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Biomedical subjects

R H Christenson

Publications and source records attributed to R H Christenson.

At least 19 recordsLinked to original sources
PubMed1998

Value of serial troponin T measures for early and late risk stratification in patients with acute coronary syndromes. The GUSTO-IIa Investigators.

BACKGROUND: The baseline cardiac troponin T (cTnT) level strongly predicts short-term mortality in acute coronary syndromes, but the added value of later measures to predict short- and long-term outcome and in the context of baseline clinical characteristics is unclear. METHODS AND RESULTS: Relations between baseline, peak, and 8- and 16-hour (late) cTnT results and outcomes were assessed in 734 patients in a GUSTO-IIa substudy. Proportional-hazards models assessed the prognostic information gained from late cTnT when added to a mortality model containing the baseline cTnT result and clinical factors. At baseline, 260 patients were cTnT-positive (>0.1 ng/mL), 323 became positive later, and 151 remained negative (</=0.1 ng/mL). Mortality at 30 days was 10% in the baseline-positive group, 5% in late-positive patients, and 0% in negative patients. After adjustment for baseline characteristics, any positive cTnT result predicted 30-day mortality (baseline, chi2=8.96, P=0.0113; 8-hour, chi2=6.51, P=0.0107; 16-hour, chi2=8.40, P=0.0038). Both the 8- and the 16-hour results added to the strength of the baseline result (baseline+8-hour, chi2=12.04, P=0.0072; baseline+16-hour, chi2=13.52, P=0.0036). Only age and ST-segment elevation were stronger predictors of 30-day mortality than baseline cTnT; results were similar for prediction of 1-year mortality. Most of the mortality difference between cTnT-positive and -negative patients occurred within the first 30 days. CONCLUSIONS: The cTnT level is a strong, independent predictor of short-term outcome in acute coronary syndromes. The addition of later samples to a baseline level is useful to evaluate the risk of serious cardiac events.

Acute Disease↗
PubMed1998

Production and characterization of monoclonal antibodies to human carbonic anhydrase III.

Carbonic anhydrase III (CAIII) is a cytosolic protein found almost exclusively in slow-oxidative skeletal muscle fibers. Upon excessive skeletal muscle activity or damage, CAIII is rapidly released into serum. CAIII is not found in cardiac muscle, whereas the muscle protein myoglobin (Myo) is found in skeletal and cardiac muscle. Because CAIII and Myo are released from injured muscle in a constant ratio, an increase in the Myo/CAIII ratio may be useful as an early diagnostic indicator of acute myocardial damage. Although several reliable Myo immunoassays have been established, no similar CAIII immunoassay is commercially available. We produced murine monoclonal antibodies (MAbs) to human CAIII using standard immunization and cell fusion procedures. Using an enzyme-linked immunoadsorbent assay (ELISA), three MAbs showed strong immunoreactivity with CAIII, but low to moderate levels of cross-reactivity with closely related isoenzymes CAI and CAII. The three MAbs demonstrated unique patterns of reactivity toward CAI, CAII, and CAIII, suggesting that different CAIII epitopes are recognized by the three MAbs. Specificity was further examined by Western blot analysis. These MAbs demonstrated potential for use in the development of an immunoassay for CAIII, and for investigating the biology of skeletal muscle injury in vivo.

Animals↗
PubMed1998

Abbott AxSYM Vancomycin II assay: multicenter evaluation and interference studies.

The authors evaluated the performance characteristics of the Abbott AxSYM Vancomycin II immunoassay in sera of patients with (n = 93 samples) and without (n = 327 patients) renal dysfunction. Correlation of vancomycin measurements with the Abbott AxSYM Vancomycin, Abbott TDx/TDxFLx, Syva enzyme-multiplied immunoassay technique (EMIT), DuPont automated chemistry analyzer (ACA), and high-performance liquid chromatography methods showed acceptable correlation as indicated by: slope values >0.95, r-values >0.97, y-intercepts <1.7 microg/ml, and S(y/x) ranging from 9% to 15% of the average vancomycin value. The AxSYM Vancomycin II assay showed acceptable correlation with AxSYM vancomycin, TDx/TDxFLx, and high-performance liquid chromatography methods in 93 samples from patients with renal dysfunction. This monoclonal antibody-based assay showed no apparent interference from the presence of human antimouse antibody (HAMA) or the microbiologically inactive vancomycin crystalline degradation product (CDP). The authors conclude that the AxSYM Vancomycin II assay showed satisfactory agreement with other methods tested in this study.

