Management of suspected pulmonary embolism (PE) by D-dimer and multi-slice computed tomography in outpatients: an outcome study

OBJECTIVES: A prospective outcome study designed to evaluate a simple strategy for the management of outpatients with suspected pulmonary embolism (PE), based on clinical probability, D-dimer, and multi-slice computed tomography (MSCT). METHODS: A cohort of 432 consecutive patients admitted to the emergency department with suspected PE was managed by sequential non-invasive testing. Patients in whom PE was ruled out were not given anticoagulants, but were followed-up for 3 months. RESULTS: Normal D-dimer and low-intermediate clinical probability ruled out PE in 103 patients [24% (95% CI 20-28)]. Seventeen patients had normal D-dimer, but high clinical probability and proceeded to MSCT. All patients proved negative for PE. A total of 329 (76%) patients underwent MSCT examination. Pulmonary embolism was diagnosed in 93 patients [21.5% (95% CI 18-26)] and was ruled out by negative MSCT in 221 patients [51% (95% CI 46-56)]. MSCT scans were determined as inconclusive in 15 (4.5%) patients. No patient developed objectively verified venous thromboembolism (VTE) during the 3-month follow-up period. However, the cause of death was adjudicated as possibly related to PE in two patients, resulting in an overall 3-month VTE risk of 0.6% (95% CI 0-2.2%). The diagnostic algorithm yielded a definite diagnosis in 96.5% of the patients. CONCLUSIONS: This simple and non-invasive strategy combining clinical probability, D-dimer, and MSCT for the management of outpatients with suspected PE appears to be safe and effective.     

Validation of the Canadian Clinical Probability Model for Acute Venous Thrombosis

OBJECTIVE: To validate the predictive value of the Canadian clinical probability model for acute venous thrombosis, which, to the best of the authors' knowledge, has not been done in emergency department (ED) settings outside of Canada. METHODS: Demographic and clinical information, rapid D-dimer testing, and venous ultrasound imaging were obtained among patients presenting with clinically suspected venous thrombosis at a university-affiliated ED. A diagnosis of deep venous thrombosis (DVT) was made based on venous ultrasound test results or objectively documented venous thromboembolism during a 12-week follow-up period. The probability of venous thrombosis was calculated using the Canadian clinical probability model. RESULTS: Among 102 patients, 17 (17%) were diagnosed as having venous thrombosis initially or during the three-month follow-up period. The frequency of venous thrombosis among patients categorized as having high probability was 10 of 17 [59%, 95% confidence interval (95% CI) = 35% to 82%], 6 of 44 (14%, 95% CI = 4% to 24%) with intermediate probability, and 1 of 41 (2%, 95% CI = 0.1% to 11%) with low probability. This compares with respective values of 49%, 14%, and 3%, reported by Canadian researchers in an ED study. Forty-one of 102 (40%) patients had an alternate diagnosis as likely or more likely than venous thrombosis, but only three (7%, 95% CI = 2% to 18%) of these had venous thrombosis. CONCLUSIONS: Use of the Canadian probability model for DVT in this ED resulted in effective risk stratification, comparable to previously published results.     

Diagnostic accuracy of biomarker D-dimer in patients after stroke suspected from venous thromboembolism: A diagnostic meta-analysis

D-dimer is a promising biomarker for identification of venous thromboembolism (VTE) in patients with stroke. The purpose of our study is to evaluate the diagnostic value of D-dimer as a promising biomarker for VTE in patients after stroke. We performed an exhaustive search of leading databases including Pubmed, Embase, the Cochrane library, China National Knowledge Infrastructure (CNKI), and China Biology Medicine disc (CBM) from inception to Oct 13, 2017. We included studies written in English and Chinese. We included studies that appraised the diagnostic value of D-dimer with reference standard for VTE diagnosis in patients after stroke. We concurrently constructed a 2 × 2 table with data extracted from included studies. We identified 8 studies that included 1490 patients after stroke from our database searches. The pooled result from limited evidence showed a sensitivity of 0.85 (95% CI 0.76–0.90) and a specificity of 0.77 (95% CI 0.73–0.81). The area under the summary receiver operating characteristic curve was 0.85(95% CI 0.81–0.88). The positive likelihood ratio (LR+) and the negative likelihood ratio (LR-) were 3.8 (95% CI 3.1–4.4) and 0.20(95% CI 0.12–0.31), respectively. In patients after stroke suspected of venous thromboembolism, D-dimer is a beneficial biomarker for diagnosis of VTE. For stroke patients with low probability of VTE, a normal D-dimer test can be used to rule-out VTE. However, we do not recommend using D-dimer as the single definitive test for VTE diagnosis. We recommend diagnosing VTE using multi-branch diagnostic strategy.     

