Proteomic analysis of the esophageal epithelium reveals key features of eosinophilic esophagitis pathophysiology.

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic non-IgE-mediated allergic disease of the esophagus. An unbiased proteomics approach was performed to investigate pathophysiological changes in esophageal epithelium. Additionally, an RNAseq-based transcriptomic analysis in paired samples was also carried out. METHODS: Total proteins were purified from esophageal endoscopic biopsies in a cohort of adult EoE patients (n = 25) and healthy esophagus controls (n = 10). Differentially accumulated (DA) proteins in EoE patients compared to control tissues were characterized to identify altered biological processes and signaling pathways. Results were also compared with a quantitative proteome dataset of the human esophageal mucosa. Next, results were contrasted with those obtained after RNAseq analysis in paired samples. Finally, we matched up protein expression with two EoE-specific mRNA panels (EDP and Eso-EoE panel). RESULTS: A total of 1667 proteins were identified, of which 363 were DA in EoE. RNA sequencing in paired samples identified 1993 differentially expressed (DE) genes. Total RNA and protein levels positively correlated, especially in DE mRNA-proteins pairs. Pathway analysis of these proteins in EoE showed alterations in immune and inflammatory responses for the upregulated proteins, and in epithelial differentiation, cornification and keratinization in those downregulated. Interestingly, a set of DA proteins, including eosinophil-related and secreted proteins, were not detected at the mRNA level. Protein expression positively correlated with EDP and Eso-EoE, and corresponded with the most abundant proteins of the human esophageal proteome. CONCLUSIONS: We unraveled for the first time key proteomic features involved in EoE pathogenesis. An integrative analysis of transcriptomic and proteomic datasets provides a deeper insight than transcriptomic alone into understanding complex disease mechanisms.

Differences between childhood- and adulthood-onset eosinophilic esophagitis: An analysis from the EoE connect registry.

BACKGROUND: Direct comparisons of childhood- and adulthood-onset eosinophilic esophagitis (EoE) are scarce. AIM: To compare disease characteristics, endoscopic and histological features, allergic concomitances and therapeutic choices across ages. METHODS: Cross-sectional analysis of the EoE CONNECT registry. RESULTS: The adulthood-onset cohort (those diagnosed at ≥18y) comprised 1044 patients and the childhood-onset cohort (patients diagnosed at <18 y), 254. Vomiting, nausea, chest and abdominal pain, weight loss, slow eating and food aversion were significantly more frequent in children; dysphagia, food bolus impaction and heartburn predominated in adults. A family history of EoE was present in 16% of pediatric and 8.2% of adult patients (p<0.001). Concomitant atopic diseases did not vary across ages. Median±IQR diagnostic delay (years) from symptom onset was higher in adults (2.7 ± 6.1) than in children (1 ± 2.1; p<0.001). Esophageal strictures and rings predominated in adults (p<0.001), who underwent esophageal dilation more commonly (p = 0.011). Inflammatory EoE phenotypes were more common in children (p = 0.001), who also presented higher eosinophil counts in biopsies (p = 0.015) and EREFS scores (p = 0.017). Despite PPI predominating as initial therapy in all cohorts, dietary therapy and swallowed topical corticosteroids were more frequently prescribed in children (p<0.001). CONCLUSIONS: Childhood-onset EoE has differential characteristics compared with adulthood-onset, but similar response to treatment.

Evaluation of a New Monoclonal Chemiluminescent Immunoassay Stool Antigen Test for the Diagnosis of Helicobacter pylori Infection: A Spanish Multicentre Study.

