Pretest Clinical Probability Score Research Articles

Pulmonary embolism risk stratification: external validation of the 4-level Clinical Pretest Probability Score (4PEPS)

BackgroundThe 4-level clinical pretest probability score (4PEPS) was recently introduced as a clinical decision rule for the diagnosis of pulmonary embolism (PE). Based on the score, patients are classified into clinical pretest probability categories (c-PTP). The “very low” category aims at excluding PE without further testing; “low” and “moderate” categories require D-dimer testing with specific thresholds, while patients with a “high” pretest directly proceed to imaging. ObjectivesTo provide further external validation of the 4PEPS model. MethodsThe 4PEPS was applied to a previously collected prospective database of 756 patients with clinically suspected PE enrolled from European emergency departments in 2002 to 2003. The safety threshold for the failure rate in our study was calculated at 1.95% based on a 26% prevalence of PE in our study, as per the International Society on Thrombosis and Haemostasis Scientific and Standardization Committee guidance. ResultsPatients were classified as follows: 90 (12%) in the very low c-PTP group, of whom 5 (5.6%; 95% CI, 2.4%-12.4%) had PE; 363 (49%) in the low c-PTP group, of whom 34 had PE (9.4%); 246 (34%) in the moderate c-PTP group, of whom 124 (50%) had PE; and 35 (5%) in the high c-PTP group of whom 30 (86%) had PE. Overall, the failure rate of the 4PEPS was 9/734 (1.2%; 95% CI, 0.59%-2.23%) Overall, 9 out of 734 patients (1.2%; 95% CI, 0.59%-2.23%) were diagnosed with PE despite a negative 4PEPS rule; 5 (5.6%) from the very low c-PTP group, 3 (1.4%) in the low c-PTP group, and 1 (3.2%) in the moderate c-PTP group. ConclusionWe provide external validation data of the 4PEPS. In this high-prevalence cohort (26% prevalence), PE prevalence in the very low-risk group was higher than expected. A prospective validation study is needed before implementing the 4PEPS model in routine clinical practice.

Derivation and Validation of a 4-Level Clinical Pretest Probability Score for Suspected Pulmonary Embolism to Safely Decrease Imaging Testing

Pulmonary embolism (PE) poses a diagnostic challenge to Emergency Medicine physicians because the signs and symptoms of PE are extremely common and unspecific. Multiple decisions tools have been created to help rule out this diagnosis and curb the overuse of imaging, particularly computed tomography pulmonary angiography (CTPA). Unnecessary CTPA places patients at risk for allergic reaction, renal failure, and long term radiation accumulation related diseases. Despite these efforts, there has been a large increase in the use of imaging to rule out PE.

Assessing the Appropriateness and Effectiveness of Coronary CT Angiography in COVID-19 Patients with Chest Pain

