1010. A Propensity Score Matched Cohort Analysis of Outcomes after Stereotactic Radiosurgery in older versus younger patients with dural arteriovenous fistula: An International Multicenter Study

Authors: Nasser Mohammed, MBBS, MCh; Yi-Chieh Hung; Zhiyuan Xu; Robert Starke; David Mathieu; Dade Lunsford; Jason Sheehan (Charlottesville, VA)

Introduction:
This study aims to evaluate the outcomes of Gamma Knife Stereotactic Radiosurgery for dAVF (dural arterio-venous fistulas) in the older patients (≥ 65 years) in comparison with the younger patients (age<65 years).
Methods:
This is a retrospective, international multicenter-matched study using data from nine medical centers that participate in the International Radiosurgery Research Foundation (IRRF).  Two groups with a total of 96 patients were selected from a database of 133 dAVF patients with a minimum 6 months follow-up. A 1:2 propensity matching was done by nearest neighbor matching criteria based on sex, Borden’s grade, maximum radiation dose given and location. The older cohort consisted of 32 patients and the younger cohort  consisted of 64 patients. The mean overall follow-up in the combined cohort was 42.4 months (range: 6-210 months).  
Results: In the older cohort, transverse sinus location  significantly predicted  obliteration (p= 0.01). The post-SRS actuarial 3-year and 5-year obliteration rates were 47.7% and 78%, respectively.  There were no cases of post-SRS hemorrhage.   In the younger cohort, the cavernous sinus location  significantly predicted obliteration (p=0.005).  The 3-year and 5-year actuarial obliteration rates were 56% and 70% respectively. Five (7.8%) patients hemorrhaged after SRS.  Low Borden’s grade (p=0.001), presence of cortical venous reflux (p=0.01) and spinal drainage (p=0.05) predicted obliteration in univariate analysis. The obliteration rate , post-SRS hemorrhage rate  and persistent symptoms post-SRS  were not statistically different between the two groups.
Conclusion: The outcomes of SRS for comparable dAVFs in the older versus younger patients were not found to be significantly different. Stereotactic radiosurgery achieves obliteration in the majority of the older dAVF patients with an acceptable rate of complication.