Trends in acute renal failure associated with coronary artery bypass graft surgery in the United States

Objective: Acute renal failure remains a major complication of coronary artery bypass graft surgery that is strongly associated with in-hospital mortality. Based on similar observations in other clinical settings, we tested the hypothesis that the diagnosis of acute renal failure associated with coronary artery bypass graft surgery is increasing in the United States.

Design: Observational cohort study.

Setting: The Nationwide Inpatient Sample database was used to test the hypothesis. This database contains discharge information from 20% of U.S. hospitals.

Patients: Hospital discharges coded for coronary artery bypass graft surgery from 1988 to 2003 comprised the study population; those also coded for acute renal failure formed the subset of interest.

Interventions: None.

Measurements and main results: Multivariable regression models were constructed, including adjustment for risk factors and comorbidities, to identify the relationship between year of surgery and diagnosis of acute renal failure and mortality. The incidence of acute renal failure diagnosis increased significantly during the study period from 1.1% to 4.1% (p < .0001). The proportion of acute renal failure cases that required dialysis decreased from 15.8% to 8.7% (p < .0001). Despite an increase in comorbid disease burden, mortality in the acute renal failure subgroup declined from 39.5% to 17.9% (p < .0001). The percentage of acute renal failure survivors with postdischarge special-care requirements increased from 35.5% to 64.5% (p < .0001).

Conclusions: Our findings suggest that the observed increase in acute renal failure diagnosis rates may be partly attributable to less restrictive criteria for acute renal failure diagnosis, consistent with acute renal failure patterns observed in other clinical settings. Although the need for dialysis is a relatively clear benchmark for diagnosing acute renal failure, use of alternate criteria to define this disorder has become more common, perhaps contributing to higher diagnosis rates. We conclude that the nationwide trend of acute renal failure associated with coronary artery bypass graft surgery has significantly increased from 1988 to 2003. Despite declining mortality, acute renal failure remains a burden on healthcare resources.