Conservative management of brain arteriovenous malformations: results of the prospective observation registry of a pragmatic trial
Bibliographic record
Abstract
OBJECTIVE: Many patients recruited in the Treatment of Brain Arteriovenous Malformations Study (TOBAS) are managed conservatively. The aim of this study was to monitor what happened to those patients. METHODS: TOBAS comprises two randomized controlled trials and multiple prospective registries. All patients with brain arteriovenous malformations (AVMs) can participate. This report concerns patients selected for conservative management. The primary trial outcome measure is related death or dependency (modified Rankin Scale [mRS] score > 2) at 10 years. Secondary outcomes include intracranial hemorrhages, nonhemorrhagic neurological events, and serious adverse events (SAEs). For this report, outcome results are presented using patient-years, Kaplan-Meier survival curves, and Cox log-rank tests. There was no blinding. RESULTS: From June 2014 to May 2021, 1010 patients were recruited, of whom 498 (49%) were proposed the prospective observation registry. After exclusions, 434 (87%) patients remained for analysis. The majority of patients had unruptured AVMs (378/434 [87%]), of which 195 (52%) were low grade (Spetzler-Martin grade I or II). During a mean follow-up period of 3.2 years (total 1368 patient-years), the primary outcome occurred in 23 of 434 (5%) patients, corresponding to an incidence of 1.7 (95% CI 1.1-2.5) per 100 patient-years. For unruptured AVMs the incidence was 1.1 (95% CI 0.7-1.9) per 100 patient-years, and for low-grade unruptured AVMs it was 0.6 (95% CI 0.2-1.7) per 100 patient-years. Poor outcomes were more frequent in patients with a history of rupture (HR 5.6 [95% CI 2.4-13.0], p < 0.001), infratentorial AVMs (HR 2.9 [95% CI 1.1-7.3], p = 0.027), and age ≥ 55 years (HR 3.2 [95% CI 1.4-7.6], p = 0.007). Major intracranial hemorrhage occurred in 35 of 434 (8%) patients (incidence of 2.6 [95% CI 1.9-3.6] per 100 patient-years; 2.0 [95% CI 1.3-2.9] per 100 patient-years for unruptured AVMs and 1.3 [95% CI 0.6-2.6] per 100 patient-years for low-grade unruptured AVMs). Major AVM hemorrhages were more frequent in ruptured (HR 4.4 [95% CI 2.1-8.9], p < 0.001), large (HR 2.6 [95% CI 1.1-6.6], p = 0.039), and high-grade (HR 2.5 [95% CI 1.2-5.3], p = 0.013) AVMs and those with deep venous drainage (HR 2.1 [95% CI 1.1-4.2], p = 0.032). SAEs occurred in 48 of 434 (11%) patients (incidence of 3.6 [95% CI 2.7-4.8] per 100 patient-years). For unruptured AVMs the incidence was 2.8 (95% CI 2.0-4.0) per 100 patient-years, and for low-grade unruptured AVMs it was 1.8 (95% CI 1.0-3.2) per 100 patient-years. CONCLUSIONS: Nearly half of TOBAS participants were observed. Rates of untoward neurological events were within expected boundaries.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.028 | 0.058 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".