<p><b><i>Background and Purpose:</i></b> 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. <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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; <i>p</i> < 0.01; previous ischemic stroke: 14.7% in left ICH vs. 19.7% in right ICH; <i>p</i> = 0.057; and presence/extent of intraventricular hemorrhage: 45.0% in left ICH vs. 53.0% in right ICH; <i>p</i> = 0.021; Graeb-score: 0 [0-4] in left ICH vs. 1 [0-5] in right ICH; <i>p</i>
= 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; <i>p</i> =
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; <i>p</i> = 0.046) in the unadjusted analysis. After adjusting for confounding variables, a well-balanced group of patients (<i>n</i>
= 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; <i>p</i>
= 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; <i>p</i> = 0.58). <b><i>Conclusion:</i></b>
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.</p