Elsevier

World Neurosurgery

Volume 79, Issues 3–4, March–April 2013, Pages 472-478
World Neurosurgery

Peer-Review Report
Rationale for Treating Unruptured Intracranial Aneurysms: Actuarial Analysis of Natural History Risk versus Treatment Risk for Coiling or Clipping Based on 14,050 Patients in the Nationwide Inpatient Sample Database

https://doi.org/10.1016/j.wneu.2012.01.038Get rights and content

Objective

The treatment of small unruptured intracranial aneurysms has been questioned based on the results of the International Study of Unruptured Intracranial Aneurysms. Our objective was to compare natural history rupture risk versus treatment risk for coiling and clipping small unruptured aneurysms using data in the Nationwide Inpatient Sample database.

Methods

Data for clipping and coiling of unruptured aneurysms was collected from the Nationwide Inpatient Sample from 2002–2008. Treatment risks were adjusted for age, gender, and medical comorbidities. Logistic regression models were used to create curves depicting the estimated probability of poor outcome as a function of patient age for clipping and coiling. These treatment risk curves were compared against natural history actuarial risk curves calculated from four prominent studies.

Results

There were 14,050 hospitalizations: 7439(53%) coiling; 6611(47%) clipping. For patients who underwent coiling or clipping, the mortality rate was 2.17% and 2.66%, and the morbidity rate was 2.16% and 4.75%, respectively. The adjusted risk of poor outcome from clipping and coiling, when modeled against most natural history studies, demonstrates a treatment benefit for clipping for patients <70 years and for coiling patients <81 years. Models using the International Study of Unruptured Intracranial Aneurysms data demonstrate a treatment benefit for clipping for patients <61 years and for coiling for patients <70 years.

Conclusions

Both clipping and coiling of unruptured intracranial aneurysms are safe. This analysis demonstrates rationale for clipping small unruptured aneurysms in patients <61–70 years and coiling small unruptured aneurysms in patients <70–80 years. Treatment beyond these age ranges is associated with increased risk of poor outcome.

Introduction

The treatment of unruptured intracranial aneurysms has been questioned based on the results of the International Study of Unruptured Intracranial Aneurysms (ISUIA), particularly for very small unruptured aneurysms in patients with no history of subarachnoid hemorrhage (9, 15, 16). Although outcomes appear to have improved during the past two decades, the consequences of aneurysmal subarachnoid hemorrhage are devastating, with overall mortality at 1 month approaching 40% (11, 14).

Previous studies have demonstrated that aneurysm treatment risk increases with increasing patient age (2, 12). Our hypothesis is that clipping or coiling of unruptured intracranial aneurysms is safe and indicated for patients in an age range, which can be determined by actuarial analysis. We used statistical models to perform an actuarial analysis of age-stratified natural history rupture risk curves, calculated using natural history studies (7, 8, 10, 13, 15) and Centers for Disease Control and Prevention life expectancy tables (1), and compared them to treatment risk curves for unruptured aneurysms calculated from data in the Nationwide Inpatient Sample (NIS) database. Therefore, we estimated the age range in which treatment of unruptured aneurysms is safe and indicated.

Section snippets

Methods

Data for clipping and coiling of unruptured intracranial aneurysms was collected from the NIS database from 2002–2008 by International Statistical Classification of Diseases and Related Health Problems, 9th edition (ICD-9) code using a method previously described (5, 6). Treatment risks were adjusted for age, gender, hospital bed size, hospital location (rural, suburban, and urban), as well as medical comorbidities including alcoholism, heart failure, chronic lung disease, chronic hypertension,

Results

From 2002–2008, there were 14,050 hospitalizations in the NIS for treatment of an unruptured cerebral aneurysm: 7439 (53%) coiling; 6611 (47%) clipping. In-hospital mortality data were available for 14,018 of the 14,050 hospitalizations; in total, 333 patients died (2.38%). For coiling, 158 of 7277 patients died (2.17%), and for clipping, 175 of 6583 patients died (2.66%) (P = 0.0614). Major morbidity rates at discharge were 2.16% for coiling and 4.75% for clipping (P < 0.0001). Baseline

Discussion

We generated an actuarial analysis of treatment risk of clipping or coiling versus natural history rupture risk for unruptured intracranial aneurysms based on 14,050 patients in the NIS and several prominent natural history studies. Our NIS data demonstrate that treatment risk increases with age, and our logistic regression model identified age as a significant predictor of poor outcome for clipping and coiling patients (Table 2, Table 3). The age-related risk of poor outcome during

Conclusions

Clipping and coiling of unruptured intracranial aneurysms are safe, and both treatment modalities have very low morbidity and mortality. Major morbidity is higher for clipping compared with coiling, 4.75% versus 2.16%, respectively (P < 0.0001). Based on NIS reported outcomes and natural history studies, there is a rationale for performing clipping and coiling of unruptured aneurysms for patients less than age 70 years for clipping and less than age 80 years for coiling.

For small aneurysms less

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Conflict of interest statement: Dr. Hoh, the senior author, is involved in neuroendovascular research and education. He has no conflicts directly related to this manuscript, but has received an honoraria from Actelion Pharmaceuticals. Dr. Mocco is also involved in neuroendovascular research and education. He has no conflicts directly related to this manuscript, but serves as a consultant for Actelion Pharmaceuticals, Nfocus, and Lazarus Effect. He has received honoraria from Edge Therapeutics. The remaining authors have no conflicts to disclose.

Oral presentation of the data at the Congress of Neurological Surgeons Annual Meeting, October 3, 2011.

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