Weight change in chronic kidney disease: Association with mortality and kidney function

Excess body weight is a risk factor for the progression of chronic kidney disease (CKD), but weight loss in CKD has been associated with higher mortality. Consequently, blanket weight loss recommendations in this population are controversial. Little data is available on the patterns of weight-change in CKD. The authors aimed to describe weight-changes in moderate/severe CKD and explore associations with mortality and renal endpoints in patients with overweight and obesity.

Non-dialysis Canberra Hospital patients with estimated glomerular filtration (eGFR) < 60 mL/min/1.73 m² and body mass index (BMI) ≥25 kg/m² were followed for up to 5.5 years. Weight-change ≥5% was considered clinically significant. The renal endpoint was defined as the commencement of dialysis or transplant or a ≥40% fall in eGFR. Relationships between weight-change in the first year of follow-up and mortality or the renal endpoint were assessed using Cox-regression.

Three hundred ten patients (median age 75, median BMI 31 kg/m²) were identified. 68% had Stage-4 CKD at baseline. Over 4.4-years median follow-up, 128 died and 140 had significant weight-change. During the first year of follow-up, 42 patients lost and 23 gained ≥5% body weight, of whom only 3 had intentionally lost weight. On multivariate regression, significant weight loss/gain at 1-year was associated with 2.74 (p < 0.0005) and 2.67 (p = 0.003) hazard of subsequent death and with 2.51 (p = 0.004) and 2.20 (p = 0.05) hazard of the renal endpoint respectively. There was no association between baseline eGFR and subsequent weight change.

Patients with moderate/severe CKD experience significant weight-change, but this has no relationship to baseline kidney function. Significant weight-change is associated with higher subsequent mortality and loss of kidney function, but this association is likely significantly affected by confounding.