血浆D-二聚体对疑似肺栓塞患者诊断价值的研究

目的：探讨血浆 D-二聚体对对疑似肺栓塞患者的诊断价值。方法采用自动化免疫比浊法测定患者血浆D-二聚体水平。统计分析血浆D-二聚体诊断肺栓塞的敏感性、特异性、阴性及阳性预测值,并绘制ROC曲线以评价其诊断价值并对D-二聚体阴性排除肺栓塞价值进行分析。结果在317例疑似肺栓塞患者中D-二聚体＜500μg/L的患者73例,其中6例被诊断为肺栓塞。D-二聚体对肺栓塞的诊断的敏感性为95.86%（95%CI：91.27%～98.08%）,特异性为38.95%（95%CI：31.98%～41.41%）,阴性预测值为91.78%（95%CI：83.21%～96.18%）,阳性预测值为56.97%（95%CI：50.69%～63.02%）,诊断准确性为64.98%（95%CI：59.58%～70.03%）。ROC曲线下面积为0.674（95%CI：0.615～0.733）。结论 D-二聚体对肺栓塞的诊断具有较高的敏感性,阴性排除肺栓塞的准确性较高,但仍可受患者年龄、测试方法等的影响。     

Tandem measurement of D-dimer and myeloperoxidase or C-reactive protein to effectively screen for pulmonary embolism in the emergency department

OBJECTIVES: The hypothesis was that the tandem measurement of D-dimer and myeloperoxidase (MPO) or C-reactive protein (CRP) could significantly decrease unnecessary pulmonary vascular imaging in emergency department (ED) patients evaluated for pulmonary embolism (PE) compared to D-dimer alone. METHODS: The authors measured the sequential combinations of D-dimer and MPO and D-dimer and CRP in a prospective sample of ED patients evaluated for PE at two centers. Patients were followed for 90 days for venous thromboembolism (VTE, either PE or deep venous thrombosis [DVT]), which required the consensus of two of three blinded physician reviewers. RESULTS: The authors enrolled 304 patients, 22 with VTE (7%; 95% confidence interval [CI] = 5% to 10%). The sensitivity and specificity of a D-dimer alone (cutoff > or = 500 ng/mL) were 100% (95% CI = 85% to 100%) and 59% (95% CI = 53% to 65%), respectively, and was followed by pulmonary vascular imaging negative for PE in 38% (115/304; 95% CI = 32% to 44%). The combination of either a negative D-dimer, or MPO < 22 mg/dL, had a sensitivity of 100% and specificity of 73% (95% CI = 67% to 78%). Thus, tandem measurement of D-dimer and MPO would have decreased the frequency of subsequent negative pulmonary vascular imaging from 38% to 25% (95% CI of the difference of -13% = -5% to -20%). The combination of CRP and D-dimer would not have significantly improved the rate of negative imaging. CONCLUSIONS: The tandem measurement of D-dimer and MPO would have significantly decreased negative pulmonary vascular imaging compared with D-dimer alone and should be validated prospectively.     

D-Dimer test in cancer patients with suspected acute pulmonary embolism

BACKGROUND: The safety of a D-dimer (DD) measurement in cancer patients with clinically suspected pulmonary embolism (PE) is unclear. OBJECTIVES: The aim of this study was to assess the accuracy of the DD test in consecutive patients with clinically suspected PE with and without cancer. METHODS: The diagnostic accuracy of DD (Tinaquant D-dimer) was first retrospectively assessed in an unselected group of patients referred for suspected PE (n = 350). Subsequently, the predictive value of the DD was validated in a group of consecutive inpatients and outpatients with clinically suspected PE prospectively enrolled in a management study (n = 519). The results of the DD test in cancer patients were assessed according to the final diagnosis of PE and the 3-month clinical follow-up. RESULTS: In the first study group, DD showed a sensitivity and a negative predictive value (NPV) of 100% and 100% in patients with cancer and 97% and 98% in those without malignancy, respectively. In the validation cohort, the sensitivity and NPV of DD were both 100% (95% CI 82%-100% and 72%-100%, respectively), whereas in patients without malignancy, the corresponding estimates were 93% (95% CI 87%-98%) and 97% (95% CI, 95%-99%), respectively. The specificity of DD was low in patients with (21%) and without cancer (53%). CONCLUSIONS: A negative DD result safely excludes the diagnosis of PE in patients with cancer. Because of the low specificity, when testing 100 patients with suspected PE, a normal DD concentration safely excludes PE in 15 patients with cancer and in 43 patients without cancer.     

