OBJECTIVE: The impact of any intervention on renal function is a crucial determinant of outcome. Open (OR) and endovascular (EVAR) abdominal aortic aneurysm (AAA) repair can affect renal function during the short and longer term. This study aimed to directly compare the effect of those different types of aneurysm repair during a period of 2 years.METHODS: This was a nested case-control study including patients undergoing either OR or EVAR of an infrarenal AAA. Three groups were included: OR, EVAR with suprarenal endograft fixation, and EVAR with infrarenal fixation. These were matched for age (within 2 years), sex, AAA size (within 1 cm), hypertension, smoking, and proximal neck diameter (within 5 mm). The primary end point was change in estimated glomerular filtration rate (eGFR) calculated by the Chronic Kidney Disease Epidemiology Collaboration formula at baseline, 6 months, 12 months, and 2 years.RESULTS: A total of 225 patients were included [(45 ORs matched vs 90 suprarenal and 90 infrarenal fixation EVARs; 35 women (16%); age, 71 ± 8 years; AAA size, 6.4 ± 1 cm]. Groups did not differ significantly in terms of diabetes, hypercholesterolemia, or baseline eGFR (P = .89). On average, those undergoing OR lost a mean 5.39 mL/min/1.73 m(2) (P = .48) within 1 year and 5.49 units (P = .42) after 2 years. The suprarenal fixation patients lost 5.58 units (P = .002) after 1 year and 6.57 units (P = .001) after 2 years. Finally, the infrarenal fixation patients lost 0.53 unit (P = .74) after 1 year and 2.24 units (P = .22) after 2 years.CONCLUSIONS: OR and suprarenal fixation EVAR are associated with significant declines in renal function during 2 years, in contrast to infrarenal EVAR fixation. The patterns of eGFR decline in OR and suprarenal fixation EVAR are not similar, suggesting different causal mechanisms.