Dynamics of Reverse Transcription-Polymerase Chain Reaction and Serologic Test Results in Children with SARS-CoV-2 Infection.

OBJECTIVES: To determine the time to reverse transcription-polymerase chain reaction (RT-PCR) negativity after the first positive RT-PCR test, factors associated with longer time to RT-PCR negativity, proportion of children seroconverting after proven severe acute respiratory syndrome coronavirus 2 infection, and factors associated with the lack of seroconversion. STUDY DESIGN: The Epidemiological Study of Coronavirus in Children of the Spanish Society of Pediatrics is a multicenter study conducted in Spanish children to assess the characteristics of coronavirus disease 2019. In a subset of patients, 3 serial RT-PCR tests on nasopharyngeal swab specimens were performed after the first RT-PCR test, and immunoglobulin G serology for severe acute respiratory syndrome coronavirus 2 antibodies was performed in the acute and follow-up (<14 and ≥14 days after diagnosis) phase. RESULTS: In total, 324 patients were included in the study. The median time to RT-PCR negativity was 17 days (IQR, 8-29 days), and 35% of patients remained positive more than 4 weeks after the first RT-PCR test. The probability of RT-PCR negativity did not differ across groups defined by sex, disease severity, immunosuppressive drugs, or clinical phenotype. Globally, 24% of children failed to seroconvert after infection. Seroconversion was associated with hospitalization, persistence of RT-PCR positivity, and days of fever. CONCLUSIONS: Time to RT-PCR negativity was long, regardless of the severity of symptoms or other patient features. This finding should be considered when interpreting RT-PCR results in a child with symptoms, especially those with mild symptoms. Seroprevalence and postimmunization studies should consider that 11 in 4 infected children fail to seroconvert.

Biological variation database: structure and criteria used for generation and update.

BACKGROUND: Numerical data on the components of biological variation (BV) have many uses in laboratory medicine, including in the setting of analytical quality specifications, generation of reference change values and assessment of the utility of conventional reference values. METHODS: Generation of a series of up-to-date comprehensive database of components of BV was initiated in 1997, integrating the more relevant information found in publications concerning BV. A scoring system was designed to evaluate the robustness of the data included. The database has been updated every 2 years, made available on the Internet and derived analytical quality specifications for imprecision, bias and total allowable error included in the tabulation of data. RESULTS AND CONCLUSIONS: Our aim here is to document, in detail, the methodology we used to evaluate the reliability of the included data compiled from the published literature. To date, our approach has not been explicitly documented, although the principles have been presented at many symposia, courses and conferences.

Rationale for using data on biological variation.

The aims of this study are: 1) to use the data included in the biological variation (BV) database to address the usability of BV estimates; and 2) to use different examples from the authors' laboratories to illustrate the use and the usefulness of BV data in laboratory medicine. The BV database is an essential tool for laboratory management. Examples of application of data derived from BV are given in this paper, such as analytical performance specifications that have been included in various quality control software designed to optimize operative rules; also they have been incorporated as acceptability limits in external quality assurance reports. BV data from pathological status are of utmost interest for monitoring patients and differences between the intra-individual coefficients of variation (CVI) estimated from healthy and patients are shown. However, for a number of analytes there are limited data available and for many there are no data, consequently new studies should be encouraged at an international level. In addition, developing international criteria to evaluate publications dealing with the estimation of BV components would be of the utmost interest. We are ready and willing to collaborate with such worthy initiatives. The first EFLM strategic conference on analytical performance specifications is an excellent opportunity for debating these ideas.

miR-143, miR-222, and miR-452 are useful as tumor stratification and noninvasive diagnostic biomarkers for bladder cancer.

