Supplementary Material for: Functional Long-Term Outcome after Left- versus Right-Sided Intracerebral Hemorrhage
Background and Purpose: Hemispheric location might influence outcome after intracerebral hemorrhage (ICH). INTERACT suggested higher short-term mortality in right hemispheric ICH, yet statistical imbalances were not addressed. This study aimed at determining the differences in long-term functional outcome in patients with right- vs. left-sided ICH with a priori-defined sub-analysis of lobar vs. deep bleedings. Methods: Data from a prospective hospital registry were analyzed including patients with ICH admitted between January 2006 and August 2014. Data were retrieved from institutional databases. Outcome was assessed using the modified Rankin Scale (mRS) score. Outcome measures (long-term mortality and functional outcome at 12 months) were correlated with ICH location and hemisphere, and the imbalances of baseline characteristics were addressed by propensity score matching. Results: A total of 831 patients with supratentorial ICH (429 left and 402 right) were analyzed. Regarding clinical baseline characteristics in the unadjusted overall cohort, there were differences in disfavor of right-sided ICH (antiplatelets: 25.2% in left ICH vs. 34.3% in right ICH; p < 0.01; previous ischemic stroke: 14.7% in left ICH vs. 19.7% in right ICH; p = 0.057; and presence/extent of intraventricular hemorrhage: 45.0% in left ICH vs. 53.0% in right ICH; p = 0.021; Graeb-score: 0 [0-4] in left ICH vs. 1 [0-5] in right ICH; p = 0.017). While there were no differences in mortality and in the proportion of patients with favorable vs. unfavorable outcome (mRS 0-3: 142/375 [37.9%] in left ICH vs. 117/362 [32.3%] in right ICH; p = 0.115), patients with left-sided ICH showed excellent outcome more frequently (mRS 0-1: 64/375 [17.1%] in left ICH vs. 43/362 [11.9%] in right ICH; p = 0.046) in the unadjusted analysis. After adjusting for confounding variables, a well-balanced group of patients (n = 360/hemisphere) was compared showing no differences in long-term functional outcome (mRS 0-3: 36.4% in left ICH vs. 33.9% in right ICH; p = 0.51). Sub-analyses of patients with deep vs. lobar ICH revealed also no differences in outcome measures (mRS 0-3: 53/151 [35.1%] in left deep ICH vs. 53/165 [32.1%] in right deep ICH; p = 0.58). Conclusion: Previously described differences in clinical end points among patients with left- vs. right-hemispheric ICH may be driven by different baseline characteristics rather than by functional deficits emerging from different hemispheric functions affected. After statistical corrections for confounding variables, there was no impact of hemispheric location on functional outcome after ICH.