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Arnaud Perrier

Publications and source records attributed to Arnaud Perrier.

54 records · Page 3Linked to original sources
PubMed2004

A new rapid point-of-care D-dimer enzyme-linked immunosorbent assay (Stratus CS D-dimer) for the exclusion of venous thromboembolism.

To evaluate the performances of a new D-dimer assay, Stratus CS D-dimer (Dade Behring, Newark, Delaware, USA), for the exclusion of venous thromboembolism and to determine the best cut-off values. This test relies on a sandwich enzyme-linked immunosorbent assay with a fluorogenic substrate in a radial partition immunoassay system in a dedicated device. It does not require laboratory staff and the results are available within 18 min. Two hundred and ninety-one frozen samples from patients suspected of either deep venous thrombosis (n = 137) or pulmonary embolism (n = 154) were measured and the results compared with the VIDAS D-dimer New assay. There were 37 deep venous thrombosis (27%) and 49 pulmonary embolism (32%) samples. Receiver-operating characteristic curve analysis indicated that the cut-off value could be set at either 300 or 400 ng/ml Fibrinogen Equivalent Units (FEU). The coefficient of variation determined with a lyophilized low-level control plasma (305 ng/ml FEU) was 6%. With a cut-off at 300 ng/ml FEU, the sensitivity, the specificity and the negative predictive value were 100% [95% confidence interval (CI), 95.8-100], 33.1% (95% CI, 26.8-40) and 100% (95% CI, 94.7-100), respectively. Raising the cut-off to 400 ng/ml FEU, the corresponding figures were 96.5% (95% CI, 90.1-99.3), 46.3% (95% CI, 39.4-53.2) and 96.9% (95% CI, 91.3-99.4), respectively. At 400 ng/ml, three results were false-negative, one with both devices and two with the Stratus D-dimer only. Stratus D-dimer appears to be suitable for the exclusion of venous thromboembolism in the emergency room setting.

Enzyme-Linked Immunosorbent Assay↗
PubMed2004

Degree of concurrency among experts in data collection and diagnostic hypothesis generation during clinical encounters.

BACKGROUND: Given that there are variations in clinicians' reasoning, methods to elaborate scoring checklists for standardised patient-based assessment need to be valid. The use of data elicited by experts solving problems independently has been advocated as a method of setting performance standards. AIMS: To determine the degree of concurrence and common characteristics among items independently elicited by doctors during patient encounters and to assess the number of experts needed to derive reliable performance standards. METHODS: Six experienced internists worked-up the same 7 chief complaints with standardised patients (SPs). A stimulated recall of the recorded encounter was then performed. The degree of concurrence of the collected history and physical examination information and the generated diagnostic hypotheses was computed. Reliability was derived from generalisability analyses. RESULTS: By case, experts elicited a mean of 114 information items (SD = 15) and generated 30 diagnostic hypotheses (SD = 6). A high concurrence (80-100%) was observed for a mean of 22 information items (20%; SD = 6) and 7 diagnostic hypotheses (24%; SD = 2). More than a third of the 153 highly concurrent information items were clarification questions. At least 3 doctors were needed to obtain a reliability of 0.80 or higher when deriving the scoring checklists. CONCLUSION: The limited concurrency in data elicited by clinicians during a patient encounter supports the use of high-fidelity methods to develop performance checklists used in SP-based assessment. It also suggests that relying only on information collected to assess clinical competence may not be sufficient. Additional criteria, such as structure and style of work-up, should be further explored.

Clinical Competence↗
PubMed2004

Effect of age on the performance of single detector helical computed tomography in suspected pulmonary embolism.

