Incidence of recurrent subarachnoid hemorrhage after clipping for ruptured intracranial aneurysms

Background and Purpose - Because intracranial aneurysms develop during life, patients with subarachnoid hemorrhage (SAH) and successfully occluded aneurysms are at risk for a recurrence. We studied the incidence of and risk factors for recurrent SAH in patients who regained independence after SAH and in whom all aneurysms were occluded by means of clipping. Methods - From a cohort of patients with SAH admitted between 1985 and 2001, we included those patients who were discharged home or to a rehabilitation facility. We interviewed these patients about new episodes of SAH. We retrieved all medical records and radiographs in case of reported recurrences. If patients had died, we retrieved the cause of death. We analyzed the incidence of and risk factors for recurrent SAH by Kaplan-Meier curves and Cox regression analysis. Results - Of 752 patients with 6016 follow-up years (mean follow up 8.0 years), 18 had a recurrence. In the first 10 years after the initial SAH, the cumulative incidence of recurrent SAH was 3.2% (95% confidence interval [CI], 1.5% to 4.9%) and the incidence rate 286 of 100 000 patient-years (95% CI, 160 to 472 per 100 000). Risk factors were smoking (hazard ratio [HR], 6.5; 95% CI, 1.7 to 24.0), age (HR, 0.5 per 10 years; 95% CI, 0.3 to 0.8) and multiple aneurysms at the time of the initial SAH (HR, 5.5; 95% CI, 2.2 to 14.1). Conclusions - After SAH, the incidence of a recurrence within the first 10 years is 22 (12 to 38) times higher than expected in populations with comparable age and sex. Whether this increased risk justifies screening for recurrent aneurysms in patients with a history of SAH requires further study.