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.

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.     

D-dimer can help differentiate suspected pulmonary embolism patients that require anti-coagulation

ObjectivesDetermine whether D-dimer concentration in the absence of imaging can differentiate patients that require anti-coagulation from patients who do not require anti-coagulation.MethodsData was obtained retrospectively from 366 hemodynamically stable adult ED patients with suspected pulmonary embolism (PE).Patients were categorized by largest occluded artery and aggregated into: ‘Require anti-coagulation’ (main, lobar, and segmental PE), ‘Does not require anti-coagulation’ (sub-segmental and No PE), ‘High risk of deterioration’ (main and lobar PE), and ‘Not high risk of deterioration’ (segmental, sub-segmental, and No PE) groups.Wilcoxon rank-sum test was used for 2 sample comparisons of median D-dimer concentrations. Receiver operating characteristic (ROC) curve analysis was utilized to determine a D-dimer cut-off that could differentiate ‘Require anti-coagulation’ from ‘Does not require anti-coagulation’ and ‘High risk of deterioration’ from ‘Low risk of deterioration’ groups.ResultsThe ‘Require anti-coagulation’ group had a maximum area under the curve (AUC) of 0.92 at an age-adjusted D-dimer cut-off of 1540 with a specificity of 86% (95% CI, 81–91%), and sensitivity of 84% (79–90%). The ‘High risk of deterioration’ group had a maximum AUC of 0.93 at an age-adjusted D-dimer cut-off of 2500 with a specificity of 90% (85–93%) and sensitivity of 83% (77–90%).ConclusionsAn age-adjusted D-dimer cut-off of 1540 ng/mL differentiates suspected PE patients requiring anti-coagulation from those not requiring anti-coagulation. A cut-off of 2500 differentiates those with high risk of clinical deterioration from those not at high risk of deterioration. When correlated with clinical outcomes, these cut-offs can provide an objective method for clinical decision making when imaging is unavailable.     

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.     

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.     

Pulmonary Embolism Risk Stratification: Pulse Oximetry and Pulmonary Embolism Severity Index

Background: Risk stratification of pulmonary embolism (PE) patients is important to determine appropriate management. Objectives: We evaluated two published risk-stratification tools in emergency department (ED) PE patients: a pulse oximetry cutoff below 92.5% oxygen (at 5280 feet elevation) and the Pulmonary Embolism Severity Index (PESI). Methods: Electronic medical records of all patients diagnosed with PE were abstracted to identify their triage vital signs, co-morbidities, and adverse short-term outcomes (AO) either requiring interventions (defined as respiratory failure, hypotension requiring pressors, and hemodynamic impairment requiring thrombolytics) or resulting in death. We applied these models to our ED PE patients and assessed their performance. Results: There were 168 PE patients identified, with an overall AO rate of 7.1% (12/168), including a 3.0% mortality rate. A room-air pulse oximetry cutoff of 92.5%, for values measured at 5280 feet, classified 89/136 patients as low risk, 1.1% of which had an AO, and 47/136 patients as high risk, of which 10.6% had AO. This pulse oximetry cutoff had a sensitivity of 83% (95% confidence interval [CI] 36–99%), specificity of 68% (95% CI 58–76%), and a negative predictive value (NPV) of 99% (95% CI 93–100%). PESI classified 91/168 patients as low risk (class I or II): 2.2% had AO but none died, and 77/168 were classified as high risk (class III, IV, or V), with an AO rate of 13.0%. A PESI cutoff score of II had a sensitivity of 83% (95% CI 52–98%), specificity of 57% (95% CI 49–65%), and NPV of 98% (95% CI 92–100%). Conclusion: Both PESI and pulse oximetry measurements are moderately accurate identifiers of low-risk patients with PE.     