The stool antigen test (SAT) represents an attractive alternative for detection of Helicobacter pylori. The aim of this study was to assess the accuracy of a new SAT, the automated LIAISON® Meridian H. pylori SA based on monoclonal antibodies, compared to the defined gold standard 13C-urea breath test (UBT). This prospective multicentre study (nine Spanish centres) enrolled patients ≥18 years of age with clinical indication to perform UBT for the initial diagnosis and for confirmation of bacterial eradication. Two UBT methods were used: mass spectrometry (MS) including citric acid (CA) or infrared spectrophotometry (IRS) without CA. Overall, 307 patients (145 naïve, 162 with confirmation of eradication) were analysed. Using recommended cut-off values (negative SAT < 0.90, positive ≥ 1.10) the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 67%, 97%, 86%, 92% and 91%, respectively, obtaining an area under the receiver operating characteristic (ROC) curve (AUC) of 0.85. Twenty-eight patients, including seven false positives and 21 false negatives, presented a discordant result between SAT and UBT. Among the 21 false negatives, four of six tested with MS and 11 of 15 tested with IRS presented a borderline UBT delta value. In 25 discordant samples, PCR targeting H. pylori DNA was performed to re-assess positivity and SAT accuracy was re-analysed: sensitivity, specificity, positive predictive value, negative predictive value, accuracy and AUC were 94%, 97%, 86%, 99%, 97% and 0.96, respectively. The new LIAISON® Meridian H. pylori SA SAT showed a good accuracy for diagnosis of H. pylori infection.

Oncología personalizada: principales biomarcadores en el pronóstico y tratamiento de tumores sólidos / Personalised oncology: main biomarkers in the prognosis and treatment of solid tumours

En las últimas décadas ha habido grandes avances en los tratamientos personalizados en pacientes oncológicos gracias a un importante desarrollo científico. El análisis genómico ha mostrado que tumores que parecían tener un origen común, en realidad constituyen un grupo de diversas entidades moleculares. Por otro lado, ha sido muy importante el desarrollo de fármacos dirigidos que actúan de forma específica en las rutas bioquímicas involucradas en el proceso oncológico. El conocimiento de la biología celular y molecular del cáncer ha hecho posible identificar los mecanismos responsables de la transformación maligna y está permitiendo utilizar nuevos marcadores de especial utilidad para definir el pronóstico y determinar el tratamiento de las enfermedades oncológicas

Due to significant scientific developments in the last decades, treatment for oncology patients has started to use more specific and personalised approaches. The genomic analysis has demonstrated that tumours that seemed similar constitute a diverse group of molecular entities. One of the most important breakthroughs is the development of targeted drugs aimed at specific biochemical pathways. Recent advances in knowledge of the cellular and molecular biology of cancer have helped in the identification of the mechanisms of cell malignant transformation, therefore allowing the use of new predictive factors and molecular treatments in cancer

El papel del laboratorio clínico en la medicina personalizada: situación actual y retos futuros / The role of the clinical laboratory in personalised medicine: Present situation and future challenges

La medicina personalizada, medicina de precisión o medicina individualizada ha sido definida como una manera de abordar el tratamiento y la prevención de las enfermedades en base a la variabilidad genética, ambiental y al estilo de vida de cada persona. Clasifica a los individuos en subpoblaciones que difieren en la susceptibilidad a desarrollar una enfermedad determinada o en la respuesta a un tratamiento específico, con el fin de aplicar el seguimiento y tratamiento más adecuado a cada paciente. La implementación de los procesos asociados a la Medicina Personalizada implica que los profesionales de laboratorio se enfrenten a una tecnología muy avanzada y poco conocida y a la dificultad de interpretación de los hallazgos, especialmente la valoración de su significación clínica. En este artículo se revisa la situación actual de la Medicina Personalizada, la función del laboratorio dentro de la misma y los retos que se deben afrontar

Personalised medicine, precision medicine, or individualised medicine has been defined as the way of preventing and treating diseases based on the genetic, environmental, and lifestyle variability for each individual. It classifies subjects into sub-populations that have different susceptibilities to develop a specific disease or to respond to a particular treatment. Its aim is to follow-up and treat each patient in the more suited to the patient. The establishment of the processes related to personalised medicine requires that specialists in Laboratory Medicine cope with cutting-edge, and little-known, technology with an interpretation that is highly complex from a clinical point of view. This review summarises the current situation of personalised medicine, the role of laboratory medicine in its implementation, and the challenges that need to be faced

