Francesca Di Serio

Integration between the Tele-Cardiology Unit and the central laboratory: methodological and clinical evaluation of point- of-care testing cardiac marker in the ambulance

Abstract The aim of this study was to identify patients with myocardial necrosis in pre-hospital phase during transport by ambulance, without ST-segment elevation (NSTE) on the ambulance ECG. The analytical performance of the i-STAT® troponin I (cTnI) method was assessed. A total of 53 NSTE ambulance ECG patients admitted to hospital were followed. The ambulance had experimental software able to receive data from the i-STAT device and transmit it to a protected address and server. cTnI mean values from 2.0 to 34μg/L showed a total CV of 3.0–5.6%. The detection limit was 0.016μg/L. A mean cTnI concentration of 0.09μg/L was associated with a CV of 8.0% (decision limit). The i-STAT cTnI method was linear for concentrations from 0 to 35μg/L. There was no effect (p<0.05) of interfering substances. For point-of-care testing (POCT), cTnI was >0.09μg/L in 20 AMI patients (91%). The median ambulance turnaround time (TAT) was 12min and median hospital TAT was 40min, a difference of 28min. The high sensitivity of the i-STAT cTnI method integrated with tele-medicine procedures could play an important role in the management of acute coronary syndrome patients related to the pre-hospital phase (early diagnosis and treatment in the ambulance). These approaches may allow improvements in patient outcomes and continuous monitoring of the POCT network in the central laboratory, thus meeting quality requirements.

Analytical evaluation of the Dade Behring Dimension RxL automated N-Terminal proBNP (NT-proBNP) method and comparison with the Roche Elecsys 2010.

Abstract Methods to quantify B-type natriuretic peptide (BNP) and N-terminal-propeptide (NT-proBNP) in plasma or serum samples are well established. We assessed the analytical performance of the Dimension RxL NT-proBNP method (Dade-Behring). Evaluation of different sample types was carried out. Controls and heparin plasma pools were used to determine the detection limit, precision, and linearity. Sample stability and the effect of interfering substances on the NT-proBNP concentrations were evaluated. Agreement between Dimension RxL and Elecsys 2010 (Roche Diagnostics) NT-proBNP methods was assessed. The influence of age and sex on NT-proBNP concentrations was evaluated in healthy subjects. Heparin plasma should be the matrix of choice. The detection limit was 2.0ng/L. The total imprecision was 2.6–3.6% for concentrations from 231 to 9471ng/L; mean NT-proBNP concentrations of 21 and 15ng/L were associated with coefficients of variation of 9.9% and 14.7%, respectively. The method was linear up to 32,650ng/L. There was no effect of temperature, freeze-thaw cycles and interfering substances. A bias was detected when Dimension RxL and Elecsys 2010 NT-proBNP methods were compared. Age and sex were significantly and independently related to NT-proBNP concentrations. The Dimension RxL NT-proBNP method, like the Elecsys 2010, is suitable for routine use in the diagnosis of heart failure.

Appropriateness of point-of-care testing (POCT) in an emergency department

BACKGROUND Acute coronary syndrome is a major cause of death, morbidity and access in emergency departments (ED). METHODS We evaluated a point-of-care testing (POCT) for the determinations of cardiac markers in an emergency department (ED), defining the clinical efficiency (management of patient with chest pain) and economic effectiveness (rationalization of preanalytical phase) related to data of Core Lab. RESULTS The results of analytical performances showed a good correlation (cTnI r(2)=0.89, myoglobin r(2)=0.84, CK-MB r(2)=0.9) between POCT and Core Lab and a significant decrease of the turn around time (TAT): difference of medians=-54 min, 95% CI from -48 to -60 min. CONCLUSIONS Our data confirmed that the accurate utilization of POCT in the ED assumes an effective triage of patient with chest pain and the improvement of preanalytical phase out of the laboratory (delivery of specimens) and within the laboratory reception, centrifugation. However, efficiency must be linked to methodological and quality control of the Core Lab, mainly through connectivity.

Evaluation of a New ELISA Assay for Detection of BP230 Autoantibodies in Bullous Pemphigoid

The diagnosis of bullous pemphigoid is based on clinical observations and on the presence of autoantibodies directed against proteins of the dermoepidermal junction. Human recombinant BP180 and BP230 peptides have been used to develop new quantitative enzyme immunoassays (EIA) for the detection of specific antibodies. This study evaluated the sensitivity and specificity of a new immunoassay for the detection of BP230 autoantibodies and clinical correlations. Serum samples were tested from patients with bullous pemphigoid, other skin diseases, and from healthy donors. Autoantibodies anti‐BP230 and anti‐BP180 were assayed using the EIA method. Diagnostic specificity for both tests was over 98%; diagnostic sensitivity was 90% and 60% for anti‐BP180 and anti‐BP230, respectively. IgG anti‐BP180 titers exhibited a significant correlation with disease activity. No patient in remission was positive for anti‐BP230. In conclusion, anti‐BP180 and anti‐BP230 assays are useful in the diagnosis of bullous pemphigoid and provide information on disease activity.

