Post-analytical Errors Research Articles

Method-to-method variability in urine albumin measurements

BackgroundUrine albumin (uALB) is a useful marker in diagnosis and treatment of renal microvascular disease. Beckman Coulter recently re-formulated their uALB reagent for the AU series of instruments to increase the analytical measurement range (AMR). MethodsPrecision, linearity, reportable range, and analytical sensitivity for the reformulated reagent were determined using the AU680. In addition, the re-formulated AU reagent was compared to the previous generation AU reagent and to the Siemens Vista using residual urine specimens. The hook effect was evaluated on five instruments by spiking serum into albumin-free urine to generate a range of albumin concentrations. ResultsPrecision and linearity within the AMR were confirmed, along with accuracy of dilutions to extend the reportable range. For patient sample correlation, the re-formulated reagent demonstrated a positive 11% bias relative to the original AU reagent and a negative 11% bias relative to the Vista. Concentrations of uALB >3000mg/dL produced falsely low results for both AU reagents. The DCA Vantage assay “hooked” at even lower uALB concentrations. ConclusionsThe re-formulated AU uALB reagent met the manufacturer claimed performance characteristics. The AU and DCA Vantage were the only instruments of those tested affected by the hook effect in the concentration range evaluated. uALB assays are clearly not standardized, yet clinical guidelines dictate result interpretation. The method-to-method biases we observed here have the potential to lead to clinically significant post-analytical errors in uALB interpretation.

Laboratory Errors: Types and Frequency in a Tertiary Hospital in Bangladesh

Introduction: In our country, very few of clinical laboratories are running proper quality control program and to the best of our knowledge the preanalytical, analytical, and postanalytical rates of laboratory errors have not been studied extensively. In this study we evaluated the preanalytical, analytical, and postanalytical components of laboratory errors in 3,200 consecutive specimens of a clinical chemistry laboratory in a tertiary hospital for measurement of different analyte concentrations in plasma or serum. Materials and methods: This study was conducted during the period from June 2009 to July 2010 on 3,200 specimens. Analytical errors were detected by repeat analysis of primary sample and by checking quality control. Results: The numbers of preanalytical, analytical and postanalytical errors were 23, 14 and 76 respectively among 32000 tests that we have done on 3,200 specimens (average 10 tests per specimen). Moreover, the causes of errors were analyzed and it was found that preanalytical errors were mostly due to specimen drawn distal to IV infusion, specimen for potassium first drawn into GREY tube (containing sodium fluoride and K EDTA) and then transferred into GREEN tube, long tourniquet time and underfilling of blood collection tube. The analytical errors were due to random and systemic errors and postanalytical errors were due to transcription errors. Conclusion: Results of our study suggest that errors mostly occur in the postanalytical part of testing and they are due to transcription errors. To reduce the laboratory errors we suggest introduction of Laboratory Information System (LIS) of the clinical laboratories connected with Hospital Management System along with stringent quality control program in preanalytical, analytical and postanalytical stages.J Bangladesh Coll Phys Surg 2015; 33(1): 3-6

Review of Postmortem Interval Estimation Using Vitreous Humor: Past, Present, and Future.

For decades, forensic scientists have sought a means of estimating the postmortem interval using laboratory analyses. The best known of these attempts uses a linear regression formula based on the increasing concentration of potassium ions in vitreous humor following death. Like all laboratory analyses, the determination of a potassium concentration is subject to pre-analytical, analytical, and post-analytical errors. Any error is magnified when entered into a regression formula that itself is subject to statistical variation, typically with a 95% confidence interval. Estimating the postmortem interval based solely on the concentration of potassium in vitreous humor proved too simplistic for accurate modeling of the myriad factors that influence postmortem changes. Research continues, using more complicated algorithms involving multivariate ion and chemical analyses and genomic sequencing of the postmortem biome. However refined estimates of the postmortem interval based on laboratory analysis become, sound medical practice will still require the integration of scene findings and information concerning the last time that a given decedent was known to be alive with the results of postmortem examination and laboratory analyses into a medical opinion concerning the postmortem interval.

