Objectives: To determine the predictability of the Spetzler-Martin Grade (SMG) with occurrence of hemorrhage in the ARUBA trial medical management arm compared with the interventional arm. Methods: Of the 223 patients enrolled in “A randomized trial of unruptured bAVMs” (ARUBA), 114 were allocated to medical therapy alone (MM), 109 to medical therapy with intervention (IT). The primary outcome is the composite endpoint of death or symptomatic stroke. The aim was to compare the relative frequency of primary outcome events between study arms depending on SMG scores at baseline. Results: For all but 2 patients (without catheter angiography) SMG scores at baseline are available for analysis. More than half of the cohort scored SMS-1 or SMS-2. After 33.7 months of follow-up, the intention-to-treat analysis showed primary outcome events were similarly distributed for bAVMs scored SMG-1 and SMG-4, but events were significantly less frequent in the MM arm for SMG-2 (7.4%) and SMG-3 (8.8%) as compared to IT (34.1%, p=0.011 and 57.1%, p<0.001, respectively). There was no trend toward increasing outcome events in IT with increasing SMG. The disparities were also found in in the as-treated analysis (see Table). Conclusion: AlthoughSMGhas long use for prediction of risk for surgical intervention, less success has been met with its use as a predictor of hemorrhage in a population not undergoing intervention,[i] And until ARUBA the SMG has not been tested in a trial. Our data to date suggest the SMG is neither a reliable predictor of risk for hemorrhage, nor indicative of increase in outcome risk with increasing grade. The later outcome for those in the ARUBA trial awaits further follow-up. [i] Hartmann A, Mast H, Choi JH, Stapf C, Mohr JP. Treatment of arteriovenous malformations of the brain. Curr Neurol Neurosci Rep. 2007 Jan;7(1):28-34.
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