Does in vitro hemolysis affect measurements of plasma apixaban concentration by UPLC-MS and anti-Xa assay?

INTRODUCTION: Hemolytic interference may impact various laboratory tests, including coagulation analyses. Apixaban is the most commonly used direct oral anticoagulant in Norway, and there is lacking knowledge on how apixaban concentration measurements might be influenced by hemolysis. Moreover, hemolysis-induced alterations in apixaban levels could potentially impact the risk of bleeding in specific clinical scenarios. We wanted to study whether hemolysis would increase apixaban concentration and investigate the impact of hemolytic interference on apixaban concentration measurements. METHODS: Blood samples from 20 apixaban-treated patients and 8 healthy controls were hemolyzed in vitro by a freeze method. The degree of hemolysis was measured with plasma free hemoglobin (PfHb) at baseline and two levels of hemolysis. Apixaban concentration was measured in plasma using both the chromogenic anti-Xa method and the ultraperformance liquid chromatography mass spectrometry (UPLC-MS). Thrombin generation assay was performed to assess coagulability. RESULTS: UPLC-MS measurements showed a mean concentration change of -1.66% (±3.2%, p = 0.005) and anti-Xa assay showed a mean concentration change of 3.37% (±6.5%, p = 0.09) with increasing hemolysis. Thrombin generation lagtime decreased, and endogenous thrombin potential and peak thrombin increased with increasing hemolysis in both the control group and the apixaban group. CONCLUSION: Apixaban concentration measurements by anti-Xa assay and UPLC-MS were not affected by hemolysis to a clinically relevant extent. Furthermore, hemolysis did not lead to hypocoagulability when assessed by thrombin generation.

Acute ischemic stroke and measurement of apixaban and rivaroxaban: an observational cohort implementation study.

Background: Treatment with intravenous thrombolysis for acute ischemic stroke is contraindicated with intake of apixaban/rivaroxaban in the last 48 hours. Recent European Stroke Organization guidelines suggest that thrombolysis can be considered if anti-factor Xa activity (AFXa) is <0.5 × 103 IU/L with low-molecular-weight (LMWH) or unfractionated heparin (UFH) calibrated assays. Some centers also use apixaban/rivaroxaban-calibrated AFXa assays to identify patients with low drug concentrations. Objectives: To prospectively evaluate the first year of implementation of drug-calibrated AFXa assays at our center with 2500 yearly admittances with suspected stroke. Methods: Samples were analyzed on Sysmex CS-5100 instruments with Innovance anti-Xa reagents. Thrombolysis could be considered with drug concentrations <25 µg/L. Patients were registered in an institutionally approved quality register. Outcomes included (1) the number of patients receiving thrombolysis after drug measurement, (2) turn-around time for drug concentration measurements, and (3) sensitivity of LMWH/UFH AFXa to apixaban and rivaroxaban. Results: Apixaban or rivaroxaban was measured in 148 samples, and 4 patients who previously would have been ineligible for thrombolysis were treated with thrombolysis. In total, thrombolysis was administered in 123 patient episodes in the study period. The median turn-around time for the drug measurements was 38 minutes. Apixaban concentrations of 25 µg/L and 50 µg/L corresponded to LMWH/UFH AFXa of 0.13 and 0.27 × 103 IU/L, respectively. There were too few rivaroxaban results for regression analysis. Conclusion: Implementation of apixaban and rivaroxaban measurements led to a small increase in the number of patients receiving thrombolysis. Excluding significant concentrations of apixaban or rivaroxaban using LMWH/UFH AFXa may be feasible.

DIAGNOSTIC ACCURACY AND ADDED VALUE OF INFECTION BIOMARKERS IN PATIENTS WITH POSSIBLE SEPSIS IN THE EMERGENCY DEPARTMENT.