Clinical probability and alveolar dead space measurement for suspected pulmonary embolism in patients with an abnormal D-dimer test result

BACKGROUND: Most patients with suspected pulmonary embolism (PE) have a positive D-dimer test and undergo diagnostic imaging. Additional non-invasive bedside tests are required to reduce the need for further diagnostic tests. OBJECTIVES: We aimed to determine whether a combination of clinical probability assessment and alveolar dead space fraction measurement can confirm or exclude PE in patients with an abnormal D-dimer test. METHODS: We assessed clinical probability of PE and alveolar dead space fraction in 270 consecutive in- and outpatients with suspected PE and positive D-dimer. An alveolar dead space fraction < 0.15 was considered normal. PE was subsequently excluded or confirmed by venous compression ultrasonography, spiral computed tomography and a 3-month follow-up. Radiologists were unaware of the results of clinical probability and capnography. RESULTS: PE was confirmed in 108 patients (40%). Capnography had a sensitivity of 68.5% (95% confidence interval [CI]: 58.9-77.1%) and a specificity of 81.5% (95% CI: 74.6-87.1%) for PE. Forty-five patients (16.6%) had both a low clinical probability and normal capnography (sensitivity: 99.1%, 95% CI: 94.9-100%) and 34 patients (12.6%) had both a high clinical probability and abnormal capnography (specificity: 100%, 95% CI: 97.7-100%). CONCLUSION: Capnography alone does not exclude PE accurately. The combination of clinical probability and capnography accurately excludes or confirms PE and avoids further testing in up to 30% of patients.     

Accuracy of clinical decision rule, D-dimer and spiral computed tomography in patients with malignancy, previous venous thromboembolism, COPD or heart failure and in older patients with suspected pulmonary embolism

BACKGROUND: The diagnostic work-up of patients with suspected pulmonary embolism (PE) has been optimized and simplified by the use of clinical decision rules (CDR), D-dimer (DD) testing and spiral computed tomography (s-CT). Whether this strategy is equally safe and efficient in specific subgroups of patients is evaluated in this study. METHODS: A diagnostic strategy including a CDR, DD test and s-CT was evaluated in patients with malignancy, previous venous thromboembolism (VTE), chronic obstructive pulmonary disease or heart failure and in older patients. PE was ruled out by either an unlikely CDR and a normal DD or a s-CT negative for PE. The safety of these tests was assessed by the 3-month incidence rate of symptomatic VTE in those without PE at baseline. The efficiency was evaluated by calculating the numbers needed to test for the different subgroups. RESULTS: The venous thromboembolic incidence rate after the combination of an unlikely CDR and a normal DD varied from 0% (95% CI: 0-7.9%) in the 482 patients older than 75 years of age to 2% (95% CI: 0.05-10.9%) in the 474 patients with a malignancy. For s-CT these incidences varied from 0.3% to 1.8%. The number needed to test in order to rule out one patient from PE with the studied strategy was highest in cancer patients and in the elderly patients (approximately 10). CONCLUSION: It appears to be safe to rule out PE by either the combination of an unlikely CDR and a normal DD or by a negative s-CT in various subgroups of patients with suspected PE. However, the clinical usefulness of the CDR in combination with the DD as the initial step in the diagnostic process varied among these patient groups.     

