Obesity-related nephropathy is associated with renal function progression. However, some studies have associated a high body mass index (BMI) with improved renal outcomes—this is referred to as the obesity paradox for renal outcomes, especially in relation to advanced chronic kidney disease (CKD). Central obesity can explain the obesity paradox in all-cause mortality. However, whether obesity or central obesity is associated with renal outcomes (renal replacement therapy or a 50% decline in the estimated glomerular filtration rate) in patients with advanced CKD remains unclear. Our study included 3605 Asian patients with CKD stages 1–5 divided into six groups according to their BMI (between 15 and 35 kg/m²). Through linear regression, BMI was positively associated with hemoglobin and albumin at CKD stages 4 and 5. In the competing risk Cox regression model, a high BMI (27.5–35 kg/m²) was associated with renal outcomes at CKD stages 1–3, but not stages 4 and 5. A high BMI was associated with renal outcomes in patients with hemoglobin ≥11 g/dL, but not <11 g/dL. A high waist-to-hip ratio was not associated with renal outcomes. We conclude that the CKD stage and anemia may explain the obesity paradox in renal outcomes in patients with CKD.

The obesity paradox, referring to the association of high body mass index (BMI) with low all-cause mortality risk, is found in patients with chronic kidney disease (CKD). Central obesity is associated with metabolic syndrome and may have better prognostic value than BMI for all-cause mortality. Whether central obesity is associated with all-cause mortality in cases of obesity paradox in CKD patients remains unknown. We included 3262 patients with stage 3–5 CKD, grouped into five quintiles (Q1–5) by waist-to-hip ratio (WHR). Low WHR and BMI were associated with malnutrition and inflammation. In Cox regression, high BMI was not associated with all-cause mortality, but BMI < 22.5 kg/m² increased the mortality risk. A U-shaped association between central obesity and all-cause mortality was found: WHR Q1, Q4, and Q5 had higher risk for all-cause mortality. The hazard ratio (95% confidence interval) of WHR Q5 and Q1 for all-cause mortality was 1.39 (1.03–1.87) and 1.53 (1.13–2.05) in male and 1.42 (1.02–1.99) and 1.28 (0.88–1.85) in female, respectively. Waist-to-height ratio and conicity index showed similar results. Low WHR or low BMI and high WHR, but not high BMI, are associated with all-cause mortality in advanced CKD.

Uric acid (UA) is elevated in metabolic syndrome (MS) and diabetes (DM). UA is associated with central obesity and blood glucose and is proposed as a criterion of MS. Previous reports showed that UA could predict renal outcome in CKD. However, recent clinical trials did not demonstrate the benefits of urate-lowering agents (ULA) for renal outcome. Whether the prognostic value of UA for renal outcome is independent of MS or secondary to MS in CKD patients is unknown. Our study included 2500 CKD stage 1–4 Asian patients divided by UA tertiles and MS/DM. In linear regression, UA was associated with obesity, C-reactive protein, and renal function. In Cox regression, high UA was associated with worse renal outcome in non-MS/DM, but not in MS/DM: hazard ratio (95% confidence interval) of UA tertile 3 was 3.86 (1.87–7.97) in non-MS/DM and 1.00 (0.77–1.30) in MS/DM (p for interaction < 0.05). MS was associated with worse renal outcome, but redefined MS (including hyperuricemia as the 6th criteria) was not. In conclusion, hyperuricemia is associated with worse renal outcome in non-MS/DM and is not an independent component of MS in CKD stage 1–4 patients. Hyperuricemia secondary to MS could not predict renal outcome.

Background: The malnutrition–inflammation score (MIS) is a practical and accessible tool for evaluating protein energy wasting (PEW) in patients on dialysis. However, the severity of PEW at each stage of chronic kidney disease (CKD), especially with late dialysis initiation, is unclear. Methods: We evaluated the MIS of 3659 patients with CKD stages 1–5 and the changes in their MIS results at baseline and at the time before dialysis initiation. Patients were defined to have PEW if they had a subjective global assessment (SGA) rating of C or lower. Results: The MIS increased substantially over a follow-up period of 6.12 years for 1124 patients just starting dialysis, with 49.3% having an MIS of 8. The pre-dialysis MIS was associated with baseline MIS, age, cardiovascular disease, and cancer. The prevalence of PEW based on an SGA rating of C or lower increased from 10.5% at baseline to 61.2% immediately before dialysis. The prevalence of PEW based on an MIS of ≥8 increased from 28.5% at baseline to 49.3% immediately before dialysis. In CKD stage 5 patients, 29.4% had PEW based on an MIS of 8 or less, and 11.6% had an SGA rating of C. The MIS was revealed to be associated with renal function, nutritional markers, and cardiometabolic disease (diabetes or cardiovascular disease). Conclusions: In conclusion, the MIS increased as CKD progressed to stages 4 and 5, as well as just prior to dialysis. Our study identified patients who required PEW assessment on the basis of their MIS results.