Laboratory evaluation of thyroid function: Dilemmas and pitfalls

Among all endocrine disorders, thyroid dysfunction is possibly most common endocrine disorder barring obesity. This implies that thyroid function tests (TFT) are routinely ordered for laboratory test for its evaluation. Furthermore, recently laboratory values of thyroid function, thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3), have gathered importance in view of rapidly changing cut-offs for treatment of thyroid disorders during pregnancy. Most of the times, interpretation of TFT is easy, indicating euthyroidism (normal FT4 and TSH), hypothyroidism (low FT4 or FT3 with high TSH), or thyrotoxicosis (high FT4 or FT3 with low TSH). However, the normal ranges reflect two standard deviations around the mean. Hence, 2.5% of the population may show minor abnormalities on both side of normal range in spite of being euthyroid. Sometimes interpretation becomes difficult when there is an alteration in relation between thyroid hormones and TSH. These pitfalls in investigations will cause dilemma in physicians and patients mind alike. Problems in hormonal evaluation can be preanalytical, analytical, and postanalytical. In an ambulatory patient, TFTs have limited preanalytical interferences such as age, pregnancy, medications, genetic mutations, systemic diseases, and critical illnesses. Analytical errors occur due to heterophile antibodies and macro-TSH. Postanalytical errors include wrong entry of the result, mistakes in the units of the parameter checked and failure to identify the normal data.

Der Laborfehler – warum das Labor nicht (immer) schuld ist

More than half of the so called "laboratory errors" has already happened before the analysis starts in the laboratory and many mistakes are made after the analysis itself. Pre- and post-analytical errors cause 60 to 90 % of all unexpected or erroneous values; only 10 to 15 % are caused by analytical problems. Internal quality control and external quality assessments are a matter of course today while standardisation still could be improved. The pre- and post-analytical processes however are only scarcely supervised. Good patient preparation, reliable patient identification and correct blood draws still cannot be taken for granted - improved training and education are necessary. There is also room for improvement in the communication of the results and the implementation of the consequences thereof. Errors in all phases of the analytical process contain valuable clues for optimisations. An improved culture of failure management would allow tapping the full potential of these clues.

Need of Quality Control in Point of Care Glucose Monitoring Devices

Point of care testing is also referred to as near patient, bedside, or extra laboratory testing. It helps in bringing the test immediately to the patient via convenient handheld, portable, or transportable devices. POCT devices facilitate ways to improve the quality and outcomes of care while decreasing cost and length of stay especially for critical care practitioners. One of the oldest applications POCT is for self-monitoring of blood glucose (SMBG) devices They were originally designed for home self-monitoring of blood glucose (SMBG) for diabetic patients to improve glucose control during regular life activities. However, ease of use of a POCGMD and its rapid reporting of BG information led to its utilization in the inpatient setting. POCGMD represents the largest commercial market for POCT. The newer POCT devices have an advanced level of connectivity with laboratory information system (LIS). They electronically capture and transmit results to a central management point (a central data station and/or a clinical or laboratory information system), ensuring that post-analytical errors are minimized. QC is an immediate check on the integrity of the POCT device. There should be regular review of QC and EQA results as part of quality improvement. The global POCT field is in need of whole-blood standards, harmonization among methods, and improved QC. Granting these 3 wishes will facilitate common sense consistency among measurement procedures performed at the point of care and, in our opinion, will ultimately improve diagnoses, treatment decisions, and patient outcomes. EQA is both desirable and required for POCT devices.

Evaluation of analytical errors in a clinical chemistry laboratory: a 3 year experience.

