Abstract No. 428 - Towards establishing an expected false positive rate for hemodialysis access screening

Abstract

To establish a suggested rate of non-intervention for patients referred for hemodialysis access fistulography and to study the clinical and fistulographic variables associated with non-intervention (ie, false positive screening). An access database spanning 2002-2016 was used to identify patients undergoing fistulography without receiving an intervention (eg PTA, stent) for any reason. A baseline non-treatment rate was established from these data. Patients from 2010 to 2016 were then selected to study potential associations between clinical indicators, physical exam and non-treatment status. The inclusion criterion for the non-treatment group (NTG) was presence of abnormal clinical indicator(s) resulting in a fistulogram and receiving no treatment because it was not needed (determined by fistulography and/or flow). A control group (CG) receiving treatment (eg, PTA, stent) was randomly selected within the same time frame. Retrospective medical record and image review were conducted. Follow up included IR follow up and non-IR follow up, depending on availability. Mean non-treatment rate for the entire study period was 9% (range, 3-14%) and plateaued in the last decade (range 2005-2016 was 9-14%, mean 11%). On physical exam, NTG had a higher proportion of patients with normal thrill than CG (65% vs 9%, p<0.0001) and a higher proportion of aneurysm as a clinical indicator than CG (95% vs. 75%, p<0.0006). On image review, NTG had a higher proportion of aneurysms (50% vs. 25%, p< 00012). On follow up, CG had a higher proportion of IR follow up and revision than NTG (96% vs. 39%, p<0.0001). The hazard of a follow up visit in CG was twice the hazard of a follow up in NTG per unit of time between visits (hazard ratio = 2.054). An initial suggested non-intervention rate for patients presenting for hemodialysis access fistulogram is 10%. Patients in the NTG have greater odds of presenting with normal physical examination, clinical indicator of aneurysms or fistulographic findings of aneurysms, than those in the CG. Somewhat paradoxically, NTG patients were less likely to require subsequent intervention.