One-Year Nutritional and Metabolic Changes in Patients on Incremental Peritoneal Dialysis Under Different Protein Diets: A Multicenter Pragmatic Cohort Study

Background: Commencing peritoneal dialysis (PD) with a lower dose (incremental PD) is a common strategy to improve patient acceptance and reduce treatment burden. However, specific dietary protein recommendations for incremental PD are lacking. Methods: An interim analysis of the I-COPE PD study cohort aimed to assess one-year changes in serum albumin, body mass index (BMI), and metabolic parameters in a cohort of patients on incremental PD. Following local protocols, patients were categorized into two groups according to protein diet prescription: protein diet (PrD) ≤ 0.6 and PrD > 0.6 g/kg/day. Longitudinal changes at baseline, 6 and 12 months were analyzed using mixed-effects models adjusted for age, sex, diabetes, residual kidney function and serum albumin at baseline. Results: We included 205 patients (mean age 63.3 ± 14.2 years; 66% male; 30% diabetes; 92.2% CAPD) and in 45.4% a PrD ≤ 0.6 g/kg/day was prescribed. Baseline demographic, clinical, lab and therapeutic characteristics were well-balanced between the two diet groups. After one year of follow-up, the prevalence of patients persisting in incremental PD was not different between the two dietary groups (59.1% in PrD ≤ 0.6 vs. 63.3% in PrD > 0.6, log-rank test = 0.759), and both groups showed a similar trend in serum albumin, characterized by an initial decline followed by stabilization (p = 0.647), with no significant differences in BMI (p = 0.461). Despite comparable dialysis adequacy, patients on PrD ≤ 0.6 exhibited significantly lower serum urea, phosphate, and potassium levels over time compared to the PrD > 0.6 group. Conclusions: In patients starting incremental PD, the prescription of a lower protein diet could be associated with better control of uremic toxins, while serum albumin levels over time remain comparable to those observed in patients under a higher-protein diet.