Racial/Ethnic Differences in Longitudinal Risk of Intracranial Hemorrhage in Brain Arteriovenous Malformation Patients

Abstract

Race/ethnicity is associated with overall incidence of intracranial hemorrhage (ICH), but its impact in patients with brain arteriovenous malformation is unknown. We evaluated whether race/ethnicity was a risk factor for ICH in the natural course in a large, multiethnic cohort of patients with brain arteriovenous malformation followed longitudinally. Data were collected prospectively for patients with brain arteriovenous malformation evaluated at the University of California, San Francisco (n=436) and retrospectively through databases and chart review in the 20 hospitals of the Kaiser Permanente Medical Care Program (n=1028). Multivariate Cox regression was performed to assess the influence of race/ethnicity on subsequent ICH, adjusting for risk factors. Cases were censored at first treatment, loss to follow-up, or death. Average follow up was 4.7+/-8.0 years for Kaiser Permanente Medical Care Program patients and 2.8+/-7.3 years for University of California, San Francisco patients with no difference in time to ICH between cohorts (log rank P=0.57). The annualized 5-year ICH rate was 2.1% (3.7% for ruptured at presentation; 1.4% for unruptured). Initial ICH presentation (hazard ratio: 3.0, 95% CI: 1.9 to 4.9, P<0.001) and Hispanic race/ethnicity (hazard ratio: 1.9, 95% CI: 1.1 to 3.3, P=0.02) were independent predictors of ICH, adjusting for age, gender, cohort, and a cohort-age interaction. The ICH risk for Hispanics versus whites increased to 3.1 (95% CI: 1.3 to 7.4, P=0.013) after further adjusting for arteriovenous malformation size and deep venous drainage in a subset of cases with complete data. Similar trends were observed for blacks (hazard ratio: 2.1, 95% CI: 0.9 to 4.8, P=0.09) and Asians (hazard ratio: 2.4, 95% CI: 0.8 to 7.1, P=0.11), although nonsignificant. This study reports the first description of race/ethnic differences in brain arteriovenous malformation, with Hispanics at an increased risk of subsequent ICH compared with whites.