Biological Variation of Cardiac Troponins in Health and Disease: A Systematic Review and Meta-analysis.

Background: Many studies have assessed the biological variation (BV) of cardiac-specific troponins (cTn), reporting widely varying within-subject BV (CVI) estimates. The aim of this study was to provide meta-analysis-derived BV estimates for troponin I (cTnI) and troponin T (cTnT) for different sampling intervals and states of health.

Methods: Relevant studies were identified by a systematic literature search.

Critical appraisal and meta-analysis of biological variation estimates for kidney related analytes.

Objectives: Kidney markers are some of the most frequently used laboratory tests in patient care, and correct clinical decision making depends upon knowledge and correct application of biological variation (BV) data. The aim of this study was to review available BV data and to provide updated BV estimates for the following kidney markers in serum and plasma; albumin, creatinine, cystatin C, chloride, potassium, sodium and urea.

Content: Relevant studies were identified from a historical BV database as well as by systematic literature searches.

European Biological Variation Study (EuBIVAS): within- and between-subject biological variation estimates for serum biointact parathyroid hormone based on weekly samplings from 91 healthy participants.

Background: The European Biological Variation Study (EuBIVAS) was created by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group on Biological Variation to establish high-quality biological variation (BV) estimates for clinically important measurands. In this study, the aim was to deliver reliable BV estimates for the biointact parathyroid hormone (PTH 1-84).

Methods: Serum samples were obtained from a population of 91 healthy individuals (38 men, 43 pre-menopausal women, and 10 post-menopausal women; 21-69 years) from 5 European countries, with all samples stored at -80 °C prior to analysis.

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 (SEQC) 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.

Systematic review and meta-analysis of within-subject and between-subject biological variation estimates of 20 haematological parameters.

Background Interpretation of the complete blood count (CBC) parameters requires reliable biological variation (BV) data. The aims of this study were to appraise the quality of publications reporting BV data for CBC parameters by applying the BV Data Critical Appraisal Checklist (BIVAC) and to deliver global BV estimates based on BIVAC compliant studies. Methods Relevant publications were identified by a systematic literature search and evaluated for their compliance with the 14 BIVAC criteria, scored as A, B, C or D, indicating decreasing compliance.

Biological variation data for lipid cardiovascular risk assessment biomarkers. A systematic review applying the biological variation data critical appraisal checklist (BIVAC).

Background: Biological variation (BV) data can be used to set analytical performance specifications (APS) for lipid assays. Poor performance will impact upon the efficacy of international guidelines for cardiovascular risk assessment (CVR) and relevant clinical decision limits. This systematic review applies the Biological Variation Data Critical Appraisal Checklist (BIVAC) to published studies of BV of CVR biomarkers enabling metanalysis of the data.

Standardization in laboratory medicine: Two years' experience from category 1 EQA programs in Spain.

Introduction: Standardization is the ability to obtain interchangeable results leading to same medical interpretation. External quality assessment (EQA) is the main support of the on-going harmonization initiatives. Aim of study was to evaluate results obtained from two years category 1 EQA program experience in Spain and determine the impact of applying this type of EQA program on the analytical standardization.

The Biological Variation Data Critical Appraisal Checklist: A Standard for Evaluating Studies on Biological Variation.

Background: Concern has been raised about the quality of available biological variation (BV) estimates and the effect of their application in clinical practice. A European Federation of Clinical Chemistry and Laboratory Medicine Task and Finish Group has addressed this issue. The aim of this report is to () describe the Biological Variation Data Critical Appraisal Checklist (BIVAC), which verifies whether publications have included all essential elements that may impact the veracity of associated BV estimates, () use the BIVAC to critically appraise existing BV publications on enzymes, lipids, kidney, and diabetes-related measurands, and () apply metaanalysis to deliver a global within-subject BV (CV) estimate for alanine aminotransferase (ALT).

Reaching consensus on communication of critical laboratory results using a collective intelligence method.

Background: There is no consensus in the literature about what analytes or values should be informed as critical results and how they should be communicated. The main aim of this project is to establish consensual standards of critical results for the laboratories participating in the study. Among the project's secondary objectives, establishing consensual procedures for communication can be highlighted.

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.

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.

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.

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.

Harmonization in hemolysis detection and prevention. A working group of the Catalonian Health Institute (ICS) experience.

Background: Hemolysis is the main cause of non-quality samples in clinical laboratories, producing the highest percentage of rejections in the external assurance programs of preanalytical quality. The objective was to: 1) study the agreement between the detection methods and quantification of hemolysis; 2) establish comparable hemolysis interference limits for a series of tests and analytical methods; and 3) study the preanalytical variables which most influence hemolysis production.

Methods: Different hemoglobin concentration standards were prepared using the reference method.

Indicators and quality specifications for strategic and support processes related to the clinical laboratory: four years' experience.

Background: Quality specifications for indicators of the key analytic processes have been defined by international consensus. However, only preliminary specifications for laboratory-related strategic and support processes have been developed. The present study attempts to increase the robustness of the preliminary proposed specifications.

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.

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.