Altered microRNA (miRNA) expression may occur early in bladder cancer and may play a role in carcinogenesis and tumor behavior. We evaluated whether alterations in miRNA expression could improve disease stratification and outcome prognosis in bladder tumors and noninvasive diagnosis in urinary samples. miR-143, miR-222, and miR-452 expression levels were analyzed by quantitative RT-PCR (RT-qPCR) in paired urinary and matching tumors and in two independent prospective series of tumors and urinary specimens. Differential expression of miR-143, miR-222, and miR-452 in urine were verified by in situ hybridization in matching tumors. Tumor miRNA expression by RT-qPCR correlated with tumor grade, size, and presence of carcinoma in situ for miR-222, recurrence (miR-222 and miR-143), progression (miR-222 and miR-143), disease-specific survival (miR-222), and overall survival (miR-222). Protein expression patterns of potential miRNA targets, including vascular endothelial growth factor, BCL2, v-erb-b2 erythroblastic leukemia viral oncogene (ERBB) homolog 3, and ERBB4, were evaluated by IHC in tissue arrays containing tumors for which miRNAs were assessed by RT-qPCR. Target expression correlated with expression of their predicted regulatory miRNAs, recurrence (ERBB3), progression (ERBB4), disease-specific survival (ERBB3 and ERBB4), and overall survival (ERBB3 and ERBB4). Furthermore, RT-qPCR of miR-452 (area under the curve, 0.848) and miR-222 (area under the curve, 0.718) in urine provided high accuracies for bladder cancer diagnosis. Thus, bladder tumors were characterized by changes in miRNA expression that could aid in tumor stratification and clinical outcome prognosis, and miRNAs were detected in urinary specimens for noninvasive diagnosis.

Temporal Series Analysis of Population Cycle Threshold Counts as a Predictor of Surge in Cases and Hospitalizations during the SARS-CoV-2 Pandemic.

Tools to predict surges in cases and hospitalizations during the COVID-19 pandemic may help guide public health decisions. Low cycle threshold (CT) counts may indicate greater SARS-CoV-2 concentrations in the respiratory tract, and thereby may be used as a surrogate marker of enhanced viral transmission. Several population studies have found an association between the oscillations in the mean CT over time and the evolution of the pandemic. For the first time, we applied temporal series analysis (Granger-type causality) to validate the CT counts as an epidemiological marker of forthcoming pandemic waves using samples and analyzing cases and hospital admissions during the third pandemic wave (October 2020 to May 2021) in Madrid. A total of 22,906 SARS-CoV-2 RT-PCR-positive nasopharyngeal swabs were evaluated; the mean CT value was 27.4 (SD: 2.1) (22.2% below 20 cycles). During this period, 422,110 cases and 36,727 hospital admissions were also recorded. A temporal association was found between the CT counts and the cases of COVID-19 with a lag of 9-10 days (p ≤ 0.01) and hospital admissions by COVID-19 (p < 0.04) with a lag of 2-6 days. According to a validated method to prove associations between variables that change over time, the short-term evolution of average CT counts in the population may forecast the evolution of the COVID-19 pandemic.

Secukinumab does not impair the immunogenic response to the influenza vaccine in patients.

Objective: To evaluate whether immunological response to influenza vaccination is impaired in patients who are receiving secukinumab. Patients and methods: Subjects suffering from psoriatic arthritis or ankylosing spondylitis who were receiving treatment with secukinumab and healthy volunteers were included.All participants received seasonal inactivated trivalent influenza vaccine recommended by the WHO in the 2017-2018 northern hemisphere influenza season, which contained an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus and a B/Brisbane/60/2008-like virus.Haemagglutination inhibition was used to evaluate basal antibody (Ab) titres against the three influenza vaccine virus strains just before vaccination and at least 4 weeks after the vaccine administration. Response to vaccine was considered as >4-fold increases in Ab titre. Results: Thirty subjects, 17 patients and 13 healthy controls, with a follow-up duration of 33±8 days, were analysed. There were no demographic differences between groups. Patients and controls achieved a median of 4.6-fold and 4.0-fold increases, respectively, for anti H1N1 and almost 4.0 (3.7) for patients and 5.3 for controls for anti-B Ab. Both groups presented a poor response against H3N2, with <1.5-fold increase. Seroconversion rates were similar in both groups. Secukinumab did not influence the response to the influenza vaccine (relative risk: 1.09 (95% CI 0.58 to 2.07) for H1N1, RR: 1.53 (95% CI 0.15 to 15.0) for H3N2 and RR: 0.72 (95% CI 0.32 to 1.83) for B strain). Conclusion: In our study, secukinumab has no effect on the immunogenic response to the influenza vaccine.

Within-subject biological variation in disease: collated data and clinical consequences.