Coronary CT Angiography (CCTA) is well established for Chest Pain (CP) evaluation to assess coronary artery stenosis. However, the appropriateness of CCTA for COVID-19 patients with CP is unclear because a cardiac cause of CP in COVID-19 patients can be multifactorial, from direct viral myocardial injury to secondary hypercoagulability and to coronary stenosis [1]. The purpose of this report is to examine the appropriateness of CCTA for CP evaluation in laboratory confirmed COVID-19 patients. We retrospectively reviewed consecutive COVID-19 patients with CP between March 7, 2020 and January 2021. COVID-19 diagnosis was confirmed using the Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) test (Cobas SARS-CoV-2, Roche, Indiana, USA and the Xpert Xpress SARS-CoV-2, Cepheid, California, USA). A waiver for individual consent was approved by the Institutional Review Board. Patient’s demographic data, vital signs and ECG were charted prospectively in the CT reporting database. The laboratory results were retrospectively collected from the electronic medical records. The European Consortium clinical pre-test probability score for coronary artery disease was calculated based from the clinical criteria including age, sex, CP type, diabetes mellitus, smoking status, hypertension, and dyslipidemia [2] where the low pretest probability was defined as <5%, intermediate probability 5-70 % and high probability >70%. Patients less than 40 years old (N=3) were treated as if they were 40 years of age in order to calculate their score. The score was calculated to predict coronary stenosis >50% by CCTA, which was performed using a 320-detector CT (Acquilion One, Vision, Canon, USA) with prospective ECG gating. Among 40 patients studied, 21 were female and the mean age was 53 years. Of those, 34 were hospitalized and 6 were outpatients. The patients’ demographics are shown in the table. No patient was known to have pre-existing coronary artery disease. Based on the clinical criteria there were 11 patients having low pretest probability <5% and the remaining 29 having intermediate probability ranging from 5% to 47%. None had high pretest probability. All patient had 12-lead ECG prior to CCTA. ST/T wave abnormalities were found in 14 (35%) and Q wave abnormality in 5 (13%) patients. Of the 32 patients who had Troponin tested, only 1 patient had Troponin I elevation. Out of the 38 patients with calcium score imaging performed, 23 (61%) had zero calcium score. To minimize radiation exposure 2 patients did not receive calcium score imaging due to young age (<30 years). The subsequent CCTA was normal in one and severely abnormal with 3-vessel disease in the other. Among the patients with low pretest probability (N=11) none had significant coronary stenosis of >50%. Of the remaining 29 patients with intermediate probability, 8 (28%) had significant stenosis. One female patient having an intermediate pre-test probability of 11% presented with an acute coronary syndrome with ST segment depression and peak cardiac Troponin-I elevation of 11.3 ng/dL. Her coronary calcium score was zero and CCTA was normal. The subsequent cardiac MRI showed acute myocardial infarction with evidence of microvascular obstruction. Another patient having intermediate probability of 47% had a coronary calcium score of 5717 who was imputed to have significant coronary stenosis without undergoing CCTA. The ECG findings of ST/T or Q wave abnormalities did not differentiate those with or without significant coronary stenosis by CCTA. Table 1: Demographics (N=40). In this case series we found that clinical risk stratification using The European Consortium pre-test probability score was effective in COVID-19 patients with CP. No patients with low pretest probability were found to have significant coronary stenosis. In contrast, 28% of patients with intermediate pretest probability had significant coronary stenosis. While fever and respiratory distress are often the most prominent clinical presentations for hospitalized COVID-19 patients, CP can also present as a major complaint or in combination with other symptoms, making the clinical assessment difficult based on symptoms alone. There are many possible cardiac causes for CP, including but not limited to acute coronary syndrome, myocarditis and pericarditis in COVID-19 patients. Even in the setting of STelevation acute myocardial infarction the absence of obstructive coronary disease is common by invasive angiography in COVID-19 patients [3]. Therefore, it is challenging to choose the appropriate diagnostic test for CP evaluation in COVID-19 patients. Nevertheless, our findings suggest that the clinical risk stratification combined with CCTA remains to be appropriate and effective for coronary artery disease evaluation in COVID-19 patients with CP.

Derivation and Validation of a 4-Level Clinical Pretest Probability Score for Suspected Pulmonary Embolism to Safely Decrease Imaging Testing

Pulmonary embolism (PE) poses a diagnostic challenge to Emergency Medicine physicians because the signs and symptoms of PE are extremely common and unspecific. Multiple decisions tools have been created to help rule out this diagnosis and curb the overuse of imaging, particularly computed tomography pulmonary angiography (CTPA). Unnecessary CTPA places patients at risk for allergic reaction, renal failure, and long term radiation accumulation related diseases. Despite these efforts, there has been a large increase in the use of imaging to rule out PE.

Derivation and Validation of a 4-Level Clinical Pretest Probability Score for Suspected Pulmonary Embolism to Safely Decrease Imaging Testing

