Detection of Ruptured and Unruptured Brain Arteriovenous Malformations Has Decreased: A Population-Based Study

The growing use and improved accessibility of noninvasive imaging modalities have increased the detection of incidental intracranial findings, such as unruptured brain arteriovenous malformations (AVMs). At the same time, existing literature presents conflicting findings regarding whether the incidence of ruptured AVMs has increased or decreased. Considering these developments, we hypothesized that the detection rate of unruptured AVMs has increased, and the detection rate of ruptured AVMs has changed over the period of 18 years, potentially reflecting shifts in underlying vascular risk profiles and preventive health behaviors.

In this retrospective population-based study, we identified all hospitalized and nonhospitalized (prehospital sudden death) individuals with AVMs in Southern Finland between 1998 and 2015 from the National Cause of Death Register autopsy reports (using ICD-10 codes I60.8, I61.0-I61.9, Q28.0-Q28.3) and the Helsinki AVM Register. European Standard Population age-standardized detection rates with 95% CIs were determined in 3-year intervals for both ruptured and unruptured AVMs. Significance in detection rate trends was analyzed with Poisson regression on 3-year sliding averages.

Between 1998 and 2015, 288 individuals (minimum age 0.2 years, mean age 41.1 years, SD = 18.0 years, 48.3% women) with AVMs were identified; 284 were hospitalized, and 4 died from AVM at home (diagnosed at medicolegal autopsy). The overall (men and women) detection rate of both ruptured and unruptured AVMs decreased from 0.91 (95% CI 0.66-1.17) to 0.40 (95% CI 0.24-0.56)/100,000 person-years during 1998-2015. The annual decrease for ruptured and unruptured AVMs was 5.7% in men (95% CI 3.6%-7.8%), 5.9% in patients <30 years (95% CI 3.2%-8.7%), 4.8% in patients aged 30-59 years (95% CI 2.7%-7.0%), and 2.2% in women (95% CI 0.0%-4.3%). Detection rates decreased by 4.6% annually for ruptured AVMs (95% CI 2.6%-6.6%) and 3.1% for unruptured AVMs (95% CI 0.7%-5.4%).

Contrary to our hypothesis, we observed a decline in the overall detection rate of unruptured AVMs over the 18-year study period. Moreover, we found a substantial reduction in the number of ruptured AVMs among men, women, and patients younger than 60 years. The reasons for these rapid changes remain unclear and warrant further investigation.