Background:Proficient laboratory service is the cornerstone of modern healthcare systems and has an impact on over 70% of medical decisions on admission, discharge, and medications. In recent years, there is an increasing awareness of the importance of errors in laboratory practice and their possible negative impact on patient outcomes.Aim:We retrospectively analyzed data spanning a period of 3 years on analytical errors observed in our laboratory. The data covered errors over the whole testing cycle including pre-, intra-, and post-analytical phases and discussed strategies pertinent to our settings to minimize their occurrence.Materials and Methods:We described the occurrence of pre-analytical, analytical and post-analytical errors observed at the Komfo Anokye Teaching Hospital clinical biochemistry laboratory during a 3-year period from January, 2010 to December, 2012. Data were analyzed with Graph Pad Prism 5(GraphPad Software Inc. CA USA).Results:A total of 589,510 tests was performed on 188,503 outpatients and hospitalized patients. The overall error rate for the 3 years was 4.7% (27,520/58,950). Pre-analytical, analytical and post-analytical errors contributed 3.7% (2210/58,950), 0.1% (108/58,950), and 0.9% (512/58,950), respectively. The number of tests reduced significantly over the 3-year period, but this did not correspond with a reduction in the overall error rate (P = 0.90) along with the years.Conclusion:Analytical errors are embedded within our total process setup especially pre-analytical and post-analytical phases. Strategic measures including quality assessment programs for staff involved in pre-analytical processes should be intensified.

Method precision and frequent causes of errors observed in point-of-care glucose testing: a proficiency testing program perspective.

Method imprecision, error rates, and explanatory causes that were identified in the Institute for Quality Management in Healthcare point-of-care (POC) glucose proficiency testing (PT) program were assessed in comparison with results obtained from laboratory glucose PT surveys. POC and laboratory glucose PT data were assessed from September 2009 to June 2011. Peer group means and coefficients of variation (CVs) were estimated using the robust algorithm recommended in the International Organization for Standardization/International Electrotechnical Commission 13528(E). Discordant finding investigations were also reviewed to determine the causes of significant and recurring errors. POC glucose CVs were higher than laboratory method CVs (median CV, 4.5% and 1.6%, respectively). While all laboratory glucose results were within the performance limits, 305 (0.59%) of 51,379 POC glucose results exceeded limits. Investigations were required for 277 (0.53%) POC results. Pre- and postanalytical errors accounted for 76% of the discordant findings. Using wrong PT items, sample mix-up on the bench, and reporting results for the wrong sample were the most frequent reasons, while 21% of discordant findings identified manufacturer issues, and 3% were of unknown origin. Both method CVs and error rates were higher in POC than in laboratory glucose methods, even though larger performance limits were used for the assessment of POC glucose.

Colour coding for blood collection tube closures - a call for harmonisation.

At least one in 10 patients experience adverse events while receiving hospital care. Many of the errors are related to laboratory diagnostics. Efforts to reduce laboratory errors over recent decades have primarily focused on the measurement process while pre- and post-analytical errors including errors in sampling, reporting and decision-making have received much less attention. Proper sampling and additives to the samples are essential. Tubes and additives are identified not only in writing on the tubes but also by the colour of the tube closures. Unfortunately these colours have not been standardised, running the risk of error when tubes from one manufacturer are replaced by the tubes from another manufacturer that use different colour coding. EFLM therefore supports the worldwide harmonisation of the colour coding for blood collection tube closures and labels in order to reduce the risk of pre-analytical errors and improve the patient safety.

Clinical Chemistry: Quality in Laboratory Diagnosis

Writteng by James H. Nichols, PhD, DABCC, FACB, and Carol A. Rauch, MD, PhD, FCP; edited by Michael Laposta, MD, PhD, 73 cases. 176 pages. New York, NY: Demos Medical Publishing. $55.00. ISBN: 978-1620700303. Clinical Chemistry: Quality in Laboratory Diagnosis is part of a series named “Diagnostic Standards of Care,” that discusses errors in laboratory test ordering, selection, and interpretation. The book is organized into 8 chapters, each of which discusses errors in particular areas related to clinical chemistry. Each chapter discusses preanalytical, analytical (if relevant), and postanalytical errors. Each error is illustrated with a real-life case …

Point-of-Care Blood Glucose Meter Accuracy in the Hospital Setting.

