Impact of Protein Intake on eGFR Slope One Year Post Kidney Transplantation: A Single- center Retrospective Study

Background The optimal protein intake following kidney transplantation remains unclear. The rate of change in kidney function during the first year post-transplant is considered a predictor of the subsequent survival and graft survival rates. This study aimed to determine the effect of evaluating protein intake during the first year post-transplant on kidney function at 1 year. Methods This retrospective study included 90 patients who underwent kidney transplantation. Patients were classified into three groups based on average daily protein intake: low (< 0.9 g/kg ideal body weight (IBW)/day), middle (≥ 0.9 and < 1.2 g/kg IBW/day) IBW/day), high (≥ 1.2 g/kg IBW/day). The primary outcome was the eGFR slope at 1 year after transplantation, and the secondary outcome was the incidence of rapid eGFR decline at 1 year after transplantation. Results Mean eGFR slope (mL/min/1.73 m ² /year) at 1 year after kidney transplantation was − 0.89, 2.44, and − 3.56 in the low, middle, and high protein intake groups, respectively (p = 0.01). Low protein intake had a greater effect than middle protein intake on eGFR slope decline (odds ratio (OR) 3.12, 95% confidence interval (CI) 1.24–7.84, p = 0.02). Rapid eGFR slope decline was more common in the high protein intake group (62.5%, p < 0.01) and high protein intake was a greater risk factor than middle protein intake (OR 22.4, 95%CI 3.21–157, p < 0.01). Conclusions Both low and high protein intake may adversely affect kidney function at 1 year after kidney transplantation. Evaluating protein intake during the first year post-transplant may help optimize eGFR at the 1-year mark.