Direct Comparison of the Diagnostic Accuracy of Fifty Protein Biological Markers of Pulmonary Embolism for Use in the Emergency Department

Objectives: Pulmonary embolism (PE) is associated with abnormal concentrations of many proteins involved in inflammation, hemostasis, and vascular injury. The authors quantified the diagnostic accuracy of a battery of protein biological markers for the detection of PE in emergency department (ED) patients. Methods: A random and a consecutive sample of ED patients evaluated for PE were prospectively enrolled at two academic EDs between August 2005 and April 2006. A plasma sample was obtained at enrollment, and all patients were followed by telephone and medical record review at 90 days for the development of venous thromboembolism (VTE) defined as PE or deep venous thrombosis (DVT), requiring the consensus of two of three blinded physician reviewers. Measurements of potential biological markers were performed by technicians blinded to the study objectives. The diagnostic accuracy of each biological marker was determined by the area under the receiver operating characteristic (ROC) curve. Results: Fifty potential biological markers were measured in 304 ED patients, including 22 patients (7%, 95% confidence interval [CI] = 4% to 10%) with VTE. Fourteen biological markers demonstrated an area under the curve (AUC) with the lower limit of the 95% CI ≥ 0.5. Of these, three demonstrated an AUC ≥ 0.7: D‐dimer (0.90), C‐reactive protein (CRP; 0.78), and myeloperoxidase (MPO; 0.78). Conclusions: From 50 candidate biological markers, only D‐dimer, CRP, and MPO demonstrated sufficient diagnostic accuracy to suggest potential utility as biological marker of PE.     

Value of Quantitative D-dimer Assays in Identifying Pulmonary Embolism: Implications from a Sequential Decision Model

Objectives: To examine the cost-effectiveness of a quantitative D-dimer assay for the evaluation of patients with suspected pulmonary embolism (PE) in an urban emergency department (ED).
Methods: The authors analyzed different diagnostic strategies over pretest risk categories on the basis of Wells criteria by using the performance profile of the ELISA D-dimer assay (over five cutoff values) and imaging strategies used in the ED for PE: compression ultrasound (CUS), ventilation–perfusion (VQ) scan (over three cutoff values), CUS with VQ (over three cutoff values), computed tomography (CT) angiogram (CTA) with pulmonary portion (CTP) and lower-extremity venous portion, and CUS with CTP. Data used in the analysis were based on literature review. Incremental costs and quality-adjusted-life-years were the outcomes measured.
Results: Computed tomography angiogram with pulmonary portion and lower-extremity venous portion without D-dimer was the preferred strategy. CUS-VQ scanning always was dominated by CT-based strategies. When CTA was infeasible, the dominant strategy was D-dimer with CUS-VQ in moderate- and high-Wells patients and was D-dimer with CUS for low-Wells patients. When CTP specificity falls below 80%, or if its overall performance is markedly degraded, preferred strategies include D-dimer testing. Sensitivity analyses suggest that pessimistic assessments of CTP accuracy alter the results only at extremes of parameter settings.
Conclusions: In patients in whom PE is suspected, when CTA is available, even the most sensitive quantitative D-dimer assay is not likely to be cost-effective. When CTA is not available or if its performance is markedly degraded, use of the D-dimer assay has value in combination with CUS and a pulmonary imaging study. These conclusions may not hold for the larger domain of patients presenting to the ED with chest pain or shortness of breath in whom PE is one of many competing diagnoses.     

Assessment of the pulmonary embolism rule-out criteria rule for evaluation of suspected pulmonary embolism in the emergency department

Background

Overuse of resources when evaluating pulmonary embolism (PE) is a concern if the D-dimer assay is improperly used in the evaluation of emergency department patients with suspected PE. The pulmonary embolism rule-out criteria (PERC) rule was derived to prevent unnecessary diagnostic testing in this patient population. The objective of this study was to assess the PERC rule's performance in an external population.

Methods

This was a secondary analysis of a prospectively collected database comparing PERC rule variables to diagnosis of PE in consecutive patients with suspicion for PE. Bivariate analysis on individual variables and the overall accuracy of the PERC rule were performed.

Results

Patients on 120 randomly assigned shifts were enrolled with a PE prevalence of 12%. The sensitivity, specificity, positive predictive, and negative predictive values of the PERC rule were 100% (95% confidence interval [CI], 79%-100%), 16% (95% CI, 10%-24%), 14% (95% CI, 8%-14%), and 100% (95% CI, 80%-100%), respectively, for the total patient population, and 100% (95% CI, 25%-100%), 33% (95% CI, 12%-35%), 2% (95% CI, 0%-11%), and 100% (95% CI, 75%-100%), respectively, for the low pretest probability population. Bivariate analysis showed unilateral leg swelling, recent surgery, and a history of venous thromboembolic event to be predictive of the diagnosis of PE.

