Causes and prognosis of acute renal failure in the very old. Madrid Acute Renal Failure Study Group.

OBJECTIVES: There is a tendency to treat older people with Acute Renal Failure (ARF) less aggressively because of the presumed less acceptable end results. This has not been proved, and their prognosis may be similar to that found in the younger population. There are no studies on the incidence, causes, and evolution of ARF in patients 80 years of age and older.

DESIGN: A multicenter, prospective, longitudinal study.

SETTING: The 13 hospitals with nephrology units that serve the 4.2 million people in Madrid, Spain.

MEASUREMENTS: A number of demographic, clinical, and therapeutic variables were studied in each case.

RESULTS: One hundred three episodes of ARF occurred in patients 80 years of age and older (Group 1), 256 in patients aged 65 to 79 years (Group 2), and 389 in people younger than age 65 (Group 3). Acute tubular necrosis was diagnosed in 39% of cases in Group 1, in 48% in Group 2, and in 55% in Group 3 (P = .004, 1 vs 3); prerenal ARF was diagnosed in 30%, 28%, and 21% (P = .054, 1 vs 3) and obstructive ARF in 20%, 11%, and 7% (P < .001, 1 vs 3) of cases, respectively. Serum creatinine at admission, peak values, values at discharge or death, duration of both admission and ARF episode, and mortality were similar in all groups. In stratified analysis, relative risk for mortality in patients aged more than 80 years was 1.09 [95%CI 0.86,1.36 (P = .562)], and in those aged 65 to 79 it was 0.99 [95%CI 0.83,1.18 (P = .954)] compared with patients aged less than 65 years. Risk of death was also similar when only acute tubular necrosis cases were considered. Sustained hypotension was associated with higher mortality (44% of nonsurviving older persons vs 9% of survivors, P < .001).

CONCLUSION: Age is not a particularly poor prognostic sign, and outcome seems to be within acceptable limits for very old patients with ARF. Acute dialysis should not be withheld from patients solely because they are more than 80 years of age.