Capacidad de la procalcitonina para predecir bacteriemia en pacientes con neumonía adquirida en la comunidad / Ability of procalcitonin to predict bacteremia in patients with community acquired pneumonia

Fundamento y objetivo: Analizar la posible utilidad y capacidad de la procalcitonina (PCT) para pronosticar la existencia de bacteriemia en los pacientes con neumonía adquirida en la comunidad (NAC) producida o no porStreptococcus pneumoniae (S. pneumoniae). Pacientes y método: Estudio observacional, prospectivo y descriptivo de pacientes diagnosticados de NAC en un servicio de urgencias (SU). Se recogieron variables sociodemográficas, de comorbilidad, el índice de Charlson, grados del Pneumonia Severity Index y criterios de NAC grave, estudios microbiológicos y determinaciones analíticas y de los biomarcadores (PCT y proteína C reactiva). Se realizó seguimiento durante 30 días. Se calculó el poder pronóstico y el rendimiento diagnóstico de bacteriemia originada o no por S. pneumoniae. Resultados: Se incluyeron 474 pacientes. Los hemocultivos fueron positivos en 85 casos (17,9%), 75 de ellos con aislamiento de S. pneumoniae (88,4%) (en 5 junto con otro patógeno). Para la predicción de bacteriemia (causada o no por S. pneumoniae) la PCT obtiene un área bajo la curva Receiver Operating Characteristic de 0,988 (intervalo de confianza del 95% 0,908-0,995; p < 0,001) y con un punto de corte de PCT ≥ 0,95 ng/ml, un valor predictivo negativo > 98%, con coeficiente de probabilidad positivo > 10. Los serotipos de S. pneumoniae más frecuentes fueron 19A, 7F, 1 y 3. Los valores medios mayores de PCT se encontraron en los serotipos 7F, 19A, 3 y 1, con diferencias significativas con el resto (p = 0,008). Los serotipos con mayor porcentaje de sepsis grave-shockséptico fueron 3, 1 y 19A, los de mortalidad a los 30 días fueron 1, 3 y 19A y los de afectación multilobar o bilateral, los serotipos 3, 19A y 6A. Conclusiones: En los pacientes con NAC en el SU la PCT consigue un gran rendimiento diagnóstico para descartar o sospechar bacteriemia y para orientar la etiología de la NAC por S. pneumoniae. Los serotipos 1, 3, 19A y 7F se presentan con mayor frecuencia, respuesta inflamatoria sistémica y gravedad clínica (AU)

Background and objective: To analyze the usefulness and ability of procalcitonin (PCT) to predict the presence of bacteremia in patients with community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae (S. pneumoniae) or other bacteria. Patients and method: This is an observational, prospective and descriptive study involving patients who were diagnosed with CAP in our Emergency Department. Data collected included socio-demographic and comorbidity variables, Charlson index, stage in the Pneumonia Severity Index and criteria of severe NAC, microbiologic studies and biomarker determinations (PCT and C reactive protein). The follow-up was carried out during 30 days to calculate the predictive power and the diagnostic performance for bacteremia caused or not by S. pneumoniae. Results: Four hundred and seventy-four patients were finally included in the study. Blood cultures were positive in 85 individuals (17.9%) and S. pneumoniae was identified as the responsible pathogen in 75 of them (88.4%) (in 5 cases together with another agent). The area under the Receiver Operating Characteristic curve for PCT to predict bacteremia (caused by S. pneumoniae or not) was 0.988 (95% confidence interval 0.908-0.995;P < .001) and, considering a cut-off value ≥ 0.95 ng/mL, the negative predictive value and the positive likelihood ratio were > 98% and > 10, respectively. The most frequently isolated serotypes of S. pneumoniaewere 19A, 7F, 1 and 3. The highest mean levels of PCT were found in serotypes 7F, 19A, 3 and 1, which showed statistically significant differences with regard to the others serotypes considered (P = .008). Serotypes associated with the highest percentage of severe sepsis-septic shock, 30-days mortality and multi-lobe or bilateral affection were 3, 1 and 19A; 1, 3 and 19A; and 3, 19A and 6A, respectively. Conclusions: PCT had a remarkable diagnostic ability to discard or suspect bacteremia and to guide the etiology of CAP caused by S. pneumoniae. Serotypes 1, 3, 19A and 7F showed greater frequency, systemic inflammatory response and clinical severity (AU)