Quantitative data on the components of biological variation (BV) are used for several purposes, including calculating the reference change value (RCV) required for the assessment of the significance of changes in serial results in an individual. Pathology may modify the set point in diseased patients and, more importantly, the variation around that set-point. Our aim was to collate all published BV data in situations other than health. We report the within-subject coefficient of variation (CV(I)) for 66 quantities in 34 disease states. We compared the results with the CV(I) determined in healthy individuals and examined whether the data derived in specific diseases could be useful for clinical applications. For the majority of quantities studied, CV(I) values are of the same order in disease and health: thus the use of RCV derived from healthy subjects for monitoring patients would be reasonable. However, for a small number of quantities considered to be disease specific markers, the CV(I) differed from those in health. This could mean that RCV derived from healthy CV(I) may be inappropriate for monitoring patients in certain diseases. Hence, disease-specific RCVs may be clinically useful.

Biologic Variation Approach to Daily Laboratory.

Biological variation gives valuable information about how the living organism regulates its constituents within and between subjects; this information on the behavior of body components allows us to derive consequences concerning reference populations and intervals. With a more pragmatic approach biological variation has three uses: setting the appropriate analytical performance specification for each analyte to limit the amount of error that laboratory could introduce in its measurements, to help distinguish health from disease, and to implement internal quality control with the automatic verification of results.

Category 1 external quality assessment program for serum creatinine.

BACKGROUND: The Commission of Analytical Quality and the Committee of External Quality Programs of Spanish Society of Laboratory Medicine (SEQC) in collaboration with the Dutch Foundation for the Quality organized the first national category 1 External Quality Assessment Programs (EQAP) pilot study. The aim is to evaluate the standardization of serum creatinine measurements in the Spanish laboratories through a category 1 external quality assurance program with commutable material and reference method assigned values. METHODS: A total of 87 Spanish laboratories were involved in this program in 2015. Each day a sample control was measured by duplicate during 6 consecutive days. Percentage deviations and coefficients of variation obtained were compared with quality specifications derived from biological variation. RESULTS: A total of 1044 creatinine results were obtained. Laboratories were coded in 11 different method-traceability combinations. Only enzymatic methods get all results within the acceptability limits. DISCUSSION: To participate in a category 1 EQAP is a valuable tool to assess the standardization degree in our country; a big effort should be made to promote laboratories to change their procedures and to use enzymatic creatinine methods, in order to achieve a satisfactory standardization degree for this important analyte.

The utility of multiparametric seven-color flow cytometry in the detection of double hit lymphoma in ascitic fluid samples.

Double-hit lymphoma (DHL) is a rare type of lymphoma with concurrent chromosomal translocations of C-MYC with BCL2 or BCL6, associated with unfavorable prognosis. We describe a case of DHL in a 79-year-old female patient previously diagnosed with diffuse large B-cell lymphoma (DLBCL) with an early relapse in the ascitic fluid. A seven-color multiparametric flow cytometry immunophenotyping study of the ascitic fluid was carried out, and revealed 99.78% of large in size and high cellular complexity B-cells positive for CD19, CD10 (64.27%), CD45 dim, CD22 dim, CD25 (60%), CD43 bright, CD38 bright, and IgM (18.53%); and negative for CD20, CD5, CD23, CD79b, CD103, CD200, CD11c, and FMC7, and 78.99% without light chain expression and 21% with Lambda chain restriction. Due to the expression of CD19 and CD10 with overexpression of BCL-2 protein and due to CD43 and CD38 positivity detected, those cells showed features between DLBCL and Burkitt lymphoma. Fluorescence in situ hybridization (FISH) confirmed both c-MYC/IGH and BCL2/IGH rearrangement. Our findings may help to identify cases requiring additional cytogenetic analysis. © 2015 International Clinical Cytometry Society.

Reticulocyte parameters of delta beta thalassaemia trait, beta thalassaemia trait and iron deficiency anaemia.

