Body mass index and etiology of intracerebral hemorrhage.

BACKGROUND AND PURPOSE Extremes of body mass index (BMI) are associated with increased incidence of intracerebral hemorrhage (ICH). Because ICH can result from different vessel pathologies, we investigated whether the effect of BMI depends on ICH etiology. METHODS We analyzed 384 consecutive ICH cases (188 lobar ICH and 196 deep ICH) and 388 control subjects enrolled between 2004 and 2009 in an ongoing single-center prospective study of primary ICH. ICH was categorized as lobar or deep based on CT imaging at admission. BMI was calculated based on subjects' height and weight at enrollment. We constructed multivariate logistic regression models including BMI and known predictors of ICH occurrence. Analyses were performed separately for lobar and deep ICH subjects versus control subjects. RESULTS Low BMI (<18.5 kg/m(2)) and very high BMI (>30.0 kg/m(2)) were associated with deep ICH risk (OR, 1.76; P=0.011 and OR, 1.75; P=0.013, respectively), whereas no effect was found for lobar ICH. Furthermore, sex-stratified analyses uncovered that among low BMI individuals, males were at higher ICH risk (OR, 2.85; P=0.041) but females were not (OR, 0.89; P=0.54, respectively). CONCLUSIONS Extremes of BMI are associated with increased risk of deep ICH, but not lobar ICH, suggesting a role for BMI in the vascular pathologies underlying deep ICH, but not in pathologies such as cerebral amyloid angiopathy that cause ICH in the lobar brain regions.