Association of obesity with mortality in patients with various stages of non-dialysis dependent CKD (NDD-CKD)

Obesity is associated with increased mortality in the general population, but with lower mortality in dialysis patients. It is unclear at what stage of CKD this reversal occurs. Furthermore, it is unclear if associations differ for body mass index (BMI) or the ponderal index (PI, the weight divided by the third power of height). We examined all-cause mortality associated with categories of BMI and PI in a national cohort of 305,895 US veterans with NDD-CKD and eGFR<60. Associations were examined in Cox models by CKD stages (3A through 5) adjusted for demographics, blood pressure and comorbidities. Patients with BMI 30-<35 had the lowest mortality (Table); mortality was higher for BMI<30 in all groups. Mortality was higher in patients with BMI>35 in CKD stages 3A-3B, but not in CKD stages 4 and 5. Results were similar for quintiles of PI (not shown). Obesity is associated with higher mortality in patients with early/moderate CKD. In patients with advanced NDD-CKD the highest BMI and PI are associated with the lowest mortality, similar to dialysis patients. Using a more ideal measure of obesity (PI) confirms the paradoxical association of obesity with lower mortality in advanced CKD. BMI (kg/m2) CKD 3A CKD 3B CKD 4 CKD 5 <18.5 3.47 (3.23-3.71) 3.39 (3.08-3.72) 2.92 (2.48-3.46) 2.60 (1.57-4.30) 18.5-<25 1.65 (1.61-1.70) 1.64 (1.58-1.69) 1.52 (1.44-1.62) 1.48 (1.26-1.73) 25-<30 1.12 (1.09-1.15) 1.15 (1.12-1.19) 1.12 (1.06-1.18) 1.24 (1.07-1.44) 30-<35 Referent Referent Referent Referent >=35 1.10 (1.06-1.14) 1.10 (1.06-1.15) 0.98 (0.91-1.06) 0.97 (0.78-1.20