Zinc alpha-2-glycoprotein in peritoneal dialysis effluent correlates with peritoneal transport characteristics, peritonitis rate, and outcome.

BACKGROUND

There were limited data on zinc alpha-2-glycoprotein (ZAG) levels and their association with peritoneal characteristics and clinical outcomes in patients undergoing peritoneal dialysis (PD). We aimed to quantify and explore the correlation between ZAG levels in PD effluent (PDE), adipose, and serum samples from PD patients, and to evaluate their association with peritoneal characteristics and outcome.

METHODS

Incident adult PD patients were enrolled in this prospective cohort study. We measured ZAG levels in PDE, serum, and pre-peritoneal fat tissue samples. Peritoneal characteristics were determined by the standard peritoneal equilibrium test. Primary and secondary outcomes were the 2-year peritonitis rate and peritonitis-related clinical outcomes, respectively.

RESULTS

We analyzed 126 patients. At baseline, PDE, adipose, and circulating ZAG levels were 1.0 ± 1.2 μg/mL, 15.3 ± 140.5-fold, and 74.4 ± 21.5 μg/mL, respectively. PDE ZAG correlated with adipose ZAG (r = 0.21, p = 0.02), but not with serum ZAG (p = 0.30). PDE ZAG independently predicted small solute peritoneal transport, i.e., dialysate-to-plasma ratio of creatinine at 4 hours (p = 0.01) and mass transfer area coefficient of creatinine (p = 0.04), but not peritoneal protein clearance (p = 0.90). After 222.7 patient-years of follow-up, 40 patients (31.7%) developed 66 peritonitis episodes, and nine patients died. PDE ZAG predicted peritonitis (unstandardized B = 0.446, p < 0.001) and peritonitis-free survival (hazard ratio, 1.36; p = 0.02) after adjustment for confounders.

CONCLUSION

PDE ZAG level significantly correlated with peritoneal transport characteristics and was associated with peritonitis and peritonitis-free survival in PD patients.