Geographic Differences in Endovascular Treatment and Retreatment of Cerebral Aneurysms

BACKGROUND AND PURPOSE: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.MATERIALS AND 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.

The International Subarachnoid Aneurysm Trial^1,2 was the landmark prospective randomized trial demonstrating the safety and effectiveness of endovascular treatment of ruptured aneurysms compared with surgical clipping. More recently, results from the Barrow Ruptured Aneurysm Trial³ further support coiling as a treatment technique associated with good patient outcomes comparable with clipping in the setting of SAH. Moreover, the results of several recently published multinational randomized controlled trials^4–6 demonstrated ruptured and unruptured aneurysms can be safely and effectively treated by using various coil types. Many comparisons generalizing results of these various trials have been made. However, comparing outcomes between trials can be difficult and misleading because of different trial designs and patient populations.⁷ Analyses of subgroups from different trials cannot overcome these problems.The very low bleeding or rebleeding rates of treated aneurysms has led most trial investigators to use angiographic outcomes to compare device performance. However, there are no agreed-upon standards for acceptable angiographic outcomes. Recently, the value of target aneurysm recurrence was explored as a new clinically relevant composite end point in a large-scale multicenter randomized trial comparing outcomes of patients with intracranial saccular aneurysms treated with 2 different embolic coil types.^4,8,9 In this study, target aneurysm recurrence was defined as clinically relevant aneurysm recurrence resulting in target aneurysm re-intervention, rupture/rerupture, and/or death from an unknown cause. The advantage of this end point is that it is definitive that the event has happened and that these events are of clear relevance to the patient. The disadvantage of these end points is the variability of the decision to retreat because physician judgment often varies with the training, economic incentives, and regulatory structure of the local health system.Both angiographic assessments and the decision to retreat aneurysms are subjective, leaving tremendous opportunity for individual or regional factors to influence trial results. We sought to understand the impact of geography on aneurysm retreatment in patients randomized in the Matrix and Platinum Science Trial.