The prevalence of pulmonary embolism increases with age, but reduces the diagnostic yield of ventilation-perfusion lung scan age. Helical computed tomography (hCT) is widely used to diagnose pulmonary embolism, and should be less susceptible to the influence of age. We studied the influence of age on the performance of hCT to verify that hypothesis. We analyzed a database of 299 consecutive outpatients suspected of pulmonary embolism, in whom pulmonary embolism was diagnosed according to accepted criteria, and who were all submitted to a helical CT. We divided the patient population into tertiles, corresponding to the following age categories: less than 59 years (group 1), 60 to 75 years (group 2), and over 75 years (group 3). Sensitivity and specificity of hCT were calculated in each age category. Overall sensitivity was 70% (95% CI: 62 to 78) and specificity was 91% (95% CI: 86 to 95). Sensitivity was 81% (95% CI: 64 to 93) in group 1, 63% (95% CI: 46 to 78) in group 2, and 67 % (95% CI: 52 to 80) in group 3. The corresponding values for specificity were 92% (95% CI: 82 to 97) in group 1, 86% (95% CI: 75 to 94) in group 2 and 96% (95% CI: 87 to 100) in group 3. Positive predictive values ranged from 75% to 94% and negative predictive values from 77% to 94%. Our data suggest that age does not have a marked influence on the diagnostic performances of hCT in clinically suspected pulmonary embolism.

Age Factors↗
PubMed2004

Validation of a risk score identifying patients with acute pulmonary embolism, who are at low risk of clinical adverse outcome.

A clinical predictive model that accurately identifies patients with pulmonary embolism who are at low risk of adverse medical outcomes may be useful for management decisions, such as outpatient treatment. We aimed to externally validate a previously derived prognostic score identifying emergency ward patients with acute pulmonary embolism at low risk of 3-month complications. One hundred and ninety-nine consecutive patients with proven pulmonary embolism were included from the emergency centres of three teaching and general hospitals. Adverse outcomes, such as death, major bleed, or recurrent venous thromboembolism, were recorded during a 3-month follow-up. We retrospectively computed the prognostic score for each patient and determined its predictive accuracy at different threshold values. The overall 3-month risk of adverse event after the diagnosis of pulmonary embolism was 9.5%. At a threshold of 2 points, eight patients with scores at or below the cut-off (5%; 95% CI 2.6-9.6) and 11 patients with scores above this cut-off (27.5%; 95% CI 16.1-42.8) presented a complication. The negative predictive value for an adverse out-come was 95.0% (95% CI 90.4-97.4). The receiver operating characteristic curve derived from the score distribution had an area of 0.77 (95% CI 0.65-0.89). This compared favourably with the characteristics of the derivation study. We conclude that the Geneva risk score has an acceptable predictive accuracy to identify patients with pulmonary embolism at low risk for 3-month adverse outcomes. Whether this score remains accurate and useful in clinical practice should be determined in a prospective multicentre validation study.

Acute Disease↗
PubMed2003

Cost-effectiveness analysis of diagnostic strategies for suspected pulmonary embolism including helical computed tomography.

We performed a formal decision analysis to evaluate the cost-effectiveness of various strategies for pulmonary embolism, including helical computed tomography (CT), and determined the most cost-effective schemes for each clinical probability of pulmonary embolism. Other tests included D-dimer (DD), lower limb venous ultrasound (US), ventilation-perfusion (V/Q) scan, and angiography. Outcome measures were 3-month survival and costs per patient managed. Baseline sensitivity of CT was 70%, corresponding to the performance of single-detector CT, and that figure was raised in sensitivity analysis to account for the expected higher sensitivity of newer multidetector CT scanners. All strategies were compared with a reference strategy, namely the V/Q scan in all patients followed when nondiagnostic by an angiogram. For low clinical probability patients, the most cost-effective strategy was DD, US, and V/Q scan, patients with a nondiagnostic V/Q scan being left untreated. Replacing V/Q scan by CT was also cost-effective. For intermediate and high clinical probability patients, a fourth test must be added, either CT or angiography in patients with nondiagnostic V/Q scan, or angiography in patients with a negative helical CT. When using sensitivity figures above 85% (in the multidetector range), DD, US, and CT became the most cost-effective strategy for all clinical probability categories. Helical CT as a single test was not cost-effective. In summary, including helical CT in diagnostic strategies for pulmonary embolism is cost-effective provided that it is combined with DD and US. In contrast, helical CT as a single test is not cost-effective.

