Chronic Kidney Disease Class Predicts Mortality After Abdominal Aortic Aneurysm Repair in Propensity-matched Cohorts From the Medicare Population

Introduction: Chronic kidney disease (CKD) predicts mortality after abdominal aortic aneurysm (AAA) repair. Few studies are adequately powered to stratify outcomes by CKD severity. This study assesses the effect of CKD severity on survival after AAA repair. Methods: Patients who underwent AAA repair from 2006 to 2007 were retrospectively identified in the Medicare database and stratified by CKD class as follows: normal (CKD class 1 and 2), moderate (CKD class 3), and severe (CKD class 4 and 5). Propensity matching (30: 1) by clinical factors and procedure type was performed to derive well-matched comparative cohorts. Primary outcomes were 30-day and long-term mortality; secondary outcomes included hospital length of stay and cost. Results: A total of 47,715 patients were included (96.7% normal, 1.88% moderate, and 1.65% severe). Propensity matching was corrected for differences between cohorts. Thirty-day mortality was higher in moderate (5.7% vs normal 2.5%; P < 0.01) and severe (9.9% vs normal 1.8%; P < 0.01) groups. Hospital length of stay increased with CKD severity (4.4 +/- 3.7 days normal vs 6.5 +/- 4.2 days moderate CKD; P < 0.01/4.7 +/- 3.8 days normal vs 9.1 +/- 4.5 days severe CKD; P < 0.01) as did cost ($23 +/- 14K normal vs $25 +/- 16K moderate; P < 0.01 /$22 +/- 11K normal vs $29 +/- 22K severe; P < 0.01). Three-year survival favored the normal cohort (80% vs 64% moderate; log rank P < 0.01 /82% normal vs 44% severe; log rank P < 0.01). Conclusions: CKD severity is an important predictor of perioperative mortality and long-term survival after AAA repair in propensity-matched cohorts. The 5-fold increase in 30-day mortality and 44% in 3-year survival suggest that elective AAA repair is contraindicated in most severe CKD patients.