Around 30% of people who are admitted to hospital with aneurysmal subarachnoid haemorrhage (SAH) will rebleed in the initial month after the haemorrhage if the aneurysm is not treated. The two most commonly used methods to occlude the aneurysm for prevention of rebleeding are microsurgical clipping of the neck of the aneurysm and occlusion of the lumen of the aneurysm by means of endovascular coiling. This is an update of a systematic review that was previously published in 2005.
To compare the effects of endovascular coiling versus neurosurgical clipping in people with aneurysmal SAH on poor outcome, rebleeding, neurological deficit, and treatment complications.
We searched the Cochrane Stroke Group Trials Register (March 2018). In addition, we searched CENTRAL (2018, Issue 2), MEDLINE (1966 to March 2018), Embase (1980 to March 2018), US National Institutes of Health Ongoing Trials Register (March 2018), and World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (last searched March 2018). We also contacted trialists.
We included randomised trials comparing endovascular coiling with neurosurgical clipping in people with SAH from a ruptured aneurysm.
Data collection and analysis
Two review authors independently extracted data, and assessed trial quality and risk of bias using the GRADE approach. We contacted trialists to obtain missing information. We defined poor outcome as death or dependence in daily activities (modified Rankin scale 3 to 6 or Glasgow Outcome Scale (GOS) 1 to 3). In the special worst‐case scenario analysis, we assumed all participants in the group with better outcome with missing follow‐up information had a poor outcome and those in the other group with missing data a good outcome.
We included four randomised trials involving 2458 participants (range per trial: 20 to 2143 participants). Evidence is mostly based on the largest trial. Most participants were in good clinical condition and had an aneurysm on the anterior circulation. None of the included trials was at low risk of bias in all domains. One trial was at unclear risk in one domain, two trials at unclear risk in three domains, and one trial at high risk in one domain.
After one year of follow‐up, 24% of participants randomised to endovascular treatment and 32% of participants randomised to the surgical treatment group had poor functional outcome. The risk ratio (RR) of poor outcome (death or dependency) for endovascular coiling versus neurosurgical clipping was 0.77 (95% confidence interval (CI) 0.67 to 0.87; 4 trials, 2429 participants, moderate‐quality evidence), and the absolute risk reduction was 7% (95% CI 4% to 11%). In the worst‐case scenario analysis for poor outcome, the RR for endovascular coiling versus neurosurgical clipping was 0.80 (95% CI 0.71 to 0.91), and the absolute risk reduction was 6% (95% CI 2% to 10%). The RR of death at 12 months was 0.80 (95% CI 0.63 to 1.02; 4 trials, 2429 participants, moderate‐quality evidence). In a subgroup analysis of participants with an anterior circulation aneurysm, the RR of poor outcome was 0.78 (95% CI 0.68 to 0.90; 2 trials, 2157 participants, moderate‐quality evidence), and the absolute risk decrease was 7% (95% CI 3% to 10%). In subgroup analysis of those with a posterior circulation aneurysm, the RR was 0.41 (95% CI 0.19 to 0.92; 2 trials, 69 participants, low‐quality evidence), and the absolute decrease in risk was 27% (95% CI 6% to 48%). At five years, 28% of participants randomised to endovascular treatment and 32% of participants randomised to surgical treatment had poor functional outcome. The RR of poor outcome for endovascular coiling versus neurosurgical clipping was 0.87 (95% CI 0.75 to 1.01, 1 trial, 1724 participants, low‐quality evidence). At 10 years, 35% participants allocated to endovascular and 43% participants allocated to surgical treatment had poor functional outcome. At 10 years RR of poor outcome for endovascular coiling versus neurosurgical clipping was 0.81 (95% CI 0.70 to 0.92; 1 trial, 1316 participants, low‐quality evidence). The RR of delayed cerebral ischaemia at two to three months for endovascular coiling versus neurosurgical clipping was 0.84 (95% CI 0.74 to 0.96; 4 trials, 2450 participants, moderate‐quality evidence). The RR of rebleeding for endovascular coiling versus neurosurgical clipping was 1.83 (95% CI 1.04 to 3.23; 4 trials, 2458 participants, high‐quality evidence) at one year, and 2.69 (95% CI 1.50 to 4.81; 1 trial, 1323 participants, low‐quality evidence) at 10 years. The RR of complications from intervention for endovascular coiling versus neurosurgical clipping was 1.05 (95% CI 0.44 to 2.53; 2 trials, 129 participants, low‐quality evidence).
The evidence in this systematic review comes mainly from one large trial, and long‐term follow‐up is available only for a subgroup of participants within that trial. For people in good clinical condition with ruptured aneurysms of either the anterior or posterior circulation the data from randomised trials show that, if the aneurysm is considered suitable for both neurosurgical clipping and endovascular coiling, coiling is associated with a better outcome. There is no reliable trial evidence that can be used directly to guide treatment in people with a poor clinical condition.
Plain language summary
Endovascular coiling versus neurosurgical clipping for people with aneurysmal subarachnoid haemorrhage
We reviewed the outcome after endovascular coiling compared with neurosurgical clipping after a subarachnoid haemorrhage.
Bleeding under the surface membrane of the brain is called a subarachnoid haemorrhage. The bleeding usually comes from the rupture of a weak spot in an artery carrying blood to the brain. This weak spot is like a small balloon, which is called an aneurysm. The outcome after subarachnoid haemorrhage from an aneurysm is generally poor: a third of all people die within three months, and one of every five people remains dependent on someone else for help with every day activities such as walking, dressing, bathing, and taking care of one’s own affairs. One of the risks in people with subarachnoid haemorrhage is rebleeding. There are two ways to try and prevent this: neurosurgical clipping of the neck of the aneurysm in an operation or blocking the aneurysm from inside by endovascular coiling.
In March 2018, we searched for randomised controlled trials (RCTs, clinical studies where people are randomly put into one of two or more treatment groups) comparing endovascular coiling with neurosurgical clipping for subarachnoid haemorrhage. We found one new RCT and additional data for previously identified RCTs, allowing us to include four RCTs involving 2458 participants.
The data from RCTs showed that the number of people who survived and were independent in their daily living was higher after endovascular coiling than after neurosurgical clipping, if both treatment options were possible. Risk of rebleeding was higher in people treated with endovascular coiling. The evidence came mainly from one large trial.
Quality of the evidence
We judged that there is sufficient evidence to guide treatment for people in a relatively good condition whose aneurysm is considered suitable for both neurosurgical clipping and endovascular treatment. There is no reliable trial evidence that can be used directly to guide treatment in people with a poor clinical condition.