Dynamic profiles and predictive values of some biochemical and haematological quantities in COVID-19 inpatients.

INTRODUCTION: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in some hospitalized patients has shown some important alterations in laboratory tests. The aim of this study was to establish the most relevant quantities associated with the worst prognosis related to COVID-19. MATERIALS AND METHODS: This was a descriptive, longitudinal, observational and retrospective study, in a cohort of 845 adult inpatients from Bellvitge University Hospital (L'Hospitalet de Llobregat, Barcelona, Spain). A multivariate regression analysis was carried out in demographic, clinical and laboratory data, comparing survivors (SURV) and non-survivors (no-SURV). A receiver operating characteristic analysis was also carried out to establish the cut-off point for poor prognostic with better specificity and sensibility. Dynamic changes in clinical laboratory measurements were tracked from day 1 to day 28 after the onset of symptoms. RESULTS: During their hospital stay, 18% of the patients died. Age, kidney disease, creatinine (CREA), lactate-dehydrogenase (LD), C-reactive-protein (CRP) and lymphocyte (LYM) concentration showed the strongest independent associations with the risk of death in the multivariate regression analysis. Established cut-off values for poor prognosis for CREA, LD, CRP and LYM concentrations were 75.0 µmol /L, 320 U/L, 80.9 mg/L and 0.69 x109/L. Dynamic profile of laboratory findings, were in agreement with the consequences of organ damage and tissue destruction. CONCLUSIONS: Age, kidney disease, CREA, LD, CRP and LYM concentrations in COVID-19 patients from the southern region of Catalonia provide important information for their prognosis. Measurement of LD has demonstrated to be very good indicator of poor prognosis at initial evaluation because of its stability over time.

Survey on Stat Tests in Catalan Clinical Laboratories.

INTRODUCTION: The Catalan Association of Clinical Laboratory Sciences (ACCLC) conducted a survey on the vast majority of hospital clinical laboratories in Catalonia. In order to establish a debate on the emergency laboratories and aspects related to the stat tests. MATERIALS AND METHODS: An online survey was distributed by ACCLC to 69 hospital laboratories in Catalonia. A 30-question survey was designed with 9 different issues. The questionnaire examined general information regarding the hospital and laboratory model, stat laboratory workload, laboratory information system, quality control, critical values results, authorization/validation of results, laboratory report and human resources, among others. The results were reported in number of laboratories and in percentage (%). RESULTS: The total survey response rate was 59 %. 68.3 % stat laboratories biochemistry, haematology and microbiology departments were integrated. The majority (60.9%) of the stat tests were integrated in part with laboratory core. All laboratories employed laboratory information system and are using barcode system. In 75.6% of laboratories all requests were made electronically. 43.9% of laboratories did not give results in international system, only in conventional units. All laboratories participated in internal and external quality assessment programs. Internal quality controls are processed more than once a day in 80.5% of laboratories. The vast majority of laboratories reported critical results (97.6%). 75% of laboratories have a medical specialist (biochemistry or analysis). The average number of laboratory technicians was 4. CONCLUSIONS: Our study highlighted the variation in how emergency laboratories and stat test are run across Catalonia.

Stability of pH, Blood Gas Partial Pressure, Hemoglobin Oxygen Saturation Fraction, and Lactate Concentration.

BACKGROUND: The storage temperature and time of blood gas samples collected in syringes constitute preanalytical variables that could affect blood gas or lactate concentration measurement results. We analyzed the effect of storage temperature and time delay on arterial or venous blood gas stability related to pH, partial pressure of carbon dioxide (pCO2) and oxygen (pO2), hemoglobin oxygen saturation (sO2), and lactate concentration. METHODS: In total, 1,200 arterial and venous blood sample syringes were analyzed within 10 minutes of collection. The samples were divided into different groups to determine parameter stability at 25, 4-8, and 0-3.9°C and at different storage times, 60, 45, 30, and 15 minutes. Independent sample groups were used for each analysis. Percentage deviations were calculated and compared with acceptance stability limits (1.65× coefficient of variation). Additionally, sample group sub analysis was performed to determine whether stability was concentration-dependent for each parameter. RESULTS: The pH was stable over all storage times at 4-8 and 0-3.9°C and up to 30 minutes at 25°C. pCO2 was stable at ≤60 minutes at all temperatures. pO2 was stable for 45 minutes at 0-3.9°C, and sO2 was stable for 15 minutes at 25°C and for ≤60 minutes at 0-3.9°C. Lactate concentration was stable for 45 minutes at 0-3.9°C. Subanalysis showed that stability was concentration-dependent. CONCLUSIONS: The strictest storage temperature and time criteria (0-3.9°C, 45 minutes) should be adopted for measuring pH, pCO2, pO2, sO2, and lactate concentration in blood gas syringes.