Anti-Bacterial Agents↗
PubMed1998

Cardiac troponin T and cardiac troponin I: relative values in short-term risk stratification of patients with acute coronary syndromes. GUSTO-IIa Investigators.

We compared cardiac troponins T (cTnT) and I (cTnI) collected within 3.5 h of ischemic symptoms for predicting clinical outcomes in 770 patients. cTnT (cutoff > 0.1 microgram/L) and cTnI (cutoff > 1.5 micrograms/L) were concordant (both positive or negative) in 90.4% of patients. Among discordant results, 66 were cTnT positive and cTnI negative vs 8 who showed the reverse (P < 0.001). Five cTnT-positive and cTnI-negative patients died within 30 days; none who were cTnT negative and cTnI positive died. cTnT showed a slightly greater association (chi 2 = 18.0, P < 0.001) with 30-day mortality than cTnI (chi 2 = 12.5, P = 0.002). The area of the ROC curve for predicting 30-day mortality was significantly larger (Z = 2.08; P = 0.0375) for cTnT, at 0.68 [95% confidence interval (CI) 0.60-0.75], compared with cTnI, at 0.64 (95% CI 0.56-0.72). When cTnI and the electrocardiogram (ECG) were put in a logistic multiple regression model, cTnT added significant information (chi 2 = 8.03, P = 0.045); however, cTnI did not add to a model containing cTnT and the ECG (chi 2 = 0.84, P = 0.657). cTnT provided more information than cTnI for predicting 30-day mortality early after presentation with acute coronary syndromes.

Aged↗
PubMed1998

Cardiac troponin I measurement with the ACCESS immunoassay system: analytical and clinical performance characteristics.

We evaluated the ACCESS cardiac troponin I (cTnI) immunoassay as a marker for myocardial infarction (MI). Total imprecision was 6.0% to 13.5%, the minimum detectable concentration was 0.007 microg/L, and the limit of quantitation was 0.046 microg/L. Comparison of cTnI measurement between the ACCESS and Stratus systems (n = 114) showed a proportional difference: ACCESS cTnI = 0.0996 Stratus cTnI + 0.049 microg/L (r = 0.811). Fifty-nine of 61 ambulatory patients without cardiac symptoms had no detectable cTnI (95% range, 0.00 to 0.025 microg/L). The optimum cutoff for discriminating MI (n = 289, 45 with MI) was 0.15 microg/L by receiver operator characteristic curve analysis; at this cutoff, the ACCESS cTnI assay showed a sensitivity of 88.9% (95% CI, 79.7-98.1%) and specificity of 91.8% (95% CI, 88.4-95.2%). The ACCESS cTnI assay results showed 89.4% and 93.0% concordance with the MB isoenzyme of creatine kinase (CK-MB) mass and Stratus cTnI results, respectively, for classification of patients with suspected MI. The ACCESS cTnI assay appears to show sensitivity and specificity comparable with those of both CK-MB mass and Stratus cTnI assays for the diagnosis of MI in patients presenting within 12 h of onset of symptoms.

Adult↗
PubMed1998

Biochemical markers of the acute coronary syndromes.

The acute coronary syndromes represent a continuum of myocardial ischemia ranging from angina, reversible tissue injury --> unstable angina, frequently associated with minor myocardial damage --> myocardial infarction and extensive tissue necrosis. Historically, coronary artery disease assessment has been mainly binary, using WHO criteria of symptoms, electrocardiography, and biochemical markers. The creatine kinase-MB isoenzyme (CK-MB) has been a benchmark for markers, but it is not specific for myocardium. Cardiac-specific isoforms of troponin T and I have emerged as sensitive myocardial infarction (MI) indicators and, importantly, for risk stratification of acute coronary syndrome patients. In addition to markers of myocardial cell necrosis, markers of plaque disruption (C-reactive protein and serum amyloid A), "angry" platelets (P-selectin), ischemia (glycogen phosphorylase-BB isoenzyme), and the procoagulant state and thrombosis (soluble fibrin) have potential use. Also, CK-MB and myoglobin have been combined with clinical indicators for monitoring reperfusion after thrombolytic therapy. Biochemical markers will continue to be an important clinical adjunct for MI diagnosis, risk assessment, and reperfusion monitoring in the future.

