Red Cell Distribution Width in Relation to Incidence of Stroke and Carotid Atherosclerosis: A Population-Based Cohort Study

BACKGROUND Increased red cell distribution width (RDW) has been related to poor prognosis in patients with cardiovascular disease, and is a predictor of cardiovascular mortality in the general population. The purpose of the present study was to investigate if RDW is associated with increased incidence of stroke and its subtypes in individuals from the general population. METHODS Red cell distribution width was measured in 26,879 participants (16,561 women and 10,318 men aged 45-73 years) without history of coronary events or stroke, from the population-based Malmö Diet and Cancer Study. Incidences of total stroke and stroke subtypes over a mean follow-up of 15.2 years were calculated in relation to sex-specific quartiles of RDW. The presence of carotid plaque and intima-media thickness, as assessed by ultrasound, was studied in relation to RDW in a randomly selected subcohort (n = 5,309). RESULTS Incidences of total stroke (n = 1,869) and cerebral infarction (n = 1,544) were both increased in individuals with high RDW. Hazard ratios (HRs) in the highest compared to the lowest quartile were 1.31 for total stroke (95% confidence interval [CI]: 1.11-1.54, p for trend = 0.004) and 1.32 for cerebral infarction (95% CI: 1.10-1.58, p for trend = 0.004) after adjustment for stroke risk factors and hematological parameters. The adjusted HR for intracerebral hemorrhage (n = 230) was 1.44 (95% CI: 0.90-2.30) and the HR for subarachnoid hemorrhage (n = 75) was 0.94 (95% CI: 0.43-2.07), in the highest compared to the lowest quartile of RDW. Red cell distribution width was positively associated with intima-media thickness of the common carotid artery (p for trend = 0.011). CONCLUSIONS Red cell distribution width in the highest quartile was associated with increased incidence of total stroke and cerebral infarction. There was no significant association between RDW and incidence of intracerebral or subarachnoid hemorrhage.