Critical Issues and New Trends on Stat Tests in Clinical Laboratory.

The IX European Symposium of the Clinical Laboratory and In Vitro Diagnostics Industry, entitled "Stat Tests in Clinical laboratory", took place in Barcelona, Catalonia (Spain), between May 17-18, 2017. The scientific program was structured in several round-tables that dealt with the following topics: emergency laboratory models, accreditation of stat tests by ISO 15189, critical issues of stat tests and the new proposals of the in vitro diagnostics industry for emergency laboratories. The aim of the Symposium was the discussion of the transformation that stat tests have generated on clinical laboratories in terms of organization, turnaround time, accreditation, and probable evolution of these laboratories coming years.

Analysis of laboratory critical values at a referral Spanish tertiary university hospital.

INTRODUCTION: The aim of this study was to analyse critical value data from our laboratory and compare our critical value reporting policy with others in the literature. MATERIALS AND METHODS: Analysis of critical values was performed on data obtained over a 6-month period in a tertiary university hospital. RESULTS: We identified 5723 critical values, of which approximately 80% came from STAT testing (4577), 15% from routine inpatients testing (884) and 5% from routine outpatients testing (262). The highest proportion of critical values corresponded to oxygen partial pressure (17.7%), followed by potassium ion (17.6%) concentrations. The parameters associated with the highest critical value notification percentage in emergency patients were pH, haematocrit, glucose, potassium ion and haemoglobin concentrations. In inpatients, these parameters were glucose, phosphate, haemoglobin, sodium ion and potassium ion concentrations. In outpatients, they were calcium and potassium concentrations. CONCLUSIONS: The analysis of critical values in our hospital is in accordance with that reported in the literature. Our findings demonstrate the importance of incorporating improvement actions not only in critical value notification, but especially in the registration of this activity.

Reference intervals for a complete blood count on an automated haematology analyser Sysmex XN in healthy adults from the southern metropolitan area of Barcelona.

BACKGROUND: The examination of peripheral blood is routinely used as a basic test in daily medical practice. Reliable reference intervals are necessary to avoid misdiagnoses, and the establishment of those intervals is an important task for clinical laboratories.The aim of the present study was to establish the reference intervals for complete blood count (CBC) on a Sysmex XN haematology analyser in healthy adults from the southern metropolitan area of Barcelona (Spain). METHODS: A total of 213 apparently healthy adults who received a general health examination at Hospital Universitari de Bellvitge were recruited to this study. Blood samples collected in K3EDTA tubes were analysed on a Sysmex XN. Statistically relevant gender based partition was assessed, outliers removed, and the reference intervals calculated in concordance with Clinical and Laboratory Standards Institute (CLSI) EP28-A3C guidelines. RESULTS: The CBC reference intervals were established in 191 adults (64 men and 127 women) who fulfilled all of the inclusion criteria. Significant gender-dependent differences in red blood cells, haematocrit, haemoglobin and platelets were found. The rest of the CBC reference intervals were obtained from the overall data. CONCLUSIONS: We report CBC reference intervals established on a Sysmex XN analyser, a widely used automated analyser for which reference intervals were previously lacking in the literature. However, these reference intervals we recommend should be validated by individual laboratories for the local population as recommended by CLSI.

Reference interval for immature platelet fraction on Sysmex XN haematology analyser in adult population.

INTRODUCTION: The Sysmex XN-series haematology analyser has newly adopted a fluorescent channel to measure immature platelet fraction (IPF). To promote the clinical utility of this promising parameter, establishing a reliable reference interval is mandatory. According to previous studies, IPF values may be affected by the employed analyser and the ethnic background of the individual, but no differences seem to be found between individuals' genders. Therefore, this study aimed to define the reference interval for IPF in a Spanish population following Clinical and Laboratory Standard Institute (CLSI) guidelines. MATERIALS AND METHODS: A total of 153 healthy Caucasian adults from Spain met the inclusion criteria. IPF measurement was performed by means of a Sysmex XN-2000 haematology analyser. A non-parametric percentile method was used to calculate the reference intervals in accordance with CLSI guidelines. RESULTS: The obtained reference interval for IPF on the Sysmex XN-2000 was 1.6-9.6% (90% confidence intervals (CIs) were 1.5-1.8 and 9.3-11.5, respectively). No significant gender difference in IPF reference intervals was observed (P = 0.101). CONCLUSIONS: This study provides, for the first time, a reference interval for IPF using a Sysmex XN-2000 in a Spanish population, ranging from 1.6 to 9.6%. These data are needed to evaluate platelet production in several conditions such as thrombocytopenia, inflammatory states and cardiovascular diseases, as well as for future research.

