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Biomedical subjects

A Perrier

Publications and source records attributed to A Perrier.

At least 55 records · Page 3Linked to original sources
PubMed2002

[Validation study of a diagnostic test: a guide to critical appraisal. Report on the role of endobronchial biopsy in the diagnosis of sarcoidosis].

The case for endobronchial biopsy in the diagnosis of sarcoidosis: Faced with the continuous development of new diagnostic tests, the clinician needs to be able to critically assess their value and their clinical applicability. Using a practical example, the performance of endobronchial biopsy in diagnosing sarcoidosis, this review provides a guide for critically appraising a study evaluating a diagnostic test. The three main steps described are: 1) assessment of the validity of the results based on the scientific methods used; 2) analysis of the results with reference to sensitivity, specificity, predictive value, likelihood ratio, and precision of the diagnostic test in question; 3) determination of whether the results are applicable to an individual patient or to a specific patient population.

Adult↗
PubMed2001

Performance of helical computed tomography in unselected outpatients with suspected pulmonary embolism.

BACKGROUND: Helical computed tomography (CT) is commonly used to diagnose pulmonary embolism, although its operating characteristics have been insufficiently evaluated. OBJECTIVE: To assess the sensitivity and specificity of helical CT in suspected pulmonary embolism. DESIGN: Observational study. SETTING: Emergency department of a teaching and community hospital. PATIENTS: 299 patients with clinically suspected pulmonary embolism and a plasma D -dimer level greater than 500 microgram/L. INTERVENTION: Pulmonary embolism was established by using a validated algorithm that included clinical assessment, lower-limb compression ultrasonography, lung scanning, and pulmonary angiography. MEASUREMENTS: Sensitivity, specificity, and likelihood ratios of helical CT and interobserver agreement. Helical CT scans were withheld from clinicians and were read 3 months after acquisition by radiologists blinded to all clinical data. RESULTS: 118 patients (39%) had pulmonary embolism. In 12 patients (4%), 2 of whom had pulmonary embolism, results of helical CT were inconclusive. For patients with conclusive results, sensitivity of helical CT was 70% (95% CI, 62% to 78%) and specificity was 91% (CI, 86% to 95%). Interobserver agreement was high (kappa = 0.823 to 0.902). The false-negative rate was lower for helical CT used after initial negative results on ultrasonography than for helical CT alone (21% vs. 30%). Use of helical CT after normal results on initial ultrasonography and nondiagnostic results on lung scanning had a false-negative rate of only 5% and a false-positive rate of only 7%. CONCLUSION: Helical CT should not be used alone for suspected pulmonary embolism but could replace angiography in combined strategies that include ultrasonography and lung scanning.

Adult↗
PubMed2001

Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score.

OBJECTIVE: To develop a simple standardized clinical score to stratify emergency ward patients with clinically suspected pulmonary embolism (PE) into groups with a high, intermediate, or low probability of PE to improve and simplify the diagnostic approach. METHODS: Analysis of a database of 1090 consecutive patients admitted to the emergency ward for suspected PE in whom diagnosis of PE was ruled in or out by a standard diagnostic algorithm. Logistic regression was used to predict clinical parameters associated with PE. RESULTS: A total of 296 (27%) of 1090 patients were found to have PE. The optimal estimate of clinical probability was based on 8 variables: recent surgery, previous thromboembolic event, older age, hypocapnia, hypoxemia, tachycardia, band atelectasis, or elevation of a hemidiaphragm on chest x-ray film. A probability score was calculated by adding points assigned to these variables. A cutoff score of 4 best identified patients with low probability of PE. A total of 486 patients (49%) had a low clinical probability of PE (score </=4), of which 50 (10.3%) had a proven PE. The prevalence of PE was 38% in the 437 patients with an intermediate probability (score of 5-8; n = 437) and 81% in the 63 patients with a high probability (score >/=9). CONCLUSIONS: This clinical score, based on easily available and objective variables, provides a standardized assessment of the clinical probability of PE. Applying this score to emergency ward patients suspected of having PE could allow a more effective diagnostic process.

Adolescent↗
PubMed2001

Comparison of four strategies for diagnosing deep vein thrombosis: a cost-effectiveness analysis.