In patients with suspected pulmonary embolism (PE), overuse of diagnostic imaging is an important point of concern. To derive and validate a 4-level pretest probability rule (4-Level Pulmonary Embolism Clinical Probability Score [4PEPS]) that makes it possible to rule out PE solely on clinical criteria and optimized D-dimer measurement to safely decrease imaging testing for suspected PE. This study included consecutive outpatients suspected of having PE from US and European emergency departments. Individual data from 3 merged management studies (n = 11 114; overall prevalence of PE, 11%) were used for the derivation cohort and internal validation cohort. The external validation cohorts were taken from 2 independent studies, the first with a high PE prevalence (n = 1548; prevalence, 21.5%) and the second with a moderate PE prevalence (n = 1669; prevalence, 11.7%). A prior definition of pretest probability target values to achieve a posttest probability less than 2% was used on the basis of the negative likelihood ratios of D-dimer. Data were collected from January 2003 to April 2016, and data were analyzed from June 2018 to August 2019. The rate of PE diagnosed during the initial workup or during follow-up and the rate of imaging testing. Of the 5588 patients in the derivation cohort, 3441 (61.8%) were female, and the mean (SD) age was 52 (18.5) years. The 4PEPS comprises 13 clinical variables scored from -2 to 5. It results in the following strategy: (1) very low probability of PE if 4PEPS is less than 0: PE ruled out without testing; (2) low probability of PE if 4PEPS is 0 to 5: PE ruled out if D-dimer level is less than 1.0 μg/mL; (3) moderate probability of PE if 4PEPS is 6 to 12: PE ruled out if D-dimer level is less than the age-adjusted cutoff value; (4) high probability of PE if 4PEPS is greater than 12: PE ruled out by imaging without preceding D-dimer test. In the first and the second external validation cohorts, the area under the receiver operator characteristic curves were 0.79 (95% CI, 0.76 to 0.82) and 0.78 (95% CI, 0.74 to 0.81), respectively. The false-negative testing rates if the 4PEPS strategy had been applied were 0.71% (95% CI, 0.37 to 1.23) and 0.89% (95% CI, 0.53 to 1.49), respectively. The absolute reductions in imaging testing were -22% (95% CI, -26 to -19) and -19% (95% CI, -22 to -16) in the first and second external validation cohorts, respectively. The 4PEPS strategy compared favorably with all recent strategies in terms of imaging testing. The 4PEPS strategy may lead to a substantial and safe reduction in imaging testing for patients with suspected PE. It should now be tested in a formal outcome study.

Venous Thromboembolism or Vermin?

A 29-year-old woman presented to her general practitioner (GP)3 with progressive dyspnea for 2 months. Her only relevant medical history was asthma, normally well-controlled on inhaled corticosteroids. Her physical examination was unremarkable, and her Wells score for pulmonary embolism, a clinical pretest probability score, was low. Her GP requested a D-dimer to exclude a pulmonary embolism, which was >4000 μg/L [cutoff 4000 μg/L. Other routine laboratory tests, including coagulation screen, full blood count, creatinine, liver function tests, C-reactive protein, glucose, and rheumatoid factor were normal. Her chest radiograph and subsequent computed tomography pulmonary angiogram were both normal. She was discharged to the care of her GP with a course of prednisone for a presumed asthma exacerbation. The GP continued to monitor her D-dimer levels, which remained grossly increased (2670, 3020, and 2590 μg/L). Testing was carried out by a new community laboratory provider using the original assay and cutoff. Because the patient was concerned about her abnormal test results, she sought a second opinion from another doctor. Biochemistry staff were consulted, …

Evaluation of the usefulness of a D dimer test in combination with clinical pretest probability score in the prediction and exclusion of Venous Thromboembolism by medical residents.

IntroductionVenous thromboembolism (VTE) requires urgent diagnosis and treatment to avoid related complications. Clinical presentations of VTE are nonspecific and require definitive confirmation by imaging techniques. A clinical pretest probability (PTP) score system helps predict VTE and reduces the need for costly imaging studies. d-dimer (DD) assay has been used to screen patients for VTE and has shown to be specific for VTE. The combined use of PTP and DD assay may improve exclusion of VTE and safely avoid imaging studies.Materials and methodsWe prospectively used the Wells PTP score and a DD test to evaluate 230 consecutive patients who presented with VTE symptoms. The receiver operating characteristic curve was used to identify a new DD cutoff value, which was applied to VTE diagnosis and compared with the upper limit of locally established reference range for prediction of thrombosis alone and in combination with the clinical PTP score.ResultsWe evaluated 118 patients with VTE symptoms fulfilling the inclusion criteria, 64 (54.2%) with clinically suspected deep vein thrombosis (DVT) and 54 (45.8%) with symptoms of pulmonary embolism (PE). The PTP was low in 28 (43.8%) and moderate/high in 36 (56.25%) of the suspected DVT patients, and low in 29 (53.7%) and moderate/high in 25 (46.3%) of the suspected PE patients. Eighteen cases were confirmed by imaging studies: 9 DVT and 9 PE. The agreement between confirmed cases and PTP was significant with PE but not DVT. The negative predictive value for both DVT and PE with current DD cutoff value of <250 μg/L DDU was 100%, whereas with the calculated cutoff the NPV was 88%.ConclusionsWe confirm that PTP score is valuable tool for medical residents to improve the detection accuracy of VTE, especially for PE. The DD cutoff value of 250 μg/L FEU is ideal for excluding most cases of low PTP; however, the calculated cutoff was less specific for the exclusion of VTE.

