Chronic kidney disease rather than illness severity predicts medium- to long-term mortality and renal outcome after acute kidney injury.
BACKGROUND
Acute kidney injury (AKI) requiring renal replacement therapy (RRT) continues to be associated with a hospital mortality of ∼50%. Longer-term outcomes have been less well studied. We sought to determine the influence of ventilation and of underlying chronic kidney disease (CKD) on medium and longterm mortality and renal outcomes.


METHODS
All patients requiring RRT for AKI in south west Scotland between 1 January 1994 and 31 December 2005 were followed prospectively. Survival of patients who were and were not ventilated and of those with and without underlying CKD was compared by odds ratio (OR), adjusting for age and sex. Renal outcomes were determined by interrogation of our biochemistry database.


RESULTS
Three hundred and ninety-six patients with AKI received RRT. One hundred and seventy-six (44%) were ventilated and 98 (25%) had underlying CKD. Patients who required ventilation had a significantly worse 90-day survival than those who did not (OR 2.10 for death; 95% CI 1.34, 3.29) whereas underlying CKD did not predict such an early adverse outcome (OR 1.49; 95% CI 0.89, 2.50). By 5 years, patients who had been ventilated during the acute illness were no longer at increased risk (OR 0.79; 95% CI 0.38, 1.62) whereas the adverse effect of underlying CKD was statistically significant (OR 6.05; 95% CI 2.23, 16.5). Underlying CKD was also a strong predictor of the need for RRT during follow-up.


CONCLUSIONS
In an unselected series of patients with AKI requiring RRT, underlying CKD rather than illness severity predicted medium- to long-term mortality.
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries DG1 4AP, UK.
Mark
M
Findlay
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries DG1 4AP, UK.
Ken
K
Donaldson
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries DG1 4AP, UK.
Sue
S
Robertson
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries DG1 4AP, UK.
Alison
A
Almond
Medicines Monitoring Unit, Ninewells Hospital, Dundee DD1 9SY, UK.
Robert
R
Flynn
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries DG1 4AP, UK chris.isles@nhs.net.
Chris
C
Isles
D058186:Acute Kidney Injury / Q000150:complications* / Q000401:mortality / Q000628:therapy; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011379:Prognosis; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000209:etiology* / Q000401:mortality / Q000473:pathology; D017582:Renal Replacement Therapy / Q000009:adverse effects / Q000401:mortality*; D012606:Scotland; D012720:Severity of Illness Index; D015996:Survival Rate; D055815:Young Adult
acute kidney injury; acute on chronic kidney disease; renal outcomes; survival