Conclusions

The PERC rule may identify a cohort of patients with suspected PE for whom diagnostic testing beyond history and physical examination is not indicated.     

Comparison of the age-adjusted and clinical probability-adjusted D-dimer to exclude pulmonary embolism in the ED

Background

Diagnosing pulmonary embolism (PE) in the emergency department (ED) can be challenging because its signs and symptoms are non-specific.

D-dimer levels in VTE patients with distal and proximal clots

Objectives

There is growing evidence that venous thromboembolism (VTE) patients with distal clots (distal calf deep vein thrombosis [DVT] and sub-segmental pulmonary embolism [PE]) may not routinely benefit from anticoagulation. We compared the D-dimer levels in VTE patients with distal and proximal clots.

Impact of Helical Computed Tomography on the Outcomes of Emergency Department Patients with Suspected Appendicitis

OBJECTIVES: To assess the impact of an emergency department (ED) guideline employing selective use of helical computed tomography (CT) on clinical outcomes of female patients with suspected appendicitis. METHODS: All patients presenting with suspected appendicitis were prospectively enrolled and managed in accordance with a guideline incorporating selective use of helical CT. Although not the objective of this investigation, male patients were included for purposes of comparison. Patients with clinically evident appendicitis were referred to the surgical service, and patients with equivocal presentations were studied with helical CT. Patients were followed to final surgical or clinical outcomes. Outcome measures included time from ED presentation to laparotomy and rate of appendiceal perforation. These measures were compared with those of a historical cohort of patients preceding the use of helical CT. RESULTS: A total of 310 consecutive patients with suspected appendicitis were enrolled; 92 had appendicitis. Sixty patients were referred to the surgical service without helical CT, and 41 had appendicitis (68%). Helical CT was performed on 250 patients; 51 had appendicitis (20%). For males, the mean interval from ED presentation to laparotomy was 559 minutes (95% CI = 444 to 674 minutes) during guideline use and 480 minutes (95% CI = 405 to 555 minutes) before. This interval for females was 433 minutes (95% CI = 326 to 540 minutes) during guideline use and 710 minutes (95% CI = 558 to 862 minutes) before. Appendiceal perforation rate for males was 0.25 (95% CI = 0.14 to 0.36) during guideline use and 0.38 (95% CI = 0.29 to 0.47) before; perforation rate for females was 0.06 (95% CI = -0.05 to 0.17) during guideline use and 0.23 (95% CI = 0.14 to 0.32) before. Helical CT had 92% sensitivity, 97% specificity, and 96% accuracy in diagnosing appendicitis. CONCLUSIONS: Helical CT is highly accurate in detecting appendicitis in patients with equivocal ED presentations. The use of a guideline employing selective helical CT was associated with a decline in the time from ED presentation to operative intervention in females.     

Potential Impact of Adjusting the Threshold of the Quantitative D-dimer Based on Pretest Probability of Acute Pulmonary Embolism

Objectives: The utility of D‐dimer testing for suspected pulmonary embolism (PE) can be limited by test specificity. The authors tested if the threshold of the quantitative D‐dimer can be varied according to pretest probability (PTP) of PE to increase specificity while maintaining a negative predictive value (NPV) of >99%. Methods: This was a prospective, observational multicenter study of emergency department (ED) patients in the United States. Eligible patients had a diagnostic study ordered to evaluate possible PE. PTP was determined by the clinician’s unstructured estimate and the Wells score. Five different D‐dimer assays were used. D‐dimer test performance was measured using 1) standard thresholds and 2) variable threshold values: twice (for low PTP patients), equal (intermediate PTP patients), or half (high PTP patients) of standard threshold. Venous thromboembolism (VTE) within 45 days required positive imaging plus decision to treat. Results: The authors enrolled 7,940 patients tested for PE, and clinicians ordered a quantitative D‐dimer for 4,357 (55%) patients who had PTPs distributed as follows: low (74%), moderate (21%), or high (4%). At standard cutoffs, across all PTP strata, quantitative D‐dimer testing had a test sensitivity of 94% (95% confidence interval [CI] = 91% to 97%), specificity of 58% (95% CI = 56% to 60%), and NPV of 99.5% (95% CI = 99.1% to 99.7%). If variable cutoffs had been used the overall sensitivity would have been 88% (95% CI = 83% to 92%), specificity 75% (95% CI = 74% to 76%), and NPV 99.1% (95% CI = 98.7% to 99.4%). Conclusions: This large multicenter observational sample demonstrates that emergency medicine clinicians currently order a D‐dimer in the majority of patients tested for PE, including a large proportion with intermediate PTP and high PTP. Varying the D‐dimer’s cutoff according to PTP can increase specificity with no measurable decrease in NPV.     

