Band 52, Heft 7

Background: The circulating levels of plasminogen activator inhibitor type 1 (PAI-1) are increased in individuals carrying the 4G allele at position –675 of the PAI-1 gene. In turn, overexpression of PAI-1 has been found to affect both atheroma and thrombosis. However, the association between PAI-1 levels and the incidence of myocardial infarction (MI) is complicated by the potentially confounding effects of well-known cardiovascular risk factors. The current study tried to investigate in parallel the association of PAI-1 activity with the PAI-1 4G/5G polymorphism, with MI, and some components of metabolic syndrome (MetS). Methods: Using meta-analytical Mendelian randomization approaches, genotype-disease and genotype-phenotype associations were modeled simultaneously. Results: According to an additive model of inheritance and the Mendelian randomization approach, the MI-related odd ratio for individuals carrying the 4G allele was 1.088 with 95% confidence interval (CI) 1.007, 1.175. Moreover, the 4G carriers had, on average, higher PAI-1 activity than 5G carriers by 1.136 units (95% CI 0.738, 1.533). The meta-regression analyses showed that the levels of triglycerides (p=0.005), cholesterol (p=0.037) and PAI-1 (p=0.021) in controls were associated with the MI risk conferred by the 4G carriers. Conclusions: The Mendelian randomization meta-analysis confirmed previous knowledge that the PAI-1 4G allele slightly increases the risk for MI. In addition, it supports the notion that PAI-1 activity and established cardiovascular determinants, such as cholesterol and triglyceride levels, could lie in the etiological pathway from PAI-1 4G allele to the occurrence of MI. Further research is warranted to elucidate these interactions.

Quality indicators (QIs) are fundamental tools for enabling users to quantify the quality of all operational processes by comparing it against a defined criterion. QIs data should be collected over time to identify, correct, and continuously monitor defects and improve performance and patient safety by identifying and implementing effective interventions. According to the international standard for medical laboratories accreditation, the laboratory shall establish and periodically review QIs to monitor and evaluate performance throughout critical aspects of pre-, intra-, and post-analytical processes. However, while some interesting programs on indicators in the total testing process have been developed in some countries, there is no consensus for the production of joint recommendations focusing on the adoption of universal QIs and common terminology in the total testing process. A preliminary agreement has been achieved in a Consensus Conference organized in Padua in 2013, after revising the model of quality indicators (MQI) developed by the Working Group on “Laboratory Errors and Patient Safety” of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). The consensually accepted list of QIs, which takes into consideration both their importance and applicability, should be tested by all potentially interested clinical laboratories to identify further steps in the harmonization project.

Although the perioperative event rate has declined over the past 30 years, as a consequence of the developments in anesthesiology and surgical techniques, perioperative cardiovascular complications are still a significant clinical problem. At the end of the last century, a pooled analysis of several large studies found a 30-day incidence of cardiac events of 2.5% in unselected patients aged >40 years. The identification of myocardial injury after non-cardiac surgery is a problematic and tough challenge, since up to 50% of cardiac deaths actually occur in patients with no history of overt heart disease. Recently, among novel sensitive and specific cardiovascular risk markers, the European Society of Cardiology and European Society of Anesthesiology guidelines for preoperative cardiac risk assessment have recommended that preoperative brain natriuretic peptide (BNP) or N-terminal fragment of proBNP (NT-proBNP) measurement should be considered in high-risk patients undergoing non-cardiac surgery. However, several recent studies and meta-analyses, published in the last 5 years, strongly support the use of both assays of cardiac B-type natriuretic peptides and troponins, for risk stratification in patients undergoing non-cardiac surgery, in order to improve operative and postoperative outcome. Indeed, an increase in specific cardiac biomarkers, as it is the case for natriuretic peptides and troponins, always indicates that the heart is under a stress condition or even actually injured, respectively. In conclusion, the authors suggest that future guidelines on cardiovascular risk evaluation in patients undergoing major surgical procedures should take into account the following evidence.

