Chief Resident (PGY6) Johns Hopkins University School of Medicine Baltimore, Maryland, United States
Disclosure(s):
Wuyang Yang: No financial relationships to disclose
Introduction: Risk of hemorrhage in brain arteriovenous malformations(bAVM) is reported at 2-4% per year. In published studies, elucidation of factors associated with hemorrhage utilized either logistic or survival analysis, but neither method accounts for rarity nor rate of all subsequent hemorrhagic events. We present a large, single institution series to elucidate the natural history of bAVM utilizing a Poisson regression model to find factors associated with hemorrhage.
Methods: All bAVM patients evaluated at Johns Hopkins from 1990-2021 were included. Hemorrhages that occurred following detection of bAVM and during untreated interval were recorded. Natural history was calculated by dividing number of hemorrhages by untreated interval. Frequency of hemorrhages followed Poisson distribution. Multivariable Poisson regression with an offset variable of untreated interval in patient-years was constructed. Model selection was through a stepwise Akaike Information Criterion(AIC) method. Stratified hemorrhagic rate was presented using different combination of significant factors.
Results: Our institutional bAVM database extracted a total of 1099 patients with complete data, with 1066 non-HHT patients harboring a single bAVM. Ninety(8.4%) patients had 101 hemorrhages during an untreated interval of 3596.33 patient-years, translating to overall hemorrhage rate of 2.8% per year. Significant factors increasing hemorrhage risk included ruptured presentation(p=0.004), increasing age(p < 0.001), female sex(p=0.047), deep location(p=0.037). In patients with unruptured bAVM, non-female sex, superficial location, risk of hemorrhage is 0.86%. In contrast, for ruptured bAVMs, female patients, and deep location, risk of hemorrhage is 6.17%, while in adult patients this risk increased to 7.09%.
Conclusion : Hemorrhage following bAVM detection occurs in 8.4% of all patients and the rate averages 2.8% per year. However, this risk varies from 0.86% to 7.09% per year depending on various risk factor combinations. Efforts should be made to stratify bAVMs hemorrhage rate by risk factors for precise estimation of bleeding risk if left untreated.