ABSTRACT: Background: Biomarkers for early recognition of infection are warranted. The hypothesis of this study was that calprotectin, C-reactive protein (CRP), IL-6 and procalcitonin (PCT), alone or in combination, provide clinically useful information to the clinicians for early identification of infection in patients with possible sepsis in the emergency department (ED). Biomarker dynamics in the first week of hospitalization were explored. Methods: Adult patients in rapid response teams in the ED were included in a prospective observational study (n = 391). Patients who received antibiotics after biomarker availability were excluded. The ED clinician (EDC) decision whether to start antibiotics was registered. Calprotectin, CRP, IL-6, and PCT were analyzed in blood samples drawn within 15 min after ED arrival and in a subgroup for 1 week. Infection likelihood was evaluated post hoc . Results: In identifying patients with infection, CRP (area under the receiver operating characteristic curve [AUC], 0.913) and IL-6 (AUC, 0.895) were superior to calprotectin (AUC, 0.777) and PCT (AUC, 0.838). The best regression model predicting infections included EDC, CRP, and IL-6. Using optimal cutoff values, CRP and IL-6 in combination reached 95% positive and 90% negative predictive values for infection. The EDC undertreated or overtreated 65 of 391 patients (17%), and CRP and IL-6 optimal cutoff values could correct this in 32 of 65 patients (49%). Longitudinal samples revealed that IL-6 peaked in the ED, whereas CRP and PCT peaked later. Conclusion: C-reactive protein and IL-6 were superior to calprotectin and PCT for recognizing infection in patients with possible sepsis in the ED. Combining these two biomarkers with different dynamics improved recognition of infection and could aid clinical management in rapid response teams in the ED.

The diagnostic accuracy of Sysmex XN for identification of pseudothrombocytopenia using various thresholds for definition of platelet aggregation.

INTRODUCTION: The aim of this study was to investigate the diagnostic accuracy of the flag PLT-Clumps from the WNR/WDF and the PLT-F channels from Sysmex XN and to study how different cut-offs for investigation for pseudothrombocytopenia (PTCP) and the definition of platelet aggregation affected the diagnostic accuracy. METHODS: A smear review was performed for samples with platelet count <150 × 109 /L and samples flagged for platelet aggregation by Sysmex XN-20. The samples were investigated for platelet aggregation in 30 fields using 40× objective. Findings were classified by size and quantity using two definitions of aggregation: the Norwegian quality improvement of laboratory investigations (Noklus) and the Groupe Francophone de'Hematologie Cellulaire (GFHC). The Q-values for the PLT-Clumps flag from the WNR/WFD channel and the PLT-F channel were compared with smear findings. RESULTS: ROC analysis showed that the diagnostic accuracy of the PLT-clumps flags increased with increasing stringency of the definition of platelet aggregation and when only samples with thrombocytopenia were investigated. With the most stringent PTCP definitions, the diagnostic accuracy of the PLT-Clumps flag from PLT-F was very high (AUC 0.97-0.98) and markedly better than for WNR/WDF. CONCLUSION: The diagnostic accuracy of PLT-F from Sysmex XN-20 for identification of PTCP was very good and superior to the WNDR/WDF channel in samples with platelet count <150 × 109 /L and a moderate to high number of aggregates in the smear. There is a need for a more precise definition of platelet aggregation.

A national surveillance program for evaluating new reagent lots in medical laboratories.

OBJECTIVES: Differences between laboratory results attributable to the use of different reagent lots can potentially affect the diagnosis and monitoring of patients. To minimize patient risks, all laboratories should verify that new reagent lots meet agreed analytical performance specifications (APS). We propose a simplified, pragmatic approach for laboratories that involves compilating results into a national surveillance program, and present the first results obtained when applying this approach to troponins, glycated hemoglobin (HbA1c), prostate-specific antigen (PSA) and D-dimer. METHODS: In the surveillance program we have (i) determined APS for selected analytes, (ii) implemented a simplified procedure for lot evaluation with patient samples used in laboratories across Norway and (iii) performed central processing of the results from the participating laboratories. RESULTS: Over a one-year period, 27 Norwegian laboratories returned results from 28 lot changes for troponin I, 11 for troponin T, and 29 for HbA1c, PSA and D-dimer. The mean difference between two reagent lots was 4.5% for troponin I (for a concentration interval of 20-32 ng/L), 5.1% for troponin T (10.7-17.5 ng/L), 2.2% for HbA1c (40-50 mmol/mol), 3.7% for PSA (3-5 µg/L) and 5.5% for D-dimer (0.4-1.0 mg/L FEU). CONCLUSIONS: A novel procedure for reagent lot evaluation is proposed in which information about multiple lot changes from different medical laboratories can be accumulated nationally. Sharing this information allows simplification of lot evaluations in individual laboratories and provides real-world data about lot-to-lot variations.

Anticoagulant reversal in intracerebral haemorrhage. / Reversering av antikoagulerende legemidler ved hjerneblødning.

Anticoagulant drugs are effective in preventing and treating blood clots, but they also increase the risk of intracerebral haemorrhage. When intracerebral haemorrhage occurs, rapid reversal of the anticoagulant effect is recommended. However, reversal treatment must be selected on the basis of the anticoagulants' various mechanisms of action, and a specific antidote is preferred where available.

Regional performance variation in external validation of four prediction models for severity of COVID-19 at hospital admission: An observational multi-centre cohort study.