Age-adjusted D-dimer cut-off in the diagnostic strategy for deep vein thrombosis: a systematic review

Background. Studies have indicated that use of an age-adjusted D-dimer cut-off value for patients above 50?years increases utility of the diagnostic strategy for pulmonary embolism. Evidence for the same approach regarding diagnosis of deep vein thrombosis (DVT) is, however, unclear. Materials and methods. A systematic literature review was conducted following the PRISMA Statement guideline to gather the existing knowledge on the use of an age-adjusted D-dimer cut-off in the diagnostic strategy for DVT. Studies were extracted from Medline and the Cochrane Library. The search period ended in November 2016. Results. Out of 73 articles retrieved, only eight studies addressed DVT either specifically or along with PE. None of these were randomized controlled trials, but were either prospective studies of consecutive outpatients or retrospective studies. Despite differences in study design, DVT prevalence, and D-dimer assay used, all studies were in favour of the age-adjusted D-dimer cut-off with negative predictive values (NPV) ranging from 91.8–100% compared to 89.7–100% for the standard D-dimer cut-off. All the studies concluded that use of an age-adjusted D-dimer cut-off resulted in an improved utility, although the results due to heterogeneity in reporting did not allow a direct comparison. Conclusion. Use of an age-adjusted D-dimer cut-off for patients above 50?years of age for ruling out DVT seems as safe as using a standard D-dimer cut-off. The recommended (and most used) adjustment is by the formula (patient’s age ×10) μg/L.     

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.     

Diagnostic accuracy of combined WBC,ANC and CRP in adult emergency department patients suspected of acute appendicitis

ObjectivesTo assess the sensitivity, specificity, and negative predictive value (NPV) of normal total white blood cell count (WBC) and normal absolute neutrophil count (ANC) combined with a normal proprietary C-reactive protein (pCRP) level in adult emergency department (ED) patients with abdominal pain suspected of possible acute appendicitis.MethodsWe prospectively enrolled patients ≥18 years of age at seven U.S. emergency departments with ≤72 h of abdominal pain and other signs and symptoms suggesting possible acute appendicitis. Sensitivity, specificity, and NPV for normal WBC and ANC combined with normal pCRP were correlated with the final diagnosis of acute appendicitis.ResultsWe enrolled 422 patients with a prevalence of acute appendicitis of 19.1%. The combination of normal WBC and pCRP exhibited a sensitivity of 97.5% (95% CI, 91.3–99.3%), an NPV of 98.8% (95% CI, 95.9–99.7%) and a specificity of 50.0% (95% CI, 44.7–55.3%) for acute appendicitis. Normal ANC and pCRP resulted in a sensitivity of 100% (95% CI, 95.4–100%), a negative predictive value of 100% (95% CI, 97.5–100%) and a specificity of 44.4% (95% CI, 39.2–49.7%) for acute appendicitis. Normal WBC and pCRP correctly identified 171 of 342 (50.0%) patients who did not have appendicitis with 2 (2.5%) false negatives, while normal ANC and pCRP identified 150 of 338 (44.3%) of patients without appendicitis with no false negatives.ConclusionThe combination of normal WBC and ANC with normal pCRP levels exhibited high sensitivity and negative predictive value for acute appendicitis in this prospective adult patient cohort. Confirmation and validation of these findings with further study using commercially available CRP assays is needed.     

Prospective validation of the bedside sonographic acute cholecystitis score in emergency department patients

BackgroundAcute cholecystitis can be difficult to diagnose in the emergency department (ED); no single finding can rule in or rule out the disease. A prediction score for the diagnosis of acute cholecystitis for use at the bedside would be of great value to expedite the management of patients presenting with possible acute cholecystitis. The 2013 Tokyo Guidelines is a validated method for the diagnosis of acute cholecystitis but its prognostic capability is limited. The purpose of this study was to prospectively validate the Bedside Sonographic Acute Cholecystitis (SAC) Score utilizing a combination of only historical symptoms, physical exam signs, and point-of-care ultrasound (POCUS) findings for the prediction of the diagnosis of acute cholecystitis in ED patients.MethodThis was a prospective observational validation study of the Bedside SAC Score. The study was conducted at two tertiary referral academic centers in Boston, Massachusetts. From April 2016 to March 2019, adult patients (≥18 years old) with suspected acute cholecystitis were enrolled via convenience sampling and underwent a physical exam and a focused biliary POCUS in the ED. Three symptoms and signs (post-prandial symptoms, RUQ tenderness, and Murphy's sign) and two sonographic findings (gallbladder wall thickening and the presence of gallstones) were combined to calculate the Bedside Sonographic Acute Cholecystitis (SAC) Score. The final diagnosis of acute cholecystitis was determined from chart review or patient follow-up up to 30 days after the initial assessment. In patients who underwent operative intervention, surgical pathology was used to confirm the diagnosis of acute cholecystitis. Sensitivity, specificity, PPV and NPV of the Bedside SAC Score were calculated for various cut off points.Results153 patients were included in the analysis. Using a previously defined cutoff of ≥ 4, the Bedside SAC Score had a sensitivity of 88.9% (95% CI 73.9%–96.9%), and a specificity of 67.5% (95% CI 58.2%–75.9%). A Bedside SAC Score of < 2 had a sensitivity of 100% (95% CI 90.3%–100%) and specificity of 35% (95% CI 26.5%–44.4%). A Bedside SAC Score of ≥ 7 had a sensitivity of 44.4% (95% CI 27.9%–61.9%) and specificity of 95.7% (95% CI 90.3%–98.6%).ConclusionA bedside prediction score for the diagnosis of acute cholecystitis would have great utility in the ED. The Bedside SAC Score would be most helpful as a rule out for patients with a low Bedside SAC Score < 2 (sensitivity of 100%) or as a rule in for patients with a high Bedside SAC Score ≥ 7 (specificity of 95.7%). Prospective validation with a larger study is required.     

