Prognosis of patients with acute renal failure in the intensive-care unit: a tale of two eras.

OBJECTIVE: To determine whether any changes occurred in the complexity of illness or survival of Mayo intensive-care unit (ICU) patients with acute renal failure (ARF) who required hemodialysis between the 1977 through 1979 period and the 1991 and 1992 era.

DESIGN: A retrospective comparison was done of 71 consecutive ICU patients with ARF during 1977 through 1979 and 71 similar consecutive patients from the 1991 and 1992 period.

MATERIAL AND METHODS: Each patient was scored for the three components of the acute physiology and chronic health evaluation (APACHE) II system (acute physiology score, age, and preexisting chronic health problems). Patient gender, postoperative status, presence of diabetes mellitus, presence of chronic renal insufficiency, and factors contributing to ARF were recorded for each patient. Patient survival and renal function at time of hospital dismissal and 12 months after initiation of hemodialysis were determined.

RESULTS: In comparison with patients in the earlier study period, those in the later study period had a signficantly improved rate of hospital survival (52% versus 32%) and 1-year survival (30% versus 21%). At 1 year, 96% and 78% of survivors in the earlier and later study groups, respectively, had recovery of renal function. The mean total APACHE II score was the same in both study periods, but patients in the later group were older and had more APACHE II points for chronic health problems. In the earlier and later study groups, patients with an APACHE II score of 21 or lower had a mortality rate of 36% and 11%, respectively, and survival among those with a score of 34 or greater was 0% and 15%, respectively. In 1991 and 1992, more patients had two or more factors contributing to the development of ARF, and intravenous administration of a contrast agent and preexisting cardiac prerenal compromise were more frequent causes of ARF than in 1977 through 1979. The occurrence of sepsis and preexisting lung disease were associated with a dismal prognosis in both study periods. In 1991 and 1992, survival was improved for patients with preexisting diabetes mellitus, postoperative status, and contrast-induced renal failure.

CONCLUSION: The prognosis of ICU patients with ARF has improved in more recent years, despite the fact that patients are now older, have more preexisting chronic health conditions, and have an increasing number of conditions contributing to development of ARF. The APACHE II scoring system demonstrated utility for quantifying the complexity of illness in these patients, but several important shortcomings may limit its usefulness as a comparative or prognostic tool in patients with ARF.