Cost-effectiveness analysis on small (< 5 mm) unruptured intracranial aneurysm follow-up strategies

Unruptured intracranial aneurysms are frequently detected during routine clinical diagnostic processes. A significant portion are small aneurysms less than 5 mm in diameter. While follow-up of patients with small aneurysms has been advocated, the cost-effectiveness of such care and the optimal follow-up interval remain unknown. This study aimed to explore the most cost-effective follow-up interval for small (< 5 mm) unruptured intracranial aneurysms.

A decision analysis study was performed using a Markov model with Monte Carlo simulations to simulate patients undergoing follow-up by MRA at different time intervals (1-, 2-, 3-, 5-, and 7-year intervals) for small (< 5 mm) unruptured intracranial aneurysms. Input data for the model were extracted from the current literature, primarily meta-analyses. Probabilistic and deterministic sensitivity analyses were performed to evaluate the robustness of the model.

Given the current literature and the model in this study, following up every 2 years with noninvasive imaging is the most cost-effective strategy (cost $126,996, effectiveness 21.9 quality-adjusted life-years), showing the highest net monetary benefit. The conclusion remains robust in probabilistic and deterministic sensitivity analyses. As the annual growth risk of small aneurysms and annual rupture risk of growing aneurysms increase, following up every year is optimal. When the cost for follow-up with MRA is less than $2223, following up every year is cost-effective.

The most cost-effective follow-up strategy for small (< 5 mm) unruptured aneurysms using MRA is following up every 2 years. More frequent follow-up strategies or prompt preventive treatment would be more appropriate in patients with higher risk factors for growth and aneurysm rupture.