Risk Stratification and Surveillance After Endovascular Coiling for Intracranial Aneurysms: Development of a Simplified RACE Scale

BACKGROUND: Aneurysm recurrence after endovascular coiling remains a clinically relevant issue, particularly for determining appropriate post-treatment surveillance. However, standardized risk stratification to guide follow-up intensity is lacking. This study aimed to identify predictors of early recurrence and to develop a simplified risk stratification tool to inform postcoiling surveillance. METHODS: We retrospectively analyzed 432 intracranial aneurysms with adequate follow-up among 487 aneurysms treated with endovascular coiling between January 2021 and December 2023. Clinical and angiographic variables included aneurysm size, morphology (bifurcation vs. sidewall), rupture status, Raymond-Roy occlusion classification (RROC), and treatment modality. Recurrence was defined as coil compaction, neck recurrence, or sac regrowth. Time-to-recurrence was assessed using Cox proportional-hazards modeling, and model performance was evaluated using receiver operating characteristic analysis and the Hosmer-Lemeshow test. RESULTS: During a mean follow-up of 14 ± 9 months, recurrence occurred in 25 aneurysms (5.8%), with retreatment required in 9 (2.1%). Independent predictors of recurrence were aneurysm size ≥10 mm (hazard ratio [HR] 4.28, P < 0.001), residual sac (RROC III; HR 6.96, P < 0.001), and bifurcation morphology (HR 2.42, P = 0.028). Stent-assisted coiling showed a borderline protective trend (HR 0.59, P = 0.15). The final model demonstrated good discrimination (area under the curve 0.86) and calibration (Hosmer-Lemeshow P = 0.74). Based on these factors, the simplified Recurrence After Coil Embolization scale stratified aneurysms into low (1%-2%), moderate (6%-8%), and high-risk (15%-20%) recurrence groups. CONCLUSION: The Recurrence After Coil Embolization scale provides a practical framework for early recurrence risk stratification after endovascular coiling and may assist postcoiling imaging surveillance, particularly for high-risk aneurysms.