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Item Factors Associated With Positive D-dimer Results in Patients Evaluated for Pulmonary Embolism(2010-06) Kabrhel, Christopher; Courtney, D Mark; Camargo, Carlos A Jr; Plewa, Michael C; Nordenholz, Kristen E; Moore, Christopher L; Richman, Peter B; Smithline, Howard A; Beam, Daren M; Kline, Jeffrey A.Objectives: Available D-dimer assays have low specificity and may increase radiographic testing for pulmonary embolism (PE). To help clinicians better target testing, this study sought to quantify the effect of risk factors for a positive quantitative D-dimer in patients evaluated for PE. Methods: This was a prospective, multicenter, observational study. Emergency department (ED) patients evaluated for PE with a quantitative D-dimer were eligible for inclusion. The main outcome of interest was a positive D-dimer. Odds ratio (ORs) and 95% confidence intervals (CIs) were determined by multivariable logistic regression. Adjusted estimates of relative risk were also calculated. Results: A total of 4,346 patients had D-dimer testing, of whom 2,930 (67%) were women. A total of 2,500 (57%) were white, 1,474 (34%) were black or African American, 238 (6%) were Hispanic, and 144 (3%) were of other race or ethnicity. The mean (±SD) age was 48 (±17) years. Overall, 1,903 (44%) D-dimers were positive. Model fit was adequate (c-statistic = 0.739, Hosmer and Lemeshow p-value = 0.13). Significant positive predictors of D-dimer positive included female sex; increasing age; black (vs. white) race; cocaine use; general, limb, or neurologic immobility; hemoptysis; hemodialysis; active malignancy; rheumatoid arthritis; lupus; sickle cell disease; prior venous thromboembolism (VTE; not under treatment); pregnancy and postpartum state; and abdominal, chest, orthopedic, or other surgery. Warfarin use was protective. In contrast, several variables known to be associated with PE were not associated with positive D-dimer results: body mass index (BMI), estrogen use, family history of PE, (inactive) malignancy, thrombophilia, trauma within 4 weeks, travel, and prior VTE (under treatment). Conclusions: Many factors are associated with a positive D-dimer test. The effect of these factors on the usefulness of the test should be considered prior to ordering a D-dimer.Item Venous Thromboembolism and D-dimer In Patients with COVID-19(Indiana Medical Student Program for Research and Scholarship (IMPRS), 2020-12-15) Hoffer, Joshua; Stewart, Lauren; Pettit, Kate; Kline, Jeffrey A.; Department of Emergency Medicine, IU School of MedicineBackground and Hypothesis: The potential association between venous thromboembolism (VTE) and COVID-19 is an area of growing research, and methods of effective prophylaxis, detection, and treatment continue to be sought. D-dimer assays have been previously established as a highly sensitive — albeit nonspecific — test to assess patient risk of VTE, but the full clinical utility of this test in COVID-19 patients is currently not well understood. We hypothesized that, in patients presenting to the emergency department (ED) and determined to be positive for COVID-19, an elevated D-dimer value is associated with an increased 30-day incidence of VTE. Project Methods: Deidentified patient encounter data was collected and analyzed from a multicenter registry of ED patients tested for SARS-CoV-2. We measured the frequency of a positive SARS-CoV-2 test and compared the incidence of VTE between SARS-CoV-2 positive and negative patients. We also compared average D-dimer values in SARS-CoV-2 positive patients with and without VTE. Results: Of 6,445 patient encounters queried, 2,051 tested positive for SARS-CoV-2 (32%). SARS-CoV-2 positive patients had a significantly higher incidence of VTE in the 30-day follow-up period compared to SARS-CoV-2 negative patients (3.2 vs. 1.6%, p= 0.0002). D-dimer values were available for 537 of these SARS-CoV-2 patients, with an average D-dimer of 1813.83 ng/mL. The average D-dimer in SARS-CoV-2 positive patients who did develop VTE tended to be higher than those who did not develop VTE (2969 ng/mL vs. 1822 ng/mL), although this difference was not statistically significant (p=0.34). The fitted areas for binomial receiver operating characteristic curves of D-dimer for detection of VTE in patients with and without SARS-CoV-2 were 0.628 and 0.829, respectively. Conclusion and Potential Impact: We found a positive SARS-CoV-2 test to be associated with a higher incidence of VTE. However, an elevated D-dimer continues to be nonspecific for VTE in SARS-CoV-2 positive patients, and performs more poorly in SARS-CoV-2 positive patients than in negative patients. Additional clinical criteria should be identified to further guide the use of diagnostic imaging modalities and prophylactic anticoagulation in COVID-19 positive patients with suspicion of VTE.