Development and Validation of a Scoring System for Hemorrhage Risk in Brain Arteriovenous Malformations

The dilemma between natural rupture risk and adverse outcomes of intervention is of major concern for patients with unruptured arteriovenous malformations (AVMs). The existing risk score for AVM rupture includes factors that are controversial and lacks prospective validation.

To develop and robustly validate a reliable scoring system to predict the rupture risk of AVMs.

This prognostic study developed a prediction model derived from a single-center cohort (derivation cohort) and validated in a multicenter external cohort (multicenter external validation cohort) and a cohort of patients receiving conservative treatment management (conservative treatment validation cohort). Patients were recruited from a nationwide multicenter prospective collaboration registry in China. A total of 4135 patients were enrolled in the registry between August 1, 2011, and September 1, 2021. Of those, 3962 patients were included in the study (3585 in the derivation cohort and 377 in the multicenter external validation cohort); 1028 patients from the derivation cohort who had time-to-event data and prerupture imaging results were included in the conservative treatment validation cohort. Data were analyzed from March 10 to June 21, 2022.

A scoring system was developed based on risk factors identified from a literature review and a robust selection process. Patients were stratified into different risk groups based on scores to calculate hemorrhage-free probability in future years, and Kaplan-Meier curves were plotted to visualize risk stratification. Receiver operating characteristic curves were used to assess the discrimination of models. Univariable analyses (logistic regression analysis for descriptive data and Cox regression analysis for survival data) were used to compare baseline information and assess bias.

Among 3962 patients (2311 men [58.3%]; median [IQR] age, 26.1 [14.6-35.5] years), 3585 patients (2100 men [58.6%]; median [IQR] age, 25.9 [14.6-35.0] years) were included in the derivation cohort, and 377 patients (211 men [56.0%]; median [IQR] age, 26.4 [14.5-39.2] years) were included in the multicenter external validation cohort. Thirty-six hemorrhages occurred over a median (IQR) follow-up of 4.2 (0.3-6.0) years among 1028 patients in the conservative treatment validation cohort. Four risk factors were used to develop the scoring system: ventricular system involvement, venous aneurysm, deep location, and exclusively deep drainage (VALE). The VALE scoring system performed well in all 3 cohorts, with areas under the receiver operating characteristic curve of 0.77 (95% CI, 0.75-0.78) in the derivation cohort, 0.85 (95% CI, 0.81-0.89) in the multicenter external validation cohort, and 0.73 (95% CI, 0.65-0.81) in the conservative treatment validation cohort. The 10-year hemorrhage-free rate was 95.5% (95% CI, 87.1%-100%) in the low-risk group, 92.8% (95% CI, 88.8%-97.0%) in the moderate-risk group, and 75.8% (95% CI, 65.1%-88.3%) in the high-risk group; the model discrimination was significant when comparing these rates between the high-risk group and the low- and moderate-risk groups (P < .001 for both comparisons).

In this prognostic study, the VALE scoring system was developed to distinguish rupture risk among patients with AVMs. The stratification of unruptured AVMs may enable patients with low risk of rupture to avoid unnecessary interventions. These findings suggest that the scoring system is a reliable and applicable tool that can be used to facilitate patient and physician decision-making and reduce unnecessary interventions or unexpected AVM ruptures.