Background: Between-method equivalence ideally is achieved by calibration against an SI-traceable reference measurement procedure. For measurement of thyroid stimulating hormone (TSH), it is unlikely to accomplish this goal in mid-term. Therefore, we investigated a statistical alternative based on a factor analysis (FA) model. Methods: The FA model was applied to TSH results for 94 samples generated by 14 immunoassays (concentration range: 0.0005–78 mIU/L). The dataset did not fulfill the assumption of a homogeneous sample from an elliptically symmetric distribution, and, therefore, required standardization prior to application of the FA model. As outliers and missing values also occurred, the key quantities of the FA model had to be estimated with a method that can handle these complications. We selected a robust alternating regressions (RAR) method, which replaces in the minimization criterion of the fitting process the squared differences between results x ij and model fit x^ij${\hat x_{ij}}$ by a weighted absolute difference. The weights are adaptively determined in successive regressions, which down weighs the outliers. The weights for missing values are set to zero. Results: The quality of the estimated targets was reflected by their central position in the distributions, and description of the relationship between results and targets by a simple two-parameter regression equation with high correlation coefficients and low SDs of the percentage-residuals. Mathematical recalibration eliminated the method differences and improved the between-method CV from 11% to 6%. Conclusions: RAR applied to a multimethod comparison dataset hampered by outliers and missing values, is fit to the purpose of harmonization.

Background: Six Sigma metrics were used to assess the analytical quality of automated clinical chemistry and immunoassay tests in a large Belgian clinical laboratory and to explore the importance of the source used for estimation of the allowable total error. Clinical laboratories are continually challenged to maintain analytical quality. However, it is difficult to measure assay quality objectively and quantitatively. Methods: The Sigma metric is a single number that estimates quality based on the traditional parameters used in the clinical laboratory: allowable total error (TEa), precision and bias. In this study, Sigma metrics were calculated for 41 clinical chemistry assays for serum and urine on five ARCHITECT c16000 chemistry analyzers. Controls at two analyte concentrations were tested and Sigma metrics were calculated using three different TEa targets (Ricos biological variability, CLIA, and RiliBÄK). Results: Sigma metrics varied with analyte concentration, the TEa target, and between/among analyzers. Sigma values identified those assays that are analytically robust and require minimal quality control rules and those that exhibit more variability and require more complex rules. The analyzer to analyzer variability was assessed on the basis of Sigma metrics. Conclusions: Six Sigma is a more efficient way to control quality, but the lack of TEa targets for many analytes and the sometimes inconsistent TEa targets from different sources are important variables for the interpretation and the application of Sigma metrics in a routine clinical laboratory. Sigma metrics are a valuable means of comparing the analytical quality of two or more analyzers to ensure the comparability of patient test results.

Background: The purpose of this study was to evaluate a combined κ and λ light chain immunofixation (CLIF) as a screening tool to detect monoclonal immunoglobulins in serum and urine. A secondary aim was to investigate the impact on workflow and reagent utilisation of a systematic implementation of CLIF in addition to routine protein electrophoresis (PE) on all samples. Methods: Light chain antisera (κ and λ) were mixed in a 1:1 ratio and loaded in the same sequence as the PE to create a superimposable image. Results: The CLIF procedure agreed significantly better with standard immunofixation procedures in the serum and urine. In 33 (22%) new patients and in 114 (15%) follow-up patients CLIF detected a band missed by PE in serum. In 34 (4.5%) of previously categorised cases the monoclonal band was below the detection limit of CLIF in serum, but still detectable by conventional immunofixation electrophoresis. In one case (0.7%) a band in a urine specimen was missed by CLIF compared to 70 (49%) missed by PE. After the systematic introduction of CLIF turn-around-times (TATs) and utilisation of laboratory consumables decreased significantly (p<0.001). Conclusions: A systematic implementation of CLIF led to the detection of monoclonal bands missed by PE with an improvement in TATs and a decrease in cost.

Background: Screening for anti-nuclear antibodies by indirect immunofluorescence (ANA-IIF) remains mandatory in the serological work-up of connective tissue diseases. Recently, automated approaches were introduced that may improve harmonization. Here, we investigated whether the introduction of automated ANA-IIF and more specifically the use of its quantitative measure, could improve ANA-IIF internal quality control (IQC) management. Methods: We retrospectively reviewed results of two cohorts of routine samples and parallel IQC data collected from January 2010 to February 2013 and from February to mid October 2013. For the first cohort, data were collected using conventional microscopy. The second cohort was analyzed by an automated ANA-IIF microscope (Zenit G sight, A. Menarini). Retrospectively, we evaluated the applicability of the probability index (PI) of control material measurements and patient results for IQC management based on Westgard multirules. This approach was also compared with monthly monitoring of the %ANA-IIF positive samples. Results: In our historical data set, we showed that monitoring of %ANA positives identified systematic errors that were not detected by monitoring control material results. Data resulting from automated microscopy showed that PI measurements on control material remained stable within the observed period and that Westgard multirules can be used for IQC follow-up. Parallel monitoring of the daily median patient PI and the monthly %ANA positives, showed that the daily median was a sensitive and fast tool for detecting systematic errors. Conclusions: The introduction of the automated ANA-IIF microscope could enable objective IQC procedures and should be considered an important step forward in ANA-IIF harmonization.

