Background: Recent studies have documented the high sensitivity of CT angiography (CTA) in detecting a ruptured aneurysm in the presence of acute subarachnoid hemorrhage (SAH). The practice of digital subtraction angiography (DSA) when CTA does not reveal an aneurysm has thus been called into question.
Objective: We examined this dilemma from a cost-effectiveness perspective using current decision analysis techniques.
Methods: A decision tree was created using TreeAge Pro Suite 2012; in one arm a CTA negative SAH was followed-up with DSA, in the other patients were observed without further imaging. Based on literature review, costs and utilities were assigned to each potential outcome. Base case and sensitivity analysis were performed to determine the cost-effectiveness of each strategy. A Monte Carlo simulation was then conducted, by sampling each variable over a plausible distribution, to evaluate the robustness of the model.
Results: Using a negative predictive value (NPV) of 95.7 % for CTA, observation was found to be the most cost-effective strategy ($6,737/QALY vs. $8,460/QALY), in the base case analysis. One-way sensitivity analysis demonstrated that DSA became the more cost-effective option if the NPV of CTA fell below 93.72%. The Monte Carlo simulation produced an incremental cost-effectiveness ratio of $83,083/QALY. At the conventional willingness-to-pay threshold of $50,000/QALY, observation was the more cost-effective strategy in 83.6% of simulations.
Conclusion: The decision to perform a DSA in CTA negative SAH depends strongly on the sensitivity of CTA, and therefore must be evaluated at each center treating these types of patients. Given the high sensitivity of CTA reported in the current literature, performing DSA on all patients with CTA negative SAH may not be cost-effective at every institution.
From: Cost-Effectiveness of Digital Subtraction Angiography in the Setting of CT Angiography Negative Subarachnoid Hemorrhage by Jethwa et al.