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。     

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.

The use of D-dimer testing and Wells score in patients with high probability for acute pulmonary embolism

Rationale, aims and objective  To investigate if a combination of Wells pre-test probability score and D-dimer testing could be used as a safe base for making clinical decisions on further investigations for patients with intermediate to high risks of pulmonary embolism (PE).
Methods  One hundred and twenty patients with signs or symptoms of acute PE were investigated with pulmonary angiography (PA) or contrast enhanced computed tomography of the pulmonary arteries (CTPA), D-dimer testing (Tinaquant^®) and clinical scoring using the Wells pre-test probability score during their first 48 hours at the hospital. Patients were recruited consecutively from emergency departments at two teaching hospitals.
Results  The cut-off value of 0.5 mg L⁻¹ in D-dimer analysis is proved adequate with a negative predictive value (NPV) of 92% in this group of patients with intermediate to high risks. The combination of D-dimer testing and Wells score increases the NPV to 94%. The specificities of both tests were low.
Conclusion  D-dimer and Wells pre-test probability scores are safe to rule out acute PE even in patients with at least an intermediate risk of PE, but the specificity is low. D-dimer testing had a higher NPV than Wells score and the combination improved the algorithm further. The cut-off level for a high risk of PE measured with the Wells score was four and it seems reasonable to use that cut-off level in future algorithms. In addition, both PA and CTPA can present false positive and negative results difficult to interpret.     

Computed tomography pulmonary angiography in the diagnosis of acute pulmonary embolism in the emergency department

This study was undertaken to evaluate the use of computed tomography pulmonary angiography (CTPA) in patients with pulmonary embolism (PE) who were followed in the emergency department (ED). The files and computer records of 850 patients older than 16 years of age who were seen in the Hacettepe University Hospital ED between April 10, 2001, and December 1, 2005, and who required CTPA for PE prediagnosis and/or another diagnosis, were studied retrospectively. PE was identified by CTPA in 9.4% of 416 women and in 5.8% of 434 men. A significant difference (P< .05) was noted in the women and men in whom PE was detected. The mean age of the patients was 58.13±17.88 y (range, 16–100 y). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for clinical susceptibility to PE among patients who underwent CTPA were assessed at 95.3%, 48.2%, 13%, and 99.2%, respectively. CTPA was done for different reasons: aortic aneurysm dissection (n=1), cough distinctive diagnosis (n=1), dyspnea distinctive diagnosis (n=6), chest pain distinctive diagnosis (n=3), PE prediagnosis (n=51), and other reasons (n=2). Also, sensitivity, specificity, PPV, and NPV were found to be 95.4%, 16.2%, 14.4%, and 96%, respectively, for D-dimer. CTPA, which is accessible on a 24-h basis in the ED, is a valuable tool for the diagnosis of PE.     

