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Outcomes of high pretest probability patients undergoing d-dimer testing for pulmonary embolism: a pilot study.
J Emerg Med. 2008 Nov; 35(4):373-7.JE

Abstract

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.

Authors+Show Affiliations

Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18343077

Citation

Kabrhel, Christopher. "Outcomes of High Pretest Probability Patients Undergoing D-dimer Testing for Pulmonary Embolism: a Pilot Study." The Journal of Emergency Medicine, vol. 35, no. 4, 2008, pp. 373-7.
Kabrhel C. Outcomes of high pretest probability patients undergoing d-dimer testing for pulmonary embolism: a pilot study. J Emerg Med. 2008;35(4):373-7.
Kabrhel, C. (2008). Outcomes of high pretest probability patients undergoing d-dimer testing for pulmonary embolism: a pilot study. The Journal of Emergency Medicine, 35(4), 373-7. https://doi.org/10.1016/j.jemermed.2007.08.070
Kabrhel C. Outcomes of High Pretest Probability Patients Undergoing D-dimer Testing for Pulmonary Embolism: a Pilot Study. J Emerg Med. 2008;35(4):373-7. PubMed PMID: 18343077.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Outcomes of high pretest probability patients undergoing d-dimer testing for pulmonary embolism: a pilot study. A1 - Kabrhel,Christopher, Y1 - 2008/03/17/ PY - 2007/02/09/received PY - 2007/05/20/revised PY - 2007/08/09/accepted PY - 2008/3/18/pubmed PY - 2009/4/17/medline PY - 2008/3/18/entrez SP - 373 EP - 7 JF - The Journal of emergency medicine JO - J Emerg Med VL - 35 IS - 4 N2 - 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. SN - 0736-4679 UR - https://www.unboundmedicine.com/medline/citation/18343077/Outcomes_of_high_pretest_probability_patients_undergoing_d_dimer_testing_for_pulmonary_embolism:_a_pilot_study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0736-4679(07)00835-9 DB - PRIME DP - Unbound Medicine ER -