Incidence and risk factors of intracranial aneurysm: A national cohort study in Korea.

Background Estimations of the intracranial aneurysm incidence require long-term follow-up of a relatively large at-risk population; as a result, the incidence remains largely unknown. Aims To investigate the national incidence of intracranial aneurysm in a Korean population. Methods After excluding 18,604 potential subjects with a previous history of stroke (I6x.x), 998,216 subjects were included in this observational cohort. The primary endpoint was the earliest date of diagnosis of either unruptured intracranial aneurysm (UIA; I67.1) or subarachnoid hemorrhage (SAH; I60.x). We collected anthropometric data, blood pressure measurements, laboratory data, and smoking, drinking, and physical exercise habits of 132,355 subjects for whom healthcare screening data were available. Factors influencing intracranial aneurysm were evaluated via multivariate Cox regression. Results The overall observation size was 8,792,214 person-years. During follow-up, 4346 subjects were diagnosed with intracranial aneurysm (SAH, 1960; UIA, 2386). The crude incidence of intracranial aneurysm was 49.4/100,000 person-years. The hazard ratio for women was 1.56 ( p < 0.01), and older subjects had an increased hazard ratio. Subjects with hypertension had an approximately 1.5-fold higher risk of intracranial aneurysm. A history of heart disease and family history of stroke were associated with respective hazard ratios of 2.08 and 1.77. Conclusions In this Korean population study, the standardized incidence of intracranial aneurysm was 52.2/100,000 person-years. Older age, female sex, hypertension, history of heart disease, and family history of stroke were independent risk factors for intracranial aneurysm.