Acute Disease↗
PubMed1998

Analytical and clinical performance characteristics of Tandem-MP Ostase, a new immunoassay for serum bone alkaline phosphatase.

The performance characteristics of the Tandem-MP Ostase assay, a new microplate immunoassay for bone-specific alkaline phosphatase (bone ALP; EC 3.1.3.1) in human sera, are described. Bone ALP is bound to streptavidin-coated microwells by a single biotinylated anti-bone ALP monoclonal antibody. Antigen is detected by the addition of p-nitrophenyl phosphate. The assay is performed at room temperature in <90 min. Imprecision was 2.3-6.1% with a detection limit of 0.6 microg/L. Method comparison of bone ALP measurements with the Tandem-MP Ostase assay and the mass-based Tandem-R Ostase assay (n = 285) indicated regression statistics of Tandem-MP Ostase = 1.03 Tandem-R Ostase + 0.22 microg/L, S(y/x) = 4.0 microg/L, r = 0.97. Serum bone ALP values in apparently healthy men and in pre- and postmenopausal women were also similar between the two Ostase assay formats. Liver ALP reactivity determined using the slope and heat inactivation methods was similar in both Ostase assays. Liver ALP reactivity ranged from 3 microg/L (heat inactivation) to 6 microg/L (slope method) per 100 U/L of liver ALP activity, whereas bone ALP reactivity was 37 microg/L per 100 U/L of bone ALP activity, indicating a liver ALP relative reactivity of 8.1-16.2%. Similar results were obtained with the Alkphase-B bone ALP immunoassay. The Tandem-MP Ostase bone ALP assay demonstrated increased concentrations of serum bone ALP in conditions where bone metabolism is increased and showed a rapid, temporal decrease in serum bone ALP in Paget disease patients on bisphosphonate therapy. In conclusion, the Tandem-MP Ostase assay for serum bone ALP is a rapid, simple, robust nonisotopic alternative to the Tandem-R Ostase immunoradiometric assay that provides an accurate and sensitive assessment of bone turnover.

Adolescent↗
PubMed1997

Assessment of coronary reperfusion after thrombolysis with a model combining myoglobin, creatine kinase-MB, and clinical variables. TAMI-7 Study Group. Thrombolysis and Angioplasty in Myocardial Infarction-7.

BACKGROUND: Several biochemical markers have been investigated for the noninvasive assessment of reperfusion after myocardial infarction. Because myoglobin is released very soon after myocardial injury and clears rapidly after reperfusion, it may prove to be an excellent marker of occlusion and reperfusion. METHODS AND RESULTS: We examined the relation between various myoglobin measures and Thrombolysis In Myocardial Infarction (TIMI) flow grade in 96 patients enrolled in a study of front-loaded thrombolysis who underwent 90-minute angiography. We also combined myoglobin measures with models that include clinical and creatine kinase-MB variables. The myoglobin level measured within 10 minutes of acute angiography showed the best overall performance and was used for later analyses. Of the clinical variables examined, only time from symptom onset to thrombolysis and chest pain grade at angiography discriminated among TIMI flow grades. Combining the 90-minute myoglobin level and these clinical variables showed a significant difference (P<.0001) between both TIMI 3 versus TIMI 0 through 2 and TIMI 2 or 3 versus TIMI 0 or 1 flow. When the 90-minute myoglobin level was added to an established predictive model containing clinical variables and creatine kinase-MB measures, its contribution remained significant (P=.044). The area under the receiver operator characteristic curve for this combined model was .88. CONCLUSIONS: A single myoglobin measurement obtained 90 minutes after the start of thrombolysis, combined with select clinical variables and creatine kinase-MB levels, enhances the noninvasive prediction of reperfusion after myocardial infarction.

Adult↗
PubMed1997

Characteristics of a 20-minute whole blood rapid assay for cardiac troponin T.