Angiography↗
PubMed2003

[Diagnostic strategies of thrombo-embolic venous disease].

The advent of non invasive tests (D-dimer and lower limb venous compression ultrasonography) and minimally invasive tests (helical CT scan) and the rehabilitation of clinical assessment have allowed the development of safe, rational and cost-effective diagnostic strategies for deep venous thrombosis and pulmonary embolism. Several algorithms have been validated in studies in which patients classified as not having venous thromboembolism are left untreated and followed up during 3 months. The safety of such strategies is established by comparing the 3-month thromboembolic risk in such patients with that of patients left untreated based on a normal venogram, pulmonary angiogram or lung scintigram. Venography or pulmonary angiography remains necessary in selected cases such as patients with a high clinical probability of venous thromboembolism and an inconclusive non invasive workup, representing only approximately 5 to 10% of all patients. Finally, suspected massive pulmonary embolism is a distinct clinical situation in which echocardiography plays a major role.

Algorithms↗
PubMed2003

Diagnostic approaches to suspected deep vein thrombosis and pulmonary embolism.

The present paper aims at reviewing our present knowledge on the diagnosis of deep vein thrombosis and pulmonary embolism with a particular emphasis on clinically suspected outpatients. The various contemporary diagnostic tools (including clinical probability assessment, fibrin D-Dimer measurement, venous compression ultrasonography, ventilation/perfusion lung scintigraphy, helical CT scan, and echocardiography) are presented and rational sequential strategies are discussed in their various aspects, including validation in outcome studies, and cost-effectiveness analyses.

Algorithms↗
PubMed2003

Exclusion of pulmonary embolism using C-reactive protein and D-dimer. A prospective comparison.

Our goal was to evaluate the diagnostic utility of C-reactive protein (CRP) alone or combined with clinical probability assessment in patients with suspected pulmonary embolism (PE), and to compare its performance to a D-dimer assay. We conducted a prospective study in which we performed a common immuno-turbidimetric CRP test and a rapid enzyme-linked immunosorbent assay (ELISA) D-dimer test in 259 consecutive outpatients with suspected PE at the emergency department of a teaching hospital. We assessed clinical probability of PE by a validated prediction rule overridden by clinical judgment. Patients with D-dimer levels > or = 500 microg/l underwent a work-up consisting of lower-limb venous ultrasound, spiral computerized tomography, ventilation-perfusion scan, or pulmonary angiography. Patients were followed up for three months. Seventy-seven (30%) of the patients had PE. The CRP alone had a sensitivity of 84% (95% confidence interval [CI).: 74 to 92%) and a negative predictive value (NPV) of 87% (95% CI: 78 to 93%) at a cutpoint of 5 mg/l. Overall, 61 (24%) patients with a low clinical probability of PE had a CRP < 5 mg/l. Due to the low prevalence of PE (9%) in this subgroup, the NPV increased to 97% (95% CI: 89 to 100%). The D-dimer (cutpoint 500 micro g/l) showed a sensitivity of 100% (95% CI: 95 to 100%) and a NPV of 100% (95% CI: 94 to 100%) irrespective of clinical probability and accurately rule out PE in 56 (22%) patients. Standard CRP tests alone or combined with clinical probability assessment cannot safely exclude PE.

Adult↗
PubMed2002

Evaluation of advanced D-dimer assay for the exclusion of venous thromboembolism.

