DATA ANALYSIS. Analyses will be performed after all patients have completed the study by the participating biostatistician, the PI or other study researchers under their supervision. In addition to the baseline and follow-up laboratory tests, relevant clinical information will be collected from patients including age, gender, ethnicity, prior vascular access and surgical history, concurrent medications, and comorbidities. With the exception of numerical variables such as laboratory values and age, all other clinical variables will be annotated as binary. At the conclusion of the study, the patient characteristics of both treatment arms will be compared to assure their equivalency. The study data will be analyzed following the recommended intention-to-treat protocol, in which all enrolled patients are accounted for at the end of the observational period. If differences in baseline characteristics are not statistically significant (p<0.05), a Fisher's exact test will be used to compare AVF blood flow and diameter between study arms. On the other hand, if significant differences are detected in one or more relevant baseline variables, logistic regression analyses will be used to adjust for the effect of baseline covariables on the secondary endpoints. An evaluation of compliance, retention rates and adverse effects will be also performed for all the patients and the distinct subpopulations. If compliance is found to be an issue, the analysis of endpoints using a per-protocol approach will be considered. The SAS statistical software package, version 9.2 (Cary, NC), will be used for all statistical analyses.