Correlation between the clinical pretest probability score and the lung ventilation and perfusion scan probability.

Purpose:Aim of the study was to determine the accuracy of the clinical pretest probability (PTP) score and its association with lung ventilation and perfusion (VQ) scan.Materials and Methods:A retrospective analysis of 510 patients who had a lung VQ scan between 2008 and 2010 were included in the study. Out of 510 studies, the number of normal, low, and high probability VQ scans were 155 (30%), 289 (57%), and 55 (11%), respectively.Results:A total of 103 patients underwent computed tomography pulmonary angiography (CTPA) scan in which 21 (20%) had a positive scan, 81 (79%) had a negative scan and one (1%) had an equivocal result. The rate of PE in the normal, low-probability, and high-probability scan categories were: 2 (9.5%), 10 (47.5%), and 9 (43%) respectively. A very low correlation (Pearson correlation coefficient r = 0.20) between the clinical PTP score and lung VQ scan. The area under the curve (AUC) of the clinical PTP score was 52% when compared with the CTPA results. However, the accuracy of lung VQ scan was better (AUC = 74%) when compared with CTPA scan.Conclusion:The clinical PTP score is unreliable on its own; however, it may still aid in the interpretation of lung VQ scan. The accuracy of the lung VQ scan was better in the assessment of underlying pulmonary embolism (PE).

Diagnosis of DVT in the emergency department: adherence to guidelines

Background Patients presenting with suspected deep vein thrombosis (DVT) are common in the emergency department. Evidence based strategies for the diagnostic evaluation of these patients exists. The diagnosis is based on three criteria: a clinical pre-test probability score (Wells score), D-dimer testing, and ultrasound examination of the deep veins. The aim of our study was to evaluate the adherence to these guidelines in our emergency department.

Deep vein thrombosis and pulmonary embolism: diagnosis, treatment and prevention

Venous thromboembolism (VTE), encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE), is a major public health issue, with an incidence of 1/1,000 and thousands of VTE-related deaths each year in the UK. The estimated cost of VTE and its complications to the NHS is in excess of £600 million. 1 PE is the most common cause of inpatient mortality, and is the leading cause of death in pregnant women. Common risk factors include hospitalisation, surgery, cancer and immobilisation; and in women, combined oral contraceptive use, hormone replacement therapy and pregnancy. Approximately a quarter of VTE episodes are unprovoked, that is without an identifiable precipitant. 2 Clinical features of DVT include swelling and pain, pitting oedema, increased warmth and superficial venous dilation of the lower limb. PE may present with or without symptoms of a DVT in addition to chest pain, breathlessness, haemoptysis, syncope, hypotension, tachycardia and hypoxia. Without prompt recognition and treatment, PE can lead to death in up to 30%. Clinical diagnosis of VTE can be challenging and, furthermore, clinically silent episodes are not uncommon. Integrated diagnostic strategies have been demonstrated to be safe, efficacious and cost effective. 3 These strategies employ the use of a clinical pretest probability score (Table 1) in combination with D-dimer to inform the need for further diagnostic imaging. Patients at low risk of DVT/PE with a negative Ddimer result (using a high sensitivity assay) require no further investigation. However, those identified as moderate or high probability, or with a raised D-dimer require definitive imaging to confirm or exclude the diagnosis. Non-invasive compression ultrasonography is increasingly used first line for investigation of DVT, with advantages over venography including superior safety and portability. Sensitivity can be adversely affected by operator experience and poor views may be obtained in the presence of severe obesity, gross oedema or a plaster cast. However, its sensitivity for symptomatic proximal DVT remains up to 97%. 4 Computed tomography (CT) pulmonary angiography is currently accepted as the investigation of choice for PE diagnosis 5 ; its increased resolution allows detection of PE to subsegmental levels, in addition to detection of alternate diagnoses, such as, infection or cancer. Treatment for VTE is primarily aimed at prevention of clot extension, embolisation and symptom relief, with additional long-term aims of minimising recurrence and preventing postthrombotic syndrome. 6 Anticoagulation is the mainstay of treatment and should be initiated at confirmation of diagnosis or when first suspected if there is a delay in diagnostic imaging. Thrombolysis or surgical thrombectomy/embolectomy should be reserved for selected patients with haemodynamic instability due to massive PE or critical limb ischaemia secondary to DVT. Low molecular weight heparins (LMWHs) are the preferred agents for initiation of anticoagulation due to improved efficacy, safety and ease of administration with once daily subcutaneous injection. 6 Monitoring of the anticoagulant effect is not required routinely with LMWH and rates of early mortality, recurrence and major bleeding are reduced compared to unfractionated heparin, as is the risk of heparin-induced thrombocytopenia. Warfarin should be initiated once the diagnosis of VTE is confirmed, in the absence of contraindications,