Integration between point-of-care cardiac markers in an emergency/cardiology department and the central laboratory: methodological and preliminary clinical evaluation

Abstract To achieve rapid assessment of chest pain in emergency/cardiology departments, a short turnaround time for cardiac marker testing is necessary. Nevertheless, Total Quality Management principles must be incorporated into the management of point-of-care testing (POCT); in this setting we implemented the Stratus CS ® assay as POCT for cardiac markers in our emergency/cardiology department. The analytical performance of the troponin I method was evaluated; information connectivity between the Stratus CS ® data management system and the laboratory information system was implemented and practical training of testing personnel was carried out at the POCT site. A total of 41 non-ST-segment elevation patients admitted to the hospital were followed to evaluate the appropriateness of hospital admission, formulated on the basis of the cardiac troponin-I level measured at the POCT site by clinical staff. Our preliminary clinical data suggest that the high sensitivity of the Stratus CS ® troponin method could play an important role in the early identification of patients with acute myocardial infarction in a low to intermediate-risk population for acute coronary syndrome. Our POCT model suggests that the central laboratory could ensure that the POCT program remains in compliance with quality requirements. Nevertheless, our comparison studies suggest that the implementation of POCT requires a high level of integration between cardiologists and pathologists to guarantee appropriate interpretation of the monitoring results for suspected ACS patients.

Clinical impact of the troponin 99th percentile cut-off and clinical utility of myoglobin measurement in the early management of chest pain patients admitted to the Emergency Cardiology Department.

ObjectiveTo verify the clinical impact of different low cut-offs for troponin I/cardiac troponin I (99th percentile to 10% CV) and for myoglobin, in early risk stratification of patients with suspected acute coronary syndrome. MethodsA total of 516 consecutive non-ST-elevation patients admitted to hospital were followed. The first measurement of cardiac markers was performed at the point-of-care in the Emergency Cardiology Department, using Stratus CS. The lowest cardiac troponin I concentration with a CV≤10% (cardiac troponin I concentration=0.07 μg/l) was used to perform an early diagnosis of cardiac damage and to admit non-ST-elevation patients to the Intensive Cardiac Unit. Final diagnosis of acute myocardial infarction was assessed according to European Society of Cardiology and American College of Cardiology diagnostic criteria: cardiac marker follow-up after hospital admission was performed in central laboratory. We retrospectively assessed how the diagnostic accuracy of an early diagnosis of myocardiac damage in the same population might have changed if different lower cardiac troponin I cut-offs had been used upon admitting patients in the Emergency Cardiology Department, independently from the analytical imprecision of the method. ResultsA diagnosis of acute myocardial infarction was performed on 110 (21.3%) of 516 non-ST-elevation-patients admitted to hospital. Seventy (13.6%) patients had cardiac troponin I >0.07 μg/l in the Emergency Cardiology Department (P>0.05). Using lowering cut-off values, the difference between the fraction of patients that was positive compared with the diagnosis according to European Society of Cardiology and American College of Cardiology criteria and had remained statistically significant (P<0.05) up to 0.03 μg/l (99th percentile upper reference limit) was considered (85 patients, 16.5%, n.s.). Relative operating characteristic analysis confirmed that the best clinical cut-off was related to the cardiac troponin I concentration that meets the 99th percentile upper reference limit. The diagnostic accuracy of myoglobin in detecting the minimum cardiac damage was significantly lower, independently from the cut-offs considered. ConclusionThe diagnostic accuracy in detecting myocardial damage early in the Emergency Cardiology Department improves when the 99th percentile is used as a decisional value of cardiac troponin I; the use of this cut-off makes the measurement of myoglobin unnecessary.

Mesothelin family proteins and diagnosis of mesothelioma: analytical evaluation of an automated immunoassay and preliminary clinical results.

Abstract Background: Studies have suggested that soluble mesothelin-related protein (SMRP) can be used as a serum marker of malignant mesothelioma. Methods: We assessed the analytical performance of the Mesomark (Fujirebio Diagnostic) two-step ELISA on an automated analyser and performed a preliminary clinical evaluation. The precision of the assay and the in vitro effect of interfering substances on SMRP concentrations were investigated. The serum marker was analysed in 109 healthy subjects never exposed to asbestos, 26 healthy subjects exposed to asbestos, 33 patients with asbestosis, 33 with asbestos-related pleural plaques, 10 with non-malignant pleural diseases, 30 with lung cancer and 24 with histological diagnosis of pleural mesothelioma. Results: Using the International Mesothelioma Interest Group classification, there were nine stage IV, two stage III, four stage II and nine stage I patients. SMRP concentrations of 4.75, 11.0 and 14 nmol/mL showed a total imprecision of 3.5%, 3.1% and 3.8%. The detection limit was 0.035 nmol/mL; the mean SMRP concentration of 0.63 nmol/mL was associated with a coefficient of variation of 10%. There was no effect (p>0.05) of interfering substances. Serum samples from patients with established pleural mesothelioma had significantly higher (p<0.05) concentrations of SMRP than control healthy and patient groups. Conclusions: SMRP measured on automated systems could be useful for the diagnosis of mesothelioma in routine clinical practice. Clin Chem Lab Med 2007;45:634–8.

