A decision analysis to determine a testing threshold for computed tomographic angiography and d-dimer in the evaluation of aortic dissection

The TTs for TAD are low and reflect the large mortality benefit from diagnosis and treatment when compared with the small risks of CTA. However, given the low prevalence of TAD (~ 0.05% among emergency department patients presenting with symptoms previously attributed to TAD), our results suggest that without high-risk features, clinicians should not order a CTA test for TAD. Depending on age, CTA should be considered for those patients with a disease probability greater than 0.3% to 2.1%, whereas d-dimer testing is appropriate in the range of pretest probabilities from 0.01% to 0.6%. Future studies should focus on clinical decision rules that place disease probabilities below, between, and above the calculated TTs.