In BriefPoint-of-care (POC) tests provide analytical information that can be used to make decisions at patients' bedside, as opposed to laboratory tests that must be run at a central laboratory. POC testing is a widely used tool to enable immediate determination of glucose levels in hospitalized patients and facilitate rapid treatment decisions in response to fluctuations in glycemia. Accurate POC glucose testing requires attention to various factors before, during, and after performance of tests. These include 1) proper preparation of test sites to avoid preanalytical errors, 2) proper identification of tested patients whose physiological status permits sampled capillary specimens to correlate with central venous blood glucose levels to avoid analytical errors, and 3) proper documentation of the fidelity of meter results with the medical record to avoid postanalytical errors.

Practice of patient based quality assessment procedure in clinical chemistry unit at diagnostic laboratories in Nepal

Background: The clinical laboratory is the major producer of information used to diagnose, treat, and monitor patients. Errors in laboratory testing may occur at many different points in the total testing process (TTP). Application of quality control plays a vital role in recognizing probable errors. The current dominant technique for error identification uses quality control materials has several inherent drawbacks; otherwise, patient based quality control procedure ensures the detection of pre-analytical errors, analytical, post-analytical errors, clerical errors, and random errors that cannot be detected using commonly used quality control methods, thereby improving the reliability of clinical tests. Objective: Thus the objective of this study was to evaluate the practice of patient based quality control procedure in clinical chemistry unit at diagnostic laboratories in Nepal. Materials and Methods: The questionnaire based study was conducted in clinical chemistry unit of diagnostic laboratories across the country. Questionnaires were personally dropped in 217 clinical biochemistry laboratories and were asked to complete a practice based questionnaire. The responses of 169 laboratories were analyzed using Microsoft Excel 2007 and expressed in terms of percentage. Results: In foremost study undertaken, a total of 169 laboratories responded to the questionnaire. A total 65.9 % of the laboratories monitored errors using patient based quality control procedure but not as a part of quality control. Very few of participant.s laboratories responded accurately regarding utility and practical aspects of patient based quality control included in the checklist. Conclusion: Practice of patient based quality control procedure was not well established to identify possible errors. Hence, the study extent the existing information and explored that the current classical approaches were not adequate to assure accurate patients test results for specific analytes. DOI: http://dx.doi.org/10.3126/stcj.v1i1.7983 Sunsari Technical College Journal Vol.1(1) 2012 9-17

Detection of West Nile virus RNA (lineages 1 and 2) in an external quality assessment programme for laboratories screening blood and blood components for West Nile virus by nucleic acid amplification testing.

A second Italian external quality assessment programme was run in 2011 to assess the performance of blood transfusion centres in detecting West Nile virus RNA in plasma. Each participant received two panels containing negative samples and samples positive for West Nile virus lineages 1 and 2, some of which with a viral concentration close to or below the 95% limit of detection of the respective commercial nucleic acid amplification test assay: the PROCLEIX WNV assay or the Cobas TaqScreen West Nile virus test. Eleven laboratories took part in the external quality assessment programme. All of them correctly identified the positive samples with a viral concentration above the 95% limit of detection. No false positive results or pre-/post-analytical errors were observed. The External quality assessment programme run in 2011 allowed participants to assess the performance of the nucleic acid amplification test methods applied in their seasonal routine screening of blood donations. The results confirm the 95% limit of detection reported by the test kits' manufacturers for both West Nile virus lineages.