OBJECTIVES: A qualitative whole blood rapid assay for cardiac troponin T (cTnT) was examined. The assay uses the same antibodies as for a benchmark ELISA, but the capture and detection roles were switched to enhance specificity. DESIGN AND METHODS: The cTnT Rapid Assay and ELISA were compared in 643 samples from patients having myocardial infarction, coronary artery bypass surgery, ischemic heart disease, musculoskeletal disease, renal failure, or other noncardiac conditions. Concordance between the methods was compared using the McNemar Test and cTnT cutoff of 0.2 micrograms/L. RESULTS: For the "cutoff" of 0.2 micrograms/L, concordance between the cTnT Rapid Assay and ELISA was in the range of 90-95% for each group except the renal failure patients, where concordance was 77.9%. There was no significant difference between the cTnT Rapid Assay and ELISA, except in the renal failure and ischemic heart disease patients, where there was a greater number (p < 0.05) of cTnT Rapid Assay negative results when the ELISA was > 0.2 micrograms/L. Overall concordance between the cTnT Rapid Assay and CK-MBmass was 78%. CONCLUSION: The McNemar test indicated that the cutoff for the cTnT Rapid Assay was 0.2 micrograms/L. Evidently the lower concordance among renal failure and ischemic heart disease patients reflects higher cTnT specificity for the Rapid Assay that was conferred by switching the capture and detection antibodies.

Adolescent↗
PubMed1997

Biochemical markers of bone metabolism: an overview.

OBJECTIVES: An overview of biochemical markers of bone metabolism is presented along with indications for their clinical utilization. DESIGN AND METHODS: The structure, cyclical metabolism, and hormone regulation of bone is reflected by markers of resorption, formation and/or turnover. Markers of resorption representing degradation of type 1 collagen, include N-telopeptides, C-telopeptides, hydroxyproline, and the collagen crosslinks pyridinoline and deoxypyridinoline; acid phosphatase, a marker of osteoclast activity, and urinary calcium are also indicators of bone resorption. Bone formation markers indicate osteoblast activity; bone-specific alkaline phosphatase and the N-terminal and C-terminal extension peptides of procollagen reflect formation of organic matrix in bone. Osteocalcin, produced by osteoblasts but also released during osteoclastic degradation, may indicate either formation when resorption and formation are coupled or turnover when they are uncoupled. RESULTS: Bone markers respond to intervention more rapidly than techniques such bone mineral density. Resorption markers respond approximately 1 to 3 months after intervention; markers of formation respond later, after 6 to 9 months. Bone markers may add useful information for assessing fracture risk and for monitoring osteoporosis, Paget's disease of bone, cancer metastasis, and metabolic disease. Various therapeutic interventions may affect release of some bone markers. CONCLUSION: Bone disease has high prevalence in adults so bone markers will become even more important for assessing fracture risk and monitoring therapy as populations age. Characteristics of bone markers are dependent on biology and the assay used. Substantial work remains in characterizing existing assays, identifying better markers and performing the clinical studies to define which bone markers should be measured and when.

Acid Phosphatase↗
PubMed1997

In vitro interference of the red cell substitute pyridoxalated hemoglobin-polyoxyethylene with blood compatibility, coagulation, and clinical chemistry testing.

OBJECTIVES: Pyridoxalated hemoglobin-polyoxyethylene (PHP) is a prototypical red cell substitute approved for phase I studies. Peripheral blood smears of human blood mixed with PHP in 1 to 4 g/dL concentrations showed dose-dependent red cell aggregation and rouleaux. Whether this aggregation limits interpretation of blood compatibility testing and whether the intense coloration of serum or plasma containing PHP affects routine coagulation and clinical chemistry measurements was tested. DESIGN: In vitro studies. SETTING: University hospital laboratory. PARTICIPANTS: Four healthy volunteers, blood types A, B, AB, and O. All were Rh+. MEASUREMENTS AND MAIN RESULTS: ABO typing, Rh typing, and antibody screening and coagulation studies were performed on blood: PHP admixtures having final concentrations of 1, 2, and 4 g/dL. For clinical chemistry interference studies, known concentrations of analytes were added to a serum matrix containing PHP. ABO (forward) and Rh typing showed no interference in the three concentrations tested. Reverse ABO typing and antibody screening showed rouleaux at 4 g/dL, which corrected with routine saline replacement. Partial thromboplastin time (PTT), prothrombin time (PT), and fibrinogen showed no clinically significant differences from the controls. Results for electrolytes, renal function analytes, and markers of cardiac injury were acceptable by standard laboratory methods. However, results of liver function tests were unacceptable in PHP-containing specimens. CONCLUSIONS: PHP-induced aggregation was observed with high PHP concentration; however, compatibility testing was not affected because agglutination was corrected by saline replacement, which is standard practice. Although routine blood banking, coagulation, and most clinical chemistry analytes can be measured reliably, alternative methods and strategies are needed for assessing liver function in the presence of PHP.