Background: This study addresses the expression of the glycosylated proteins known as advanced glycation end products (AGEs), the calcium binding protein S100B and the apoptotic parameters cytochome c and caspase-3 activity in peripheral lymphocyte cytosolic extracts from a sample of bipolar disorder (BD) patients and healthy (control) subjects. Methods: Cross-sectional study of 35 patients with a clinical diagnosis of bipolar disease (10 euthymic, 12 depressed, 13 manic) and 10 healthy control subjects. Lymphocytes were used as a surrogate model in BD diagnosis and treatment. AGEs and S100B in lymphocyte cell extracts were measured by commercially available enzyme-linked immunosorbent assay. Results: AGEs were lower in all BD patients compared to healthy subjects. Depressed patients had approximately two-fold higher S100B levels compared to healthy subjects. Manic and depressed BD patients had increased superoxide dismutase mRNA levels. Apoptosis as measured by BAX/Bcl2 ratio, cytochrome c release, caspase-3 activity was increased in manic and depressed patients compared to healthy subjects. In the depressed patients, S100B levels correlated with cytochrome c release. Conclusions: In conclusion, our study shows decreased AGEs and increased S100B levels and caspase down-stream apoptosis in peripheral lymphocytes of BD patients that may underlie disease etiopathogenesis.

Background: The concentrations of glucose and lactate in cerebrospinal fluid (CSF) provide important information about energy metabolism in the CSF compartment. To improve our understanding of this information we introduced a new parameter resulting from a formula for calculating the fictitious production of adenosine triphosphate, i.e., the coefficient of energy balance (KEB). Methods: We evaluated cytology, the concentrations of glucose and lactate and the KEB in the CSF of 948 patients, who were divided into five groups. For statistical analysis we used the Kruskal-Wallis test with post-hoc analysis using the Dunn method and multinomial regression analysis. We determined the specificities and sensitivities of the cytological pictures and the KEB. Results: A KEB>28.0 corresponded to normal energy metabolism in the CSF. A KEB<28.0 corresponded to an increased level of anaerobic metabolism in the CSF during inflammation in the CNS. A KEB<10.0 corresponded to a high level of anaerobic metabolism in the CSF during severe inflammation with an oxidative burst of professional phagocytes in the CNS. The KEB parameter increased the specificities of cytological examinations of the CSF in all cases. Conclusions: The KEB represents an equation for calculating the fictitious average number of ATP molecules produced in the CSF compartment from one molecule of glucose, and we used it successfully as a new parameter for evaluating energy metabolism status in the CSF.

Background: The aim of the study was to investigate the interconversion of the stone chemical composition of two recurrent stone episodes in stone formers. Methods: The data of 1098 stones analyses from 549 patients with a history of two renal stone episodes were selected and reviewed. The stone composition between the two recurrent episodes of stones was compared. Results: The percent occurrences of stones caused by infection, known as infection stones, in new episodes of stones significantly increased by 7% and uric acid stones increased by 3.8% while the calcium oxalate stones decreased by 13.1% (each p<0.05). The mean recurrent interval of new episodes of stones was 34.2 months. Infection stones had a significant shorter interval time compared to calcium oxalate stones (p<0.001). On a patient-by-patient investigation, 32.9% of patients underwent conversions of stone compositions, with 31.9% and 34.1% in men and female, respectively (p=0.590). The mutual conversion of infection stones to calcium oxalate stones was most common. The 61.1% of patients with uric acid recurrent stones were composed of calcium oxalate in the previous episode of stones, and 5% and 51.7% of patients with infection stones developed stones of uric acid or calcium oxalate in the new episode, respectively. Conclusions: Alterations of stone components during follow-up were found in as high as 32.9% of patients with no gender difference. The impetus of these shifts is not readily apparent. Accurate and repeated stone analyses throughout the course of recurrent stone disease are highly warranted, which may be useful to prevent recurrence of composition-specific stones.