AIMS: To analyse the differences in reticulocyte indices between delta beta thalassaemia trait (δß-TT), beta thalassaemia trait (ß-TT) and iron deficiency anaemia (IDA), and to correlate those differences with the physiopathological features of these three types of microcytoses. METHODS: We performed a descriptive study of 428 samples (43 δß-TT, 179 ß-TT and 206 IDA) that were run on Advia 2120 analyser (Siemens). The following reticulocyte indices were assessed: absolute reticulocyte count (ARC), percentage of reticulocytes, mean corpuscular volume of reticulocytes (MCVr), haemoglobin content of reticulocytes (CHr), mean corpuscular haemoglobin concentration of reticulocytes, red blood cell distribution width of reticulocytes (RDWr), haemoglobin distribution width of reticulocytes (HDWr) and reticulocyte subpopulations based on their fluorescence according to mRNA (low (L-R), medium (M-R) and high (H-R)), MCV ratio and MCHC ratio. Correlation between fetal haemoglobin (HbF) and RDWr in patients with thalassaemia was evaluated. RESULTS: RDWr was significantly higher in δß-TT compared with ß-TT (15.03% vs 13.82%, p<0.001), and so were HDWr (3.65% vs 3.27%, p<0.001), CHr (23.68 vs 22.66 pg, p<0.001) and MCVr (88.3 vs 85.5 fL, p<0.001). A good correlation was observed between HbF and RDWr (r=0.551, p<0.001). IDA subjects have more immature reticulocytes, but less ARC than ß-TT, suggesting a certain degree of inefficient erythropoiesis in IDA in comparison with ß-TT. CONCLUSIONS: Previously described differences between δß-TT, ß-TT and IDA in the corpuscular indices of mature red blood cell can also be observed in reticulocytes. The degree of anisocytosis in reticulocytes from patients with thalassaemia is correlated with HbF.

Laboratory parameters provided by Advia 2120 analyser identify structural haemoglobinopathy carriers and discriminate between Hb S trait and Hb C trait.

BACKGROUND: Haemoglobinopathies have spread owing to human migration, and the number of people needing diagnosis and management of these conditions is increasing. Clinicians need to accurately identify carriers and provide adequate genetic counselling in order to prevent the occurrence of homozygous or compound heterozygous offspring. OBJECTIVES: To identify red blood cell (RBC) laboratory parameters that discriminate between structural haemoglobinopathy carriers and healthy subjects, and to compare RBC laboratory indices between HbAS and HbAC individuals. METHODS: Samples of 500 variant Hb carriers (355 HbAS, 104 HbAC, 19 HbAD, 7 HbAE, 7 HbAO-Arab, 4 α-chain variants and 4 Hb Lepore) and 251 normal controls were run on an Advia 2120 analyser (Siemens). Classic haematological parameters and RBC populations were assessed in all subjects. A multivariable binary logistic regression model was created to predict the probability of a subject carrying any structural haemoglobinopathy. HbAS (n=355, 71%) and HbAC (n=104, 20.8%) subjects were compared. RESULTS: A clinical prediction rule was developed by assigning one point to each of the most efficient variables: mean corpuscular volume (MCV) <88.4 fL, RBC distribution width >13.4%, percentage of microcytic RBCs (%MICRO) >0.7% and the ratio of microcytic RBCs to hypochromic RBCs >0.8. A score of 0, 1, 2, 3 or 4, resulted in a probability of 9.6%, 36.3%, 66.7%, 85.2% or 98.3%, respectively. Among the most frequent variant Hb, HbAC subjects had lower values of parameters related to cell size (MCV, %MICRO) and higher values of parameters related to haemoglobin concentration (MCHC, %HYPER) than HbAS subjects. Coexistence of α-thalassaemia in both HbAS and HbAC individuals resulted in decreased Hb, MCV, MCH and MCHC. CONCLUSIONS: Structural haemoglobinopathy should be investigated in subjects belonging to ethnic groups with high prevalence of variant Hb and with a score of 3 or 4. Erythrocytes of HbAC subjects are smaller and denser than those of HbAS subjects.

Integration of data derived from biological variation into the quality management system.

BACKGROUND: [corrected] Data on within- and between-subject biological variation are available for around 250 analytes commonly used in medical laboratories. METHODS: Integration of this data into the quality system occurs at all three levels of laboratory activity: (a) Preanalytic process: biological variation provides the basis for selecting the most appropriate specimen for analysis, for defining sample stability and for deciding suitable timing between samplings; (b) analytic process: biological variation-derived goals are fundamental for designing internal quality control procedures, and for evaluating laboratory performance; and (c) postanalytic process: delta checks based on within-subject biological variation values are used for validating results and for interpreting serial results from a patient. CONCLUSION: The biological variation is a pillar for managing quality in laboratory medicine.

δß-Thalassemia trait: how can we discriminate it from ß-thalassemia trait and iron deficiency anemia?

