What is the clinical evidence from this study?

Study design: Cohort. Population: Acute renal failure requiring dialysis following cardiac surgery (n=82). Intervention: Elderly age (≥70 years) vs. Younger age (<70 years). Primary outcome: In-hospital mortality.

March 14, 2003Open Access

Outcome in a post-cardiac surgery population with acute renal failure requiring dialysis: does age make a difference?

Q: What are the key findings of this study?

Elderly age (≥70 years) was not associated with increased in-hospital mortality compared to younger age (50.0% vs 61.9%) in patients requiring dialysis for acute renal failure post-cardiac surgery.

Key Result

Elderly age (≥70 years) was not associated with increased in-hospital mortality compared to younger age (50.0% vs 61.9%) in patients requiring dialysis for acute renal failure post-cardiac surgery.

Study Design

Type

Cohort (n=82)

PICO

Population

82 patients with acute renal failure requiring dialysis following cardiac surgery, evaluated to compare in-hospital mortality between elderly (≥70 years) and younger (<70 years) patients.

Exposure / Comparator

Elderly age (≥70 years) vs Younger age (<70 years)

Primary Outcome

In-hospital mortality

Main Result

Absolute Event Rate: 50% vs 61.9%

Abstract

BACKGROUND: Acute renal failure (ARF), requiring dialysis (ARF-d), develops in 1-5% of patients undergoing cardiac surgery and is associated with higher in-hospital mortality. Age is one of the known risk factors for the development of ARF. As the ageing population is increasing, the nephrologist will be faced with a large population of elderly patients requiring dialysis following cardiac surgery. The aim of our study was to evaluate the influence of age on and the risk factors for in-hospital mortality. METHODS: Eighty-two patients with ARF following cardiac surgery and requiring dialysis between January 1997 and October 2001 were included. Two groups of patients were studied: the younger population (/=70 years, 40 patients, mean age 76+/-4). Severity of disease was evaluated using the SAPS (Simplified Acute Physiology Score), the Liano score and the SHARF (Stuivenberg Hospital Acute Renal Failure) score. RESULTS: Overall mortality in the population with ARF-d was 56.1%. No difference in mortality rate was found between the younger (61.9%) and elderly patient group (50.0%). The two groups were very similar in baseline and procedural characteristics with exception of body weight (P=0.02) and preoperative glomerular filtration rate (P=0.0001). No significant difference was found in the scoring systems between the old and the young (SAPS P=0.52; Liano P=0.96; SHARF T0 P=0.06; SHARF T48 P=0.15). Mortality in the elderly was significantly correlated with hypotension before starting renal replacement therapy (RRT) (P=0.002), mechanical ventilation (P=0.002), presence of multiorgan failure (MOF) (P=0.0001) and higher scores in the severity models (SAPS: P=0.01; Liano: P<0.0001 and SHARF: P<0.0001). CONCLUSION: The outcome in the elderly requiring dialysis due to ARF post-cardiac surgery is comparable with the outcome in a younger population. No significant difference was found in severity of disease between the elderly and the younger. Variables predicting mortality in the elderly are the presence of MOF, mechanical ventilation and hypotension 24 h before starting RRT. These findings indicate that at the time the nephrologist is called for an elderly patient requiring dialysis due to ARF following cardiac surgery, age per se is not a reason to withhold RRT.