Association of duration of residence in the southeastern United States with chronic kidney disease may differ by race: the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort study

BACKGROUND: Prior evidence suggests that longer duration of residence in the southeastern United States is associated with higher prevalence of diabetes and hypertension. We postulated that a similar association would exist for chronic kidney disease (CKD). METHODS: In a national population-based cohort study that enrolled 30,239 men and women ≥ 45 years old (42% black/58% white; 56% residing in the Southeast) between 2003 and 2007, lifetime southeastern residence duration was calculated and categorized [none (0%), less than half (>0-< 50%), half or more (≥50-< 100%), and all (100%)]. Prevalent albuminuria (single spot urinary albumin:creatinine ratio of ≥30 mg/g) and reduced kidney function (estimated glomerular filtration rate <60 ml/min/1.73 m(2)) were defined at enrollment. Incident end-stage renal disease (ESRD) during follow-up was identified through linkage to United States Renal Data System. RESULTS: White and black participants most often reported living their entire lives outside (35.7% and 27.0%, respectively) or inside (27.9% and 33.8%, respectively) the southeastern United States. The prevalence of neither albuminuria nor reduced kidney function was statistically significantly associated with southeastern residence duration, in either race. ESRD incidence was not statistically significantly associated with all vs. none southeastern residence duration (HR = 0.50, 95% CI, 0.22-1.14) among whites, whereas blacks with all vs. none exposure showed increased risk of ESRD (HR = 1.63, 95% CI, 1.02-2.63; P(raceXduration) = 0.011). CONCLUSIONS: These data suggest that blacks but not whites who lived in the Southeast their entire lives were at increased risk of ESRD, but we found no clear geographic pattern for earlier-stage CKD.