Race, ethnicity, and state-by-state geographic variation in hemorrhagic stroke in dialysis patients

Geographic variation in stroke rates is well established in the general population, with higher rates in the South than in other areas of the United States. A similar pattern of geographic variation in ischemic strokes has also recently been reported in patients undergoing long-term dialysis, but whether this is also the case for hemorrhagic stroke is unknown.

Medicare claims from 2000 to 2005 were used to ascertain hemorrhagic stroke events in a large cohort of incident dialysis patients. A Poisson generalized linear mixed model was generated to determine factors associated with stroke and to ascertain state-by-state geographic variability in stroke rates by generating observed-to-expected (O/E) adjusted rate ratios (ARRs) for stroke.

A total of 265,685 Medicare-eligible incident dialysis patients were studied. During a median follow-up of 15.5 months, 2397 (0.9%) patients sustained a hemorrhagic stroke. African Americans (ARR, 1.43; 95% confidence interval [CI], 1.30 to 1.57), Hispanics (ARR, 1.78; 95% CI, 1.57 to 2.03), and individuals of other races (ARR, 1.51; 95% CI, 1.26 to 1.80) had a significantly higher risk for hemorrhagic stroke compared with whites. In models adjusted for age and sex, four states had O/E ARRs for hemorrhagic stroke that were significantly greater than 1.0 (California, 1.15; Maryland, 1.25; North Carolina, 1.25; Texas, 1.19), while only 1 had an ARR less than 1.0 (Wisconsin, 0.79). However, after adjustment for race and ethnicity, no states had ARRs that varied significantly from 1.0.

Race and ethnicity, or other factors that covary with these, appear to explain a substantial portion of state-by-state geographic variation in hemorrhagic stroke. This finding suggests that the factors underlying the high rate of hemorrhagic strokes in dialysis patients are likely to be system-wide and that further investigations into regional variations in clinical practices are unlikely to identify large opportunities for preventive interventions for this disorder.