Blood Coagulation↗
PubMed1997

Multicenter study of Abbott AxSYM Digoxin II assay and comparison with 6 methods for susceptibility to digoxin-like immunoreactive factors.

Performance characteristics of the Abbott nonpretreatment AxSYM Digoxin II assay were evaluated for quantification of digoxin at four independent sites. Correlation of digoxin measurements with the Abbott pretreatment AxSYM, Baxter Stratus II, Abbott TDx/ TDxFLx II, Abbott IMx, Emit 2000, and Beckman Synchron CX digoxin assays showed acceptable agreement, as indicated by: slope values > 0.84, r > 0.90, y-intercepts for all comparisons at or below the assay detection limit, and Sy/x ranging between 7.5% and 15.4% of the average digoxin value. Susceptibility to interference from digoxin-like immunoreactive factors (DLIFs) was examined in 233 samples from renal patients, liver disease patients, cord blood, and third-trimester pregnancies; the AxSYM Digoxin II assay demonstrated the least DLIFs interference. DLIF susceptibility for four of the methods was significantly greater (P < 0.05) than in the AxSYM Digoxin II assay; susceptibilities of the Stratus II and Emit 2000 methods were similar to the AxSYM Digoxin II assay.

Autoanalysis↗
PubMed1997

Cardiac markers in the assessment of acute coronary syndromes.

Biochemical markers provide clinicians with an important tool for the assessment of acute coronary syndromes. Biochemical markers, including total creatine kinase (total CK), creatine kinase-MB (CK-MB), the MB isoforms, and myoglobin, as well as the troponins--cardiac troponin T (cTnT) and cardiac troponin I (cTnI)--are all used for assessment of the suspected acute myocardial infarction (AMI) patient. In the context of myocardial infarction (MI) diagnosis, total CK is a relatively sensitive marker, but it lacks myocardial specificity because skeletal muscle contains high concentrations of CK. CK-MB is the benchmark for biochemical markers and has both high sensitivity and specificity; however, CK-MB is also present in skeletal muscle and is not diagnostic until eight to twelve hours after onset of symptoms. The MB isoforms are diagnostic earlier but have the same cardiac specificity issues as CK-MB. Myoglobin becomes abnormal about one hour after onset of symptoms and is a sensitive marker for MI; however, myoglobin is cleared quickly and is not cardiac specific. Both cTnT and cTnI are cardiac specific and show high sensitivity and specificity for MI. Risk stratification of acute coronary syndrome patients is another role for biochemical markers; CK-MB, cTnT and cTnI have all been proposed for this function. Compared with CK-MB, both cTnT and cTnI are better able to predict short-term mortality following the index event. Analysis using a logistic regression model that included the electrocardiogram, cTnT, and cTnI showed that cTnT was the most useful marker for risk stratification. Finally, cTnT was reported to be able to predict which patients will benefit from treatment with regimens of low molecular weight heparin.

Angina Pectoris↗
PubMed1996

Cardiac troponin T levels for risk stratification in acute myocardial ischemia. GUSTO IIA Investigators.

BACKGROUND: The prognosis of patients hospitalized with acute myocardial ischemia is quite variable. We examined the value of serum levels of cardiac troponin T, serum creatine kinase MB (CK-MB) levels, and electrocardiographic abnormalities for risk stratification in patients with acute myocardial ischemia. METHODS: We studied 855 patients within 12 hours of the onset of symptoms. Cardiac troponin T levels, CK-MB levels, and electrocardiograms were analyzed in a blinded fashion at the core laboratory. We used logistic regression to assess the usefulness of baseline levels of cardiac troponin T and CK-MB and the electrocardiographic category assigned at admission-ST-segment elevation, ST-segment depression, T-wave inversion, or the presence of confounding factors that impair the detection of ischemia (bundle-branch block and paced rhythms)-in predicting outcome. RESULTS: On admission, 289 of 801 patients with base-line serum samples had elevated troponin T levels (> 0.1 ng per milliliter). Mortality within 30 days was significantly higher in these patients than in patients with lower levels of troponin T (11.8 percent vs. 3.9 percent, P < 0.001). The troponin T level was the variable most strongly related to 30-day mortality (chi-square = 21, P < 0.001), followed by the electrocardiographic category (chi-square = 14, P = 0.003) and the CK-MB level (chi-square = 11, P = 0.004). Troponin T levels remained significantly predictive of 30-day mortality in a model that contained the electrocardiographic categories and CK-MB levels (chi-square = 9.2, P = 0.027). CONCLUSIONS: The cardiac troponin T level is a powerful, independent risk marker in patients who present with acute myocardial ischemia. It allows further stratification of risk when combined with standard measures such as electrocardiography and the CK-MB level.

