PREOPERATIVE RENAL RISK STRATIFICATION

Background After cardiac surgery, acute renal failure (ARF) requiring dialysis develops in 1% to 5% of patients and is strongly associated w ith perioperative morbidity and mortality. Prior studies have attempte d to identify predictors of ARF but have had insufficient power to per form multivariable analyses or to develop risk stratification algorith ms. Methods and Results We conducted a prospective cohort study of 43 642 patients who underwent coronary artery bypass or valvular heart su rgery in 43 Department of Veterans Affairs medical centers between Apr il 1987 and March 1994. Logistic regression analysis was used to ident ify independent predictors of ARF requiring dialysis. A risk stratific ation algorithm derived from recursive partitioning was constructed an d was validated on an independent sample of 3795 patients operated on between April and December 1994. The overall risk of ARF requiring dia lysis was 1.1%. Thirty-day mortality in patients with ARF was 63.7%, c ompared with 4.3% in patients without ARF. Ten clinical variables rela ted to baseline cardiovascular disease and renal function were indepen dently associated with the risk of ARF. A risk stratification algorith m partitioned patients into low-risk (0.4%), medium-risk (0.9% to 2.8% ), and high-risk (greater than or equal to 5.0%) groups on the basis o f several of these factors and their interactions. Conclusions The ris k of ARF after cardiac surgery can be accurately quantified on the bas is of readily available preoperative data. These findings may be used by physicians and surgeons to provide patients with improved risk esti mates and to target high-risk subgroups for interventions aimed at red ucing the risk and ameliorating the consequences of this serious compl ication.