PURPOSE: Four strategies for the diagnosis of deep vein thrombosis have been validated recently. The strategies use various combinations of assessment of a patient's clinical probability of having deep venous thrombosis, serial lower limb venous compression ultrasonography, and measurement of plasma D-dimer levels. We compared the cost-effectiveness of these diagnostic strategies. MATERIALS AND METHODS: We performed a formal cost-effectiveness analysis using a decision-analysis model. Outcomes considered were costs per patient, 3-month quality-adjusted survival, number of lives saved per 1,000 patients, and incremental costs per quality-adjusted life-year (QALY) gained. RESULTS: Under baseline conditions, with a 24% prevalence of deep vein thrombosis in tested patients, the effectiveness of all strategies was similar (4.6 to 4.8 lives saved per 1,000 patients managed). The most expensive strategy was serial ultrasound (repeat ultrasound on day 7 in all patients with a normal initial ultrasound) at a cost-effectiveness of $10,716 per additional QALY. Performing a repeat ultrasound only in patients with an elevated D-dimer level (serial ultrasound with D-dimer) was somewhat less expensive at $10,281 per additional QALY. Taking clinical probability into account by repeating ultrasound only in patients with an intermediate clinical probability of deep vein thrombosis (risk-based serial ultrasound) yielded further savings and cost $10,090 per additional QALY. The least expensive and most cost-effective option was to perform D-dimer as the initial test, followed by a single ultrasound if the D-dimer level was abnormal, and by phlebography in patients with a normal ultrasound and a high clinical probability of deep vein thrombosis (D-dimer with risk-based single ultrasound) at $8,897 per additional QALY. This strategy allowed a 17% reduction in incremental costs compared with the most expensive algorithm and reduced resource consumption (70 ultrasound procedures per 100 patients managed vs 130 to 170 with the other diagnostic strategies). CONCLUSIONS: Combining clinical probability and D-dimer with a single ultrasound in the diagnostic workup of patients with possible deep vein thrombosis is highly cost-effective, allowing a reduction in costs and resource use without any substantial increase in mortality. Serial ultrasonography is less cost-effective.

Algorithms↗
PubMed2001

Diagnosis of pulmonary embolism in outpatients by sequential noninvasive tools.

Considerable progress has been made in pulmonary embolism (PE) diagnosis during the last 10 years. New, noninvasive tools such as D-dimer measurement and lower limb venous compression ultrasonography have been introduced as diagnostic strategies. Clinical evaluation of the likelihood of PE has been rehabilitated and has proven to be accurate and useful. The interpretation of lung scan results has become more standardized and clear to clinicians. Finally, two diagnostic strategies have been validated in large scale outcome studies. Both rely on a sequential combination of the aforementioned instruments and have safely treated more than 90% of patients without use of pulmonary angiography. The 3-month venous thromboembolic risk in patients in whom PE was ruled out and, hence, who did not undergo anticoagulation was less than 1% in both studies. In the absence of a formal comparison of their respective cost-effectiveness, choosing between these strategies rests on local preferences or logistics. Finally, spiral computed tomography (CT) seems promising and might modify the diagnostic work-up of PE in the near future. However, it is insufficiently validated, and its place in a rational diagnostic algorithm is not defined.

Ambulatory Care Facilities↗
PubMed2001

Clinical and laboratory diagnosis of deep vein thrombosis: new cost-effective strategies.

Diagnosis of deep vein thrombosis (DVT) has been made easier, less invasive, and somewhat safer over the past 2 decades. This has been due mainly to the development of venous compression ultrasonography (US). The prevalence of the disease in patients clinically suspected of DVT has steadily decreased during the past 10 years, likely as a consequence of the accurate noninvasive test, ultrasound imaging. This has led to the development of diagnostic tools that aim at reducing the number of unnecessary US exams. These include clinical probability assessment and fibrin D-dimer. Several strategies combining these tools have been validated in large-outcome studies and compared in a formal cost-effectiveness analysis. The results indicate that they should now be implemented in daily practice, taking into account local facilities and expertise.

Algorithms↗
PubMed2001

Pulmonary embolism: from clinical presentation to clinical probability assessment.

The rehabilitation of clinical assessment of venous thromboembolism (VTE) is certainly one of the major breakthroughs of the last decade in the field of pulmonary embolism (PE) diagnosis. Although the value of isolated clinical findings in suspected PE is limited due to the poor sensitivity and specificity of its symptoms and signs, their combination, whether empiric or explicit through prediction rules, allows a fairly accurate assessment of the likelihood of the disease in a given patient. This allows the identification of a large subset of patients with a low prevalence of the disease in whom a combination of noninvasive tests rules out PE effectively despite these tests' limited individual sensitivity. The best validated example is the combination of a low probability lung scan and a normal venous compression ultrasound in a patient with low clinical probability of PE, which is associated to a low 1 to 2% 3-month risk of VTE in such patients left untreated by anticoagulants. Finally, clinical assessment contributes significantly to the cost savings associated with modern noninvasive strategies.