Reference values assessment in a Mediterranean population for small dense low-density lipoprotein concentration isolated by an optimized precipitation method.

BACKGROUND: High serum concentrations of small dense low-density lipoprotein cholesterol (sd-LDL-c) particles are associated with risk of cardiovascular disease (CVD). Their clinical application has been hindered as a consequence of the laborious current method used for their quantification. OBJECTIVE: Optimize a simple and fast precipitation method to isolate sd-LDL particles and establish a reference interval in a Mediterranean population. MATERIALS AND METHODS: Forty-five serum samples were collected, and sd-LDL particles were isolated using a modified heparin-Mg2+ precipitation method. sd-LDL-c concentration was calculated by subtracting high-density lipoprotein cholesterol (HDL-c) from the total cholesterol measured in the supernatant. This method was compared with the reference method (ultracentrifugation). Reference values were estimated according to the Clinical and Laboratory Standards Institute and The International Federation of Clinical Chemistry and Laboratory Medicine recommendations. sd-LDL-c concentration was measured in serums from 79 subjects with no lipid metabolism abnormalities. RESULTS: The Passing-Bablok regression equation is y = 1.52 (0.72 to 1.73) + 0.07x (-0.1 to 0.13), demonstrating no significant statistical differences between the modified precipitation method and the ultracentrifugation reference method. Similarly, no differences were detected when considering only sd-LDL-c from dyslipidemic patients, since the modifications added to the precipitation method facilitated the proper sedimentation of triglycerides and other lipoproteins. The reference interval for sd-LDL-c concentration estimated in a Mediterranean population was 0.04-0.47 mmol/L. CONCLUSION: An optimization of the heparin-Mg2+ precipitation method for sd-LDL particle isolation was performed, and reference intervals were established in a Spanish Mediterranean population. Measured values were equivalent to those obtained with the reference method, assuring its clinical application when tested in both normolipidemic and dyslipidemic subjects.

Estimation of Alert and Change Limits of Haematological Quantities and its Application in the Plausibility Control.

INTRODUCTION: In the process of quality assurance of the measured values of the clinical laboratory, one of the purposes is to perform the validation of patients' measured values in the most objective way. This validation process is called plausibility control which may be defined as the set of procedures used to decide if a patient's measured value is valid according to established clinical and biological criteria. The aim of this study is to propose a model to estimate alert and change limits of measured values of the blood cell count, to be applied to detect doubtful patients' measured values. METHODS: Some alert and change limits were estimated from the emergency laboratory database of the year 2010 using different percentiles. A verification of the suitability of the proposed model was also performed. RESULTS: Most of the fractions of the measured values excluded by the alert and change limits were according to the theoretical expected. The overall fraction of the number of doubtful clinical laboratory reports ranged between 0.6 and 47.6 %. CONCLUSIONS: The proposed model helps, improves and standardizes the process of detection of doubtful measured values since they are produced objectively. These limits can also be configured in a laboratory information system letting the clinical laboratory professional staff to save time and efforts.

Evaluación multicéntrica del nuevo sistema analítico BioSystems BA 400 ® y comparación de procedimientos de medida / Multicentre evaluation of the new analytical system BioSystems BA 400 ® and comparison of measurement procedures