An error management system in a veterinary clinical laboratory

Error recording and management is an integral part of a clinical laboratory quality management system. Analysis and review of recorded errors lead to corrective and preventive actions through modification of existing processes and, ultimately, to quality improvement. Laboratory errors can be divided into preanalytical, analytical, and postanalytical errors depending on where in the laboratory cycle the errors occur. The purpose of the current report is to introduce an error management system in use in a veterinary diagnostic laboratory as well as to examine the amount and types of error recorded during the 8-year period from 2003 to 2010. Annual error reports generated during this period by the error recording system were reviewed, and annual error rates were calculated. In addition, errors were divided into preanalytical, analytical, postanalytical, and "other" categories, and their frequency was examined. Data were further compared to that available from human diagnostic laboratories. Finally, sigma metrics were calculated for the various error categories. Annual error rates per total number of samples ranged from 1.3% in 2003 to 0.7% in 2010. Preanalytical errors ranged from 52% to 77%, analytical from 4% to 14%, postanalytical from 9% to 21%, and other error from 6% to 19% of total errors. Sigma metrics ranged from 4.1 to 4.7. All data were comparable to that reported in human clinical laboratories. The incremental annual reduction of error shows that use of an error management system led to quality improvement.

Análisis de resultados del Programa de Control de Calidad Externo SEIMC de carga viral del VIH-1, del VHC y del VHB. Año 2010

Human immunodeficiency virus type 1 (HIV-1) and hepatitis B (HBV) and C virus (HCV) viral load determinations are among the most important markers for the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarized the results obtained in the 2010 External Quality Control Program of the Spanish Society of Infectious Diseases and Clinical Microbiology for HIV-1, HCV, and HBV viral loads and HCV genotyping. In the HIV-1 program, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 3-5 log(10) copies/mL; two of these standards were identical, with the aim of determining repeatability. A significant proportion of the laboratories (22.6% on average) obtained values out of the accepted range (mean ± 0.2 log(10)copies/mL), depending on the standard and on the method used for quantification. Repeatability was very good, with up to 95% of laboratories reporting results within the limits (Δ<0.5 log(10)copies/mL). The HBV and HCV program consisted of two standards with different viral load contents. Most of the participants, 86.1% in the case of HCV and 87.1% in HBV, obtained all the results within the accepted range (mean ± 1.96 SD log(10)UI/mL). Post-analytical errors due to mistranscription of the results were detected in these controls. Data from this analysis reinforce the utility of proficiency programs to ensure the quality of the results obtained by a particular laboratory, as well as the importance of the post-analytical phase in overall quality. Due to interlaboratory variability, use of the same method and the same laboratory for patient follow-up is advisable.

Interlaboratory study to evaluate the performance of laboratories involved in West Nile virus RNA screening of blood and blood components by nucleic acid amplification testing in Italy.

An Italian interlaboratory study was run in 2010 to assess the performance of Blood Transfusion Services in detecting the genome of West Nile virus (WNV) in plasma. Each laboratory received a panel of samples containing four samples negative for WNV and six positive samples with a nominal viral concentration close to or below the 95% detection limit of two commercially available nucleic acid amplification tests (NAT) for WNV, the PROCLEIX® WNV kit and the Cobas® TaqScreen West Nile Virus kit. Ten laboratories took part in the study. All correctly identified the positive samples with a viral concentration above the 95% detection limit. No pre- or post-analytical errors were observed. The interlaboratory study run in 2010 allowed participants to assess the performance of the NAT methods applied in their seasonal routine screening of blood donations.

The point-of-care testing in diabetology

In diabetic patients glucose, haemoglobin A1c, ketones, lipids, and urinary albumin monitoring allows prevention, early detection, and treatment of diabetes-related acute and chronic complications. The point-of-care testing (PoCT) technology offers convenient aspects, as long as pre-analytical, analytical, and post-analytical errors are minimised. The overview summarises the current state-of-the-art of PoCT in diabetes care.

The frequency and potential clinical impact of non-analytical errors in the RCPA Microbiology QAP 1987-2008