Cost-Benefit Analysis↗
PubMed2001

Diagnostic strategies for suspected pulmonary embolism among outpatients.

Diagnosis of pulmonary embolism (PE) has been made easier, less invasive, and somewhat safer over the past 2 decades. This has been due mainly to the development of lung scan and to the recognition of VTE as an entity comprising deep vein thrombosis and PE. The prevalence of the disease in patients clinically suspected of PE has steadily decreased during the past 10 years. This has led to the development of diagnostic tools that aim at reducing the number of unnecessary pulmonary angiograms. These include clinical probability assessment and fibrin D-dimer. Several strategies combining these tools have been validated in large outcome studies and compared in a formal cost-effectiveness analysis. The results indicate that they should now be implemented in daily practice taking into account local facilities and expertise. The exact place of helical computed tomography in such sequential algorithms remains to be established.

Algorithms↗
PubMed2001

Performances of a new, automated latex assay for the exclusion of venous thromboembolism.

The performance of a new latex-enhanced turbidimetric assay, D-Dimer PLUS, has been evaluated with two analyzers performing various coagulation assays: the BCS Analyzer and the BCT Analyzer. A precision study showed total coefficients of variation ranging from 2.7 to 11.1% with the BCS Analyzer and from 2.5 to 6.6% with the BCT Analyzer. We investigated the ability of D-Dimer PLUS to exclude venous thromboembolism in 312 outpatients suspected of either pulmonary embolism or deep venous thrombosis. Three months follow-up was available for all patients. With the BCS Analyzer, we determined a cut-off value of 190 ng/ml, which gave a sensitivity of 97.9% [95% confidence interval (CI), 92.6-99.7%], a specificity of 37.9% (95% CI, 30.9-43.8%) and a negative predictive value of 97.6% (95% CI, 91.7-99.7%). With the BCT Analyzer, at a cut-off value of 130 ng/ml, sensitivity was 96.8% (95% CI, 91.0-99.3%), specificity was 45.2% (95% CI, 38.5-51.2%) and the negative predictive value was 97% (95% CI, 91.6-99.4). This new assay is fast and fully automated, and its performance is suitable to exclude venous thromboembolism. Management studies should be performed to assess its utility.

Adult↗
PubMed2001

New methods for estimating pretest probability in the diagnosis of pulmonary embolism.

The clinical assessment of the probability of pulmonary embolism is a key step in proposed diagnostic strategies for pulmonary embolism, because the interpretation of noninvasive test results is conditional on the pretest probability derived from the presence or absence of clinical factors. The past year has brought important progress in the general area of clinical prediction of pulmonary embolism with the publication of two new simple clinical prediction rules. Each of the prediction rules includes a total of seven clinical variables that, when combined, allow for the categorization of patients into categories of low, intermediate, or high pretest probability of pulmonary embolism. Although these clinical prediction rules are perhaps only slightly better than the estimates of experienced clinicians, they provide an explicit method for estimating the probability of PE as an adjunct to diagnostic testing. Further validation work is now needed to assess how well these new prediction rules perform in settings other than the derivation sites.

Algorithms↗
PubMed2001

Cost-effective diagnosis of deep vein thrombosis and pulmonary embolism.

Suspected acute venous thromboembolism is a frequent and challenging clinical problem. Phlebography and pulmonary angiography are costly and invasive and, hence, ill-suited for diagnosing a disease present in only 20% of patients in whom it is suspected. Novel noninvasive instruments, such as plasma D-dimer measurement, lower limb compression ultrasonography and helical CT scan are important breakthroughs in the management of patients with suspected venous thromboembolism. However, none of these instruments is ideal, and they must be combined in rational and cost-effective diagnostic algorithms including clinical assessment, which is increasingly standardized. Such strategies must be validated in management studies, in which patients without venous thromboembolism are not treated and followed up during 3 months. Suspected massive pulmonary embolism is a distinct clinical situation requiring a specific diagnostic approach, in which echocardiography plays a major role. This paper reviews the performance of clinical evaluation and diagnostic tests for venous thromboembolism, and recently validated diagnostic schemes.

Algorithms↗