The Diagnostic Dilemma of Pulmonary Embolism: Is It a Clinico-Investigatory Portrayal or Only an Investigatory Portrayal? A Clinically Based Study

Objectives: A balanced comparison between single photon emission computed tomographic (SPECT) lung scintigraphy with the planar imaging and multislice (MS) spiral computed tomography (CT) and correlating the outcomes with the clinical probabilities. Background: Pulmonary embolism (PE) is a potentially lethal serious problem with a confusing clinical database to diagnose. In the majority of the studies, the clinical probabilities were always in the scope of the secondary consideration, although they are the gates, patients step through to the investigatory zone. Methods: 68 patients suspected for PE (66% females and 34% males, mean age 43.5±15.3) were evaluated for pretest clinical probability score (PCPS) and investigated with ventilation/perfusion lung scintigraphy (planner & SPECT) and MS spiral CT. Results: 63% and 45.5% were positive for dyspnoea and deep venous thrombosis, respectively. They have low, intermediate and high PCPS of 47.1, 17.6 and 35.3%, respectively. Planner and SPECT studies were positive in 28/68 and 33/68 cases, respectively. SPECT showed 25 % more positives in the high clinical probability group (p-value 0.02). MS spiral CT was positive in 9/25 and negative in 16/25, with 2/25 false positive with SPECT and 4/25 disagreement with planner scans. Sensitivity, specificity, positive and negative predictive values were (100%, 87.5%, 81.8% and 100%) and (77.8%, 87.5%, 77.8% and 87.5%) for planner and SPECT, respectively. Conclusion: SPECT scintigraphy potentiates the diagnostic power of the clinical probability of the suspected cases with PE. It detects more positives and changes the planner based PIOPED categories, so we advise its routine use.

Impact of gender on the clinical presentation and diagnosis of deep-vein thrombosis

It is uncertain whether gender influences the clinical presentation of deep-vein thrombosis (DVT) and the discriminative value of the Wells diagnostic pretest probability score. The aim of the study was to determine whether gender impacts the clinical presentation and diagnosis of DVT. The study analysed a cohort of 4,976 outpatients with clinically suspected DVT of the leg prospectively recruited by 326 vascular medicine physicians in the German ambulatory care sector between October and December 2005. The diagnosis of DVT was based on compression ultrasonography in 96% of patients. Among 4,777 patients who had a diagnostic work-up for DVT there were more women (n=2,998) than men (n=1,779). However, the prevalence of confirmed DVT was 37.0% (658/1779) in men vs. 24.3% (730/2,998) in women (p<0.001). Among patients with confirmed DVT, proximal DVT was more common in men (59.6% vs. 44.5% in women, p<0.001). Swelling of the leg, pitting oedema and dilated superficial veins were more frequently reported by men (p<0.001). The percentage of patients with a high probability Wells clinical pretest score was higher in men than in women (67.0% vs. 57.0%, p<0.001). However, overall, the score equally discriminated risk groups for DVT in both sexes. In conclusion, women were more frequently referred for a diagnostic work-up for DVT than men, but the prevalence of DVT was higher in men and their thrombotic events were more severe. Nevertheless, the Wells clinical pretest probability score correctly identified low- and high-risk groups in both genders.

