A Primer on Diagnostic and Financial Implications of D-dimer Testing.

Given the high incidence of deep vein thrombosis/pulmonary embolism (DVT/PE) (300,000 to 600,000 per year in the U.S.) and the 30 percent mortality rate associated with undiagnosed PE, diagnostic evaluation is very important. One of the tools used to evaluate for DVT and PE is D-dimer testing. A negative D-dimer test, along with a low Wells clinical probability score, can safely rule out DVT/PE without the need for additional imaging. This approach can reduce cost; however, D-dimer testing is not indicated in all patients. D-dimers can be elevated in patients without DVT/PE, like the elderly. The consequences of over utilizing D-dimer testing can lead to excessive imaging, unnecessary contrast exposure, unnecessary exposure to radiation, and increased cost. In this primer, we provide a brief literature review of D-dimer testing for the diagnosis of DVT and PE. We also discuss the overutilization of D-dimer testing and its financial burden on the health care industry.

Cost associated with D-Dimer screening for acute aortic dissection.

INTRODUCTION: D-Dimer (DD) has been described as a useful predictor of both morphologic changes in acute thoracic aortic dissection (TAD) and of TAD-associated mortality. This study analyzed the use of DD screening to screen patients with chest pain for acute (TAD) to determine if it improves diagnosis and cost effectiveness. This study also looked at the association of DD levels with diagnoses frequently seen in patients with dyspnea or chest pain. METHODS: At the Helios Hospital, Krefeld, the authors analyzed the data of all patients (n = 1053, age (mean, SD) 62 ± 19 years, 49% males) admitted for chest pain to the nonsurgical emergency department (ED) in February 2010. Chest pain was the second most frequent symptom causing 138 (13.1%) admissions, 102 of which had DD testing (Inniovance® D-Dimer Assay, Dade Behring/Siemens, Germany). To assess the diagnostic reliability of DD testing, the sensitivity, specificity, and odds ratio, including 95% confidence interval, were estimated. RESULTS: None of the patients admitted were found to have acute TAD. Had the authors used a computerized tomography (CT) scan to rule out TAD in every patient with chest pain, actual costs would have been euro 12,328. A restriction of CT scans to patients with elevated DD levels would have lowered costs to euro 5360. The actual costs were euro 670.30 for CT scans and euro 540.60 for DD tests. On analyzing the association with other diagnoses, both sensitivity and specificity were low, with the exception of pneumonia. CONCLUSION: Owing to the low incidence of TAD, DD screening increases diagnostic efforts and costs but it remains unclear whether it would actually speed up TAD diagnosis. In a clinical setting DD did not help to discriminate other relevant diagnoses. Despite the high sensitivity of DD for aortic dissection published in the literature, the physician's clinical judgment remains paramount.

Value of quantitative D-dimer assays in identifying pulmonary embolism: implications from a sequential decision model.

OBJECTIVES: To examine the cost-effectiveness of a quantitative D-dimer assay for the evaluation of patients with suspected pulmonary embolism (PE) in an urban emergency department (ED). METHODS: The authors analyzed different diagnostic strategies over pretest risk categories on the basis of Wells criteria by using the performance profile of the ELISA D-dimer assay (over five cutoff values) and imaging strategies used in the ED for PE: compression ultrasound (CUS), ventilation-perfusion (VQ) scan (over three cutoff values), CUS with VQ (over three cutoff values), computed tomography (CT) angiogram (CTA) with pulmonary portion (CTP) and lower-extremity venous portion, and CUS with CTP. Data used in the analysis were based on literature review. Incremental costs and quality-adjusted-life-years were the outcomes measured. RESULTS: Computed tomography angiogram with pulmonary portion and lower-extremity venous portion without D-dimer was the preferred strategy. CUS-VQ scanning always was dominated by CT-based strategies. When CTA was infeasible, the dominant strategy was D-dimer with CUS-VQ in moderate- and high-Wells patients and was D-dimer with CUS for low-Wells patients. When CTP specificity falls below 80%, or if its overall performance is markedly degraded, preferred strategies include D-dimer testing. Sensitivity analyses suggest that pessimistic assessments of CTP accuracy alter the results only at extremes of parameter settings. CONCLUSIONS: In patients in whom PE is suspected, when CTA is available, even the most sensitive quantitative D-dimer assay is not likely to be cost-effective. When CTA is not available or if its performance is markedly degraded, use of the D-dimer assay has value in combination with CUS and a pulmonary imaging study. These conclusions may not hold for the larger domain of patients presenting to the ED with chest pain or shortness of breath in whom PE is one of many competing diagnoses.