Poder diagnóstico y pronóstico de los biomarcadores para mejorar el manejo de la neumonía adquirida en la comunidad en los servicios de urgencias / Diagnostic and prognostic power of biomarkers to improve the management of community acquired pneumonia in the emergency department

OBJETIVOS: Analizar la utilidad y la capacidad de los biomarcadores (proteína C reactiva [PCR], región medial de la proadrenomedulina [MR-proADM], procalcitonina [PCT]) y lactato para pronosticar mortalidad a corto y medio plazo comparándolas con las escalas pronósticas de gravedad (EPG) habitualmente utilizadas en la neumonía adquirida en la comunidad (NAC) y para orientar la sospecha etiológica de Streptococcus pneumoniae y bacteriemia. MÉTODOS: Estudio observacional, prospectivo y analítico de pacientes diagnosticados de NAC en un servicio de urgencias (SU). Se recogieron variables sociodemográficas, de comorbilidad, índice de Charlson, nivel de prioridad según el sistema español de triaje (SET), grados del Pneumonia Severity Index (PSI) y CURB-65 (acrónimo de confusión, urea, frecuencia respiratoria, presión arterial y edad ≥ 65 años), criterios de NAC grave, estudios microbiológicos, determinaciones analíticas y de los biomarcadores. Se realizó seguimiento durante 180días para calcular el poder pronóstico de mortalidad y el rendimiento diagnóstico de bacteriemia y etiológico. RESULTADOS: Se incluyeron 127pacientes. La mortalidad a los 30 días fue del 10,3% (13) y a los 180 días de 22,6% (28). Los hemocultivos fueron positivos en 29 casos (23%) y se diagnosticó S.pneumoniae como patógeno causante en 28 (22,2%). El lactato y la MR-proADM consiguen un área bajo la curva ROC (ABC-ROC) para predecir mortalidad a los 30días de 0,898 (IC 95%: 0,824-0,973; p < 0,0001) y de 0,892 (IC95%: 0,811-0,974; p < 0,0001), respectivamente, y la MR-proADM, de 0,921 (IC95%: 0,874-0,968; p < 0,0001) a los 180días. Para la predicción de bacteriemia la PCT obtiene un ABC-ROC de 0,952 (IC95%: 0,898-1; p < 0,0001) y con un punto de corte PCT ≥ 0,95 ng/ml, un valor predictivo negativo (VPN) del 97,8% y coeficiente de probabilidad positivo (CP+) de 9,03. Para predecir etiología por S.pneumoniae una PCT > 0,85 ng/ml obtiene un valor VPN del 96,6% y CP+ de 5,89. CONCLUSIONES: En los pacientes con NAC la MR-proADM y el lactato presentan una capacidad pronóstica de mortalidad intrahospitalaria a los 30días similar o superior al PSI, CURB-65, SET y criterios de NAC grave (p > 0,05), mientras que para la predicción de mortalidad a 180días la MR-proADM es superior a las EPG y al resto de biomarcadores (p < 0,05), y aumenta su ABC al combinarla con el PSI, CURB-65 y SET. Por otro lado, la PCT consigue un gran rendimiento diagnóstico para descartar bacteriemia y orientar la etiología por S.pneumoniae

