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

Abstract 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. Objectives We evaluated the diagnostic performance and compared the health system cost for previously suggested cutoffs and a new D- dimer cutoff for low-risk emergency department (ED) deep venous thrombosis (DVT) patients. Methods We conducted a retrospective cohort study in two large EDs involving patients aged > 50 years who had low pretest probability for DVT and had a D- dimer performed. The outcome was a diagnosis of DVT at 30 days. We evaluated the diagnostic accuracy and estimated the difference in cost for cutoffs of 500 ng/mL and the age-adjusted (age × 10) rule. A derived cutoff of 1000 ng/mL was also assessed. Results Nine hundred and seventy-two patients were included (median age 66 years; 59.5% female); 63 (6.5%) patients were diagnosed with DVT. The conventional cutoff of Conclusions Among patients aged > 50 years with suspected DVT, the age-adjusted D- dimer and a cutoff of 1000 ng/mL improved specificity without compromising sensitivity, and lowered the health care system cost compared to that for the conventional approach.