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Original Investigation
January 2018

Management of Tiny Unruptured Intracranial AneurysmsA Comparative Effectiveness Analysis

Author Affiliations
  • 1Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut
  • 2Department of Radiology and Biomedical Imaging, of Economics, of Management, and of Public Health, Yale School of Medicine, New Haven, Connecticut
  • 3Department of Neurosurgery and of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut
  • 4Interventional Neuroradiology, Radiology, Nuclear Medicine, Neurology and Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland
  • 5Department of Radiology, Northwell Health, Long Island, New York
JAMA Neurol. 2018;75(1):27-34. doi:10.1001/jamaneurol.2017.3232
Key Points

Question  What is the optimal management of tiny (≤3 mm) unruptured intracranial aneurysms?

Findings  In this comparative effectiveness analysis, calculations show that routine preventive treatment (coiling) or aggressive imaging follow-up have lower health benefits from a societal perspective than no preventive treatment or imaging follow-up.

Meaning  Routine treatment or frequent imaging follow-up is not effective in the general population with tiny unruptured intracranial aneurysms, but may be more appropriate in selected patients at high risk of rupture.


Importance  Unruptured intracranial aneurysms (UIAs) are relatively common in the general population and are being increasingly diagnosed; a significant proportion are tiny (≤3 mm) aneurysms. There is significant heterogeneity in practice and lack of clear guidelines on the management of incidental, tiny UIAs. It is important to quantify the implications of different management strategies in terms of health benefits to patients.

Objective  To evaluate the effectiveness of routine treatment (aneurysm coiling) vs 3 strategies for imaging surveillance compared with no preventive treatment or routine follow-up of tiny UIAs.

Design, Setting, and Participants  A decision-analytic model-based comparative effectiveness analysis was conducted from May 1 to June 30, 2017, using inputs from the medical literature. PubMed searches were performed to identify relevant literature for all key model inputs, each of which was derived from the clinical study with the most robust data and greatest applicability. Analysis included 10 000 iterations simulating adult patients with incidental detections of UIAs 3 mm or smaller and no history of subarachnoid hemorrhage.

Interventions  The following 5 management strategies for tiny UIAs were evaluated: annual magnetic resonance angiography (MRA) screening, biennial MRA screening, MRA screening every 5 years, aneurysm coiling and follow-up, and no treatment or preventive follow-up.

Main Outcomes and Measures  A Markov decision model for lifetime rupture was constructed from a societal perspective per 10 000 patients with incidental, tiny UIAs. Outcomes were assessed in terms of quality-adjusted life-years. Probabilistic, 1-way, and 2-way sensitivity analyses were performed.

Results  In this analysis of 10 000 iterations simulating adult patients with a mean age of 50 years, the base-case calculation shows that the management strategy of no treatment or preventive follow-up has the highest health benefit (mean [SD] quality-adjusted life-years, 19.40 [0.31]). Among the management strategies that incorporate follow-up imaging, MRA every 5 years is the best strategy with the next highest effectiveness (mean [SD] quality-adjusted life-years, 18.05 [0.62]). The conclusion remains robust in probabilistic and 1-way sensitivity analyses. No routine follow-up remains the optimal strategy when the annual growth rate and risk of rupture of growing aneurysms are varied. When the annual risk of rupture of nongrowing UIAs is less than 1.7% (0.23% in base case scenario), no follow-up is the optimal strategy. If annual risk of rupture is more than 1.7%, coiling should be performed directly.

Conclusions and Relevance  Given the current literature, no preventive treatment or imaging follow-up is the most effective strategy in patients with aneurysms that are 3 mm or smaller, resulting in better health outcomes. More aggressive imaging surveillance for aneurysm growth or preventive treatment should be reserved for patients with a high risk of rupture. Given these findings, it is important to critically evaluate the appropriateness of current clinical practices, and potentially determine specific guidelines to reflect the most effective management strategy for patients with incidental, tiny UIAs.