The impact of selection bias in the treatment for ruptured anterior communicating artery aneurysms: different results or different patients?

Background: Anterior communicating artery is one of the most frequent locations for the development of intracranial aneurysm. The availability and advances of different treatments modalities allows for case-specific selection, but potentially impacts our ability to assess equipoise among them.

Objective: Investigate and compare clinical and morphological variables among surgical and endovascular treatment groups with ruptured anterior communicating artery aneurysms.

Methods: Data from patients from a single university hospital treated for ruptured anterior communicating aneurysms after multidisciplinary discussion in a period from January 2009 to January 2020 were retrospectively reviewed. Demographics, clinical status, aneurysm morphologic features and in-hospital complications were registered for each treatment (endovascular coiling vs. microsurgical clipping). Clinical assessment was made from outpatient evaluation at 1-year follow-up.

Results: A total of 119 patients was obtained adding surgical ( = 80) and endovascular ( = 39) treatment groups. No significant changes between groups were detected regarding gender, age of treatment or other risk factors. Global complication rate ( = 0.335,  = 0.225,  = 0.428) and clinical outcome ( = 0.802) was similar among both groups. Univariate and multivariate analysis revealed statistically significant differences between endovascular and surgical treatment groups regarding dome orientation ( = 0.011), aneurysm height ( < 0.001) and maximum diameter ( < 0.001), aspect-ratio ( < 0.001), dome-to-neck ratio ( < 0.001) and dome diameter ( = 0.014).

Conclusions: Despite similar clinical outcomes and rate of complications, morphological differences highlight the presence of a selection bias and high heterogeneity, which hampers inferential analysis when comparing both techniques.