Background: Defining common reference intervals (RIs) are encouraging. The aim of this study is to establish RIs for complete blood count (CBC) in a Chinese Han population and probe their age- and sex-related CBC trends. Additionally, we will compare the CBC RIs of Han with those of other races. Methods: In total 1259 Han individuals (584 male and 675 female) were recruited in North China. CBC was processed on Sysmex XE-2100, Coulter LH750 and Mindray BC5800 whose traceability was well verified. The non-parametric 2.5th–97.5th percentiles RIs were calculated. Results: The RIs for CBC parameters did not show apparent analyzer-specificity, apart from mean cellular volume (MCV), mean platelet volume (MPV), plateletcrit (PCT) and platelet distribution width (PDW). Red blood cell (RBC), hemoglobin (HBG), hematocrit (HCT), mean cellular hemoglobin (MCH), and mean cellular hemoglobin concentration (MGHC) are higher in males; and their male mean values tend to drop after 40 years; conversely, the female mean values tend to rise. Platelet (PLT) is higher in females and tends to drop after 40 years in both sexes. White blood cell (WBC) and absolute count of neutrophils (NE) and monocytes (MO) are higher in males, but there is no apparent change with age. Lymphocytes (LY) absolute count declines with age in males, but the same change in females is not obvious. RIs for HBG and HCT are similar among Han, Nordic, US European and US Mexican populations and are lower in US Africans. WBC RIs for Han and US African populations are lower than that for US Europeans and US Mexicans. Conclusions: RIs for major blood cell parameters are not method-dependent; variations obviously exist in age, sex and race. Consequently, common RIs for most CBC parameters appear inapplicable.

Background: This study aimed to investigate the significance of circulating HER2 and MYC gene fragments quantification in the diagnosis of gastric cancer. Methods: Levels of HER2 and MYC genes were evaluated by fluorescence in situ hybridization and real-time PCR in 81 gastric cancer tissues, and by real-time PCR in 36 gastritis tissues. Real-time PCR for HER2 and MYC products was also performed on 184 plasma samples from 81 gastric cancers, eight gastric adenomas, 63 gastritis patients, and 32 healthy individuals. Results: HER2/HBB and MYC/HBB ratios in tissue and cell-free plasma from gastric cancer patients were significantly higher than those of gastritis tissue and cancer-free individuals. An optimized cut-off value of plasma target gene to HBB ratio, used to differentiate cancer patients from cancer-free individuals, was evaluated using receiver operating characteristic (ROC) curves. Values of 2.0 were calculated for HER2 [area under the ROC curve (AUC), 0.760] and 2.725 for MYC (AUC, 0.767). A combination model of HER2 and MYC provided a better differentiation condition than that for HER2 or MYC only (AUC, 0.850). HER2/HBB ratios in plasma from gastric cancer patients correlated with MYC/HBB ratios. Conclusions: Our findings suggest that the measurement of plasma HER2 and MYC gene levels could improve the screening of gastric cancer.

Background: Cardiac troponins (cTnI and cTnT) are the recommended biomarkers of myocardial infarction. As cTn-specific autoantibodies (cTnAAb) can interfere with the cTn detection by state-of-the-art cTnI assays, our objective was to develop a sensitive cTnI immunoassay free from this analytical interference. Methods: The assay used antibody-coated spots containing three capture Mabs/Fabs directed against the N-terminus, midfragment and C-terminus of cTnI and a europium chelate-labeled tracer Mab against the C-terminus. Following a 3-h sample incubation and washing, cTnI was quantified by time-resolved fluorometry. Results: The limit of detection (LoD) was 2.9 ng/L and the assay was linear up to 50,000 ng/L. The total precision of 10% CV was not reached, but 20% CV was reached at 10 ng/L. Mean cTnI (10–50,000 ng/L) recoveries were 100% and 119% in three cTnAAb-positive and two cTnAAb-negative individuals, respectively, verifying the interference resistance of the antibody design used. On average, Architect hs-cTnI assay gave seven-fold higher cTnI concentrations than the new assay but the correlation between the assays was good (r=0.958). Of apparently healthy individuals (n=159), 18% had measurable cTnI values (>LoD) and 10% were cTnAAb-positive. The proportion of measurable cTnI values, however, was significantly higher in cTnAAb-positive individuals (13/16, median cTnI 8.5 ng/L) than in cTnAAb-negative individuals (15/143, median cTnI <LoD) (p<0.001). Conclusions: Although the developed sensitive cTnI assay without cTnAAb interference takes too long for diagnostic purposes, it could serve as an important analytical tool for exploring the impact of cTnAAbs for cTn testing and for unraveling the etiology behind cTn-related autoimmune responses.

