BACKGROUND: Our aim was to assess the long-term risks of death, disability, and 
rebleeding in patients randomly assigned to clipping or endovascular coiling 
after rupture of an intracranial aneurysm in the follow-up of the International 
Subarachnoid Aneurysm Trial (ISAT).
METHODS: 2143 patients with ruptured intracranial aneurysms were enrolled 
between 1994 and 2002 at 43 neurosurgical centres and randomly assigned to 
clipping or coiling. Clinical outcomes at 1 year have been previously reported. 
All UK and some non-UK centres continued long-term follow-up of 2004 patients 
enrolled in the original cohort. Annual follow-up has been done for a minimum of 
6 years and a maximum of 14 years (mean follow-up 9 years). All deaths and 
rebleeding events were recorded. Analysis of rebleeding was by allocation and by 
treatment received. ISAT is registered, number ISRCTN49866681.
FINDINGS: 24 rebleeds had occurred more than 1 year after treatment. Of these, 
13 were from the treated aneurysm (ten in the coiling group and three in the 
clipping group; log rank p=0.06 by intention-to-treat analysis). There were 8447 
person-years of follow-up in the coiling group and 8177 person-years of 
follow-up in the clipping group. Four rebleeds occurred from a pre-existing 
aneurysm and six from new aneurysms. At 5 years, 11% (112 of 1046) of the 
patients in the endovascular group and 14% (144 of 1041) of the patients in the 
neurosurgical group had died (log-rank p=0.03). The risk of death at 5 years was 
significantly lower in the coiling group than in the clipping group (relative 
risk 0.77, 95% CI 0.61-0.98; p=0.03), but the proportion of survivors at 5 years 
who were independent did not differ between the two groups: endovascular 83% 
(626 of 755) and neurosurgical 82% (584 of 713). The standardised mortality 
rate, conditional on survival at 1 year, was increased for patients treated for 
ruptured aneurysms compared with the general population (1.57, 95% CI 1.32-1.82; 
p<0.0001).
INTERPRETATION: There was an increased risk of recurrent bleeding from a coiled 
aneurysm compared with a clipped aneurysm, but the risks were small. The risk of 
death at 5 years was significantly lower in the coiled group than it was in the 
clipped group. The standardised mortality rate for patients treated for ruptured 
aneurysms was increased compared with the general population.
FUNDING: UK Medical Research Council.