OBJECTIVES: To analyse the usefulness and performance of several biomarkers [C-reactive protein (CRP), mid-regional pro-adrenomedullin (MR-proADM), procalcitonin (PCT)] and lactate in predicting short- and medium-term mortality compared with the prognostic severity scales (PSS) usually employed for community-acquired pneumonia (CAP) and in assessing the aetiological suspicion of infection by Streptococcus pneumoniae and bacteraemia. METHODS: Observational, prospective and analytical study was conducted on patients who were diagnosed with CAP in our emergency department (ED). The data collected included socio-demographic and comorbidity variables, Charlson index, priority level according to the Spanish Triage System (STS), stage in the Pneumonia Severity Index (PSI) and in the CURB-65 (confusion, urea, respiratory rate, blood pressure and age ≥65years), criteria of severe CAP, microbiological studies, and biomarkers determinations. The patients were followed-up for 180 days to calculate the prognostic power and the diagnostic performance for bacteraemia and aetiology. RESULTS: A total of 127patients were finally enrolled in the study. The 30-day mortality was 10.3% (13), and 22.6% (28) at 180 days. Blood cultures were positive in 29 patients (23%) and S.pneumoniae was identified as the responsible pathogen in 28 cases (22.2%). The area under the ROC curve (AUC-ROC) for lactate and MR-proADM to predict 30-day mortality was 0.898 (95% CI: 0.824-0.973; P < .0001) and 0.892 (95% CI: 0.811-0.974; P < .0001), respectively, and for MR-proADM at 180 days it was 0.921 (95% CI: 0.874-0.968; P < .0001). The AUC-ROC for PCT to predict bacteraemia was 0.952 (95% CI: 0.898-1.000; P < .0001) and, considering a cut-off value ≥0.95ng/ml, the negative predictive value (NPV) and the likelihood ratio (LR+) were 97.8% and 9.03, respectively. Using a PCT cut-off value > 0.85 ng/ml, the NPV and the LR+ were 96.6% and 5.89%, respectively, to predict a S.pneumoniae infection. CONCLUSIONS: MR-proADM and lactate showed a similar or even better performance for 30-day intra-hospital mortality than PSI, CURB-65, STS and CAP severity criteria in patients diagnosed with CAP (P > .05). Furthermore, the MR-proADM capacity to predict 180-day mortality was higher than PSS and the rest of biomarkers (P > .05), and its AUC-ROC increased if it was used in combination with PSI, CURB65 and STS. The determination of PCT has a remarkable diagnostic performance to rule out bacteraemia and to orientate the aetiology towards a S.pneumoniae infection

A multicentre analysis of four low-density lipoprotein cholesterol direct assays in samples with extreme high-density lipoprotein cholesterol concentrations.

BACKGROUND: Although LDL-C has been traditionally estimated using the Friedewald formula (FF), several direct homogeneous assays have been developed to overcome the limitations of this formula and the complicated manual procedure required in the reference method. However, several differences have been reported between these assays in certain situations. METHODS: Two groups of 105 samples with extreme low and high HDL-C concentrations were processed, employing four different instruments and with the reagents for total cholesterol, triglycerides, HDL-C and LDL-C provided by the distinct manufacturers. RESULTS: Statistical tests indicated important differences between HDL-C and LDL-C homogeneous methods. Poor correlation, significant bias and high discrepancy in cardiovascular disease risk classification were observed for LDL-C direct assays in the low HDL-C group, whereas better results were obtained when comparing LDL-C levels estimated with the FF. In contrast, three of the four instruments generated LDL-C direct results with a good agreement in the high HDL-C group, even though an appreciable misclassification percentage in risk categories must be taken into account. CONCLUSIONS: Our results indicate that extreme low or high HDL-C levels can represent a non-previously described source of variation between commercially available LDL-C homogeneous assays.