BACKGROUND: Prediction models should be externally validated to assess their performance before implementation. Several prediction models for coronavirus disease-19 (COVID-19) have been published. This observational cohort study aimed to validate published models of severity for hospitalized patients with COVID-19 using clinical and laboratory predictors. METHODS: Prediction models fitting relevant inclusion criteria were chosen for validation. The outcome was either mortality or a composite outcome of mortality and ICU admission (severe disease). 1295 patients admitted with symptoms of COVID-19 at Kings Cross Hospital (KCH) in London, United Kingdom, and 307 patients at Oslo University Hospital (OUH) in Oslo, Norway were included. The performance of the models was assessed in terms of discrimination and calibration. RESULTS: We identified two models for prediction of mortality (referred to as Xie and Zhang1) and two models for prediction of severe disease (Allenbach and Zhang2). The performance of the models was variable. For prediction of mortality Xie had good discrimination at OUH with an area under the receiver-operating characteristic (AUROC) 0.87 [95% confidence interval (CI) 0.79-0.95] and acceptable discrimination at KCH, AUROC 0.79 [0.76-0.82]. In prediction of severe disease, Allenbach had acceptable discrimination (OUH AUROC 0.81 [0.74-0.88] and KCH AUROC 0.72 [0.68-0.75]). The Zhang models had moderate to poor discrimination. Initial calibration was poor for all models but improved with recalibration. CONCLUSIONS: The performance of the four prediction models was variable. The Xie model had the best discrimination for mortality, while the Allenbach model had acceptable results for prediction of severe disease.

Prognostic Value of Nucleated RBCs for Patients With Suspected Sepsis in the Emergency Department: A Single-Center Prospective Cohort Study.

OBJECTIVES: Increase of nucleated RBCs in peripheral blood has been shown to be predictive of mortality in ICU patients. The aim of this study was to explore the prognostic value of nucleated RBCs in the first blood sample taken at admission to the emergency department from patients with suspected sepsis. DESIGN: Single-center prospective cohort study. SETTING: Emergency department. PATIENTS: One-thousand two-hundred thirty-one consecutive adult patients with suspected sepsis were included in a prospective quality register-based cohort study. Inclusion criteria were as follows: patients received in rapid response team with blood cultures taken and immediate antibiotics given in the emergency department. INTERVENTION: Not applicable. MEASUREMENT AND MAIN RESULTS: Nucleated RBCs, Sequential Organ Failure Assessment score, Quick Sequential Organ Failure Assessment, Charlson Comorbidity Index, and commonly used laboratory tests measured in the emergency department were compared with 30-day mortality. Nvaucleated RBC counts were divided into five groups, called "Nucleated RBC score," according to nucleated RBC count levels and analyzed with logistic regression together with the Sequential Organ Failure Assessment score and Charlson Comorbidity Index. Of the 262 patients with nucleated RBCs equal to or higher than the detection limit (0.01 × 109/L), 26% died within 30 days, compared with 12% of the 969 patients with nucleated RBCs below the detection limit (p < 0.0001). Mortality was significantly higher for each increase in Nucleated RBC score, except from score 2 to 3, and was 62% in the highest group. In multivariate logistic regression, odds ratios for 30-day mortality were as follows: Nucleated RBC score: 1.33 (95% CI, 1.13-1.56), Sequential Organ Failure Assessment score: 1.32 (1.29-1.56), and Charlson Comorbidity Index: 1.17 (1.09-1.25). CONCLUSIONS: Most patients with suspected sepsis in emergency department had undetectable nucleated RBCs at admission to the emergency department. However, increased nucleated RBCs significantly predicted 30-day mortality. Nucleated RBCs may provide additional prognostic information to Sequential Organ Failure Assessment score and other laboratory tests.

Evaluation and improvement of the National Early Warning Score (NEWS2) for COVID-19: a multi-hospital study.

