Performance and costs of rule-out protocols for acute aortic syndromes: analysis of pooled prospective cohorts

Abstract

Background: Acute aortic syndromes (AAS) are deadly conditions causing unspecific symptoms, such as chest/abdominal/back pain, syncope and neurological deficit. They are diagnosed with computed tomography angiography (CTA), but the patient selection is challenging. To support physicians and standardize management, protocols combining a clinical score with D-dimer (DD) have been developed. However, direct comparison of their diagnostic performance and cost-effectiveness is lacking.

Methods: We used individual patient data from 3 prospective diagnostic studies of patients with suspected AAS, enrolled in 12 centers from 5 countries. Diagnostic accuracy, failure rate and costs were calculated for 5 protocols, applying 3 scores (aortic dissection detection [ADD], AORTAs and Canadian) and 2 DD thresholds (500 ng/mL [DD₅₀₀], age-adjusted [DD_age]). Costs were estimated using Italian and German reimbursements.

Results: Among 4907 patients, 506 (10.3 %) had an AAS. The sensitivity of the diagnostic protocols ranged from 97.6 % for Canadian/DD₅₀₀ to 99.4 % for AORTAs/DD₅₀₀ or DD_age (P = 0.022). The specificity was lowest for AORTAs/DD₅₀₀ (46.8 %; P < 0.001 vs AORTAs/DD₅₀₀) and highest for ADD/DD_age (61.5 %; P < 0.001). The number of potential AAS misses was 4-fold higher with Canadian/DD₅₀₀ vs AORTAs/DD₅₀₀ or DD_age. The net clinical benefit was highest for ADD/DD_age. All protocols reduced CTA exams and costs over a CTA-to-all strategy. Numbers of predicted CTA exams and costs per 100 patients were lowest for ADD/DD_age (447 CTAs, 34,366 EUR) and highest (579 CTAs, 43,628 EUR) for AORTAs/DD₅₀₀.

Conclusions: Guideline-compliant clinical score/DD based protocols are highly sensitive. Differences in specificity and efficiency are present. Data may guide decision-making based on policies and resources.

Keywords: Aorta; Cost; D-dimer; Diagnosis; Dissection; Probability; Score.