Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR): rationale, design, and initial characterization of patient cohort
Authors: Guniganti Ridhima , Giordan Enrico , Chen Ching-Jen , Abecassis Isaac Josh , Levitt Michael R. , Durnford Andrew , Smith Jessica , Samaniego Edgar A. , Derdeyn Colin P. , Kwasnicki Amanda , Alaraj Ali , Potgieser Adriaan R. E. , Sur Samir , Chen Stephanie H. , Tada Yoshiteru , Winkler Ethan , Phelps Ryan R. L. , Lai Pui Man Rosalind , Du Rose , Abla Adib , Satomi Junichiro , Starke Robert M. , van Dijk J. Marc C. , Amin-Hanjani Sepideh , Hayakawa Minako , Gross Bradley A. , Fox W. Christopher , Bulters Diederik , Kim Louis J. , Sheehan Jason , Lanzino Giuseppe , Piccirillo Jay F. , Kansagra Akash P. , Zipfel Gregory J. , _ _ , _ _ , Zipfel Gregory J. , Kansagra Akash P. , Guniganti Ridhima , Piccirillo Jay F. , Raman Hari , Lipsey Kim , Lanzino Giuseppe , Giordan Enrico , Brinjikji Waleed , Vine Roanna , Cloft Harry J. , Kallmes David F. , Pollock Bruce E. , Link Michael J. , Sheehan Jason , Chen Ching-Jen , Patibandla Mohana Rao , Ding Dale , Buell Thomas , Paisan Gabriella , Kim Louis J. , Levitt Michael R. , Abecassis Isaac Josh , Meyer R. Michael , Kelly Cory , Bulters Diederik , Durnford Andrew , Duffill Jonathan , Ditchfield Adam , Millar John , Macdonald Jason , Fox W. Christopher , Polifka Adam J. , Laurent Dimitri , Hoh Brian , Smith Jessica , Lockerman Ashley , Gross Bradley A. , Lunsford L. Dade , Jankowitz Brian T. , Hayakawa Minako , Derdeyn Colin P. , Samaniego Edgar A. , Gutierrez Santiago Ortega , Hasan David , Roa Jorge A. , Rossen James , Guerrero Waldo , McGruder Allen , Amin-Hanjani Sepideh , Alaraj Ali , Kwasnicki Amanda , Charbel Fady T. , Aletich Victor A. , Rose-Finnell Linda , van Dijk J. Marc C. , Potgieser Adriaan R. E. , Starke Robert M. , Peterson Eric C. , Yavagal Dileep R. , Sur Samir , Chen Stephanie H. , Satomi Junichiro , Tada Yoshiteru , Kanematsu Yasuhisa , Yamamoto Nobuaki , Kinouchi Tomoya , Korai Masaaki , Yamaguchi Izumi , Yamamoto Yuki , Abla Adib , Winkler Ethan , Phelps Ryan R. L. , Lawton Michael , Rutkowski Martin , Du Rose , Lai Pui Man Rosalind , Aziz-Sultan M. Ali , Patel Nirav , Frerichs Kai U. 
Published: September 2021

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 Outcomes 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 literature. 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 tinnitus or orbital phenomena, 258 (24%) presented with intracranial hemorrhage, and 167 (16%) presented with nonhemorrhagic 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.