BACKGROUND: The National Early Warning Score (NEWS2) is currently recommended in the UK for the risk stratification of COVID-19 patients, but little is known about its ability to detect severe cases. We aimed to evaluate NEWS2 for the prediction of severe COVID-19 outcome and identify and validate a set of blood and physiological parameters routinely collected at hospital admission to improve upon the use of NEWS2 alone for medium-term risk stratification. METHODS: Training cohorts comprised 1276 patients admitted to King's College Hospital National Health Service (NHS) Foundation Trust with COVID-19 disease from 1 March to 30 April 2020. External validation cohorts included 6237 patients from five UK NHS Trusts (Guy's and St Thomas' Hospitals, University Hospitals Southampton, University Hospitals Bristol and Weston NHS Foundation Trust, University College London Hospitals, University Hospitals Birmingham), one hospital in Norway (Oslo University Hospital), and two hospitals in Wuhan, China (Wuhan Sixth Hospital and Taikang Tongji Hospital). The outcome was severe COVID-19 disease (transfer to intensive care unit (ICU) or death) at 14 days after hospital admission. Age, physiological measures, blood biomarkers, sex, ethnicity, and comorbidities (hypertension, diabetes, cardiovascular, respiratory and kidney diseases) measured at hospital admission were considered in the models. RESULTS: A baseline model of 'NEWS2 + age' had poor-to-moderate discrimination for severe COVID-19 infection at 14 days (area under receiver operating characteristic curve (AUC) in training cohort = 0.700, 95% confidence interval (CI) 0.680, 0.722; Brier score = 0.192, 95% CI 0.186, 0.197). A supplemented model adding eight routinely collected blood and physiological parameters (supplemental oxygen flow rate, urea, age, oxygen saturation, C-reactive protein, estimated glomerular filtration rate, neutrophil count, neutrophil/lymphocyte ratio) improved discrimination (AUC = 0.735; 95% CI 0.715, 0.757), and these improvements were replicated across seven UK and non-UK sites. However, there was evidence of miscalibration with the model tending to underestimate risks in most sites. CONCLUSIONS: NEWS2 score had poor-to-moderate discrimination for medium-term COVID-19 outcome which raises questions about its use as a screening tool at hospital admission. Risk stratification was improved by including readily available blood and physiological parameters measured at hospital admission, but there was evidence of miscalibration in external sites. This highlights the need for a better understanding of the use of early warning scores for COVID.

Aggregation of monocytes and platelets interferes in measurement of monocyte viability with phosphatidylserine expression but not with Mitochondrial membrane potential in whole blood.

BACKGROUND: Bacterial lipopolysaccharides (LPS) induce cell death and procoagulant tissue factor (TF) in purified cultured human monocytes. Phosphatidylserine (PS)-expression on the outer membrane of monocytes following cell death contributes to increased procoagulant activity. LPS also induce TF on monocytes in whole blood (WB), but it is unknown whether LPS induce cell death. Activated platelets that aggregate with monocytes in non-EDTA anticoagulated WB also express PS and may potentially interfere in viability measurement on monocytes in WB. METHODS: Viability of monocytes was estimated in purified monocytes and unlysed citrated WB incubated without and with LPS using two markers of early cell death; Lactadherin (PS-exposure) and Mitoprobe™ DilC (Mitochondrial Membrane Potential, MMP), and one late marker Sytox® Blue (membrane impermeant DNA stain). To study the interfering effect of monocyte-platelet aggregates (MPAs) on estimated monocyte viability, addition of EDTA or anti-CD62P was used to inhibit monocyte-platelet binding. RESULTS: In WB, the median percentage of viable monocytes without and with EDTA was 21% and 93% with PS-exposure and 89% and 99% with MMP, respectively. Addition of EDTA reduced the percentage of MPAs (81%-8.2%). Addition of anti-CD62P also reduced the percentage of MPAs (97-42%) and PS-expression on monocytes (MFI 28.9-3.9). LPS induced death of monocytes after 3 h in purified monocytes, but not in WB. CONCLUSIONS: MPAs interfered in monocyte viability measurement in citrated WB with PS-exposure, but not with MMP. LPS induced death of monocytes in purified culture, but not in WB. © 2015 International Clinical Cytometry Society.

Aggregation of monocytes and platelets interferes in measurement of monocyte viability with phosphatidylserine expression but not with mitochondrial membrane potential in whole blood.

Background: Bacterial lipopolysaccharides (LPS) induce cell death and procoagulant tissue factor (TF) in purified cultured human monocytes. Phosphatidylserine (PS)-expression on the outer membrane of monocytes following cell death contributes to increased procoagulant activity. LPS also induce TF on monocytes in whole blood (WB), but it is unknown whether LPS induce cell death. Activated platelets that aggregate with monocytes in non-EDTA anticoagulated WB also express PS and may potentially interfere in viability measurement on monocytes in WB. Methods: Viability of monocytes was estimated in purified monocytes and unlysed citrated WB incubated without and with LPS using two markers of early cell death; Lactadherin (PS-exposure) and Mitoprobe™ DilC (Mitochondrial Membrane Potential, MMP), and one late marker; Sytox® Blue (membrane impermeant DNA stain). To study the interfering effect of monocyte-platelet aggregates (MPAs) on estimated monocyte viability, addition of EDTA or anti-CD62P was used to inhibit monocyte-platelet binding. Results: In WB, the median percentage of viable monocytes without and with EDTA was 21% and 93% with PS-exposure and 89% and 99% with MMP, respectively. Addition of EDTA reduced the percentage of MPAs (81% to 8.2%). Addition of anti-CD62P also reduced the percentage of MPAs (97% to 42%) and PS-expression on monocytes (MFI 28.9 to 3.9). LPS induced death of monocytes after 3 hours in purified monocytes, but not in WB. Conclusions: MPAs interfered in monocyte viability measurement in citrated WB with PS-exposure, but not with MMP. LPS induced death of monocytes in purified culture, but not in WB. © 2014 Clinical Cytometry Society.