The predictive characteristics of D-dimer testing in outpatients with suspected venous thromboembolism: a Bayesian approach

BACKGROUND: Despite the widespread use of quantitative methods to measure D-dimer, clinical decisions commonly are based only on binary test information (positive/negative). This study aimed to determine the significance of quantitative D-dimer results in the evaluation of venous thromboembolism (VTE) by means of a differentiated Bayesian approach. METHODS: Prospective study in 118 outpatients referred for workup of suspected pulmonary embolism (n = 75) or deep vein thrombosis (n = 43). The sensitivity and specificity of D-dimer results obtained by DD VIDAS (Biomerieux, France), STA Liatest (Diagnostica Stago, France), and D-dimer plus (Dade, US) were assessed for five different cut-offs. Further, predictive values and multilevel likelihood ratios were calculated in order to assess the operative test characteristics in excluding or confirming VTE. RESULTS: At a cut-off of 500 ng/ml and pretest probabilities < 47%, the VIDAS provides a negative predictive value (NPV) > 95%, whereas a positive predictive value (PPV) > 95% is obtained in patients with a D-dimer > 10,000 ng/ml and pretest probabilities > 50%. At a cut-off of 500 ng/ml and pretest probabilities < 33%, the Liatest exhibits a NPV > 95%, whereas a PPV > 95% is obtained in patients with a D-dimer >10,000 ng/ml and pretest probabilities > 37%. Finally, with the D-dimer plus, a NPV > 95% is seen at a cut-off of 150 ng/ml and pretest probabilities < 30%, whereas a PPV > 95% is obtained at a cut-off > 1000 ng/ml and pretest probabilities > 67%. CONCLUSIONS: D-dimer measurements in outpatients cannot only allow for exclusion but, in some situations, also for confirmation of venous thromboembolism. It is therefore advisable to conduct a quantitative interpretation of D-dimer results.     

Management studies using a combination of D-dimer test result and clinical probability to rule out venous thromboembolism: a systematic review

BACKGROUND: While the number of patients with suspected venous thromboembolism (VTE) referred to hospital emergency units increases, the proportion in whom the diagnosis can be confirmed is decreasing. A more efficient but safe diagnostic strategy is needed. OBJECTIVE: To evaluate the safety of withholding anticoagulant therapy in patients suspected of VTE based on a diagnostic work-up that combines a clinical decision rule (CDR) with a D-dimer test result without performing additional diagnostic tests. PATIENTS/METHODS: We searched Medline (January 1996-December 2004)-related articles and reference lists of studies in English for prospective clinical studies that managed consecutive patients suspected of VTE and used a D-dimer assay combined with an explicit CDR or implicit clinical judgment. RESULTS: We identified 11 studies in which 6837 consecutive outpatients suspected of VTE were included. In the combined management studies, the overall rate of thromboembolic events was nine out of 2056 patients (0.44 %, 95% CI 0.2%-0.83%) in whom anticoagulants were withheld based on the D-dimer result and a low clinical score. Similar results were obtained with qualitative and quantitative D-dimer tests and with different decision rules. The rate of exclusion varied between 30% and 50% and was highest with a low incidence of VTE among those referred. CONCLUSION: Withholding anticoagulant treatment in patients suspected of VTE on the basis of a work-up consisting of a low clinical probability combined with either a qualitative or quantitative D-dimer test result is safe.     

Utilization and Yield of Chest Computed Tomographic Angiography Associated with Low Positive D-dimer Levels

Background

It is unclear to what degree broadly applied D-dimer testing combined with a low threshold for imaging with even minimally positive results may be contributing to the utilization of chest computed tomographic angiography (CTA).

Study Objectives

To determine what proportion of chest CTAs for suspected pulmonary embolism (PE) were performed in the setting of minimally elevated D-dimer levels, and to determine the prevalence of PE in those patients when stratified by clinical risk.

Methods

Retrospective chart review of all patients who had chest CTA for the evaluation of suspected PE during the years 2002–2006 in a suburban community teaching hospital emergency department.

