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Abstract: FR-PO548

CKD and the Adiposity Paradox: Valid or Confounded?

Session Information

Category: Health Maintenance, Nutrition, and Metabolism

  • 1302 Health Maintenance, Nutrition, and Metabolism: Clinical

Authors

  • Ziolkowski, Susan, Stanford University School of Medicine , Palo Alto, California, United States
  • Long, Jin, Stanford University, Palo Alto, California, United States
  • Chertow, Glenn Matthew, Stanford University School of Medicine , Palo Alto, California, United States
  • Leonard, Mary B., Stanford School of Medicine, Stanford, California, United States
Background

Obesity is associated with decreased mortality risk in in patients with end-stage renal disease and mild to moderate chronic kidney disease (CKD), a phenomenon termed the obesity paradox. Indices of obesity, including Quételet’s (body mass) index (BMI, kg/m2) and % body fat (%BF) are confounded by muscle mass, while DXA derived fat mass index (FMI, kg/m2) overcomes this limitation. We aimed to compare the associations between adiposity and mortality in persons with CKD using alternative estimates of adiposity, and to determine whether muscle mass, inflammation and recent weight loss modify these associations.

Methods

DXA-derived FMI, BMI, and %BF were calculated in 2,852 NHANES participants with CKD from 1999-2006, used to define obesity according to established cut-offs, and linked to death certificate data in the National Death Index with follow up through 2011. Cox proportional hazards models assessed associations between mortality and estimates of adiposity. Sequential models adjusted for percent weight change since the maximum reported weight and interactions with measures of inflammation and muscle mass.

Results

In adjusted models, obesity based on FMI (obeseFMI) was associated with lower mortality (HR 0.82, 95% CI, 0.70 to 0.97). As continuous variables, higher FMI, BMI and %BF were associated with lower mortality. The protective effect of obesity was less pronounced among those with higher lean mass.The prevalence of >10% weight loss was 20% in obeseFMI participants, compared with 40.4% in the non-obeseFMI participants. Prior weight loss was strongly associated with mortality, and the protective effect of obesity was no longer significant after adjustment for prior weight loss. Inflammation did not modify these associations.

Conclusion

These data demonstrated an apparent protective effect of high fat mass in CKD, particularly among persons with low muscle mass. The prevalence of prior weight loss was two-fold less among obese compared to non-obese persons and confounded these associations.

Funding

  • NIDDK Support