Abstract: Objective  To explore the factors affecting the long-term trends of peritoneal water transport and solute transport in incident peritoneal dialysis patients.  Methods   Incident peritoneal dialysis patients were recruited at Peking University First Hospital from January 1, 2016, to April 30, 2019. Baseline data including demographics, clinical biochemistry, dialysis prescription, and dialysis adequacy and transport test were collected. Spearman's correlation analysis was used to explore the factors affecting patients' baseline ultrafiltration per glucose load and 24-hour dialysate-to-plasma creatinine ratio (24h D/P Cr). Factors that influenced the trends of patients' ultrafiltration per glucose load and 24h D/P Cr were analyzed using mixed linear modeling. Results A total of 197 incident peritoneal dialysis patients who were clinically stable were included in this study. A positive correlation between continuous dialysis (r=0.227, P=0.001), baseline exposure of glucose (r=0.140, P=0.049) and baseline 24h D/P Cr was observed. Cardiovascular disease (r=0.144, P=0.043), new-onset peritonitis (r=0.168, P=0.018), and baseline exposure of glucose at baseline (r=0.252, P＜0.001) were positively correlated with baseline ultrafiltration per glucose load. In contrast, baseline blood albumin (r=-0.192, P=0.007) and renal Kt/V (r=-0.340, P＜0.001) showed a negative correlation with ultrafiltration per glucose load. A gradual increasing trend in ultrafiltration per glucose load (t=-4.196，P＜0.001) was observed in our peritoneal dialysis patients using mixed linear modeling but was not associated with age, gender, diabetes, cardiovascular disease, Charlson comorbidity score, baseline hemoglobin, baseline blood albumin, baseline hypersensitive C-reactive protein (hs-CRP), baseline diastolic blood pressure, baseline systolic blood pressure, new-onset peritonitis, intermittent or continuous dialysis, baseline renal Kt/V, and aquaporin-1 (AQP1) promoter genotype (P>0.050). Meanwhile, 24h D/P Cr remained relatively stable (t=-1.486，P=0.138) during follow-up.  Conclusion  This study demonstrated that an increasing trend in ultrafiltration per glucose load and a stable trend in 24h D/P Cr were observed in our incident peritoneal dialysis patients, which may be associated with our incremental dialysis and glucose-sparing strategies. This supported that peritoneal membrane function in peritoneal dialysis patients is influenced by a combination of environmental and genetic factors.

Key words: Peritoneal dialysis, Water transport, Solute transport