[Diagnostic and prognostic power of biomarkers to improve the management of community acquired pneumonia in the emergency department]. / Poder diagnóstico y pronóstico de los biomarcadores para mejorar el manejo de la neumonía adquirida en la comunidad en los servicios de urgencias.

OBJECTIVES: To analyse the usefulness and performance of several biomarkers [C-reactive protein (CRP), mid-regional pro-adrenomedullin (MR-proADM), procalcitonin (PCT)] and lactate in predicting short- and medium-term mortality compared with the prognostic severity scales (PSS) usually employed for community-acquired pneumonia (CAP) and in assessing the aetiological suspicion of infection by Streptococcus pneumoniae and bacteraemia. METHODS: Observational, prospective and analytical study was conducted on patients who were diagnosed with CAP in our emergency department (ED). The data collected included socio-demographic and comorbidity variables, Charlson index, priority level according to the Spanish Triage System (STS), stage in the Pneumonia Severity Index (PSI) and in the CURB-65 (confusion, urea, respiratory rate, blood pressure and age ≥65years), criteria of severe CAP, microbiological studies, and biomarkers determinations. The patients were followed-up for 180days to calculate the prognostic power and the diagnostic performance for bacteraemia and aetiology. RESULTS: A total of 127patients were finally enrolled in the study. The 30-day mortality was 10.3% (13), and 22.6% (28) at 180 days. Blood cultures were positive in 29 patients (23%) and S.pneumoniae was identified as the responsible pathogen in 28 cases (22.2%). The area under the ROC curve (AUC-ROC) for lactate and MR-proADM to predict 30-day mortality was 0.898 (95%CI: 0.824-0.973; P<.0001) and 0.892 (95%CI: 0.811-0.974; P<.0001), respectively, and for MR-proADM at 180 days it was 0.921 (95%CI: 0.874-0.968; P<.0001). The AUC-ROC for PCT to predict bacteraemia was 0.952 (95%CI: 0.898-1.000; P<.0001) and, considering a cut-off value ≥0.95ng/ml, the negative predictive value (NPV) and the likelihood ratio (LR+) were 97.8% and 9.03, respectively. Using a PCT cut-off value >0.85ng/ml, the NPV and the LR+ were 96.6% and 5.89%, respectively, to predict a S.pneumoniae infection. CONCLUSIONS: MR-proADM and lactate showed a similar or even better performance for 30-day intra-hospital mortality than PSI, CURB-65, STS and CAP severity criteria in patients diagnosed with CAP (P>.05). Furthermore, the MR-proADM capacity to predict 180-day mortality was higher than PSS and the rest of biomarkers (P>.05), and its AUC-ROC increased if it was used in combination with PSI, CURB65 and STS. The determination of PCT has a remarkable diagnostic performance to rule out bacteraemia and to orientate the aetiology towards a S.pneumoniae infection.

[Ability of procalcitonin to predict bacteremia in patients with community acquired pneumonia]. / Capacidad de la procalcitonina para predecir bacteriemia en pacientes con neumonía adquirida en la comunidad.

