The safety of a low-protein diet in older adults with advanced chronic kidney disease

Background: A low-protein diet (LPD) is recommended to patients with advanced chronic kidney disease (CKD), whereas geriatric guidelines recommend a higher amount of protein. The aim of this study was to evaluate the safety of LPD treatment in older adults with advanced CKD. Methods: The EQUAL study is a prospective, observational study including patients ≥65 years of age with an incident estimated glomerular filtration rate <20 ml/min/1.73 m² in six European countries with follow-up through 6 years. Nutritional status was assessed by a 7-point subjective global assessment (SGA) every 3-6 months. Prescribed diet (g protein/kg of bodyweight) was recorded on every study visit; measured protein intake was available in three countries. Time to death and decline in nutritional status (SGA decrease of ≥2 points) were analysed using marginal structural models with dynamic inverse probability of treatment and censoring weights. Results: Of 1738 adults (631 prescribed LPD at any point during follow-up), there were 1319 with repeated SGA measurements, of which 267 (20%) decreased in SGA ≥2 points and 565 (32.5%) who died. There was no difference in survival or decrease in nutritional status for patients prescribed a LPD ≤0.8 g/kg ideal bodyweight {odds ratio [OR] for mortality 1.15 [95% confidence interval (CI) 0.86-1.55)] and OR for decrease in SGA 1.11 [95% CI 0.74-1.66]} in the adjusted models. In patients prescribed a LPD <0.6 g/kg ideal bodyweight, the results were similar. There was a significant interaction with LPD and older age >75 years, lower SGA and higher comorbidity burden for both mortality and nutritional status decline. Conclusions: In older adults with CKD approaching end-stage kidney disease, a traditional LPD prescribed and monitored according to routine clinical practice in Europe appears to be safe.