title: Geographic Differences in Endovascular Treatment and Retreatment of Cerebral Aneurysms.
abstract: OBJECTIVE
  Comparing outcomes between endovascular aneurysm coiling trials can be difficult because of heterogeneity in patients and end points. We sought to understand the impact of geography on aneurysm retreatment in patients enrolled in the Matrix and Platinum Science Trial.
  
  
  METHODS
  Post hoc analysis was performed on data from the Matrix and Platinum Science trial. Patients were stratified as either North American or international. Baseline patient demographics, comorbidities, aneurysm characteristics, procedural complications, and clinical and angiographic outcomes were compared.
  
  
  RESULTS
  We evaluated 407 patients from 28 North American sites and 219 patients from 15 international sites. Patient demographics differed significantly between North American and international sites. Aneurysms were well occluded postprocedure more often at international than North American sites (P< .001). Stents were used significantly more often at North American sites (32.7% [133 of 407]) compared with international sites (10.0% [22 of 219];P< .001). At 455 days, there was no difference in the proportion of patients alive and free of disability (P= .56) or with residual aneurysm filling (P= .10). Ruptured aneurysms were significantly more likely to have been retreated at North American sites within the first year (P< .001) and at 2 years (P< .001). Among all patients for whom the treating physician believed there to be Raymond 3 aneurysm filling at follow-up, absolute rates of retreatment at international and North American sites were similar by 2-year follow-up.
  
  
  CONCLUSIONS
  Data from the Matrix and Platinum Science Trial demonstrate that aneurysm retreatment occurs with different frequency and at different times in different regions of the world. This trend has critical value when interpreting trials reporting short-term outcomes, especially when judgment-based metrics such as retreatment are primary end points that may or may not take place within the defined study follow-up period. Though these variations can be controlled for and balanced within a given randomized trial, such differences in practice patterns must be accounted for in any attempt to compare outcomes between different trials. Despite these differences, endovascular-treated intracranial aneurysms around the world have similar clinical outcomes.
authors.affiliation: From the Departments of Radiology (A.S.T.) turk@musc.edu.|Neurosurgery (A.S.T.), Medical University of South Carolina, Charleston, South Carolina.
authors.forename: A S
authors.identifier: http://orcid.org/0000-0001-8375-0410
authors.initials: AS
authors.lastname: Turk
authors.affiliation: Clinical and Translational Science Institute (S.C.J.), University of California, San Francisco, San Francisco, California.|Dell Medical School at The University of Texas at Austin (S.C.J.), Austin, Texas.
authors.forename: S C
authors.identifier: http://orcid.org/0000-0002-2912-0714
authors.initials: SC
authors.lastname: Johnston
authors.affiliation: Department of Radiology and Biomedical Imaging (S.H.), University of California, San Francisco School of Medicine, San Francisco, California.
authors.forename: S
authors.identifier: http://orcid.org/0000-0001-5885-7259
authors.initials: S
authors.lastname: Hetts
authors.affiliation: Department of Neurosurgery (J.M.), Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: J
authors.identifier: http://orcid.org/0000-0001-5489-2524
authors.initials: J
authors.lastname: Mocco
authors.affiliation: California Pacific Medical Center (J.E.), San Francisco, California.
authors.forename: J
authors.identifier: http://orcid.org/0000-0001-8943-6000
authors.initials: J
authors.lastname: English
authors.affiliation: Department of Neurosurgery (Y.M.), Jikei University Hospital, Tokyo, Japan.
authors.forename: Y
authors.identifier: http://orcid.org/0000-0003-3490-385X
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: Department of Neurological Surgery (C.J.P.), University of Medicine and Dentistry of New Jersey, Newark, New Jersey.
authors.forename: C J
authors.identifier: http://orcid.org/0000-0002-5979-2378
authors.initials: CJ
authors.lastname: Prestigiacomo
authors.affiliation: Department of Neurosurgery (D.L.), Rush University Medical Center, Chicago, Illinois.
authors.forename: D
authors.identifier: http://orcid.org/0000-0002-6280-0113
authors.initials: D
authors.lastname: Lopes
authors.affiliation: Department of Neurosurgery (Y.P.G.), Weill Cornell Medical College, New York, New York.
authors.forename: Y P
authors.identifier: http://orcid.org/0000-0002-3774-9096
authors.initials: YP
authors.lastname: Gobin
authors.affiliation: Stryker Corporation (K.C.), Fremont, California.
authors.forename: K
authors.identifier: http://orcid.org/0000-0002-9861-0274
authors.initials: K
authors.lastname: Carroll
authors.affiliation: Department of Neurosurgery (C.M.), Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona.
authors.forename: C
authors.identifier: http://orcid.org/0000-0001-7372-7049
authors.initials: C
authors.lastname: McDougall