Laakso, Aki

Importance Annual rates of first intracranial hemorrhage (ICH) from unruptured brain arteriovenous malformations (AVMs) are often quoted as 2% to 4% in clinical practice. Precise estimates and risk factors are unavailable to inform treatment decisions. Objective To provide estimates of rates and risk factors for first ICH in a large cohort study of unruptured brain AVMs. Design, Setting, and Participants The Multicenter Arteriovenous Malformation Research Study (MARS) included data from 9 cohorts, each contributing 100 or more unruptured brain AVMs. The study was conducted from 2017 to 2023 with retrospective and prospective data collection for existing cohorts and/or new recruitment. This was an international study (2 population-based and 7 referral-based cohorts) that included participants diagnosed with an unruptured brain AVM. Exposures Demographic, clinical, and angiographic characteristics. Main Outcome and Measure The primary outcome was time to first ICH after diagnosis of unruptured brain AVM. Data were collected using standardized definitions; missing data were imputed. Cox regression analysis was performed, censoring at first brain AVM treatment, death, or last visit, and allowing baseline hazards to vary by cohort. Results A total of 3225 individuals were eligible for participation in this study. After 195 exclusions, 3030 participants (median [IQR] age, 38 [25-50] years; 1524 female [50.3%]) were included. Among 2989 participants with unruptured brain AVMs, 1333 (45%) presented with seizure. The median (IQR) maximal brain AVM diameter was 3.1 (2.2-4.4) cm, 248 of 2466 AVMs (10%) had exclusively deep venous drainage, 297 of 2690 (11%) were in supratentorial deep or cerebellar locations, and 457 of 2440 (19%) had associated arterial aneurysms. First ICH occurred in 159 participants over 11 339 person-years of follow-up for an ICH rate of 1.40 (95% CI, 1.20-1.64) per 100 person-years. Significant independent risk factors included (1) increasing age category at diagnosis (hazard ratio [HR], 0.87; 95% CI, 0.53-1.41 for those aged 20 to 39 years; HR, 1.23; 95% CI, 0.74-2.04 for those aged 40 to 59 years; and HR, 2.01; 95% CI, 1.14-3.57 for those aged 60 years vs younger than 20 years; P = .008), (2) presence of associated aneurysms (HR, 1.66; 95% CI, 1.06-2.59; P = .03), and (3) cerebellar or supratentorial deep location (HR, 1.87; 95% CI, 1.16-3.00; P = .01). Conclusions and Relevance The annual ICH rate from unruptured brain AVM was lower than that commonly cited in clinical practice. Increasing age, associated arterial aneurysms, and cerebellar or supratentorial deep brain AVM location were associated with risk of first ICH. These results may be used to counsel patients about the natural history of unruptured brain AVMs.

Introduction: The long-term effects of interventional treatment (with surgery, stereotactic radiosurgery, or endovascular embolization) for unruptured brain arteriovenous malformations (uBAVM) are uncertain. We address this in a large multi-center international cohort study comparing risk of intracranial hemorrhage (ICH) in the treated and untreated course of uBAVM patients. Methods: We pooled individual patient data (n=3,291) from 10 cohorts and imputed missing data. Survival analysis was performed from time of uBAVM diagnosis to intracranial hemorrhage (ICH) using Cox models, stratified by cohort, censoring at death or last follow-up, and including BAVM interventional treatment as a time-varying covariate. We tested for an interaction of treatment with follow-up time, then estimated the association of interventional treatment with ICH, adjusting for propensity quintile. Individual treatment propensity scores were calculated using logistic regression with Spetzler-Martin grade, sex, diagnosis age and year, cohort, and presence of presenting symptoms (seizures, headaches, and/or deficits). Results: Median cohort age was 36 years, 48% were female, and 77% received ≥1 treatment modality for uBAVM during follow-up. 373 ICH occurred during 32,054 person-years of follow-up (median=6.6y), for an ICH rate of 1.16 per 100 P-Y. Overall, treatment was not associated with risk of ICH (HR=1.12, 95% CI=0.89-1.51, p=0.33). However, we observed a strong interaction between treatment and follow-up time (p<0.001): between 0-1 year, treatment was associated with higher risk of ICH (HR=3.48, 95% CI: 2.26-5.37, p<0.001); between 1-10 years, we found no association between treatment and risk of ICH (HR=1.02, 95% CI: 0.73-1.45, p=0.87); after 10 years, treatment was associated with a lower risk of ICH (HR=0.46, 95% CI: 0.30-0.70, p<0.001). Survival curves for untreated and treated courses crossed around 17 years. Conclusion: After accounting for treatment propensity for uBAVM, we found an initial increased risk of ICH in the treated relative to untreated course, which continually declined over time with survival curves crossing around 17 years. These results require confirmation in a randomized controlled trial of uBAVM with long-term follow-up.