Combined use of pretest clinical probability score and latex agglutination D-dimer testing for excluding acute deep vein thrombosis

Currently, the latex agglutination D-dimer assay is widely used for excluding deep vein thrombosis (DVT) but is considered less sensitive than the enzyme-linked immunosorbent assay-based D-dimer test. The purpose of the present study was to determine if a combination of different cutoff points, rather than a single cutoff point of 1.0 microg/mL, on the latex agglutination D-dimer assay and the pretest clinical probability (PTP) score would be able to reduce the use of venous duplex ultrasound (DU) scanning in patients with suspected DVT. The PTP score and D-dimer testing were used to evaluate 989 consecutive patients with suspected DVT before venous DU scanning. After calculating the clinical probability scores, patients were divided into low-risk (< or =0 points), moderate-risk (1-2 points), and high-risk (> or =3 points) pretest clinical probability groups. Receiver operating characteristic (ROC) curve analysis was used to determine the appropriate D-dimer cutoff point for each PTP with a negative predictive value of >98% for a positive DU scan. There were 886 patients enrolled. The study group included 609 inpatients (68.7%) and 277 outpatients (31.3%). The prevalence of DVT in this series was 28.9%. There were 508 patients (57.3%) classified as low-risk, 237 (26.8%) as moderate-risk, and 141 (14.9%) as high-risk PTP. DVT was identified in 29 patients (5.7%) with low-risk, 118 (49.8%) with moderate-risk, and 109 (77.3%) with high-risk PTP scores. ROC curve analysis was used to select D-dimer cutoff points of 2.6, 1.1, and 1.1 microg/mL for the low-, moderate- and high-risk PTP groups, respectively. In the low-risk PTP group, specificity increased from 48.9% to 78.2% (P < .0001) with use of the different D-dimer cutoff value. In the moderate- and high-risk PTP groups, however, the different D-dimer levels did not achieve substantial improvement. Despite this, the overall use of venous DU scanning could have been reduced by 43.0% (381 of 886) if the different D-dimer cutoff points had been used. Combination of a specific D-dimer level with the clinical probability score is most effective in low-risk PTP patients for excluding DVT. In moderate- and high-risk PTP patients, however, the recommended cutoff points of 1.0 microg/mL may be preferable. These results show that different D-dimer levels for patients differing in risk is feasible for excluding DVT using the latex agglutination D-dimer assay.

Comparison of an immuno‐turbidometric method (STalia®d‐DI) with an established enzyme linked fluorescent assay (VIDAS®) d‐dimer for the exclusion of venous thromboembolism

The use of d-dimer tests for the exclusion of venous thromboembolism is an important advance in clinical practice and also has economic benefits. The Stalia D-Di (Diagnostica Stago, Asnieres, France) is a semi automated system for the quantification of d-dimer using an immuno-turbidometric method incorporating a suspension of latex microparticles coated with two different monoclonal antibodies specifically targeted against human d-dimer fragments. Results are available rapidly in <10 min compared with 35 min for the established VIDAS D-dimer automated enzyme-linked immunosorbent assay (ELISA, BioMerieux, Basingstoke, UK). During November and December 2005, 100 consecutive patients attending the outpatient deep venous thrombosis (DVT) clinic were tested using the VIDAS D-dimer as part of the routine DVT investigation. Using the same samples, D-dimer estimation was also performed on the STalia D-Di for comparison. Across a wide range of data (Vidas 83-5656) and (STali <200->4000), there was good agreement between the two methods. Using cutoff's of 500 microg/l fibrinogen equivalent units (Keeling et al., 1999), 42% (42/100) patients were negative (<500) and 46% (46/100) were positive (>500) on both systems. Six per cent (6/100) were positive on the Vidas but negative on the STalia and another 6% (6/100) were positive on the STalia but negative on the Vidas. In conclusion, 88% (88/100) of patients showed agreement and in the other 12% (12/100), one had a DVT as identified by Compression ultrasonography (CUS). In this study, there were seven patients with a DVT as identified by CUS and they all scored as 'likely' on a pretest clinical probability score and so negative D-dimer would not be used clinically to rule out the disease. The Vidas is a well established instrument for D-dimer measurement in outpatient DVT clinics, and in this small study the STalia compares very well and therefore would fit into an outpatient setting for D-dimer measurement. But ideally a larger study would be required before implementing new methodology in a clinical setting.

