BACKGROUND: The aim of intervention for unruptured intracranial aneurysms (UIAs) is safe, effective treatment. OBJECTIVE: To analyze a prospective database for variables influencing the risk of surgery to produce a risk model adjusting this risk for effectively treated aneurysms. METHODS: First, we identified variables to create a model from multiple logistic regression for complications of surgery leading to a 12-month modified Rankin Scale score >1. Second, we established the long-term cumulative incidence of freedom from retreatment or rupture (treated aneurysm) from Kaplan-Meier analysis. Third, we combined these analyses to establish a model of risk of surgery per effective treatment. RESULTS: One thousand twelve patients with 1440 UIA underwent 1080 craniotomies. We found that 10.1% (95% confidence interval [CI], 8.4-12.0) of craniotomies resulted in a complication leading to a modified Rankin Scale score >1 at 12 months. Logistic regression found age (odds ratio, 1.04; 95% CI, 1.02-1.06), size (odds ratio, 1.12; 95% CI, 1.09-1.15), and posterior circulation location (odds ratio, 2.95; 95% CI, 1.82-4.78) to be significant. Cumulative 10-year risk of retreatment or rupture was 3.0% (95% CI, 1.3-7.0). The complication-effectiveness model was derived by dividing the complication risk by the 10-year cumulative freedom from retreatment or rupture proportion. Risk per effective treatment ranged from 1% for a 5-mm anterior circulation UIA in a 20-year-old patient to 70% for a giant posterior circulation UIA in a 70-year-old patient. CONCLUSION: Complication-effectiveness analyses increase the information available with regard to outcome for the management of UIAs. ABBREVIATIONS: CE, complication-effectiveness CI, confidence interval CTA, computed tomographic angiography DSA, digital subtraction angiography ISUIA, International Study of Unruptured Intracranial Aneurysms MRA, magnetic resonance angiography mRS, modified Rankin Scale UIA, unruptured intracranial aneurysm.
- Cohort study
- Intracranial aneurysm