The closure of arteriovenous fistula is associated with a significant acceleration of eGFR decline in kidney transplant recipients

Background
The creation of arteriovenous fistula (AVF) may retard chronic kidney disease progression in the general population. Conversely, there is limited literature regarding the impact of AVF closure on renal function in kidney transplant recipients (KTR).

Methods
All KTR were retrospectively identified from 01/01/2007 to 31/12/2013, and grouped into: (0) no AVF; (1) closed AVF; and (2) left open AVF. Glomerular filtration rate was estimated (eGFR) upon MDRD and FAS equations. Linear mixed models calculated the slope and intercept of eGFR decline versus time, starting at 3 months post transplantation (Tx). Comparative analyses of eGFR slopes were performed among groups, as well as before vs after AVF closure in group 1. For the latter, time was balanced before vs after AVF closure, with at least 10 observations per patient.

Results
The cohort included 285 KTR (Table 1), with a median follow-up of 1750 days [1665; 2028].
Focusing on group 1, AVF closure occurred after a mean time of 653 ± 441 days post Tx, with a thrombosis/ligation ratio of 19/95. Balanced study periods before vs after AVF closure lasted 15.7 and 14.9 months, respectively. No difference was found between corresponding intercepts (p, 0.11). By contrast, eGFR slopes were significantly different before (0.043 ml/min/year) versus after (-0.176 ml/min/year) AVF closure (p, 0.0115). Similar observations were obtained using FAS equation

Conclusion
A significant acceleration of eGFR decline is observed over the 15 months following the closure of functioning AVF in KTR.