Interpretation of EQA results and EQA-based trouble shooting

Important objectives of External Quality Assessment (EQA) is to detect analytical errors and make corrective actions. The aim of this paper is to describe knowledge required to interpret EQA results and present a structured approach on how to handle deviating EQA results. The value of EQA and how the EQA result should be interpreted depends on five key points: the control material, the target value, the number of replicates, the acceptance limits and between lot variations in reagents used in measurement procedures. This will also affect the process of finding the sources of errors when they appear. The ideal EQA sample has two important properties: it behaves as a native patient sample in all methods (is commutable) and has a target value established with a reference method. If either of these two criteria is not entirely fulfilled, results not related to the performance of the laboratory may arise. To help and guide the laboratories in handling a deviating EQA result, the Norwegian Clinical Chemistry EQA Program (NKK) has developed a flowchart with additional comments that could be used by the laboratories e.g. in their quality system, to document action against deviations in EQA. This EQA-based trouble-shooting tool has been developed further in cooperation with the External quality Control for Assays and Tests (ECAT) Foundation. This flowchart will become available in a public domain, i.e. the website of the European organisation for External Quality Assurance Providers in Laboratory Medicine (EQALM)

Handling of hemolyzed serum samples in clinical chemistry laboratories: The Nordic hemolysis project

Under embargo until: 2020-07-09Hemolysis of blood samples is a pre-analytical challenge that often leads to sample rejection in medical laboratories [1]. Hemolysis occurs when blood cells break down and the intracellular contents leak into the surrounding fluid [2]. When hemolyzed blood samples are analyzed in medical laboratories, the content released from the blood cells can interfere with the measurement procedure, leading to erroneous results that may not reflect the patient’s clinical condition. How, and to what extent, hemolysis may affect test results depends on the analyte and the measurement method used [1]. Interference studies are performed to establish how much the various analytes, when measured by different methods, will be affected by hemolysis [3]. Based on the results, instrument-specific cut-off points are determined to prevent hemolysis from significantly affecting the clinical interpretation of laboratory results. Most instruments used in medical laboratories today can measure cell-free hemoglobin (Hb) in individual blood samples and transfer the result to the laboratory information system (LIS). These Hb results may be combined with predefined Hb cut-off points, enabling the laboratories to automatically reject or comment upon test results significantly affected by hemolysis [4]. Cut-off points for rejection of samples are commonly recommended by the manufacturers of in vitro diagnostic (IVD) analytical systems. The Clinical and Laboratory Standards Institute (CLSI) recommends that the laboratories verify the intended usefulness, strengths and limitations of manufacturer-derived cut-off points before they are implemented [5]. This is time and resource consuming for the laboratory, and may be difficult as manufacturers’ package inserts often lack information about experiment design and how the cut-off points were defined [6], [7], [8]. Consequently, many laboratories use the manufacturers’ cut-off points for hemolysis, without further verification studies [8]. The Nordic cooperation of External Quality Assurance (EQA) organizers, EQAnord, performed a large interference study in 2002 to obtain data on the effect of hemolysis on analytical performance on different clinical chemistry instruments [9]. The aims of the current study were (1) to obtain updated information about how hemolysis affects clinical chemistry test results on different instrument platforms, and (2) to obtain data on how test results from hemolyzed samples are reported in medical biochemistry hospital laboratories in the Nordic countries.publishedVersio

Pre-analytical practices for routine coagulation tests in European laboratories. A collaborative study from the European Organisation for External Quality Assurance Providers in Laboratory Medicine (EQALM)

Background: Correct handling and storage of blood samples for coagulation tests are important to assure correct diagnosis and monitoring. The aim of this study was to assess the pre-analytical practices for routine coagulation testing in European laboratories. Methods: In 2013–2014, European laboratories were invited to fill in a questionnaire addressing pre-analytical requirements regarding tube fill volume, citrate concentration, sample stability, centrifugation and storage conditions for routine coagulation testing (activated partial thromboplastin time [APTT], prothrombin time in seconds [PT-sec] and as international normalised ratio [PT-INR] and fibrinogen). Results: A total of 662 laboratories from 28 different countries responded. The recommended 3.2% (105–109 mmol/L) citrate tubes are used by 74% of the laboratories. Tube fill volumes ≥90% were required by 73%–76% of the laboratories, depending upon the coagulation test and tube size. The variation in centrifugation force and duration was large (median 2500 g [10- and 90-percentiles 1500 and 4000] and 10 min [5 and 15], respectively). Large variations were also seen in the accepted storage time for different tests and sample materials, for example, for citrated blood at room temperature the accepted storage time ranged from 0.5–72 h and 0.5–189 h for PT-INR and fibrinogen, respectively. If the storage time or the tube fill requirements are not fulfilled, 72% and 84% of the respondents, respectively, would reject the samples. Conclusions: There was a large variation in pre-analytical practices for routine coagulation testing in European laboratories, especially for centrifugation conditions and storage time requirements.publishedVersio