Objetivo. El objetivo de este trabajo fué evaluar, mediante un estudio multicéntrico, la imprecisión y la veracidad de un elevado número de procedimientos de medida en el nuevo sistema analítico BioSystems BA 400(R). Material y método. El estudio de la imprecisión se llevó a cabo siguiendo recomendaciones establecidas y utilizando sueros control con 2 concentraciones distintas. El estudio de la veracidad se ha realizado mediante la comparación de los procedimientos de medida del nuevo sistema con los utilizados habitualmente en los centros evaluadores. Resultados. Los resultados obtenidos para la imprecisión interdiaria con el nuevo analizador han sido en general excelentes en relación a los errores máximos permitidos. Se han encontrado algunas diferencias no despreciables y estadísticamente significativas entre los distintos procedimientos de medida, que son debidas a diferencias en el mensurando en algunos casos (transaminasas, inmunoanálisis) y a diferencias en los calibradores en otros. Conclusiones. La evaluación ha demostrado las excelentes prestaciones de precisión y veracidad del sistema. El nuevo analizador proporciona resultados en muestras de pacientes que son equivalentes a los obtenidos con otros analizadores (Olympus AU5400 y AU2700, Roche Cobas C711 y Siemens ADVIA 2400, 1800 y BNII) (AU)

Background. The purpose of the study was a multicentre evaluation of the imprecision and of the trueness of a wide variety of measurement procedures with the new analytical system BioSystems BA 400(R). Methods. The imprecision study was performed following established recommendations and using control sera with two different concentrations. The trueness was studied by means of a comparison of the measurement procedures of the new analyser with those of routine use in the evaluating centres. Results. The results obtained for the between-day imprecision with the new analyser have been in general excellent in relation to the maximum allowed errors. Several differences that are not worthless and that are statistically significant have been found between the measurement procedures. The differences are due to measurand differences in some cases (transaminases, immunoanalysis), and to the calibration in other. Conclusion. The evaluation study has demonstrated the excellent performance of the system regarding precision and trueness. The results obtained for patient samples with the new analyzer are equivalent to those obtained with other analyzers (Olympus AU5400 y AU2700, Roche Cobas C711 y Siemens ADVIA 2400, 1800 y BNII) (AU)

Measurement uncertainty in manual differential leukocyte counting.

BACKGROUND: One of the most frequently requested examinations in the clinical laboratory is the differential leukocyte count. Despite many technological improvements, thousands of differential leukocyte counts are made by microscopic examination of a blood smear, counting 100 leukocytes and expressing the fraction of the specific leukocyte types as percentages (rounded to integer values) of the total leukocyte count. Although in the clinical laboratory it is not usual practice to report measurement uncertainties, currently the ISO 15189 standard considers measurement uncertainty as a very helpful element for a comprehensive interpretation of any measurement result. METHODS: The estimation of the measurement uncertainty of each differential leukocyte count result was carried out according to international guidelines. The sources of standard uncertainty taken into account were: pre-metrological variation, random distribution, between-examiner reproducibility, and rounding to an integer. RESULTS: In this example, a sample of blood with a concentration number of leukocytes of 3,5x10(9)/L (1)) is taken into consideration. For each differential leukocyte count result, the standard uncertainties corresponding to each source of measurement uncertainty, as well as the combined and the expanded uncertainties, were estimated with information from the literature. CONCLUSIONS: The procedure presented here to estimate the measurement uncertainty of differential leukocyte count results is appropriate to fulfill the requirements of the ISO 15189 standard related to measurement uncertainty. Knowledge of this uncertainty is helpful in interpreting sequential results obtained in the same patient.

Pre-analytical variation of some haematological quantities.

BACKGROUND: It is customary to assume that pre-analytical variation is negligible if all pre-analytical sources of variation have been standardised. The aim of this study was to quantify the pre-analytical variation of some haematological quantities frequently measured in clinical laboratories. METHODS: The experimental design considers different sources of pre-analytical variation that usually occur day-to-day for samples from patients. RESULTS: The results demonstrate that for concentrations of erythrocytes, haemoglobin, leukocytes, neutrophilocytes (segmented) and lymphocytes, and for the volume fraction of erythrocytes ("packed cell volume") in blood, the pre-analytical variance is not negligible. CONCLUSIONS: We suggest that these variances should be taken into account when estimating the uncertainty of measurement for patient results.

Guideline for the production of multicentre physiological reference values using the same measurement system. A proposal of the Catalan Association for Clinical Laboratory Sciences.

This article is intended as a guide for the production of biological reference values of healthy people (physiological reference values) by several clinical laboratories using the same measurement system. This guide is a proposal from the Catalan Association of Clinical Laboratory Sciences to be applied worldwide at a regional level. This guide makes it possible for all clinical laboratories in a region using the same measurement system to adopt the same physiological reference limits. The model presented here is based on the assumption that the production of physiological reference values is a professional task that should be shared by both clinical laboratories and the in vitro diagnostics industry.