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Biomedical subjects

A Perrier

Publications and source records attributed to A Perrier.

At least 19 recordsLinked to original sources
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

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

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↗
PubMed2000

Effects of age on the performance of common diagnostic tests for pulmonary embolism.

PURPOSE: The diagnosis of pulmonary embolism in the elderly is often difficult because of comorbid medical conditions, and perhaps also because diagnostic tests have a lower yield. We analyzed the diagnostic performance of common diagnostic tests for pulmonary embolism in different age groups. METHODS: We analyzed data from two large studies that enrolled 1,029 consecutive patients presenting to the emergency department with clinically suspected pulmonary embolism. The clinical probability of pulmonary embolism (high [>/=80%], intermediate, or low [</=20%]) was estimated by the treating physician. All patients underwent a sequential diagnostic protocol, including ventilation-perfusion lung scan, measurement of plasma D-dimer level, lower limb venous compression ultrasonography, and pulmonary angiography if the noninvasive work-up was inconclusive. RESULTS: The prevalence of pulmonary embolism increased progressively, from 12% in patients <40 years of age to 44% in those >/=80 years of age. The positive predictive value of a high clinical probability of pulmonary embolism was greater in the elderly (71% to 78% in those >/=60 years old versus 40% to 64% in those </=59 years old). The sensitivity of D-dimer testing was 100% in all age groups, but its specificity decreased markedly with age, from 67% in those </=40 years old to 10% in those >/=80 years old. The diagnostic yield of lower limb compression ultrasonography was greater in the elderly. The proportion of lung scans that were diagnostic (normal, near-normal, or high probability) decreased from 68% to 42% with increasing age. CONCLUSIONS: Age affects the performance of common diagnostic tests for pulmonary embolism and should be kept in mind when evaluating patients suspected of having this condition.

Adult↗
PubMed2000

Using clinical evaluation and lung scan to rule out suspected pulmonary embolism: Is it a valid option in patients with normal results of lower-limb venous compression ultrasonography?

BACKGROUND: In patients with a low clinical probability of pulmonary embolism (PE) and a nondiagnostic lung scan, the prevalence of PE is theoretically very low. We assessed the safety and usefulness of this association for ruling out PE. METHODS: We analyzed data from 2 consecutive cohort management studies performed in 2 university hospitals (Geneva University Hospital, Geneva, Switzerland, and Hospital Saint-Luc, Montreal, Quebec), which enrolled 1034 consecutive patients who came to the emergency department with clinically suspected PE. All patients were submitted to a sequential diagnostic protocol of lung scan, D-dimer testing, lower-limb venous compression ultrasonography (US), and pulmonary angiography in case of inconclusive results of noninvasive workup. RESULTS: The prevalence of PE was 27.6%. Empirical assessment was accurate for identifying patients with a low likelihood of PE (8.2% prevalence of PE in the low clinical probability category). One hundred eighty patients had a low clinical probability of PE and a nondiagnostic lung scan. Among these patients, US showed deep vein thrombosis in 5. Hence, PE could be ruled out by a low clinical probability, a nondiagnostic lung scan, and a normal US in 175 patients (21.5%). The 3-month thromboembolic risk in these patients was low (1.7%; 95% confidence interval, 0.4%-4.9%). CONCLUSIONS: Anticoagulant treatment could be safely withheld in patients with a low clinical probability of PE and a nondiagnostic lung scan, provided that the US is normal. This combination of findings avoided pulmonary angiography in 21.5% of patients with suspected PE in this series.

Adult↗
PubMed2000

Diagnosis of acute pulmonary embolism: an update.

