Stroke and the “Stroke Belt” in Dialysis

Abstract

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. ESRD is a potent risk factor for stroke, but whether regional variations in stroke risk exist among dialysis patients is unknown. Medicare claims from 2000 to 2005 were used to ascertain ischemic stroke events in a large cohort of 265,685 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 for stroke. Older age, female sex, African American race and Hispanic ethnicity, unemployed status, diabetes, hypertension, history of stroke, and permanent atrial fibrillation were positively associated with ischemic stroke, whereas body mass index .30 kg/m 2 was inversely associated with stroke (P,0.001 for each). After full multivariable adjustment, the three states with O/E rate ratios .1.0 were all in the South: North Carolina, Mississippi, and Oklahoma. Regional efforts to increase primary prevention in the "stroke belt" or to better educate dialysis patients on the signs of stroke so that they may promptly seek care may improve stroke care and outcomes in dialysis patients.

Temporal Trends in the Outcomes of Dialysis Patients Admitted With Acute Ischemic Stroke

“…In their study, patients on dialysis had significantly higher odds of experiencing AIS than non‐dialysis patients (odd ratio 6.1, and 10.1 for white males and females and 4.3 and 6.5 for black males and females, P <0.001 for all). Other studies investigating the incidence of AIS in dialysis patients were single center, non‐contemporary or primarily involved non‐US population 2, 8, 16, 17, 18. To our knowledge, this is the largest study examining contemporary rates of AIS in the dialysis and non‐dialysis population.…”

“…Patients with end‐stage renal disease receiving maintenance dialysis have higher incidences of both ischemic and hemorrhagic strokes compared with the general population 2, 3, 4, 5. In addition, distinctive risk profiles, mechanisms of stroke, and racial disparities have been suggested in several population studies of ischemic stroke in the dialysis population 2, 3, 4, 5, 6, 7, 8, 9. Dialysis status has also been shown to be an independent predictor of in‐hospital mortality following acute stroke 2, 5, 10, 11, 12.…”

Race, Ethnicity, and State-by-State Geographic Variation in Hemorrhagic Stroke in Dialysis Patients

“…This finding was concordant with our person-level model in which African Americans, Hispanics, and individuals of other races had, approximately, 1.4-, 1.8-, and 1.5-fold increases in hemorrhagic stroke compared with whites, even after adjustment for a wide range of other factors. We have recently reported the existence of an ischemic "Stroke Belt" in dialysis patients centered on the southern United States (11). This same basic finding was present when we combined ischemic and hemorrhagic strokes in the outcome of "total strokes" (authors' unpublished data).…”

“…The presence of congestive heart failure and its antecedent condition, coronary artery disease, was inversely associated with hemorrhagic stroke risk, probably because individuals with these conditions tend to have lower BP by the time they are receiving dialysis. Notably, lower body mass index was associated with hemorrhagic stroke, a finding that was also in evidence in ischemic strokes (11) and that may be attributable to paradoxical associations (36).…”

“…We have recently reported the existence of an ischemic "Stroke Belt" in United States dialysis patients, centered in the southern states (11). That report focused on ischemic stroke, which is approximately 4.5-fold more common than hemorrhagic stroke in United States dialysis patients (12).…”