Uses of different D-dimer levels can reduce the need for venous duplex scanning to rule out deep vein thrombosis in patients with symptomatic pulmonary embolism

This study investigated the prevalence and distribution of deep vein thrombosis (DVT) in patients with symptomatic pulmonary embolism (PE) to establish a screening protocol to reduce unnecessary venous duplex scanning using different D-dimer level rather than single cutoff point of 0.5 microg/mL in patients with low and moderate pretest clinical probability (PTP). The PTP score and D-dimer testing were used to evaluate 85 consecutive patients with symptomatically proven PE before venous duplex scanning. After calculating the PTP score, patients were divided into low (<or=0 points), moderate (1 to 2 points), and high (>or=3 points) PTP groups. The receiver operating characteristic (ROC) curves analysis was used to determine the appropriate D-dimer cutoff point in low and moderate PTP, with a negative predictive value of >98%. The study enrolled 81 patients. The prevalence of DVT was 63%, with 27 patients (33%) classified as low, 38 (47%) as moderate, and 16 (20%) as high PTP. DVT was detected in nine patients (33%) in the low PTP group, in 27 (71%) in the moderate group, and in 15 (94%) in the high group. In the low PTP patients, the difference in the value of D-dimer assay between positive-scan and negative-scan patients was statistically significant (9.99 +/- 7.33 vs 3.46 +/- 4.20, respectively; P = .008). Conversely, no significant difference in the D-dimer assay value between positive and negative scan results was found in the moderate PTP patients. ROC curves analysis were used to select D-dimer cutoff points of 2.0 microg/mL for the low PTP group and 0.7 microg/mL for the moderate PTP groups. For both groups, D-dimer testing provided 100% sensitivity and 100% negative predictive value in the diagnosis of DVT. In the low PTP group, specificity increased from 33% to 67% (P = .046). In the moderate PTP group, however, the determined D-dimer level did not improve the specificity. Overall, venous duplex scanning could have been reduced by 17% (14/81) by using different D-dimer cutoff points. A combination of specific D-dimer level and clinical probability score is most effective in the low PTP patients in excluding DVT. In the moderate PTP group, however, the recommended cutoff point of 0.5 microg/mL may be preferable. These results show that a different D-dimer level is more useful than single cutoff point of 0.5 microg/mL in excluding DVT in established PE patients.

The role of fibrin monomers in optimizing the diagnostic work-up of deep vein thrombosis

Despite the use of a clinical score and D-dimers to exclude deep vein thrombosis (DVT), the majority of patients still need repeated ultrasound (US). The aim of the study was to investigate whether fibrin monomers (FMs), as markers of thrombin generation, have additional value in the diagnosis of DVT. This is a posthoc analysis of 464 outpatients, participants in a management study using D-dimers (Tina-Quant and a clinical score in the exclusion of DVT. Two new FM assays (Auto LIA-FM and IATRO SF, Japan) were performed. Overall sensitivity, negative predictive value (NPV) and specificity of the D-dimer test were 98%, 98% and 42%. The optimal cut-off point for the Auto LIA-FM test was <or=3 microg/ml with values of 88%, 88% and 59%, respectively. The IATRO SF test had an optimal cut-off point of <or=2 microg/ml with values of 92%, 81 and 22%, respectively. The NPV of a non-high clinical score and a normal D-dimer (n=97) was 100%. In patients with a high clinical score (n=160), the NPV of the D-dimer was 88%. In these patients, a single US combined with a normal D-dimer or FM test had an equal NPV as serial US (100 versus 98%, respectively) and lead to a reduction in the need for US by 36-53%, respectively. In patients with abnormal D-dimer concentrations (n=343), a normal US combined with a normal Auto LIA-FM test had a NPV of 97%, which was also true for serial US. This could lead to a reduction in the need for US by 45%. The present studied FMs are inferior to the Tina-Quant D-dimer test when used as primary screening tool to exclude DVT. Adding these FMs to patients with a normal Tina-Quant D-dimer has no benefit. In patients with a high pretest clinical probability score, a single US in combination with a normal D-dimer or FM test might be as safe as serial US. In patients with abnormal D-dimer concentrations and a normal US, a normal FM test might be able to replace the second US.