Nursing home patients with diabetes: Prevalence, drug treatment and glycemic control

Aims: Determine prevalence of diabetes, and describe use of blood glucose lowering (BGL) drugs and glycemic control in Norwegian nursing homes. Methods: In this cross-sectional study we collected details of BGL drugs, capillary blood glucose measurements (CBGM) in the last four weeks and HbA1c measurements in the last 12 months from the medical records of patients with diabetes, within a population of 742 long-term care patients from 19 randomly selected nursing homes in Western Norway. Descriptive statistics were applied, and Pearson’s chi-squared (P 0.05) or non-overlapping 95% confidence intervals were interpreted as significant effects. Results: 116 patients (16%) had diabetes, 100 of these gave informed consent and medical data were available. BGL treatment was as follows: (1) insulin only (32%), (2) insulin and oral antidiabetics (OADs) (15%), (3) OADs only (27%) and (4) no drugs (26%). Patients with cognitive impairment were less likely to receive medical treatment (P = 0.04). CBGM and HbA1c measurements were performed for 73% and 77% of patients, respectively. Mean HbA1c was 7.3% (57 mmol/mol), 46% of patients had an HbA1c <7.0% (53 mmol/mol), and CBGM consistent with risk of hypoglycemia was found for 60% of these patients. Conclusions: Prevalence of diabetes and BGL treatment in Norwegian nursing homes is comparable to other European countries. Although special care seems to be taken when choosing treatment for patients with cognitive impairment, there are signs of overtreatment in the population as a whole. The strict glycemic control unveiled may negatively affect these frail patients’ quality of life and increase the risk of early death

Handling of hemolyzed serum samples in clinical chemistry laboratories: The Nordic hemolysis project

Hemolysis of blood samples is a pre-analytical challenge that often leads to sample rejection in medical laboratories [1]. Hemolysis occurs when blood cells break down and the intracellular contents leak into the surrounding fluid [2]. When hemolyzed blood samples are analyzed in medical laboratories, the content released from the blood cells can interfere with the measurement procedure, leading to erroneous results that may not reflect the patient’s clinical condition. How, and to what extent, hemolysis may affect test results depends on the analyte and the measurement method used [1]. Interference studies are performed to establish how much the various analytes, when measured by different methods, will be affected by hemolysis [3]. Based on the results, instrument-specific cut-off points are determined to prevent hemolysis from significantly affecting the clinical interpretation of laboratory results. Most instruments used in medical laboratories today can measure cell-free hemoglobin (Hb) in individual blood samples and transfer the result to the laboratory information system (LIS). These Hb results may be combined with predefined Hb cut-off points, enabling the laboratories to automatically reject or comment upon test results significantly affected by hemolysis [4]. Cut-off points for rejection of samples are commonly recommended by the manufacturers of in vitro diagnostic (IVD) analytical systems. The Clinical and Laboratory Standards Institute (CLSI) recommends that the laboratories verify the intended usefulness, strengths and limitations of manufacturer-derived cut-off points before they are implemented [5]. This is time and resource consuming for the laboratory, and may be difficult as manufacturers’ package inserts often lack information about experiment design and how the cut-off points were defined [6], [7], [8]. Consequently, many laboratories use the manufacturers’ cut-off points for hemolysis, without further verification studies [8]. The Nordic cooperation of External Quality Assurance (EQA) organizers, EQAnord, performed a large interference study in 2002 to obtain data on the effect of hemolysis on analytical performance on different clinical chemistry instruments [9]. The aims of the current study were (1) to obtain updated information about how hemolysis affects clinical chemistry test results on different instrument platforms, and (2) to obtain data on how test results from hemolyzed samples are reported in medical biochemistry hospital laboratories in the Nordic countries