboratories, Abbott Park, USA) and samples were stored at 2-8 °C. Measurements were conducted in primary plasma tubes at specific time points up to 48 hours, with an additional stability study in plasma aliquots extending the time storage up to 96 hours. The stability limit was estimated considering the total limit of change criteria. Results: Of the 29 studied parameters, 24 demonstrated stabilities within a 48-hour storage period in primary plasma tubes. However, five analytes: aspartate aminotransferase, glucose, lactate dehydrogenase, inorganic phosphate and potassium evidenced instability at different time points (7.9 hours, 2.7 hours, 2.9 hours, 6.2 hours and 4.7 hours, respectively). The stability study in plasma aliquots showed that all parameters remained stable for 96 hours, except lactate dehydrogenase, with a stability limit of 63 hours. Conclusions: A reduced stability of primary plasma samples was observed for five common biochemical analytes ordered in an emergency context. To ensure the quality of add-on testing for these samples, plasma aliquots provide stability for a longer period.

Characterization of add-on testing before and after automation at a core laboratory.

Objectives: Add-on testing refers to the process that occurs in clinical laboratories when clinicians request that additional tests be performed on a previously analysed specimen. This is a common but inefficient procedure, highly time-consuming, especially at core laboratories and could be optimised by automating these procedures. The aims of this study are: 1) To describe patterns of add-on testing at a core laboratory at a tertiary hospital, 2) To evaluate turnaround time (TAT) before and after automation of the pre-, post- and analytical phases. Methods: Retrospective, observational study conducted at the biochemistry area of a core laboratory of all add-on orders received in two different months (pre-automation and post-automation). Results: A total of 2464 add-on orders were analysed, representing around 5 % of total requests. Most orders were for either one (>50 %) or two (≈20 %) tests. Most orders were received during the week (from Monday to Friday), particularly during the morning shift (>50 %). More than 50 % of requests were made by the Emergency Department. The two most common add-on parameters were C-reactive protein and N-terminal pro-brain natriuretic peptide. After automation, the median TAT decreased by 42.3 % (from 52 to 22 min). The largest decreases in TAT were observed for routine samples (58.89 %) and fully automated analyses (56.86 %). Conclusions: Automation of our core laboratory substantially reduced turnaround time for add-on testing, indicating an increase in efficiency. Automation eliminated several manual steps in the process, leading to a mean reduction of 15 work hours per day (more than 2 full-time equivalents).

Continuous Glucose Monitoring Time-in-Range and HbA1c Targets in Pregnant Women with Type 1 Diabetes.

The CONCEPTT trial compared real-time Continuous Glucose Monitoring (RT-CGM) to capillary glucose monitoring in pregnant women with type 1 diabetes. We analyzed CGM and glycated hemoglobin (HbA1c) measures in first (n = 221), second (n = 197), and third (n = 172) trimesters, aiming to examine target glucose attainment and associations with pregnancy outcomes. CGM targets were Time-in-range (TIR) > 70%, Time-above-range (TAR) <25%, and Time-below-range (TBR) < 4%, and HbA1c targets < 6.5% (National Institute for Health and Care Excellence [NICE]) and HbA1c < 6.0% in second and third trimesters (American Diabetes Association [ADA]). TIR/TAR/TBR targets were achieved by 7.7/14.5/30.3% participants in first, 10.2/14.2/52.8% in second, and 35.5/37.2/52.9% in third trimesters. CGM target attainment was low but increased during pregnancy and with RT-CGM use. In the adjusted analyses, achieving TBR target was associated with a higher risk of pre-eclampsia and neonatal hypoglycemia. ADA HbA1c target attainment was low and unchanged during pregnancy (23.5/27.9/23.8%) but increased with RT-CGM use. In the adjusted analyses, HbA1c target attainment was associated with a lower risk of preterm birth, large-for-gestational age and neonatal hypoglycemia. We conclude that CONCEPTT trial participants had a low rate of CGM and of HbA1c target attainment. Attainment of CGM and NICE HbA1c targets increased throughout gestation and all targets (both NICE/ADA HbA1c and CGM) were more likely to be achieved by RT-CGM users, at 34 weeks' gestation. ADA HbA1c target achievement was independently associated with better perinatal outcomes, while the independent association of TBR target achievement with increased risk warrants further study. ClinicalTrials.gov Registration Identifier NCT01788527.

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.

[Swelling of the bronchial mucose and quickness of onset in acute asthma]. / Edema de la mucosa bronquial y rapidez de instauración de la crisis de asma.

BACKGROUND AND OBJECTIVE: The plasma protein leakage produced in the bronchial mucose of patients with acute asthma might be associated to the quickness of the onset exacerbation. The aim of this study was to study this association. PATIENTS AND METHOD: 22 patients with acute asthma were recruited, and the magnitude of plasma protein leakage was measured by the concentrations of albumin and alpha2-macroglobulin in sputum. RESULTS: Days of onset in acute asthma correlated negatively with albumin sputum concentration (r = -0.563; p = 0.006), alpha2-macroglobulin sputum concentration (r = -0.603; p = 0.003), and related relative coefficients of albumin sputum/serum (r = -0.538; p = 0.01) and alpha2-macroglobulin sputum/serum (r = -0.514; p = 0.014). When the sample was divided by the following daily cutoff: < or = 4, patients suffering from a shorter onset of acute asthma showed a higher concentration of alpha2-macroglobulin in sputum: mean (standard deviation) of 14.4 (18) versus 5.3 (5.4) (p = 0.028). CONCLUSIONS: Plasma protein leakage seems to play an important role in the inflammatory pathogenesis of asthma exacerbation. The quicker onset of asthma the more plasma protein extravasation to the bronchial lumen.

