Treatment of Unruptured Intracranial Aneurysms: a Nationwide Assessment of Effectiveness

Higashida RT, Lahue BJ, Torbey MT, et al.
AJNR Am J Neuroradiol 2007;28:146–5

Background: The ISAT study has demonstrated a better outcome in patients after SAH treated by coil occlusion compared to the neurosurgical approach. However, data on outcome after treatment of incidental aneurysms are sparse.

Material and Methods: In a retrospective cohort study data were collected over a 1-year time interval from 429 hospitals in the USA, representing 58% of the US population. A total of 2,535 treated, unruptured cerebral aneurysm cases were evaluated. The measurements used were effectiveness as measured by hospital discharge outcomes: (1) mortality (in-hospital death), (2) adverse outcomes (death or discharge to a rehabilitation or nursing facility), (3) length of stay, and (4) hospital charges. Univariate analyses compared endovascular versus neurosurgical discharge outcomes. Multivariable models were adjusted for age, sex, region, Medicaid insurance status, year, hospital case volume, comorbidity score, and admission source.

Results: Endovascular treatment was associated with fewer adverse outcomes (6.6% vs. 13.2%), decreased mortality (0.9% vs. 2.5%), shorter lengths of stay (4.5 vs. 7.4 days), and lower hospital charges ($ 42,044 vs. $ 47,567) compared with neurosurgical treatment (p < 0.05). After multivariable adjustment, neurosurgical cases had 70% greater odds of an adverse outcome, 30% increased hospital charges, and 80% longer length of stay compared with endovascular cases (p < 0.05).

Conclusion: This study indicates that endovascular therapy is associated with significantly less morbidity, less mortality, and decreased hospital resource use at discharge, compared with conventional neurosurgical treatment for all unruptured aneurysms. Endovascular therapy, as a treatment alternative to surgical clipping, should be offered as a viable therapeutic option to all patients considering treatment of an unruptured cerebral aneurysm.

Comment

The ISAT trial (International Subarachnoid Aneurysm Trial Collaborative Group) has significantly changed clinical practice in the treatment of ruptured aneurysms by demonstrating improved outcome after the endovascular treatment [1]. However, the treatment modality of unruptured aneurysms has been under debate, and data comparing the endovascular with the neurosurgical approach are sparse. It has been suggested that surgery is less problematic in unruptured aneurysms because no blood or brain swelling is present. In this first large, multicenter trial in the USA, early outcomes (i.e., until discharge) were assessed in patients undergoing treatment for an unruptured aneurysm either surgically or by the endovascular approach. Both neurosurgeons and interventional neuroradiologists participated in this trial. The results are unequivocal: adverse outcomes were substantially lower in the endovascular group which was associated with a shorter length of stay in the hospital and lower hospital charges. Most importantly, these data were collected in the “early” days of endovascular aneurysm treatment (1999/2000). Since then, new devices have been introduced in the market (i.e., new spherical or soft finishing coils, compliant balloons) allowing a more effective and safe occlusion of aneurysms. Probably, nowadays the difference between both groups would be even more evident. It has to be remembered though, that this study comes with some limitations: like in every nonrandomized trial a bias in patient selection may be present. In this study, about 75% of the aneurysms were treated surgically. It is possible that the more difficult and complex treatment cases were referred for endovascular therapy, or vice versa. Moreover, this was a study focused on outcome at discharge. No long-term data on outcome, aneurysm retreatment or even late hemorrhage are available. However, the long-term data of the ISAT trial indicate that rebleeding is not significantly more frequent in aneurysms occluded by the endovascular approach compared with the neurosurgical treatment [2]. Moreover, the advantage of coil-occluded aneurysms in terms of outcome was still present in the long run.

Despite these methodological limitations of a retrospective design, the data of this large study give interventional neuroradiologists a robust basis to advise patients with unruptured aneurysms to undergo endovascular treatment.

References

1. Molyneux AJ, Kerr RSC, Stratton I, Sandercock P, Clarke M, Shrimpton J, Holman R, International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping vs. endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002;360:1267–74.
2. International Subarachnoid Trial Study Group, Molyneux AJ, Kerr RSC, et al. Final one year results of a randomised trial of 2,143 patients comparing neurosurgical clipping with endovascular coiling of ruptured intracranial aneurysms. Lancet 2005;366:809–17.

(submitted April 5, 2007)

Martin Bendszus, Würzburg