Process and risk analysis to reduce errors in clinical laboratories

Abstract Background: An important point in improving laboratory quality is the definition of some indicators to be monitored as measures of a laboratory trend. The continuous observation of these indicators can help to reduce errors and risk of errors, thus enhancing the laboratory outcome. In addition, the standardization of risk evaluation techniques and the definition of a set of indicators can eventually contribute to a benchmarking process in clinical laboratories. Methods: Five Italian hospital laboratories cooperated in a project in which methodologies for process and risk analysis, usually applied in fields other than healthcare (typically aeronautical and transport industries), were adapted and applied to laboratory medicine. The collaboration of a board of experts played a key role in underlining the limits of the proposed techniques and adapting them to the laboratory situation. A detailed process analysis performed in each center was the starting point, followed by risk analysis to evaluate risks and facilitate benchmarking among the participants. Results and conclusions: The techniques applied allowed the formulation of a list of non-conformities that represented risks of errors. The level of risk related to each was quantified and graphically represented for each laboratory to identify the risk area characteristic for each of the centers involved. Clin Chem Lab Med 2007;45:742–8.

PATHFAST NT-proBNP (N-terminal-pro B type natriuretic peptide): a multicenter evaluation of a new point-of-care assay.

Abstract Background: The biochemical determination of cardiac natriuretic peptides, primarily brain natriuretic peptide (BNP) and the amino-terminal fragment of its pro-hormone proBNP (NT-proBNP), are reliable tools for diagnosing cardiac disease, establishing prognosis and evaluating the effectiveness of treatment. These biomarkers have proven to be of particular value in the management of chronic and acute heart failure patients, and in the outpatient and the emergency setting. Methods: A multicenter evaluation was performed to assess the practicability, and the analytical and clinical performance of a new point-of-care testing (POCT) PATHFAST™ NT-proBNP assay. This is an immunochemiluminescent assay using two polyclonal antibodies in a sandwich test format, and performed with a PATHFAST™ automated analyzer. Results: The limit of detection (mean+3 SD of the signal of 20 replicates of the zero calibrator obtained in one run) was 0.535 ng/L. An imprecision study, performed in accordance with the CLSI protocol, showed coefficients of variation of 4.0%–6.4% (within-run imprecision), 0.0%–3.4% (between-run imprecision), 5.5%–7.2% (between-day imprecision), 7.6%–8.9% (total imprecision). The method was linear to 28,755 ng/L. Slopes and intercepts ranged from 0.89 to 0.90 and from 10.96 to 22.85, respectively when lithium-heparin plasma samples (n=100) were used to compare the assay under evaluation with the routine laboratory methods (Dimension RxL®, Stratus® CS). When testing matched samples (n=52), a significant difference was found between the 50th percentile NT-proBNP concentration in K2EDTA whole blood, K2EDTA plasma, lithium-heparin plasma and serum. No significant interference was observed for NT-proBNP in lipemic (tryglicerides up to 28.54 mmol/L), icteric (total and conjugated bilirubin up to 513 and 13 μmol/L, respectively) or hemolyzed (hemoglobin up to 13.50 g/L) samples. The NT-proBNP concentration in a group of 180 healthy donors was significantly influenced by age and gender. In a selected population of patients (n=56) with acute dyspnea admitted to the emergency department, a marked reduction in cardiac natriuretic peptide concentrations was observed in hospitalized patients suffering from heart failure who had a better prognosis compared with those with a poorer prognosis (NT-proBNP mean Δ change, % from –22 to –71 vs. +9 to –11). Conclusions: The satisfactory analytical and clinical performance of the PATHFAST™ NT-proBNP assay, together with its excellent practicability, suggests that it would be a reliable tool in clinical practice, in the emergency setting for point-of-care testing, as well as in the central laboratory. Clin Chem Lab Med 2010;48:1029–34.

Laboratory testing during critical care transport: point-of-care testing in air ambulances

Abstract Air and ground transport are used for prehospital transport of patients in acute life-threatening situations, and increasingly, critically ill patients undergo interhospital transportation. Results from clinical studies suggest that critical tests performed during the transport of critically ill patients presents a potential opportunity to improve patient care. Our project was to identify, according to the recommendations published at this time, a model of point-of-care testing (POCT) (arterial blood gases analysis and glucose, sodium, potassium, ionized calcium, hematocrit/hemoglobin measurements) in air ambulances. In order to identify the key internal and external factors that are important to achieving our objective, an analysis of the Strengths, Weaknesses, Opportunities, and Threats (SWOT analysis) was incorporated into our planning model prior to starting the project. To allow the entire POCT process (pre-, intra-, and post-analytic steps) to be under the control of the reference laboratory, an experimental model of information technology was applied. Real-time results during transport of critically ill patients must be considered to be an integral part of the patient care process and excellent channels of communication are needed between the intensive care units, emergency medical services and laboratories. With technological and computer advances, POCT during critical care transport will certainly increase in the future: this will be a challenge from a laboratory and clinical context. Clin Chem Lab Med 2010;48:955–61.