Elsevier

World Neurosurgery

Volume 136, April 2020, Pages e371-e379
World Neurosurgery

Original Article
Propensity Score Matching Analysis for the Patients of Unruptured Cerebral Aneurysm from a Post Hoc Analysis of a Nationwide Database in Japan

https://doi.org/10.1016/j.wneu.2020.01.005Get rights and content

Background

This study aimed to compare the functional outcome at discharge for unruptured cerebral aneurysms (UCAs) between surgical clipping and endovascular coiling in total, nonelderly (<65 years), and elderly (≥65 years) patients by nonbiased analysis based on a national database in Japan.

Methods

A total of 15,671 patients with UCA were registered in the Diagnosis Procedure Combination, the nationwide database, from 2010 to 2015 in Japan. The outcome of the Barthel Index (BI) at discharge was investigated, and propensity score–matched analysis was conducted in total, nonelderly, and elderly patient groups.

Results

Propensity score–matched analysis found no significant difference for in-hospital mortality between the 2 treatment methods in the total and both age-groups. The rate of morbidity of BI <90 at discharge was higher after surgical clipping than after endovascular coiling in the total (4.9% vs. 3.9%; P = 0.040; risk difference, –1.0%; 95% confidence interval, –3.6 to 2.3%) and the elderly age-group (8.1% vs. 5.0%; P < 0.001; risk difference, –3.1%; –4.8% to 1.5%), however, no significant association between the 2 treatment methods (2.4% vs. 2.6%; P = 0.67; risk difference, 0.22%; –0.79 to 1.22%) was found in the nonelderly group.

Conclusions

In elderly patients with UCA, a better outcome at discharge after endovascular coiling was found. However, no significantly different functional outcome at discharge between surgical clipping and endovascular coiling for UCA in nonelderly patients was confirmed by propensity score–matched analysis from a nationwide database in Japan.

Introduction

Many asymptomatic unruptured cerebral aneurysms (UCAs) have recently been found by magnetic resonance imaging screening. The precise and unbiased results after surgical clipping and endovascular coiling were unclear in nonelderly and elderly patients with UCA; however, some patients should receive interventional treatment according to the individual risk of rupture. The number not only of surgical clipping but also of endovascular coiling has been increasing recently for elderly patients with UCA per 100,000 Medicare beneficiaries.1 The crude morbidity and mortality of a nationwide study were 8.4%–14.8% and 0.7%–1.6%, respectively, for surgical clipping for UCA and 4.0%–7.6% and 0.5%–0.7%, respectively, for endovascular coiling.2, 3, 4 A recent meta-analysis5 included 106,433 patients with 108,263 UCAs. Surgical treatment (54 studies) showed a pooled complication risk of 8.34% (range, 6.25%–11.10%) and a case-fatality rate of 0.10% (range, 0.00%–0.20%). Endovascular treatment (74 studies) showed a pooled clinical complication risk of 4.96% (95% confidence interval [CI], 4.00–6.12) and a case-fatality rate of 0.30% (95% CI, 0.20–0.40). However, almost all studies used biased data, and there have been few studies with propensity score analysis of reduced bias,6,7 and there has never been a propensity score analysis according to age-group.

This study aimed to clarify nonbiased morbidity at discharge and in-hospital mortality after surgical clipping and endovascular coiling for UCAs in nonelderly (<65 years) and elderly (≥65 years) patients, based on the Diagnosis Procedure Combination database, the national database of in-hospital patients in Japan.

Section snippets

Ethical Approval

This study was approved by the institutional review board of the University of Hiroshima (number E-629) and the University of Tokyo (number 3501- [1]).

Informed Consent

Because of the anonymous nature of the data, the requirement for informed consent was waived.

Data Source

The Japanese Diagnosis Procedure Combination database is a national database of in-hospital patients in Japan, as described elsewhere.8, 9, 10 The database contains administrative claims and abstract discharge data including the diagnoses and

Results

Table 1 shows the baseline characteristics and outcome of UCAs by surgical clipping and endovascular coiling. Almost all valuables were significantly different in backgrounds.

Table 2 shows the patient characteristics in the propensity score–matched analysis of total patients of BI at discharge after surgical clipping and endovascular coiling. Baseline populations included 9922 cases in the surgical clipping group and 3638 cases in the endovascular coiling group. Propensity score–matched

Discussion

Many studies worldwide have reported better outcome after endovascular coiling than after surgical clipping.2, 3, 4 According to some studies with nonbiased propensity score matching analysis,6,7 surgical clipping was associated with similar mortality risk but significantly higher morbidity risk compared with endovascular coiling, as in the total cases in our study. In addition, we analyzed nonelderly and elderly groups. As a result, no significantly different functional outcomes at discharge

Conclusions

In elderly patients with UCA, a better outcome at discharge was found after endovascular coiling. However, no significantly different functional outcome at discharge between surgical clipping and endovascular coiling for UCA in nonelderly patients was confirmed by propensity score–matched analysis from a nationwide database in Japan.

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Cited by (1)

  • Tenets for the Proper Conduct and Use of Meta-Analyses: A Practical Guide for Neurosurgeons

    2022, World Neurosurgery
    Citation Excerpt :

    Matching according to measured baseline variables reduces the extent of confounding in matched cohort studies. For example, a study of surgical clipping versus endovascular coiling for UIAs matched individuals in a 1:1 ratio using propensity scores, and reported in-hospital mortality of 7 of 1751 (0.4%) versus 5 of 1751 (0.3%), respectively.29 Although these numbers could be entered directly into meta-analysis software as event numbers and denominators, the preferred approach is to extract estimates of treatment effect from an analysis that accounts for the paired nature of the data.30

Conflict of interest statement: This work was supported by the Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C) 17K10829.

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