Acute kidney injury predicts outcomes of non-critically ill patients

Abstract

Objective: To evaluate whether acute kidney injury (AKI), defined as an increase in the serum creatinine level of 0.3 mg/dL or more within 48 hours, predicts outcomes of non-critically ill patients.

Patients and methods: Among the adults admitted from June 1, 2005, to June 30, 2007, to the medical wards of a community teaching hospital, 735 patients with AKI and 5089 controls were identified. Demographic and health information, serum creatinine values, and outcomes were abstracted from patients' computerized medical records. Outcomes of patients with AKI were compared with those of controls. In an additional case-control analysis, more detailed clinical information was abstracted from the medical records of 282 pairs of randomly selected, age-matched AKI cases and controls. Conditional multivariate logistic regression analyses were used to adjust for potential confounders of AKI effect on outcomes.

Results: Overall, patients with AKI had higher in-hospital mortality (14.8% vs 1.5%; P<.001), longer lengths of stay (median 7.9 vs 3.7 days; P<.001), and higher rates of transfer to critical care areas (28.6% vs 4.3%; P<.001); survivors were more likely to be discharged to an extended care facility (43.1% vs 20.3%; P<.001). Conditional multivariate logistic regression analyses of the 282 pairs of cases and controls showed that patients with AKI were 8 times more likely to die in hospital (odds ratio [OR], 7.9; 95% CI [confidence interval], 2.9-15.3) and were 5 times more likely to have prolonged (>or=7 days) hospital stays (OR, 5.2; 95% CI, 3.5-7.9) and require intensive care (OR, 4.7; 95% CI, 2.7-8.1), after adjustment for age, comorbidities, and other potential confounders.

Conclusion: In this study, AKI was associated with adverse outcomes in non-critically ill patients.

FIGURE.

Flow of patients through the study. AKI = acute kidney injury; ICU = intensive care unit; RRT = renal replacement therapy. ^a For patients with multiple admissions, only the first admission was included. ^b Patients with no or only one creatinine value during their hospital stay. ^c Patients with creatinine increase of >0.3 mg/dL (to convert to μmol/mL, multiply by 88.4) in >48 h, including those with missing creatinine data within 48 h. ^d Cases were defined as patients with an absolute increase in serum creatinine of >0.3 mg/dL within 48 h. ^e Controls were defined as patients with no absolute increase in serum creatinine >0.3 mg/dL during their hospital stay.