Incidence, cause, and outcome of acute renal failure in critically ill patients

Introduction: Acute renal failure (ARF) in critically ill patients continues to be associated with morbidity, mortality and expense despite advances in care. The purpose of this study was to determine the incidence, associated factors, and outcomes of critically ill patients who develop acute renal failure (ARF). These findings were compared to previous findings in the literature. Methods: This is a prospective study of all critically ill patients admitted during a one-month period to the Medical Intensive Care Unit (ICU) and Surgical ICU of a university hospital. Medical records were reviewed and patients were followed from admission to the ICUs throughout the rest of their hospital stay. ARF was defined as serum creatinine > 2.0 milligrams per deciliter in a patient without chronic renal failure (CRF) or a rise of > 0.5 milligram per deciliter per day. CRF was defined as baseline creatinine of > 1.5 milligrams per deciliter. Results: Of 250 patients, 74 (30%) developed ARF with 36% of patients in the MICU and 22% of patients in the SICU. Those with ARF were older (63 versus 56 years) and had higher Apache II scores (21 versus 13). When patients with ARF were compared to those without ARF, the presence of shock (p<0.001), aminoglycoside administration (p<0.001), and underlying CRF (p<0.001) were significant. The administration of IV contrast media was not significant (p=0.696). Patients with ARF had longer hospital lengths of stay (LOS) (29.9 ± 50.3 versus 9.4 ± 10.3 days), and ICU LOS (9.1 ± 11.0 versus 3.7 ± 6.4 days). ARF patients had higher costs of hospitalization ($53,098 ± $100,278 versus $17,720 ± $18,796). Mortality with ARF was 36% versus only 7% in patients without ARF. Compared to previously published studies, in our population the incidence of ARF in the ICU is increased, while in comparison the mortality seems to be decreased. Conclusions: ARF is common in the critically ill, and probably increasing in incidence. Older, sicker patients who have CRF, are in the MICU, develop shock, and receive aminoglycosides are more likely to develop ARF. Patients with ARF have a longer and costlier LOS. Mortality in ARF although high, may be decreasing.