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Title: Obesity end stage renal disease and survival in an elderly cohort with cardiovascular disease

Author
item LEA, JANICE
item CRENSHAW, DARYL
item Onufrak, Stephen
item NEWSOME, B
item MCCLELLAN, WILLIAM

Submitted to: Obesity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2009
Publication Date: 3/23/2009
Citation: Lea, J.P., Crenshaw, D., Onufrak, S.J., Newsome, B., Mcclellan, W. 2009. Obesity end stage renal disease and survival in an elderly cohort with cardiovascular disease. Obesity. 17(12):2216-2222. doi:10.1038/oby.2009.70.

Interpretive Summary: Blacks face an increased risk of developing end stage renal disease (ESRD) but the reasons for this disparity are unknown. Obesity is a risk factor for ESRD and occurs more frequently among blacks. The purpose of this study was to examine if obesity was a stronger risk factor for ESRD among blacks as compared to whites. We found that among patients who were hospitalized for a heart attack, obesity was not associated with increased risk of ESRD among blacks or whites. Furthermore, obese black and white patients also experienced better survival after a heart attack as compared to normal weight and underweight patients.

Technical Abstract: Obesity is highly prevalent in African-Americans and is associated with increased risk of end stage renal disease (ESRD) and death. It is not known if the effect of obesity is similar among Blacks and whites. The aim of this study is to examine racial differences in the association of obesity with ESRD and survival. Data were obtained for 234,754 Medicare patients seen at 6,684 hospitals in all 50 states for acute myocardial infarction (AMI) between February 1994 and July 1995 and follow-up was through June 2004. BMI was calculated as weight (kilograms) divided by height (meters squared). We evaluated the association of BMI class with ESRD incidence and death using multivariate Cox proportional hazards models, testing for race-BMI interactions. All analyses were conducted using SAS software version 9.1 (SAS Institute Inc, Cary NC). After exclusions, there were 78,994 patients available for analysis. Compared to whites, African Americans had higher BMI (27.0 vs. 26.0, p<0.0001) and estimated GFR (72.6 ml/min/1.73 m2 vs.66.8 ml/min/1.73 m2, p<.0001). Crude ESRD rates increased with increasing obesity among whites but not among blacks. However, after adjusting for age, sex, and other comorbidities, BMI was not associated with ESRD rate among blacks or whites and the interaction between race and BMI was not significant. For both races, patients classified as overweight, class 1 obese, or class 2 obese had similar, significantly better survival compared to normal weight patients. Class 3 obesity was also associated with better survival compared to normal BMI among whites but not among blacks (p<0.05 for race-BMI interaction). Our results suggest that obesity does not impart increased risk of ESRD among black or white elderly subjects with prevalent coronary heart disease. Furthermore, both blacks and whites in this population experience a survival benefit if they are obese. Further studies need to explore this obesity paradox.