Acute Disease↗
PubMed1996

Lesion-directed administration of alteplase with intracoronary heparin in patients with unstable angina and coronary thrombus undergoing angioplasty.

Percutaneous coronary revascularization in patients with unstable angina and coronary thrombus carries a high complication rate. A new strategy to reduce thrombus burden before revascularization was tested in a multicenter prospective trial. Patients with unstable angina and coronary thrombus (n = 45) received alteplase through an infusion catheter at the proximal aspect of the target lesion and concomitant intracoronary heparin via a standard guiding catheter. Angiography was performed before and alter lesion-directed therapy and post-intervention. Systemic fibrinogen depletion and thrombin activation were not observed, while fibrinolysis was evident for > or = 4 hr after treatment. Target lesion stenosis did not change significantly after lesion-directed therapy, but thrombus score was reduced, particularly among patients who had large thrombi (mean 2.2 vs. 1.6, P = 0.02). Revascularization was successful in 89% of patients. Median final stenosis was 30% and mean final thrombus score was 0.4. Complications included recurrent ischemia (11%), MI (7%), abrupt closure (7%), severe bleeding (4%), and repeat emergency angioplasty (2%). Patients with overt thrombus appeared to derive the most angiographic benefit from lesion-directed alteplase plus intracoronary heparin. Later revascularization was highly successful. This strategy may be a useful adjunct to percutaneous revascularization for patients with unstable angina and frank intracoronary thrombus.

Adult↗
PubMed1996

The case for cardiac troponin T: marker for effective risk stratification of patients with acute cardiac ischemia.

Availability of markers such as cardiac troponin T (cTnT) has brought new insights into ischemic heart disease (IHD). cTnT is a distinct protein that differs from other markers in biological function, molecular mass, and cytosolic pool. cTnT has been utilized for diagnosis of acute myocardial infarction (AMI) and risk stratification of patients with IHD. For AMI diagnosis, cTnT showed high sensitivity (94-100%) but generally lower specificity (46-99%), possibly because of increases in non-AMI patients with minor myocardial damage. Outcome studies have demonstrated that IHD patients with increased cTnT are at significantly greater risk for cardiac events; revascularization in patients with increased cTnT may improve outcome. Estimated costs for batched ES 300 cTnT results and for a cTnT rapid assay run "on demand" were $17.48 and $21.65, respectively. cTnT currently has no specific common procedure test code; expected reimbursement is $18.32 for the ES 300 and is not established for the rapid assay.

Biomarkers↗
PubMed1995

Thyroid function testing evaluated on three immunoassay systems.

Total thyroxine (TT4), tracer uptake, thyroid-stimulating hormone (TSH), and free T4 (FT4) testing was examined in the ACS 180, Abbott IMx, and Stratus II systems. TSH sensitivity studies demonstrated that the ACS and IMx are second-generation assays; the Stratus showed between first- and second-generation performance. Except for one control below the detection limit, TSH imprecision was 3-10%. TSH accuracy was adequate for all systems. TT4 imprecision was 4-7%, except for the lowest control with the Stratus (18%). TT4 method agreement showed bias of about 20% between the systems. TT4 accuracy was compromised at the low end for the Stratus II, but was satisfactory otherwise. FT4 imprecision was 20% for the Stratus, < 5% for the IMx and 6% for the ACS. Uptake assays showed imprecision of 5-10%. The laboratory diagnosis indicated by each system's FT4 and calculated FT4 Index results were compared to determine diagnostic accuracy. In routine specimens, different clinical classifications were observed for 25% of specimens with the ACS, 19% with the Stratus, and 7% with the IMx; in the altered protein group, the Stratus showed 9% discordant results, the ACS showed 3%, and the IMx 0%. Of the three systems examined here, the Abbott IMx system showed the best overall performance.

Humans↗