The performances for thromboembolic disease exclusion of a new microlatex-enhanced D-dimer immunoassay have been evaluated. Advanced D-dimer (Dade-Behring, Marburg, Germany) was tested with two automated analyzers, namely BCS and CA-1500. Precision studies yielded coefficients of variation (within-run and run-to-run) of 3% and 6.3% at D-dimer levels near the cut-off value, for BCS and CA-1500 respectively. Frozen samples from 294 consecutive symptomatic outpatients suspected of either deep venous thrombosis (140) or pulmonary embolism (154) from a previous management study were tested with both analyzers, as well as with the VIDAS New assay (BioMerieux, Marcy-l'Etoile, France). For BCS, sensitivity and specificity were 96.6% (95% CI, 90.5, 99.3) and 42% (35.1, 49.0) respectively at a cut-off value of 1.35 microg/ml. For CA-1500, the corresponding figures were 95.5% (88.9, 98.8) and 47.8% (40.8, 54.9) at a cutt-off value of 1.1 microg/ml. This assay appears promising and should be validated in clinical practise to assess its place in the work-up schemes of thromboembolism.

Calibration↗
PubMed2002

Comparison of two clinical prediction rules and implicit assessment among patients with suspected pulmonary embolism.

PURPOSE: Two prediction rules for pulmonary embolism have been described recently: the Wells' rule, which was derived from both outpatients and inpatients, and which includes a subjective element; and the Geneva rule, which is entirely standardized and is suitable only for emergency department patients. We compared the predictive accuracy and the concordance of the two methods, as well as the Geneva score overridden by implicit clinical judgment. SUBJECTS AND METHODS: We studied 277 consecutive patients admitted to the emergency departments of three teaching hospitals. Clinical probability was assessed prospectively with the Geneva score and the Geneva score overridden by implicit clinical judgment in case of a disagreement. The Wells' score was calculated retrospectively. RESULTS: The three methods classified similar proportions of patients as having a low (53% to 58% of patients), intermediate (37% to 41% of patients), or high (4% to 10% of patients) probability of pulmonary embolism. The actual frequencies of pulmonary embolism in each category were also similar (5% to 13% in the low, 38% to 40% in the intermediate, and 67% to 91% in the high clinical probability categories). Receiver operating characteristic curve analysis showed no difference between the two prediction rules, but the Geneva score overridden by implicit evaluation had a marginally higher accuracy. Concordance between the two prediction rules was fair (kappa coefficient = 0.43). Clinicians disagreed with the Geneva score in 21% of patients (n = 57). CONCLUSIONS: The two prediction rules had a similar predictive accuracy for pulmonary embolism among emergency department patients. The Geneva rule appears to be more accurate when combined with clinical judgment, although it does not apply to inpatients.

Adult↗
PubMedDate not supplied

Clinical usefulness of D-dimer depending on clinical probability and cutoff value in outpatients with suspected pulmonary embolism.

BACKGROUND: We evaluated whether a highly sensitive D-dimer test is clinically useful and safe for ruling out pulmonary embolism (PE) in patients with a high clinical probability and whether adopting different cutoff values according to the clinical probability category might increase the proportion of patients in whom PE is ruled out. METHODS: We retrospectively analyzed the databases of 2 outcome studies on the diagnosis of PE with a 3-month follow-up that included 1409 patients. We evaluated the usefulness of D-dimer testing by calculating the number needed to test to rule out one PE, and its safety by measuring the 3-month thromboembolic risk in patients not treated by anticoagulant agents based on a normal D-dimer level. RESULTS: The sensitivity of D-dimer was 100% in all clinical probability categories, but the number needed to test increased with increasing clinical probability of PE. The 95% confidence interval (0%-23%) of the 3-month thromboembolic risk (0%) among 13 of 121 patients with a normal D-dimer level and a high clinical probability of PE was wide. Increasing the cutoff value to 700 mug/L in patients with a low clinical probability would rule out PE in an additional 5% of the entire patient cohort at the expense of a lower sensitivity (93% [95% confidence interval, 83%-97%]). CONCLUSIONS: The safety of D-dimer testing in patients with a high clinical probability of PE is not established, and testing results are rarely negative in such patients. Increasing the enzyme-linked immunosorbent assay D-dimer cutoff value only marginally increased the test's usefulness.

Aged↗