SAN DIEGO – The practice patterns for endovascular treatment of intracranial aneurysms appear to differ widely between sites inside and outside of North America, "likely reflecting practice variation rather than individual patient differences," according to Dr. Charles J. Prestigiacomo. "This is important to keep in mind when we’re establishing and designing multinational trials."
In terms of clinical outcomes, however, "everybody is doing very good work, no matter where you are in the world. I think that’s a testament to the technology and a testament to the physicians who are taking such good care of these patients," he said at the annual meeting of the Society of Neurointerventional Surgery.
Numerous international studies have shown that aneurysms can be safely and effectively treated via various coil types, "but we’ve had trouble trying to compare the efficacy of one international study with [that of] another, because there are differences in the primary end points of most of these studies," said Dr. Prestigiacomo, who chairs the department of neurological surgery at New Jersey Medical School, Newark. "The very low bleeding or rebleeding rates of treated aneurysms has led most investigators to use angiographic outcomes to compare devices. However, angiographic assessments are operator dependent and can potentially affect trial results."
In an effort to understand the impact of geography on aneurysm treatment, Dr. Prestigiacomo and his associates evaluated data from 626 patients who were enrolled in the MAPS (Matrix and Platinum Science) trial, a prospective, multicenter, multinational trial that compared bare platinum Guglielmi detachable coils and Matrix2 detachable coils, with the primary end point being target aneurysm recurrence. Patients were stratified into two groups: 407 who were treated at 28 North American (NA) sites, which included the United States, Canada, and Mexico, and 219 who were treated at 15 international (INTL) sites, which included South America, Europe, Asia, and the Asia-Pacific region. The researchers analyzed baseline patient demographics, comorbidities, and aneurysm characteristics, and compared procedural complications and clinical and angiographic outcomes between the two groups.
Several patient demographic factors differed significantly between the NA and INTL groups, including the proportion of female patients (76% vs. 60%, respectively), patients with ruptured aneurysms (28% vs. 52%), white patients (86% vs. 72%), and patients with two or more cardiovascular risk factors (31% vs. 15%), all with a P value less than .0001. NA patients were also more likely than their INTL counterparts to have a Hunt and Hess scale grade III or IV aneurysm (33% vs. 21%; P = .0452), to have more posterior-circulation aneurysms treated (16% vs. 8%; P = .0064), to have more aneurysms with a neck size of 4 mm or larger (39% vs. 31%; P = .0353), and to have more patients older than 55 years (54% vs. 40%; P = .0014).
The researchers found that a similar proportion of patients in the NA and INTL groups were alive and living independently at 1 year after the procedure (90% vs. 91% among those with ruptured aneurysms, respectively, and 95% vs. 97% among those with unruptured aneurysms), whereas a higher proportion of NA patients with ruptured aneurysms were discharged within 30 days, compared with their INTL counterparts (89% vs. 72%; P = .007). "I don’t think that is because of a clinical issue with the patients; it’s more of an issue of the health care system within the INTL community vs. the NA community," Dr. Prestigiacomo said.
Immediately post procedure, there was a lower incidence of complete or near complete occlusion in the NA group, compared with the INTL group (56% vs. 73%, respectively; P = .0002). The packing density of more than 25% was similar (43% vs. 39%) and the use of stents was more common in the NA group (45% vs. 19%; P less than .0001).
When the researchers evaluated 1-year angiographic outcomes, they noted no differences between the NA and INTL groups in the incidence of residual aneurysm (37% vs. 29%, respectively; P = .08) and retreatment rates for unruptured aneurysms (11% vs. 7%; P = .2285). But retreatment for ruptured aneurysms occurred significantly more often among those in the NA group than in the INTL group (22% vs. 4%; P = .001).
"When you look at when patients were treated, in North America there seems to be a higher probability of treating recurrent aneurysms within 1 year, and then the lines converge at 2 years," Dr. Prestigiacomo said. "In part, these differences may exist because there is a higher incidence of unruptured aneurysms in the North American population."