OBJECTIVES: To analyze the differences not only in classic hematologic parameters but also in RBC subpopulations among δß-thalassemia trait (δß-TT), ß-thalassemia trait (ß-TT), and iron deficiency anemia (IDA) and to evaluate the role of fetal hemoglobin (HbF) in elevated RBC distribution width (RDW). METHODS: Samples from 553 patients with microcytosis (74 δß-TT, 272 ß-TT, and 207 IDA) were run on an Advia 2120i analyzer (Siemens Medical Solutions Diagnostics, Tarrytown, NY). Classic hematologic parameters and RBC subpopulations were assessed. The correlation between HbF and RDW in patients with thalassemia (both ß and δß) was evaluated. An independent sample t test was used to compare classic hematologic parameters and RBC subpopulations among ß-TT, IDA, and δß-TT and receiver operating characteristic curves performed in the significant comparisons. RESULTS: RDW was significantly higher in δß-TT compared with ß-TT (18.79% vs 16.04%, P < .001), as was mean corpuscular volume (66.39 vs 64.82 fL, P < .001), mean corpuscular hemoglobin (20.73 vs 20.04 pg, P < .001), and mean corpuscular hemoglobin concentration (31.16 vs 30.66 g/dL, P = .03). Pearson coefficient showed a good correlation between HbF and RDW. The values obtained for all the parameters were significantly different (P < .001) between patients with thalassemia (ß and δß) and IDA. CONCLUSIONS: RDW is the best parameter to discriminate δß-TT from ß-TT. The degree of anisocytosis in patients with ß-TT and δß-TT is strongly correlated with HbF.

Accelerated renal disease is associated with the development of metabolic syndrome in a glucolipotoxic mouse model.

Individuals with metabolic syndrome are at high risk of developing chronic kidney disease (CKD) through unclear pathogenic mechanisms. Obesity and diabetes are known to induce glucolipotoxic effects in metabolically relevant organs. However, the pathogenic role of glucolipotoxicity in the aetiology of diabetic nephropathy is debated. We generated a murine model, the POKO mouse, obtained by crossing the peroxisome proliferator-activated receptor gamma 2 (PPARγ2) knockout (KO) mouse into a genetically obese ob/ob background. We have previously shown that the POKO mice showed: hyperphagia, insulin resistance, hyperglycaemia and dyslipidaemia as early as 4 weeks of age, and developed a complete loss of normal ß-cell function by 16 weeks of age. Metabolic phenotyping of the POKO model has led to investigation of the structural and functional changes in the kidney and changes in blood pressure in these mice. Here we demonstrate that the POKO mouse is a model of renal disease that is accelerated by high levels of glucose and lipid accumulation. Similar to ob/ob mice, at 4 weeks of age these animals exhibited an increased urinary albumin:creatinine ratio and significantly increased blood pressure, but in contrast showed a significant increase in the renal hypertrophy index and an associated increase in p27(Kip1) expression compared with their obese littermates. Moreover, at 4 weeks of age POKO mice showed insulin resistance, an alteration of lipid metabolism and glomeruli damage associated with increased transforming growth factor beta (TGFß) and parathyroid hormone-related protein (PTHrP) expression. At this age, levels of proinflammatory molecules, such as monocyte chemoattractant protein-1 (MCP-1), and fibrotic factors were also increased at the glomerular level compared with levels in ob/ob mice. At 12 weeks of age, renal damage was fully established. These data suggest an accelerated lesion through glucolipotoxic effects in the renal pathogenesis in POKO mice.

Biological variability of thyroid autoantibodies (anti-TPO and anti-Tg) in clinically and biochemically stable patients with autoimmune thyroid disease.

The biological variation of anti-TPO and anti-Tg autoantibodies was studied in 17 clinically and biochemically stable female patients with autoimmune thyroid disease (AITD), at regular monthly intervals over a period of 6 consecutive months. The mean and standard deviation (SD), within-subject coefficient of variation (CV), between-subject CV, index of individuality, reliability coefficient, and critical differences were as follows: for anti-TPO 238 (197) U/ml, 9.2%, 81.4%, 0.11, 0.96, and 27.6%; and for anti-Tg 1,785 (3,170) U/ml, 6.9%, 174%, 0.04, 0.99, and 22.3%. The data indicate a low within-subject CV, and a high between-subject CV that is particularly pronounced for anti-Tg. The high individuality of both autoantibodies indicates that an isolated result compared to conventional population-based reference intervals is of very little value for diagnosis. Furthermore, the near to 1 reliability coefficient for both autoantibodies correctly classifies the patient with respect to his or her homeostatic mean antibody concentration in a 6-month period of clinical and biochemical stability of thyroid disease. Imprecision goals for anti-TPO and anti-Tg antibodies are attainable with current methodology.