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Potential impact of adjusting the threshold of the quantitative D-dimer based on pretest probability of acute pulmonary embolism.
Acad Emerg Med. 2009 Apr; 16(4):325-32.AE

Abstract

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.

Authors+Show Affiliations

Department of Emergency Services, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Multicenter Study
Validation Study

Language

eng

PubMed ID

19298619

Citation

Kabrhel, Christopher, et al. "Potential Impact of Adjusting the Threshold of the Quantitative D-dimer Based On Pretest Probability of Acute Pulmonary Embolism." Academic Emergency Medicine : Official Journal of the Society for Academic Emergency Medicine, vol. 16, no. 4, 2009, pp. 325-32.
Kabrhel C, Mark Courtney D, Camargo CA, et al. Potential impact of adjusting the threshold of the quantitative D-dimer based on pretest probability of acute pulmonary embolism. Acad Emerg Med. 2009;16(4):325-32.
Kabrhel, C., Mark Courtney, D., Camargo, C. A., Moore, C. L., Richman, P. B., Plewa, M. C., Nordenholtz, K. E., Smithline, H. A., Beam, D. M., Brown, M. D., & Kline, J. A. (2009). Potential impact of adjusting the threshold of the quantitative D-dimer based on pretest probability of acute pulmonary embolism. Academic Emergency Medicine : Official Journal of the Society for Academic Emergency Medicine, 16(4), 325-32. https://doi.org/10.1111/j.1553-2712.2009.00368.x
Kabrhel C, et al. Potential Impact of Adjusting the Threshold of the Quantitative D-dimer Based On Pretest Probability of Acute Pulmonary Embolism. Acad Emerg Med. 2009;16(4):325-32. PubMed PMID: 19298619.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Potential impact of adjusting the threshold of the quantitative D-dimer based on pretest probability of acute pulmonary embolism. AU - Kabrhel,Christopher, AU - Mark Courtney,D, AU - Camargo,Carlos A,Jr AU - Moore,Christopher L, AU - Richman,Peter B, AU - Plewa,Michael C, AU - Nordenholtz,Kristen E, AU - Smithline,Howard A, AU - Beam,Daren M, AU - Brown,Michael D, AU - Kline,Jeffrey A, Y1 - 2009/03/06/ PY - 2009/3/21/entrez PY - 2009/3/21/pubmed PY - 2009/10/15/medline SP - 325 EP - 32 JF - Academic emergency medicine : official journal of the Society for Academic Emergency Medicine JO - Acad Emerg Med VL - 16 IS - 4 N2 - 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. SN - 1553-2712 UR - https://www.unboundmedicine.com/medline/citation/19298619/Potential_impact_of_adjusting_the_threshold_of_the_quantitative_D_dimer_based_on_pretest_probability_of_acute_pulmonary_embolism_ L2 - https://doi.org/10.1111/j.1553-2712.2009.00368.x DB - PRIME DP - Unbound Medicine ER -