Reliable reporting of laboratory results is an important component in the diagnosis and management of infectious diseases. We investigated the frequency of pre- and post-analytical errors by participants in the Royal College of Pathologists of Australasia (RCPA) Microbiology Quality Assurance Program (MQAP). We retrospectively reviewed MQAP data 1987-1991 and 2004-2008. Pre-analytical error rates were based on participants' detection rate of clerical error for patient name and identification number for the given test item. Fictitious errors were defined as the reporting of a labelling error when in fact there was no discrepancy. Post-analytical error rates were based on clear transcription errors resulting in the test result being incorrectly assigned to another test item. When there was one clerical error 10.6% of participants failed to report it. When there were two errors 5.3% failed to report either error and 8.8% only reported one error. Fictitious errors were reported by 1.1% of participants. Pre-analytical errors have not decreased over time. Of the 106 items where direct transposition errors were possible, 73 (69%) had at least one participant who transposed the results. During 2004-2008 transposition of mycobacterial smear and culture results occurred in 18% and 16% of participants, respectively. Pre- and post-analytical errors are not rare amongst participants in the RCPA MQAP. These non-analytical components of the testing pathway require improvement because of their potential to adversely affect patient care.

Análisis de resultados del Programa de Control de Calidad Externo SEIMC de carga viral del VIH-1 y del VHC. Año 2009

Human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) viral load determinations are among the most important markers in the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarizes the results obtained from the SEIMC's External Quality Control Program for HIV-1 and HCV viral loads in 2009. In the HIV-1 program, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 2-5 log(10) copies/mL; two of these standards were identical, aiming to determine repeatability. A significant proportion of the laboratories (21.5% on average) obtained values outside the accepted range (mean ± 0.2 log(10) copies/mL), depending on the standard and on the method used for quantification. Repeatability was very good, with up to 95 % of laboratories reporting results within the accepted limits (Δ<0.5 log10 copies/mL). Post-analytical errors due to mistranscription of the results were detected for HIV-1. The HCV program consisted of two standards with different viral load contents. Most of the participants (79.7%) obtained results within the accepted range (mean ± 1.96 SD log(10) UI/mL). Data from this analysis reinforce the utility of proficiency programs to ensure the quality of the results obtained by a particular laboratory, as well as the importance of the post-analytical phase in overall quality. Due to marked interlaboratory variability, use of the same method and the same laboratory for patient follow-up is advisable.

Point-of-Care Testing in Diabetes Care

Assessing modifiable risk factors for metabolic and cardiovascular diseases prior to the onset of disease could allow effective prevention initiatives. Equally, monitoring in diabetic people glucose, haemoglobin A1c, ketones, lipid profiles, and urinary microalbumin concentrations allows the prevention, early detection, and treatment of diabetes-related acute and chronic complications and has a positive impact on the process of care in the management of patients with diabetes. The point-of-care testing (PoCT) technology offers convenient aspects: immediate results, decision-making without the need for repeated visits, use of fingerstick blood samples. More patients could be identified at early stages of their disease/complication provided that pre-analytical, analytical, and post-analytical errors are minimised. Indeed, prediction requires instruments with proved precision, accuracy, validity, and reliability. Reference laboratory services are now available to manufacturers so to confirm PoCT results. There are several PoC devices on the market that may allow for "real time" screening, diagnosis, and monitoring in diabetes care. Tight glucose control has a key role in long-term health of diabetic people and in the primary prevention of diabetic chronic complications. Diabetic patients are currently educated to control capillary glucose levels daily in order to maintain them within target limits. Blood glucose meters are widely used not only by diabetic patients to self-manage their disease but also by physicians to monitor critically ill patients. Glycated haemoglobin A1c can now be measured with fast and easy automated PoCT instruments to monitor long-term serum glucose regulation. Urinalysis dipsticks and blood betahydroxybutyrate meter allow measuring urine and blood ketones to prevent ketoacidosis. Since the routine measurement of urinary albumin has been suggested in diabetes mellitus as a predictor of overt diabetic nephropathy, semi-quantitative visual dipsticks and quantitative automated methods of urine testing became available for bedside detection of urine albumin at low concentrations and for the determination of the microalbumin creatinine ratio. While the National Cholesterol Education Program recommends that all adults aged 20 years and over have their blood cholesterol checked at least once every 5 years, adult diabetic patients should measure fasting lipid profile at least annually or every two years in case of low-risk lipid values. There are PoCT devices on the market that provide a full lipid panel (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides). The overview summarises current state-of-the-art of PoCT in diabetes care.