Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR): rationale, design, and initial characterization of patient cohort

OBJECTIVE Cranial dural arteriovenous fistulas (dAVFs) are rare lesions, hampering efforts to understand them and improve their care. To address this challenge, investigators with an established record of dAVF investigation formed an international, multicenter consortium aimed at better elucidating dAVF pathophysiology, imaging characteristics, natural history, and patient outcomes. This report describes the design of the Consortium for Dural Arteriovenous Fistula Out-comes Research (CONDOR) and includes characterization of the 1077-patient cohort. METHODS Potential collaborators with established interest in the field were identified via systematic review of the litera- ture. To ensure uniformity of data collection, a quality control process was instituted. Data were retrospectively obtained. RESULTS CONDOR comprises 14 centers in the United States, the United Kingdom, the Netherlands, and Japan that have pooled their data from 1077 dAVF patients seen between 1990 and 2017. The cohort includes 359 patients (33%) with Borden type I dAVFs, 175 (16%) with Borden type II fistulas, and 529 (49%) with Borden type III fistulas. Overall, 852 patients (79%) presented with fistula-related symptoms: 427 (40%) presented with nonaggressive symptoms such as tin- nitus or orbital phenomena, 258 (24%) presented with intracranial hemorrhage, and 167 (16%) presented with nonhemor- rhagic neurological deficits. A smaller proportion (224 patients, 21%), whose dAVFs were discovered incidentally, were asymptomatic. Many patients (85%, 911/1077) underwent treatment via endovascular embolization (55%, 587/1077), surgery (10%, 103/1077), radiosurgery (3%, 36/1077), or multimodal therapy (17%, 184/1077). The overall angiographic cure rate was 83% (758/911 treated), and treatment-related permanent neurological morbidity was 2% (27/1467 total procedures). The median time from diagnosis to follow-up was 380 days (IQR 120-1038.5 days). CONCLUSIONS With more than 1000 patients, the CONDOR registry represents the largest registry of cranial dAVF patient data in the world. These unique, well-annotated data will enable multiple future analyses to be performed to better understand dAVFs and their management.