High Risk Clinical Features for Acute Aortic Dissection: A Case-Control Study.

BACKGROUND: Acute aortic dissection (AAD) is a rare condition with a high mortality that is often missed. The objective of our study was to assess the diagnostic accuracy of clinical and laboratory findings for AAD, in confirmed cases of AAD and in a low-risk control group.

METHODS: This was a historical matched case-control study: participants were adults > 18 years old presenting to two tertiary care emergency departments (EDs) or one regional cardiac referral center. Cases were patients with new ED or in-hospital diagnosis of nontraumatic AAD confirmed by computed tomography or echocardiography. Controls were patients with a triage diagnosis of truncal pain (<14 days) and an absence of a clear diagnosis on basic investigation. Cases and controls were matched in a 1:4 ratio by sex and age. A sample size of 165 cases and 660 controls was calculated based on 80% power and confidence interval of 95% to detect an odds ratio of greater than 2.

RESULTS: Data were collected from 2002 to 2014 yielding 194 cases of AAD and 776 controls (mean ± SD age = 65 ± 14.1 years; 66.7% male). Absence of abrupt-onset pain (sensitivity = 95.9%, negative likelihood ratio = 0.07 [0.03-0.14]) can help rule out AAD. Presence of tearing/ripping pain (specificity = 99.7%, positive likelihood ratio [LR+] = 42.1 [9.9-177.5]), aortic aneurysm (specificity = 97.8%, LR+ = 6.35 [3.54-11.42]), hypotension (specificity = 98.7%, LR+ = 17.2 [8.8-33.6]), pulse deficit (specificity = 99.3, LR+ = 31.1 [11.2-86.6]), neurologic deficits (specificity = 96.9%, LR+ = 5.26 [2.9-9.3]), and a new murmur (specificity = 97.8%, LR+ = 9.4 [5.5-16.2]) can help rule in the diagnosis of AAD.

CONCLUSIONS: Patients with one or more high-risk feature should be considered high risk, whereas patients with no high-risk and multiple low-risk features are at low risk for AAD.