Background: Interleukin-6 receptor (IL-6R) gene Asp358Ala (A>C, rs2228145) polymorphism has been associated with lower circulating inflammation biomarkers in coronary artery disease (CAD), such as C-reactive protein (CRP) or fibrinogen, but its role in the pathogenesis of aortic valve stenosis (AS) remains unknown. Since the pathogenesis of AS and atherosclerosis shares several similarities, we tested the hypothesis that IL-6R Asp358Ala polymorphism is associated with the severity of AS. Methods: A total of 284 AS patients aged 64.3±11.1 years were studied, in whom IL-6R polymorphism was determined by TaqMan genotyping. Results: The genotype distribution was as follows: AA-43.7% (n=124); AC-37.0% (n=105); and CC-19.4% (n=55). For every copy of C allele inherited, mean concentration of CRP was reduced by 22% (95% CI 13.8–30.4; p<0.0001). Carriers of the C allele compared to the AA homozygotes were also characterized by lower mean and maximal transvalvular gradients [44.8 (30.5–60.0) vs. 52.7 (40.5–69.0) mmHg, p=0.0005; and 78.1±26.5 vs. 87.3±27.6 mmHg; p=0.008, respectively], and larger aortic valve area [0.8 (0.6–1.0) vs. 0.7 (0.5–0.9) cm 2 , p=0.005]. Conclusions: Our study is the first to show that the presence of the IL-6R 358Ala allele in AS patients is associated with attenuated systemic inflammatory state and less severe AS.

Background: People with hyperglycemia, especially those who are pregnant, depend on accurate blood glucose measurements for correct diagnosis of diabetes and monitoring. Glycolysis after blood draw, however, decreases glucose concentrations in blood that is collected at room temperature in the absence of a stabilizer. Cold temperatures (4°C) inhibit glycolysis; but prompt cooling and processing of each blood sample in the cold is difficult to achieve in routine clinical practice. Therefore, preservatives are used to stabilize glucose during blood collection and processing procedures that are performed at room temperature. This study examined the effect of different anticoagulants (EDTA, heparin, oxalate), with or without glycolysis inhibitors (NaF, citrate), on the stability of glucose in plasma samples – obtained from blood that was collected and stored at room temperature for up to 24 h. Methods: Venous blood was collected from 60 volunteers; each donor blood sample was divided into six tubes, each one containing a different anti-glycolysis–anticoagulant composition. Terumo VENOSAFE ™ Glycemia tubes contained NaF/citrate buffer)/Na 2 EDTA; NaF/Na-heparin; and NaF/K 2 oxalate. Sarstedt tubes contained NaF/citrate; NaF/Na 2 EDTA; and K 2 EDTA. At 0, 2, 8 and 24 h, plasma was obtained for glucose measurements using the Glucose Hexokinase and Glucose Oxidase methods, and the ADVIA ® 1800 Clinical Chemistry System. Results: Both methods demonstrated minimal glycolysis by 24 h (<3.8%) for the three Terumo VENOSAFE ™ Glycemia tubes, and the Sarstedt S-Monovette GlucoEXACT tube that contained NaF/citrate. Glycolysis was higher in tubes containing NaF/Na 2 EDTA-alone (11.7%) and K 2 EDTA-alone (85%). Conclusions: Terumo VENOSAFE ™ Glycemia tubes (containing NaF/citrate buffer/Na 2 EDTA; NaF/Na-heparin; and NaF/K 2 oxalate) and the Sarstedt S-Monovette ® GlucoEXACT tubes (containing NaF/citrate) are suitable for shipping venous whole blood samples to the testing laboratory within 24 h at room temperature.

