Impact of preexisting chronic kidney disease on acute and long-term outcome of critically ill patients on a medical intensive care unit.

BACKGROUND: Chronic kidney disease (CKD) increases acute and long-term mortality of many diseases. Limited data are available, in how far a preexisting non-dialysis dependent CKD affects the outcome of critically ill patients treated for non-renal causes.
METHODS: In a retrospective study, we assessed the outcome of 524 patients with need for mechanical ventilation at our medical intensive care unit between 2002 and 2007. Patients were divided into 5 CKD stages depending on their calculated glomerular filtration rate at hospital admission excluding patients with pre-existing end-stage renal failure. In-hospital and long-term outcome up to 5 years were assessed.
RESULTS: Advanced stages of CKD at admission were associated with higher age (p < 0.001) and diabetes (p = 0.003). Patients with higher CKD stages suffered more often from acute renal failure (p < 0.001), required longer renal replacement therapy (p < 0.001) and more often in-hospital resuscitation (p = 0.019). 405 patients died during follow-up (226 in-hospital). Multivariate Cox regression analysis identified eGFR as independent predictor of 30-day- (HRR 0.994, 95 % CI 0.990-0.998) and 1-year-mortality (HRR 0.996, 95 % CI 0.993-1.000). Long-term survival decreased significantly with increasing CKD stages (p = 0.004) and occurrence of acute renal failure (p < 0.001).
CONCLUSIONS: In critically ill patients requiring mechanical ventilation, preexisting non-dialysis dependent CKD has marked impact on occurrence of acute renal failure, 30-day- and 1-year-mortality.