The Source for Neurovascular News and Education

July 14, 2024

Key Points:

  • Retrospective review of Medicare data analyzes trends in clipping, coiling for unruptured intracranial aneurysms
  • Use of both therapies increased and outcomes improved over time, but no gains made in combatting subarachnoid hemorrhage

Coiling and clipping have become more commonly used to treat patients with unruptured intracranial aneurysms in recent years, according to a study published online August 6, 2015, ahead of print in Stroke. While outcomes have mostly improved, the shifts were accompanied by a slight increase in the rate of subarachnoid hemorrhage. 


The Take Home


“It is reasonable to suspect that for some patients… the value of clipping or coiling their [unruptured intracranial aneurysms] is either modest or nonexistent,” the study authors write.


Jessica J. Jalbert, PhD, of Weill Cornell Medical College (New York, NY), and colleagues reviewed data on 12,299 Medicare beneficiaries who underwent clipping (n = 4,357) or coiling (n = 7,942) between 2000 and 2010.

Over the study period, the combined rate of clipping or coiling increased from 1.4 to 6.0 procedures per 100,000 Medicare beneficiaries, driven mostly by the growth of coiling. Endovascular therapy, which represented a small portion of treatments in 2000, overtook surgery in 2003. The rise in clipping and coiling was more prominent in patients between ages 65 and 74 years than in their older counterparts.

Most Outcomes Improve

For the outcomes analysis, the investigators grouped patients by year of treatment:

  • 2001-2003 (n = 2,111)
  • 2004-2007 (n = 4,501)
  • 2008-2010 (n = 5,687)

Patient risks were comparable between the clipping and coiling groups, and outcomes of both procedures improved with time. However, by 2008-2010, coiling was associated with slightly lower rates of short-term mortality, readmission, and procedural complications and a shorter length of hospital stay (table 1).

Table 1. Unadjusted Outcomes for Clipping and Coiling, 2008-2010




(n = 1,684)


(n = 4,003)

In-Hospital Mortality



In-Hospital Complications



30-Day Mortality



30-Day Readmission



Mean Length of Stay, days




Age- and sex-adjusted subarachnoid hemorrhage rates were stable at about 20 per 100,000 patients until 2007, but beginning in 2008, the rate increased to about 25 per 100,000.

No More Than ‘Modest’ Treatment Benefit

The authors of the study describe the rise of subarachnoid hemorrhage as “concerning” due to the fact that “[t]he primary purpose of preventative… clipping and coiling is to reduce the risk of aneurysmal [subarachnoid hemorrhage] occurrence.”

They deem it “reasonable to suspect that for some patients in this age group, the value of clipping or coiling their [unruptured intracranial aneurysms] is either modest or nonexistent, particularly in light of procedural complications and the effect of procedure-associated morbidity and hospitalizations on quality of life.”

In addition, Dr. Jalbert and colleagues suggest that the rise in treatment “may be related to increased detection of [unruptured intracranial aneurysms],” consistent with the growth of noninvasive imaging over the study’s time period. The growth of endovascular therapy in particular points to “the fact that coiling is considered less physiologically stressful and safer than clipping.” 

Nonetheless, the risk of adverse outcomes decreased for both therapies during the study, an improvement “probably due to advancements in endovascular techniques, general improvements in postprocedural care, and increasing past-year clipping and coiling volumes,” they say.

But these gains “do not necessarily justify increased preventative… treatment,” the authors caution. They note that clinicians should weigh the value of treatment against life expectancy and rupture risk; the latter is so low that “some patients do not live long enough to benefit from the primary purpose of the procedure: [subarachnoid hemorrhage] prevention.”

In the end, the value of preventative treatment may vary. Many patients with small, asymptomatic aneurysms may be comfortable just “monitoring their aneurysms with imaging over time,” said Demetrius Lopes, MD, of Rush University Medical Center (Chicago, IL). However, “patients who undergo treatment of unruptured aneurysms are also looking for peace of mind of not having to live their lives worrying about a sudden rupture of their aneurysm,” no matter how unlikely it is to occur, he added.



  • The study was supported by the National Institute of Neurological Disorders and Stroke.
  • Dr. Jalbert reports serving as a consultant for pharmaceutical and medical device companies as an employee of LASER Analytica.
  • Dr. Lopes reports serving on the advisory board for Medtronic, Penumbra, Siemens, and Stryker.

Jalbert JJ, Isaacs AJ, Kamel H, et al. Clipping and coiling of unruptured intracranial aneurysms among Medicare beneficiaries, 2000 to 2010. Stroke. 2015;Epub ahead of print.

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