Background: Previous studies of participants with plasma glucose concentrations at or near the glucose reference range demonstrate glucose loss following delayed separation and extraction of plasma from the cellular components of blood, of ≤7% per hour. We aimed to assess pre-analytical glucose loss in diabetic subjects, focusing on the first hour after sample collection. Methods: Venous blood was collected from diabetes clinic attendees, into a series of lithium heparin PST™ (plasma separator tube) and fluoride oxalate Vacutainers™. Baseline (reference) plasma glucose measurements were undertaken on samples prepared under refrigerated conditions. The remaining samples underwent a series of controlled pre-analytical delays in sample preparation, at room temperature. Plasma glucose was measured using the hexokinase method. Results: Median baseline glucose (mmol/L) for the 62 participants was 10.6 (range 3.4–31.1). Using lithium heparin PST™ tubes, mean glucose loss (95% CI) was 0.16 (0.09–0.23) after 30 min delay in plasma preparation and 0.28 (0.21–0.34) after 60 min delay. Glucose loss was independent of both baseline glucose and also individual cellular count. Fluoride failed to inhibit glucose loss within the first hour after sample collection. Immediate plasma centrifugation of PST™ tubes, followed by delayed plasma extraction (median delay 92 min), produced a mean glucose loss of 0.02 mmol/L (–0.05–0.09). Conclusions: Samples collected into lithium heparin PST™ tubes show pre-analytical glucose loss at 1 h that is independent of baseline glucose and cellular count. Furthermore, immediate plasma separation using these tubes attenuates glucose loss across a wide range of glucose concentrations.

Background: In Denmark, the use of HbA 1c in the diagnosis of diabetes was adopted from March 2012. We evaluated the change in the number of diabetes cases diagnosed by haemoglobin A 1c (HbA 1c ) versus fasting venous plasma glucose (FPG), and estimated the influence of analytical variation and bias on the HbA 1c -based prevalence of diabetes. Methods: The study population constituted 4239 individuals not known to have diabetes randomly selected from all inhabitants aged 25–75 years in the former County of Vejle, Denmark. The number of undiagnosed patients with diabetes in the study population using FPG or HbA 1c as the diagnostic criterion was estimated. Furthermore, changes in the analytical bias and coefficient of variation (CV) for HbA 1c analysis were simulated and the effect on the number of diabetes cases was observed. Results: Changing the diagnostic test from FPG to HbA 1c reduced the number of patients with diabetes by approximately 46% based on one measurement. The predictive value of one test of HbA 1c was 91% versus only 66% for one test of FPG. Analytical variation had a much greater impact on the number of patients with diabetes than bias. At a bias of 0%, an increase of CV analytical from 2.7% to 3.7% increased the number of diabetes cases by 90%. Conclusions: In the study population, the percentage of undiagnosed patients with diabetes aged 25–75 years was reduced from 3.6% (95% CI 3.0%–4.2%) based on one FPG measurement (FPG ≥7.0 mmol/L) to only 1.9% (95% CI 1.5%–2.3%) if the diagnosis of diabetes was based on the criterion of HbA 1c ≥48 mmol/mol (6.5% DCCT).

Background: Point-of-care testing (POCT) of blood glucose (BG) is performed by medical personnel in clinical settings as well as by patients themselves for self-monitoring of blood glucose (SMBG) at home. We investigated if a system mainly intended for SMBG by people with diabetes, but also suitable for BG measurements by medical personnel, can achieve measurement accuracy on capillary blood samples comparable with professional-use POCT systems. Methods: System accuracy was evaluated under standardised conditions, following the ISO standard 15197:2003. For each system (one SMBG system with three test strip lots and six professional-use systems), measurement results from capillary blood samples of 100 subjects were compared with a standardised laboratory glucose oxidase method (YSI 2300 glucose analyser). Results: The seven evaluated systems showed 99.5% or 100% of the measurement results within the required system accuracy limits of ISO 15197:2003 (±0.83 mmol/L at BG concentrations <4.2 mmol/L and ±20% at BG concentrations ≥4.2 mmol/L). Applying the more stringent requirements of the revision ISO 15197:2013, the systems showed between 99% and 100% of the measurement results within the accuracy limits (±0.83 mmol/L at BG concentrations <5.55 mmol/L and ±15% at BG concentrations ≥5.55 mmol/L) and between 82% and 98% when even more restrictive limits were applied (±0.56 mmol/L and ±10%, respectively). Conclusions: Data from this study, which focused on system accuracy, suggest that SMBG systems can achieve system accuracy that is comparable with professional-use systems when measurements are performed on capillary blood samples by trained personnel in a standardised and controlled setting.