Results

There were 1136 eligible patient visits, of which 353 (31.1%) were found to have D-dimer levels in the low positive range (0.5–0.99 μg/mL). Of these 353 patients, 9 (2.6%; 95% confidence interval [CI] 0.9–4.2%) were diagnosed with PE. There were also 109 patients (9.6%) who had normal D-dimer levels (<0.5 μg/mL). Two of these 109 (1.8%; 95% CI 0–4.2%) were diagnosed with PE. When stratified by the Pulmonary Embolism Rule-out Criteria, 99 of 353 patients with low positive D-dimer levels (28.0%; 95% CI 23.4–32.7%), and 14 of 109 with normal D-dimer levels (12.8%; 95% CI 6.6–19.1%) were classified as low risk, none of whom had PE.

Conclusions

Nearly one-third of all chest CTAs were done for patients with minimally elevated D-dimer levels, and another 9.6% for patients with normal D-dimer levels with very low yield. Further research to define clinical criteria identifying patients with minimal risk of PE despite low positive D-dimer levels represents an opportunity to improve both patient safety and utilization efficiency of chest CTA.     

Risk factors and clinical outcome of unsuspected pulmonary embolism in cancer patients: a case‐control study

Summary. Background: Little is known about the risk factors and outcome of unsuspected pulmonary embolism (UPE) in cancer patients. Objectives: To assess the risk factors and outcome of UPE in cancer patients. Methods: The charts of 66 patients diagnosed with UPE were reviewed. Two control groups were selected: 132 cancer patients without pulmonary embolism (PE) and 65 cancer patients with clinically suspected PE. Variables associated with UPE were identified by multivariable analysis. Six‐month survival and recurrent venous thromboembolism were compared by use of Cox proportional analysis. Results: Twenty‐seven (40.9%) patients with UPE had symptoms suggesting PE. Adenocarcinoma (odds ratio [OR] 4.45; 95% confidence interval [CI] 1.98–9.97), advanced age (OR 1.18; 95% CI 1.02–1.38), recent chemotherapy (OR 4.62; 95% CI 2.26–9.44), performance status > 2 (OR 7.31; 95% CI 1.90–28.15) and previous venous thromboembolism (OR 4.47; 95% CI 1.16–17.13) were associated with UPE. When adjusted for tumor stage and performance status, 6‐month mortality did not differ between patients with UPE and patients without PE (hazard ratio 1.40; 95% CI 0.53–3.66; P = 0.50). Patients with UPE were more likely to have central venous catheters and chemotherapy and less likely to have proximal clots than patients with clinically suspected PE. Recurrent venous thromboembolism occurred in 6.1% and 7.7% of patients with UPE and symptomatic PE, respectively. Conclusion: UPE is not associated with an increased risk of death. Patients with clinically suspected PE and those with UPE have similar risks of recurrent venous thromboembolism.     

Differential value of risk factors and clinical signs for diagnosing pulmonary embolism according to age

INTRODUCTION: The diagnostic value of clinical presentation of pulmonary embolism (PE) is uncertain in the elderly, who often have concomitant cardiopulmonary diseases that may mimic PE. The aim of our study was to assess the differential value of risk factors, symptoms and clinical signs of venous thromboembolism, results of electrocardiogram and chest X-ray for the diagnosis of PE in suspected patients according to age. METHODS: We analyzed data from two outcome studies which enrolled 1721 consecutive patients presenting in the emergency department with clinically suspected PE defined as acute onset of new or worsening shortness of breath or chest pain without any other obvious etiology. All patients underwent a sequential diagnostic work-up and a 3-month follow-up. RESULTS: The proportion of confirmed PE was 24.2% (416 of 1721). Strength of the association with PE did not differ according to age group for history of venous thromboembolism (VTE), recent surgery, tachypnea at admission or right ventricular strain on electrocardiogram. Active malignancy, hemoptysis, tachycardia, hemidiaphragmatic elevation and pleural effusion at chest X-ray were no more associated with PE in the patients aged of 75 years or more. Finally, symptoms and signs of deep venous thrombosis, and an alternative diagnosis less probable than PE were associated with PE in all age groups, but the strength of this association decreased significantly with advancing age. CONCLUSION: Some risk factors, symptoms and signs of VTE are less strongly or even not at all associated with PE in the elderly. Physicians should take this into account when attending elderly patients suspected of PE and when assessing their clinical probability of PE.