Automated alarm to detect antigen excess in serum free immunoglobulin light chain kappa and lambda assays.

BACKGROUND: Antigen excess causing a falsely low concentration result may occur when measuring serum free immunoglobulin light chains (SFLC). Automated antigen excess detection methods are available only with some analyzers. We have now developed and verified such a method. METHODS: Residuals of sera with known SFLC-κ and -λ concentrations were analyzed using Binding Site reagents and methods adapted to the Roche Cobas® c.501 analyzer. RESULTS: We analyzed 117 sera for SFLC-κ and -λ and examined how the absorbance increased with time during the 7 minutes of reaction (absorbance reading points 12-70). From this an antigen excess alarm factor (ratio of absorbance increases between reading points 68-60 and 20-12, multiplied by 100) was defined. Upon our request, Roche added to our two SFLC assays a program which calculated this antigen excess alarm factor and triggered an alarm when the factor was below a defined value. We verified this antigen excess alarm function by analyzing serum from 325 persons of whom 143 were multiple myeloma patients. All samples with a known concentration above 30 mg/L triggered either an antigen excess alarm, an 'above test' alarm or both. Also, all samples above 200 mg/L (SFLC-λ) and 300 mg/L (SFLC-κ) triggered the antigen excess alarm and all but one triggered the above test alarm. CONCLUSIONS: The antigen excess alarm function presented here detected all known antigen excess samples at no increased time of analysis, a reduced workload and reduced reagent cost.

Absolute neutrophil counts from automated hematology instruments are accurate and precise even at very low levels.

Using 106 samples from patients with an absolute neutrophil count (ANC) less than 2.0 × 10(9)/L, two 5-part differential hematology instruments (Sysmex XE-2100, Sysmex, Kobe, Japan, and Advia 2120i, Siemens Healthcare Diagnostics, Deerfield, IL), two 3-part differential hematology instruments (Sysmex K4500, Sysmex, and Advia 60, Siemens Healthcare Diagnostics), and an automated system for examination of microscopic slides (CellaVision DM96, CellaVision, Lund, Sweden) were compared with a flow cytometric (FCM) neutrophil count using monoclonal antibodies for cell classification. The precision and accuracy of the 5-part differential instrument ANC was very good at more than 0.1 × 10(9)/L, although a small systematic difference (10.3%) was found between the 2 instruments. The ANC of the 3-part differential instruments was less reliable, but the WBC count correlated very well with the WBC count from the 5-part differential instruments. Also, the neutrophil count from the CellaVision DM96 compared very well with FCM. When used in the correct laboratory setting, all of the evaluated instruments provide ANCs and WBCs with adequate accuracy and precision.

Is the blood basophil count sufficiently precise, accurate, and specific?: three automated hematology instruments and flow cytometry compared.

We compared the performance of the basophil count of 3 hematology instruments with a flow cytometric method (FCM) in which CD123 and CD193 were used as basophil markers. By analyzing 112 patient samples, we found the ADVIA 120 (Siemens Healthcare Diagnostics, Deerfield, IL) and CELL-DYN Sapphire (Abbott Diagnostics, Santa Clara, CA) to underestimate the number of basophils by approximately 50% and the Sysmex XE-2100 (Sysmex, Kobe, Japan) and ADVIA to overestimate the basophil count in some samples with pathologic leukocytes. All 3 instruments had large (25%-50%) analytic within-run coefficients of variation. Compared with the FCM, we found a relatively good correlation for the CELL-DYN basophil count (r = 0.81), an intermediate correlation for the Sysmex (r = 0.64), and a poor correlation for the ADVIA (r = 0.24). When excluding the 52 samples flagged for the presence of pathologic leukocytes, these correlations were found to be 0.84, 0.90, and 0.57, respectively. The basophil count of the 3 instruments is, at least presently, of unsatisfactory quality.