Considerable progress has been made in pulmonary embolism diagnosis during the last ten years. New diagnostic instruments such as plasma D-dimer measurement and lower venous compression ultrasonography have been developed. Clinical evaluation of the likelihood of pulmonary embolism has been rehabilitated and proven accurate and valid. The interpretation of lung scan results has become more simple and clear to clinicians. Finally, two diagnostic strategies have been validated in large scale outcome studies. Both rely on a sequential combination of the above mentioned instruments and have been able to safely manage more than 90% of patients without a pulmonary angiogram. The 3-month venous thromboembolic risk in patients without pulmonary embolism and, hence, not anticoagulated was less than 1% in both studies. In the absence of a formal comparison of their respective cost-effectiveness, choosing between these strategies may rest on local preferences or logistics. Finally, spiral CT scan is highly promising and may considerably modify the diagnostic workup of pulmonary embolism in the near future. However, it is insufficiently validated and its position in a rational algorithm for diagnosing pulmonary embolism is not yet defined.

Acute Disease↗
PubMed2000

Prevalence of factor V Leiden and prothrombin G20210A mutations in unselected patients with venous thromboembolism.

We determined the prevalence of factor V Leiden and of prothrombin G20210A mutations in a cohort of unselected outpatients (n = 748) referred for suspected deep vein thrombosis (DVT) and/or pulmonary embolism (PE) and a pooled analysis of similar studies was also performed. Based on the clinical presentation, the prevalence of factor V Leiden was 15.7% in the 83 patients with DVT and 14.1% in the 99 patients with PE compared with 5.3% in patients without DVT and/or PE (control group). The prevalence of the prothrombin G20210A mutation did not differ among the three groups (3.9% for controls, 4. 8% for DVT and 3.9% for PE patients). We then divided the 99 patients with PE by separately analysing those with PE but without DVT (n = 57) and those with PE and DVT (n = 42). Compared with the control group, the prevalence of factor V Leiden was 10.5%, odds ratio (OR) 2.10 [95% confidence interval (95% CI) 0.68-5.45] in patients with primary PE and 19.1%, OR 4.20 (95% CI 1.54-10.30) in patients with DVT and PE. For the prothrombin G20210A mutation, no statistically significant differences were found between the control group and the three other groups. In conclusion, our data and the pooled analysis indicate that patients with primary PE are less often affected by the factor V Leiden mutation. No statistically significant differences were observed between patients and controls for the prothrombin G20210A mutation.

Adult↗
PubMed2000

Clinical assessment of suspected deep vein thrombosis: comparison between a score and empirical assessment.

OBJECTIVES: To assess the accuracy and agreement of two methods of clinical evaluation: a formal score based on a number of items of fixed value (the so-called Wells' score), and an empirical assessment based on a predefined list of items that can be weighted individually. Clinical probability is essential to manage suspected deep vein thrombosis (DVT) and should be assessed before any diagnostic test. DESIGN: An open, nonrandomised, one-centre study. SETTING: One centre in Switzerland (a university hospital delivering primary-tertiary care). SUBJECTS: Two hundred and seventy outpatients with a prevalence of DVT of 21.1% (final diagnosis), out of an initial population of 328 patients, of which 52 had to be excluded because of a history of DVT (score not applicable) or because of insufficient clinical information (n = 6). RESULTS: Agreement between the two assessment tools was poor (kappa value of 0.32), but accuracy was excellent, with a prevalence of DVT of 1.3%, 18.1%, and 100% (empirical assessment), and 3.2%, 19.4%, and 73.9% (Wells' score), for a low, intermediate or high clinical probability estimate, respectively. The main differences between the two methods were that (i) the empirical method performed slightly better in categorizing patients in the high probability class, and (ii) Wells' score categorized more patients in the low probability class. When applied to two validated diagnostic strategies, the empirical assessment required slightly fewer phlebograms in both strategies, and Wells' score required fewer repeat ultrasonograms (in the strategy that requires this procedure). CONCLUSIONS: Clinical probability assessment can be done with a similar accuracy either empirically or using a score. Institutions should incorporate clinical probability assessment with either method depending upon their diagnostic strategy for suspected DVT.

Adult↗