BACKGROUND AND OBJECTIVE: To analyze the usefulness and ability of procalcitonin (PCT) to predict the presence of bacteremia in patients with community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae (S. pneumoniae) or other bacteria. PATIENTS AND METHOD: This is an observational, prospective and descriptive study involving patients who were diagnosed with CAP in our Emergency Department. Data collected included socio-demographic and comorbidity variables, Charlson index, stage in the Pneumonia Severity Index and criteria of severe NAC, microbiologic studies and biomarker determinations (PCT and C reactive protein). The follow-up was carried out during 30 days to calculate the predictive power and the diagnostic performance for bacteremia caused or not by S. pneumoniae. RESULTS: Four hundred and seventy-four patients were finally included in the study. Blood cultures were positive in 85 individuals (17.9%) and S. pneumoniae was identified as the responsible pathogen in 75 of them (88.4%) (in 5 cases together with another agent). The area under the Receiver Operating Characteristic curve for PCT to predict bacteremia (caused by S. pneumoniae or not) was 0.988 (95% confidence interval 0.908-0.995; P<.001) and, considering a cut-off value≥0.95ng/mL, the negative predictive value and the positive likelihood ratio were>98% and>10, respectively. The most frequently isolated serotypes of S. pneumoniae were 19A, 7F, 1 and 3. The highest mean levels of PCT were found in serotypes 7F, 19A, 3 and 1, which showed statistically significant differences with regard to the others serotypes considered (P=.008). Serotypes associated with the highest percentage of severe sepsis-septic shock, 30-days mortality and multi-lobe or bilateral affection were 3, 1 and 19A; 1, 3 and 19A; and 3, 19A and 6A, respectively. CONCLUSIONS: PCT had a remarkable diagnostic ability to discard or suspect bacteremia and to guide the etiology of CAP caused by S. pneumoniae. Serotypes 1, 3, 19A and 7F showed greater frequency, systemic inflammatory response and clinical severity.

Biological variation and reference change values of common clinical chemistry and haematologic laboratory analytes in the elderly population.

BACKGROUND: Biological variation (BV) and reference change values (RCVs) have been widely described for the general population, but the use of these data derived from adults in the elderly population is a controversial issue. We determined the within- and between-subject BV and RCV in both elderly and young people and compared them with previously published analyses. METHODS: Samples were collected from 135 volunteers over 80 years of age at weekly intervals over 4 weeks. Eighteen biochemical and eight haematological analytes were measured. The Fraser and Harris methods were used to calculate the components of BV and RCV. To perform a comparative analysis, a reference group of 118 young subjects was studied under the same conditions. RESULTS: The obtained coefficients of BV showed statistical differences in many cases, but in general, both the elderly and young patient data fall within the ranges previously described for the general population. The indexes of individuality for the analytes investigated did not exceed 1.4 in any case and were <0.6 for some analytes. The RCVs derived from elderly subjects were similar to those published in the young population, both in healthy and diseased individuals. CONCLUSIONS: The strong individuality observed supports the preferential use of RCVs rather than population-based reference intervals in elderly people. For most of the analytes studied, data from the young population can be applied to elderly people, but the specific elderly coefficients of BV and RCVs are a recommended option.

A proposed reference change value for an IgA anti-tissue transglutaminase immunoassay to improve interpretation of serial results in celiac patients.

BACKGROUND: Celiac disease (CD) is an autoimmune disorder caused by an inappropriate immunological response to gluten ingestion in genetically susceptible individuals. IgA anti-tissue transglutaminase (tTG) antibodies have been widely employed as a specific biochemical marker for CD. Recent studies have also shown its usefulness in evaluating patient compliance with a gluten-free diet. METHODS: A group of 28 subjects with CD was selected for the study. Each fulfilled the requirement of a gluten-free diet for more than one year. IgA anti-tTG determination was performed every two months for half a year. These data were used to estimate the biological variation (BV) of IgA anti-tTG in celiac patients and to calculate the reference change value (RCV). RESULTS: The within-subject biological variation (CVI) and between-subject biological variation (CV(G)) were 19.2% and 75.6%, respectively, and the index of individuality was 0.25. The RCV calculated using these data together with our analytical imprecision (5.7%) was 55.5% for a 95% level of significance. CONCLUSIONS: We have determined for the first time the BV and the RCV for IgA anti-tTG in a celiac population. This value and the probability curve generated from our data could be a valuable tool for monitoring patients' adherence to dietary treatment.