Cystatin C as a marker of GFR--history, indications, and future research.

OBJECTIVE: To summarize recent knowledge on the small molecular weight protein cystatin C (cys-C) and its use as a marker of the glomerular filtration rate (GFR). METHODS: A multinational expert meeting was held in April 2002 in Marburg, Germany. Contributors summarized their main findings. CONCLUSIONS: Cys-C is at least equal if not superior to serum creatinine as a marker of GFR. The independence from height, gender, age, and muscle mass is advantageous. Select patient groups such as children, the elderly, and patients with reduced muscle mass benefit in particular.

High sensitivity troponin T concentrations in patients undergoing noncardiac surgery: a prospective cohort study.

OBJECTIVES: To determine the proportion of noncardiac surgery patients exceeding the published 99th percentile or change criteria with the high sensitivity Troponin T (hs-TnT) assay. DESIGN AND METHODS: We measured hs-TnT preoperatively and postoperatively on days 1, 2 and 3 in 325 adults. RESULTS: Postoperatively 45% (95% CI: 39-50%) of patients had hs-TnT≥14ng/L and 22% (95% CI:17-26%) had an elevation (≥14ng/L) and change (>85%) in hs-TnT. CONCLUSION: Further research is needed to inform the optimal hs-TnT threshold and change in this setting.

[Inflammatory response of rapid onset asthma exacerbation]. / Respuesta inflamatoria de la exacerbación asmática de instauración rápida.

UNLABELLED: The association between onset of asthma exacerbation and the inflammatory response has not been sufficiently studied. OBJECTIVE: To determine the differential mechanisms of the rapid onset (RO) asthma exacerbation. METHODS: We designed a prospective, multicentre study that included 34 patients who suffered from asthma exacerbation. They were distributed into three groups of asthmatics, depending of the time of onset: from 0 to 24h, from 25 to 144h and more than 145h. We collected clinical data, sputum, blood and urine samples when first seen at the clinic and the next 24h later, and differential cell counts and biomarkers were determined RESULTS: The asthmatics who suffered a RO exacerbation showed a higher elastase concentration, (1.028±1.140; 310±364; 401±390ng/ml) (P<0.05) and albumin (46.2±4.3; 42±3.4; 39.9±4.8g/l) (P<0.05) in the blood sample. Neutrophils, eosinophils (blood or sputum), eosinophil cationic protein (ECP) (blood), interleukin 8 (IL(8)) (blood) and leukotriene E4 (LTE(4)) (urine) were high in the three groups (P>0.05). We demonstrated an association between the onset of exacerbation and the severity of obstruction (FEV(1)) (r=-0.360; P=0.037), eosinophils in sputum (r=-0.399; P=0.029), albumin (r=-0.442; P=0.013), and IL(8) in sputum (r=0.357; P=0.038). CONCLUSIONS: The results suggest a rapid inflammatory response, both neutrophilic and eosinophilic, in the asthmatic exacerbation. However, the swelling in the bronchi may play an important role in the initial inflammatory response in the exacerbations depending of time of onset.

Preanalytical quality control program - an overview of results (2001-2005 summary).

BACKGROUND: Preanalytical variables, such as sample collection, handling, transport, and storage, may affect patient results. The number of errors in the preanalytical phase may decrease by following standardized procedures. METHODS: A retrospective analysis (2001-2005) of results obtained through the Spanish Society of Clinical Chemistry and Molecular Pathology Quality Assessment Program for the Preanalytical Phase has been carried out to summarize data regarding the main factors affecting the preanalytical phase quality. In such a program, participants are asked to register rejections and causes for rejection of routine or stat samples usually and locally collected at their laboratories. RESULTS: Results discussed refer to 105 laboratories. Of the 4,715,132 tubes expected to be received during the data collection period among participating laboratories and according to determinations included by clinicians in the request form, 32,977 (0.699%) offered a cause for rejection. Whole blood-EDTA samples and serum samples accounted for 75.6% of all samples collected among laboratories, although they only corresponded to 55.8% of all registered rejections. In total, 81% of rejections arose as a result of the following reasons: "specimen not received" (37.5%), "hemolysis" (29.3%), and "clotted sample" (14.4%). Moreover, plasma-citrate-erythrocyte sedimentation rate exhibited the highest percentage of rejection (1.473%), whereas the lowest rate corresponded to whole blood-EDTA (0.381%). CONCLUSIONS: Overall percentage of rejection is similar to previously published data. As some of the included variables have turned out to be irrelevant, the program has been simplified from the year 2006 onwards.