Multiple epidemiological studies suggest that the incidence of non-traumatic intracranial hemorrhage (ICH) is higher among black and Hispanic populations than among non-Hispanic whites of similar age. The specific reasons for this disparity, however, are poorly understood. Woo and colleagues describe the methodology and recruitment progress of the ethnic/racial variations of intracerebral hemorrhage (ERICH) study, the most comprehensive health disparities study of ICH to date.
ERICH is a multicenter, prospective case-control study that seeks to recruit 1,000 non-Hispanic white, 1,000 black and 1,000 Hispanic ICH patients along with 3,000 demographically-matched control subjects. In addition to ICH risk factors, the study centers collect neuroimaging including an MRI on every fifth patient and blood samples for genetic analysis. Study recruitment has gone well in the ICH group and lagged slightly in the control group thus far. The end of recruitment is targeted for February, 2015.
The chosen methodology for the ERICH study is appropriate. Case-control studies are often viewed less favorably than prospective cohort or population based studies due to difficulty identifying appropriate control subjects and risk of recall bias. The authors allay these concerns, however, through persuasive arguments regarding the impracticality of alternative study designs and careful recruitment of control subjects from the same populations.
Opportunities to improve our understanding of ICH from the future ERICH results abound. Cerebral amyloid angiopathy (CAA) is challenging to diagnose on CT alone due to difficulty identifying old microbleeds. The large number of MRI studies planned for collection in ERICH promises to better answer whether rates of CAA truly vary across individuals of different ethnic/racial background and identify any associated risk factors. The planned genetic analysis in ERICH is rigorous, and will even determine the genetic ancestry of all study subjects enrolled. As a result, we may finally be able to answer what proportion of the increased rate of ICH among minority populations is genetic and what fraction is due to modifiable risk factors.