Importancia de la selección de una especificación de calidad adecuada en la aplicación del modelo Seis-Sigma en el laboratorio clínico / Importance of selecting an appropriate quality specification for the application of Six-Sigma model in the clinical laboratory

Introducción. El modelo Seis-Sigma constituye una herramienta de gestión de calidad basada en la cuantificación de la variabilidad de un proceso en función del ratio de defectos por millón (DPM). Sin embargo, su estimación durante la fase analítica es dependiente del error total admisible (ETa). Nuestro objetivo es demostrar que la selección inadecuada de las especificaciones de calidad puede originar interpretaciones erróneas del rendimiento del laboratorio. Material y métodos. El cálculo del Sigma se realizó mediante la ecuación (ETa - sesgo)/coeficiente de variación. Se emplearon diferentes especificaciones de calidad, basadas en la variabilidad biológica (VB), el consenso de mínimos de SEQC/AEFA/AEBM y las especificaciones legislativas americanas y alemanas. La imprecisión y sesgo propios del laboratorio fueron estimados a partir del control interno/externo. Resultados. Los valores de Sigma obtenidos son inversamente proporcionales a la exigencia de la especificación de calidad escogida en todos los casos. Las especificaciones legislativas o recomendadas por expertos son las que proporcionalmente se correlacionan con Sigmas más elevados. El uso de la VB deseable y óptima se asocia a Sigmas inaceptables en el 44 y 94% de las determinaciones respectivamente. Conclusiones. La selección de especificaciones de calidad poco exigentes por parte del laboratorio supone elevaciones del Sigma, el cual no se asocia en todos los casos con una mejora en la detección de errores clínicamente significativos. Con objeto de evitar falsas elevaciones en informes de rendimiento y evitar comparaciones inter-laboratorio sesgadas, se recomienda informar el valor de Sigma en todo caso junto al ETa empleado en su estimación (AU)

Introduction. The Six-Sigma model is a quality management tool based on the variability of a process in terms of defects per million (DPM). In the analytical phase, sigma value estimation is dependent of the allowable total error (TEa). Our goal is to demonstrate that the improper selection of quality specifications can lead to erroneous interpretations of the laboratory status. Material and methods. The Sigma value was estimated using the equation (TEa - bias)/coefficient of variation. We used different quality specifications based on biological variability (BV), the consensus of the SEQC/AEFA/AEBM, and the American and German legislative specifications. The laboratory imprecision and bias were estimated from the internal/external control quality. Results. Sigma values are inversely proportional to the requirement for quality specification. Specifications based on German and American laws or the consensus of the Spanish experts were proportionally correlated with higher Sigma values. The optimal and desirable BV was associated with high rates of determinations that did not exceed the minimum Sigma requirement. Conclusions. The selection of less demanding quality specifications involves elevations in Sigma values, which is not necessarily associated with an improvement in the detection of clinically significant errors. In order to avoid false elevations in performance reports and errors in the inter-laboratory comparison, we recommend indicating the sigma value and the TEa (AU)

Extreme concentrations of high density lipoprotein cholesterol affect the calculation of low density lipoprotein cholesterol in the Friedewald formula and other proposed formulas.

OBJECTIVES: To investigate the effect of extreme levels of high density lipoprotein cholesterol (HDL-C) in the calculation of low density lipoprotein cholesterol (LDL-C) using Friedewald's formula (FF) and other formulas proposed recently. DESIGN AND METHODS: Lipoprotein profile was performed in 2603 samples with HDL-C ≤ 20 mg/dL and 1953 samples with HDL-C ≥ 100 mg/dL. RESULTS: Wilcoxon's and Student's t-tests showed significant differences (p<0.001) between calculated LDL-C by different formulas and direct determination in the two groups of HDL-C values. Passing-Bablok regression and Bland-Altman plot showed disagreement for the four formulas studied, except for Vujovic formula in the HLD-C ≥ 100 mg/dL group. CONCLUSIONS: Our results suggested that none of the formulas under analysis should be used for estimating LDL-C in samples with extreme HDL-C concentrations due to absence of statistical correlation with LDL-C direct measurement.

Importancia de la sospecha clínica y confirmación de bacteriemia en los servicios de urgencias / Importance of clinical suspicion and confirmation of bacteremia in emergency units

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