Introduction: Accurately balancing risks of interventional treatment and intracranial hemorrhage (ICH) in the untreated course of unruptured brain arteriovenous malformation (uBAVM) patients is critical for optimal management. Observational studies of uBAVM afford an opportunity to address important gaps and previous criticisms of randomized data to help guide treatment decisions and assess long-term risk/benefit ratio. We previously published an individual patient data meta-analysis (IPDMA) in 4 MARS cohorts and identified ICH presentation and increasing age as significant predictors of ICH during follow-up, but was not powered to detect predictors in those with uBAVM. Thus, the goals of this project are to identify risk factors for ICH in uBAVMs, to estimate the risk with precision, and to create personalized, risk-prediction models. Methods: MARS is an international, multi-center study of 11 cohorts with target enrollment of 4,500 uBAVM patients ascertained through population-based or referral-based studies. We are harmonizing both retrospective and prospective data, including clinical, lifestyle, imaging, and angiographic factors. Treatments, complications, and functional outcomes (physician and patient-reported) will be updated annually between 2018-2022. We propose to: 1) identify predictors of outcome in uBAVMs using IPDMA; 2) test whether long-term outcomes differ by treatment using statistical approaches for causal inference and unbiased estimates; 3) compare treatment outcomes in randomized and non-randomized data to address generalizability; and 4) validate models and provide a novel tool for calculating individualized risks. Eligible sites have: a) prior BAVM publications; b) data from a minimum of 100 uBAVM patients; c) agree to random outcome adjudication; and d) agree to MARS data sharing policy. Discussion: The NIH-funded MARS consortium will provide important and comprehensive characterization of the untreated and treated course of uBAVMs, using large observational datasets and sophisticated epidemiological approaches. The data and models generated will be a useful resource for decision-making. We welcome participation from eligible sites with longitudinal data on uBAVM patients

Background Intracranial aneurysms ( IAs ), abdominal aortic aneurysms ( AAAs ), and thoracic aortic aneurysms ( TAAs ) all have a familial predisposition. Given that aneurysm types are known to co‐occur, we hypothesized that there may be shared genetic risk factors for IAs , AAAs, and TAAs . Methods and Results We performed a mega‐analysis of 1000 Genomes Project‐imputed genome‐wide association study ( GWAS ) data of 4 previously published aneurysm cohorts: 2 IA cohorts (in total 1516 cases, 4305 controls), 1 AAA cohort (818 cases, 3004 controls), and 1 TAA cohort (760 cases, 2212 controls), and observed associations of 4 known IA , AAA , and/or TAA risk loci (9p21, 18q11, 15q21, and 2q33) with consistent effect directions in all 4 cohorts. We calculated polygenic scores based on IA ‐, AAA ‐, and TAA ‐associated SNP s and tested these scores for association to case‐control status in the other aneurysm cohorts; this revealed no shared polygenic effects. Similarly, linkage disequilibrium–score regression analyses did not show significant correlations between any pair of aneurysm subtypes. Last, we evaluated the evidence for 14 previously published aneurysm risk single‐nucleotide polymorphisms through collaboration in extended aneurysm cohorts, with a total of 6548 cases and 16 843 controls ( IA ) and 4391 cases and 37 904 controls ( AAA ), and found nominally significant associations for IA risk locus 18q11 near RBBP 8 to AAA (odds ratio [ OR ]=1.11; P =4.1×10 −5 ) and for TAA risk locus 15q21 near FBN 1 to AAA ( OR =1.07; P =1.1×10 −3 ). Conclusions Although there was no evidence for polygenic overlap between IAs , AAAs , and TAAs , we found nominally significant effects of two established risk loci for IAs and TAAs in AAAs . These two loci will require further replication.