Outcomes of high pretest probability patients undergoing d-dimer testing for pulmonary embolism: a pilot study

ELISA (enzyme-linked immunosorbent assay) D-dimer testing is commonly used in the evaluation of possible pulmonary embolism (PE) in the emergency department, but is not recommended in high pretest probability patients. Whether a negative ELISA D-dimer can safely rule out PE in these patients is not known, as there have been no large studies comparing ELISA D-dimer results and outcomes in high pretest probability patients. This was a prospective observational pilot study of emergency department patients evaluated for PE. Patients evaluated for PE had pretest probability assessed by the Wells PE Score. High pretest probability was defined as: dichotomized Wells Score > 4 points and patients with trichotomized Wells Score > 6 points. Patients had an ELISA D-dimer ordered by the treating physician. Pulmonary embolism was defined as: positive computed tomography scan, high probability ventilation/perfusion scan, positive pulmonary angiogram, or PE on 3-month follow-up. We calculated sensitivity, specificity, positive and negative predictive value, and likelihood ratios for the ELISA D-dimer. We prospectively enrolled 541 patients who underwent D-dimer testing for PE, of whom 130 patients had Wells Score > 4 and 33 patients had Wells Score > 6 (not mutually exclusive). Of subjects with Wells Score > 4, 23 (18%) were diagnosed with PE and 40 (31%) had a negative D-dimer. No patient with Wells Score > 4 (sensitivity 100%, 95% confidence interval [CI] 82%–100%; specificity 37%, 95% CI 28%–47%) or Wells Score > 6 (sensitivity 100%, 95% CI 63%–100%; specificity 56%, 95% CI 35%–76%) who had a negative D-dimer was diagnosed with PE. The likelihood ratio for a negative D-dimer was 0 for both the Wells > 4, and Wells > 6 groups, however, the upper limits of the confidence interval around the post-test probability for PE were 16% and 33%, respectively, for these high probability groups. In this pilot study, the rapid ELISA D-dimer had high sensitivity and negative predictive value even when applied to patients with high pretest probability for PE. However, with the post-test probability of PE still as high as 16–33% in the negative D-dimer groups, this precludes applying the results to patient care at present. Further testing is warranted to determine whether these findings can be safely incorporated into practice.     

Diagnostic Accuracy and Financial Implications of Age-Adjusted D-Dimer Strategies for the Diagnosis of Deep Venous Thrombosis in the Emergency Department

Background

Multiple D-dimer cutoffs have been suggested for older patients to improve diagnostic specificity for venous thromboembolism. These approaches are better established for pulmonary embolism.

Assessing 2 d-dimer age-adjustment strategies to optimize computed tomographic use in ED evaluation of pulmonary embolism

Study ObjectiveValidate the sensitivity and specificity of 2 age adjustment strategies for d-dimer values in identifying patients at risk for pulmonary embolism (PE) compared with traditional d-dimer cutoff value (500 ng/mL) to decrease inappropriate computed tomography pulmonary angiography (CTPA) use.MethodsThis institutional review board–approved, Health Insurance Portability and Accountability Act-compliant retrospective study included all adult emergency department patients evaluated for PE over a 32-month period (1/1/11–8/30/13). Only patients undergoing CTPA and d-dimer testing were included. We used a validated natural language processing algorithm to parse CTPA radiology reports and determine the presence of acute PE. Outcome measures were sensitivity and specificity of 2 age-adjusted d-dimer cutoffs compared with the traditional cutoff. We used χ² tests with proportional analyses to assess differences in traditional and age-adjusted (age × 10 ng/mL) d-dimer cutoffs, adjusting both by decade and by year.ResultsA total 3063 patients with suspected PE were evaluated by CTPA during the study period, and 1055 (34%) also received d-dimer testing. The specificity of age-adjusted d-dimer values was similar or higher for each age group studied compared with traditional cutoff, without significantly compromising sensitivity. Overall, had decade age-adjusted cutoffs been used, 37 CTPAs could have been avoided (19.6% of 189 patients aged > 60 years with Wells score ≤ 4); had yearly age-adjusted cutoffs been used, 52 CTPAs (18.2% of 286 patients aged > 50 years with Wells score ≤ 4) could have been avoided.ConclusionEach age-adjusted d-dimer cutoff strategy for the evaluation of PE was associated with increased specificity and statistically insignificant decreased sensitivity when compared with the traditional d-dimer cutoff value.     