Evaluation of clinical model for deep vein thrombosis: a cheap alternative for developing countries

Background : Deep vein thrombosis is an important cause of morbidity and mortality worldwide. The clinical features are non-specific and the clinical diagnosis is unreliable. The objective testing for the correct diagnosis is not usually available in most developing countries and the expertise are not readily available couple with the high cost of such investigations. Objectives : This study was intended therefore to evaluate a validated clinical model for deep vein thrombosis and to see if there is correlation between the clinical model and results of the Doppler sonography, in suspected cases of deep vein thrombosis. Method : A prospective evaluation of 21 inpatients with suspected deep vein thrombosis seen at the department of Haematology and Radiology of the University of Maiduguri Teaching Hospital over a period of 24 months from October 2002 to October 2004. Results : Twelve (57.1% of the 21 patients evaluated had a high pretest clinical probability score of 3 and above, 6(28.6%) of them had intermediate score of 1 or 2 and 3 (14.3%) had a low score of 0 or less. There was a 100% correlation between the high-risk categories and the ultrasound findings and no correlation for both the intermediate and the low-risk categories. Conclusion : The study suggest that a high pretest clinical probability score of 3 and above is reliable for the diagnosis of deep vein thrombosis and treatment can be initiated in at least emergency situation without much delay. Also a D-dimer assay is recommended for all patients with a low or intermediate pretest clinical probability score so as to avoid unnecessary use of ultrasonography. Keywords : clinical model, DVT, developing countries Sahel Medical Journal Vol. 9(1) 2006: 15-18

Prospective Evaluation of a Screening Protocol to Exclude Deep Vein Thrombosis on the Basis of a Combination of Quantitative D-Dimer Testing and Pretest Clinical Probability Score

Clinical signs and symptoms such as swelling, pain, and redness are unreliable markers of deep vein thrombosis (DVT). Because of this venous duplex scanning (VDS) has been heavily used in DVT detection. The purpose of this study was to determine if a combination of D-dimer testing and pretest clinical score could reduce the use of VDS in symptomatic patients with suspected DVT. One hundred seventy-four consecutive patients with suspected DVT were prospectively evaluated using pretest clinical probability (PCP) score and D-dimer testing before VDS. After calculating clinical probability scores developed by Wells and associates, patients were divided into low risk (<or= 0 points), moderate risk (1 to 2 points), and high risk (>or=3 points) PCP. One hundred fifty-eight patients were enrolled. The prevalence of DVT in this study was 37%. Thirty-eight patients (24%) were classified as low risk, 64 (41%) as moderate risk, and 56 (35%) as high risk PCP. DVT was identified in only one patient (2.6%) with low risk PCP. In contrast, DVT was found in 22 (34%) with moderate risk, and 35 (63%) with high risk PCP. In the high and moderate risk PCP groups, positive scan patients had a markedly higher value of D-dimer assay than negative scan patients (p=0.0001 and p=0.0057, respectively). In the low risk PCP patients, D-dimer testing provided 100% sensitivity, 46% specificity, 4.8% positive predictive value, and 100% negative predictive value in the diagnosis of DVT. Similarly, in the moderate risk PCP, the D-dimer testing showed 100% sensitivity, 45% specificity, 49% positive predictive value, and 100% negative predictive value. In the high risk group, D-dimer testing achieved 100% sensitivity, 57% specificity, 80% positive predictive value, and 100% negative predictive value in the diagnosis of DVT. These results suggested that 36 of 158 patients who had a non-high PCP (low and moderate PCP) and a normal D-dimer concentration were considered to have no additional investigation, so VDS could have been reduced by 23% (36/158). A combination of D-dimer testing and clinical probability score may be effective in avoiding unnecessary VDS in suspected symptomatic DVT in the low and moderate PCP patients. The need for VDS could be reduced by 23% despite a relatively high prevalence of DVT.

Reduced efficacy of clinical probability score and d‐dimer assay in elderly subjects suspected of having deep vein thrombosis

The combined strategy of a pretest clinical probability (PCP) score and D-dimer has shown to be of value in the diagnosis of deep vein thrombosis (DVT). As D-dimer concentrations increase with age, the effect of age on the usefulness of this strategy was retrospectively investigated in outpatients suspected of having DVT. In all patients, participants of a prospective management trial, a PCP score and D-dimer (Tina-quant) were performed. In a total of 812 patients, 317 (39%) had thrombosis. Patients were divided into quartiles according to their age. Sensitivity and negative predictive value of a low/moderate PCP score and a normal D-dimer were 98-100% and did not differ between the different age quartiles. Specificity in the highest quartile was 17.4% compared with 49.2% in the youngest (P < 0.000001). The proportion of patients with a low/moderate PCP score and a normal D-dimer decreased with age: 12% in the highest quartile (>73.8 years) versus 25% in younger patients (P = 0.00005). We therefore conclude that the combined strategy of a low/moderate PCP score with a normal D-dimer test is safe for excluding DVT in all age groups, but is less useful in the elderly.