Abstract P216: Could There be an Offsetting Impact of Insulin Resistance on Ischemic Stroke and Intracerebral Hemorrhage? The REasons for Geographic And Racial Differences in Stroke (REGARDS) Study
Introduction: Higher insulin resistance (IR) is associated with thicker carotid intimal-medial thickness and greater coronary calcium scores for whites but not African Americans (AAs). Only a single study has reported racial differences in the link of IR and ischemic stroke risk - showing higher risk in whites but not AAs. The association of IR with intracerebral hemorrhage (ICH) has not been examined.
Methods: IR was assessed by the homeostasis model (HOMA) in 14,085 whites and 7,984 AAs who were stroke-free at baseline and not taking insulin for diabetes. Stroke cases were identified during semi-annual follow-up calls, and medical records for suspected stroke retrieved and adjudicated by a panel of clinicians. Proportional hazards analysis was used to assess the association of IR with risk of ischemic and ICH stroke stratified by race after adjustment for demographics (age, sex), and further adjustment for risk factors (ischemic stroke: systolic blood pressure (SBP), antihypertensive use, diabetes, left ventricular hypertrophy, atrial fibrillation and history of heart disease; ICH: SBP and antihypertensive use). IR was considered by quartiles, and log of IR as a continuous factor (to reduce skew).
Results: Over 5.7-year follow-up, there were 227 ischemic and 29 ICH strokes in whites, and 148 ischemic and 19 ICH strokes in AAs. In whites, there was a monotonic increasing risk of ischemic stroke across quartiles and a significant association with LN(IR) (HR = 1.15; 95% CI: 1.01 - 1.31). This association was partially attenuated and became insignificant with risk factor adjustment. There was a monotonic decreasing risk of ICH across quartiles and LN(IR) (HR = 0.59; 95% CI: 0.35 - 1.00), not attenuated by risk factor adjustment. No association with either ischemic stroke or ICH was observed in AAs.
Discussion: In whites, higher levels of IR were associated with higher risk of ischemic stroke, but this may be offset by a surprisingly lower risk of ICH. The associations with stroke risk in whites, but not AAs require further investigation.
- © 2013 by American Heart Association, Inc.