D-二聚体在急性主动脉夹层中的诊断价值

目的 探讨血浆D-二聚体水平在急性主动脉夹层(acute aortic dissection,AAD)早期诊断中的价值.方法 选取2006年1月至2009年3月因胸痛就诊于复旦大学中山医院患者共80例,其中40例经动脉三维CT血管成像(CTA)检查确诊为急性主动脉夹层病例作为ADD组,同期以类似症状就诊但最终排除急性主动脉夹层的40例为对照组,所有患者胸痛发生12 h内检测血浆 D-二聚体,比较ADD组与对照组血浆 D-二聚体水平,分析D-二聚体诊断急性主动脉夹层的敏感性、特异性、阳性预测值、阴性预测值,并绘制D-二聚体诊断急性主动脉夹层的受试者工作曲线(receiver operating char-acteristic curve,ROC曲线).所有数据用SPSS 11.5统计软件分析处理,计量资料采用均数±标准差(χ±s)表示,两组间均数比较采用Mann-Whitney检验,以P<0.05为差异具有统计学意义.结果 ADD组血浆在D-二聚体水平明显高于对照组[(5.48±7.95)vs.(0.64±0.75),P<0.01];D-二聚体(>0.5 μg/mL)诊断急性主动脉夹层的敏感性、特异性、阳性预测值和阴性预测值分别为87.5%,62.5%,70%和83.3%,受试者工作曲线下面积为0.848±0.042,95%CI为0.766-0.930.结论 D-二聚体可作为急性主动脉夹层早期诊断有效的筛选指标.     

Combining clinical risk with D-dimer testing to rule out deep vein thrombosis

We sought to determine whether the combination of low-intermediate clinical risk of acute lower extremity deep vein thrombosis (DVT) and negative ELISA D-dimer assay can eliminate the need for duplex ultrasonography. Three hundred thirty-six patients prospectively underwent clinical risk stratification (low, intermediate, and high), D-dimer testing, and duplex ultrasonography. Thirteen of 145 intermediate-risk patients had acute DVT; 11 (85%) had a positive D-dimer. Two of 118 low-risk patients had acute DVT; both had a positive D-dimer. Intermediate-high risk stratification alone had sensitivity of 93.9% (95% CI: 80.3-98.3%) and a NPV of 98.3% (95% CI: 94.0-99.5%) for acute DVT. For all patients, a positive D-dimer alone had a sensitivity of 93.9% (95% CI: 80.3-98.3%) and a NPV of 98.6% (95% CI: 95.1-99.6%). The combination of D-dimer and intermediate-high risk classification had a sensitivity of 100% (95% CI: 89.4-100%) and a NPV of 100% (95% CI: 98.9-100%). In suspected acute lower extremity DVT, the combination of intermediate-high clinical risk and positive D-dimer has a high sensitivity and NPV, possibly eliminating the need for duplex ultrasound in this group of patients.     

Pulmonary embolism and COVID-19: A comparative analysis of different diagnostic models performance

ObjectivePulmonary embolism (PE) is a common complication of SARS-CoV-2 infection. Several diagnostic prediction rules based on pretest probability and D-dimer have been validated in non-COVID patients, but it remains unclear if they can be safely applied in COVID-19 patients. We aimed to compare the diagnostic accuracy of the standard approach based on Wells and Geneva scores combined with a standard D-dimer cut-off of 500 ng/mL with three alternative strategies (age-adjusted, YEARS and PEGeD algorithms) in COVID-19 patients.MethodsThis retrospective study included all COVID-19 patients admitted to the Emergency Department (ED) who underwent computed tomography pulmonary angiography (CTPA) due to PE suspicion. The diagnostic prediction rules for PE were compared between patients with and without PE.ResultsWe included 300 patients and PE was confirmed in 15%. No differences were found regarding comorbidities, traditional risk factors for PE and signs and symptoms between patients with and without PE. Wells and Geneva scores showed no predictive value for PE occurrence, whether a standard or an age-adjusted cut-off was considered. YEARS and PEGeD algorithms were associated with increased specificity (19% CTPA reduction) but raising non-diagnosed PE. Despite elevated in all patients, those with PE had higher D-dimer levels. However, incrementing thresholds to select patients for CTPA was also associated with a substantial decrease in sensitivity.ConclusionNone of the diagnostic prediction rules are reliable predictors of PE in COVID-19. Our data favour the use of a D-dimer threshold of 500 ng/mL, considering that higher thresholds increase specificity but limits this strategy as a screening test.