Assessment of the Safety and Efficiency of Using an Age-Adjusted D-dimer Threshold to Exclude Suspected Pulmonary Embolism

• Published in: Chest Vol. 146; no. 6; pp. 1444 - 1451
• Main Authors: Woller, Scott C., MD, Stevens, Scott M., MD, Adams, Daniel M., MD, Evans, R. Scott, PhD, Lloyd, James F., BS, Snow, Gregory L., PhD, Bledsoe, Joseph R., MD, Gay, David Z., MD, Patten, Richard M., MD, Aston, Valerie T., RRT, Elliott, C. Gregory, MD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2014
• Subjects: Age Factors; Aged; Aged, 80 and over; Aging - physiology; Biomarkers - blood; Cohort Studies; Confidence Intervals; Emergency Service, Hospital; False Negative Reactions; Female; Fibrin Fibrinogen Degradation Products - analysis; Geriatric Assessment; Humans; Male; Middle Aged; Odds Ratio; Patient Safety; Pulmonary Embolism - blood; Pulmonary Embolism - diagnosis; Pulmonary/Respiratory; Retrospective Studies; Sensitivity and Specificity; ICD-9; Revised Geneva Score; International Classification of Diseases, Ninth Revision; CT pulmonary angiography; PE; pulmonary embolism; CTPA; RGS
• ISSN: 0012-3692; 1931-3543
• DOI: 10.1378/chest.13-2386

Abstract BACKGROUND: D-dimer levels increase with age, and research has suggested that using an age-adjusted D-dimer threshold may improve diagnostic efficiency without compromising safety. The objective of this study was to assess the safety of using an age-adjusted D-dimer threshold in the workup of patients with suspected pulmonary embolism (PE). METHODS: We report the outcomes of 923 patients aged > 50 years presenting to our ED with suspected PE, a calculated Revised Geneva Score (RGS), and a D-dimer test. All patients underwent CT pulmonary angiography (CTPA). We compared the false-negative rate for PE of a conventional D-dimer threshold with an age-adjusted D-dimer threshold and report the proportion of patients for whom an age-adjusted D-dimer threshold would obviate the need for CTPA. RESULTS: Among 104 patients with a negative conventional D-dimer test result and an RGS ≤ 10, no PE was observed within 90 days (false-negative rate, 0%; 95% CI, 0%-2.8%). Among 273 patients with a negative age-adjusted D-dimer result and an RGS ≤ 10, four PEs were observed within 90 days (false-negative rate, 1.5%; 95% CI, 0.4%-3.7%). We observed an 18.3% (95% CI, 15.9%-21.0%) absolute reduction in the proportion of patients aged > 50 years who would merit CTPA by using an age-adjusted D-dimer threshold compared with a conventional D-dimer threshold. CONCLUSIONS: Use of an age-adjusted D-dimer threshold reduces imaging among patients aged > 50 years with an RGS ≤ 10. Although the adoption of an age-adjusted D-dimer threshold is probably safe, the CIs surrounding the additional 1.5% of PEs missed necessitate prospective study before this practice can be adopted into routine clinical care.