[Causes and prognosis of acute renal failure in elderly patients]

Abstract

The prolonged life span of populations is the obvious reason for an increasing proportion of elderly patients with acute renal failure (ARF). The role of age as a factor indicative of a poor prognosis is a matter of controversy.

Objective: To evaluate this role we have analyzed the final outcome of elderly patients with ARF treated in our Nephrology Service.

Material and methods: Among 361 ARF cases prospectively studied during a two-year period (January 1995 to December 1996), 130 (36%) occurred in patients over 70 years of age. Etiology, clinical course and prognosis were analyzed. The average age was 76.0 +/- 4.7 years, varying from 70 to 94 years; 84 patients (65%) were male, and surgical causes accounted for 51% of geriatric ARF.

Results: The most frequent causes were: ischemic (volume depletion, arterial hypotension, and/or low cardiac output) in 48 patients (38%), sepsis in 40 (312%), nephrotoxic drugs in 46 (35%) and obstructive abnormalities in 10 (7.7%); in other 14 (11%) they were diagnosed more than a causal agent. Oliguria was present in 37. 2% (81 patients), and dialysis was needed in 50 patients (39%). The mortality in the population with age below 70 years was 43% and in the elderly patients was 53.8%; total mortality was similar in both groups of patients (p=0.085). Oliguria, need for dialysis, presence of surgical causes of ARF, and ARF acquired within the intensive care unit were associated with poor prognosis in elderly group.

Conclusion: We concluded that the percentile of elderly patients with ARF is elevated; they presented mortality about of 50%, and this is not superior to the observed in the youngest population; oliguria, dialysis need, ICU cares and surgery are factors of unfavorable prognostic in these patients.