Outcome in a post-cardiac surgery population with acute renal failure requiring dialysis: does age make a difference?
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, 42 patients, mean age 59+/-10) and an elderly 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).


CONCLUSIONS
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.
Van Den Noortgate
Nele
N
Division of Geriatric Medicine, Department of Internal Medicine, University Hospital Gent, Belgium. nele.vandennoortgate@rug.ac.be
Mouton
Veerle
V
Lamot
Caroline
C
Van Nooten
Guido
G
Dhondt
Annemieke
A
Vanholder
Raymond
R
Afschrift
Marcel
M
Lameire
Norbert
N
D058186:Acute Kidney Injury / Q000453:epidemiology* / Q000209:etiology* / Q000628:therapy; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001530:Belgium; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D005260:Female; D006331:Heart Diseases / Q000473:pathology / Q000601:surgery*; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009102:Multiple Organ Failure / Q000209:etiology / Q000401:mortality; D011183:Postoperative Complications / Q000401:mortality; D006435:Renal Dialysis; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis