Assessment of Postoperative Renal Dysfunction Requiring Prolonged Renal Replacement Therapy and the Associated Mortality Rate

Introduction: Postoperative renal dysfunction requiring renal replacement therapy (RRT) is associated with a poor postoperative outcome. The aim of this study was to evaluate perioperative renal function among patients who required postoperative RRT. Methods: This was a retrospective cohort study of Japanese patients who required RRT within 6 months of surgery at our institution over the previous 10-year period of observation. Following data were extracted from electronic patient records for analysis: preoperative renal function, incidence of RRT, recovery rate from RRT, and mortality rate at 6 months after surgery. Univariate and multivariate logistic regression analyses were conducted to determine the odds ratio (OR) for postoperative RRT dependence. Results: Among 48677 patients who underwent surgery, 769 required RRT postoperatively. Of these latter patients, 159 did not receive RRT preoperatively. Therefore, the inductive rate of new RRT was 0.33% (159 of 48067 patients). The mortality rate was 42.1% (67 of 159) in patients who required new RRT. In patients who received new RRT without preoperative renal dysfunction, the recovery rate from RRT was 100% compared with 80.4% in patients with preoperative renal dysfunction. In multivariate analysis, the preoperative estimated glomerular filtration rate [adjusted OR = 0.76 (0.63-0.92), p = 0.005) was a significant risk factor for postoperative RRT dependence. The mortality rate related to multiple organ failure and sepsis in patients requiring postoperative RRT was 83.8%-90%. Conclusions: Preoperative renal function is the most important factor influencing postoperative renal outcome.