To explore the natural history of
critically ill patients with
acute renal failure due to acute tubular
necrosis, we evaluated 256 patients enrolled in the placebo arm of a randomized clinical trial. Death and the composite outcome, death or the provision of dialysis, were determined with follow-up to 60 d. The relative risks (RR) and 95% confidence intervals (95% CI) associated with routinely available demographic, clinical, and laboratory variables were estimated using proportional hazards regression. Ninety-three (36%) deaths were documented; an additional 52 (20%) patients who survived received dialysis. Predictors of mortality included male gender (RR, 2.01; 95% CI, 1.21 to 3.36),
oliguria (RR, 2.25; 95% CI, 1.43 to 3.55),
mechanical ventilation (RR, 1.86; 95% CI, 1.18 to 2.93), acute
myocardial infarction (RR, 3.14; 95% CI, 1.85 to 5.31),
acute stroke or seizure (RR, 3.08; 95% CI, 1.56 to 6.06), chronic immunosuppression (RR, 2.37; 95% CI, 1.16 to 4.88),
hyperbilirubinemia (RR, 1.06; 95% CI, 1.03 to 1.08 per 1 mg/dl increase in total
bilirubin) and
metabolic acidosis (RR, 0.95; 95% CI, 0.90 to 0.99 per 1 mEq/L increase in serum
bicarbonate concentration). Predictors of death or the provision of dialysis were
oliguria (RR, 5.95; 95% CI, 3.96 to 8.95),
mechanical ventilation (RR, 1.53; 95% CI, 1.07 to 2.21), acute
myocardial infarction (RR, 1.95; 95% CI, 1.24 to 3.07),
arrhythmia (RR, 1.51; 95% CI, 1.04 to 2.19), and
hypoalbuminemia (RR, 0.56; 95% CI, 0.42 to 0.74 per 1 g/dl increase in
serum albumin concentration). Neither mortality nor the provision of dialysis was related to patient age. These observations can be used to estimate risk early in the course of acute tubular
necrosis. Furthermore, these and related models may be used to adjust for case-mix variation in quality improvement efforts, and to objectively stratify patients in future intervention trials aimed at favorably altering the course of hospital-acquired
acute renal failure.