Incidence and Prognostic Implications of Acute Kidney Injury on Admission in Patients With Community-Acquired Pneumonia

Background: A consensus definition of acute kidney injury (AKI)-the risk, injury, failure, loss, and end-stage kidney disease (RIFLE) classification-predicts mortality in general hospital and ICU populations. We aimed to assess its value on admission in patients with community-acquired pneumonia (CAP).

Methods: A prospective observational study with CAP was carried out. We classified each patient according to his or her maximum RIFLE class using admission creatinine (risk, >= 1.5 x baseline creatinine; injury, >= 2 x baseline; failure, >= 3 x baseline; no-AKI, <1.5 x baseline). Outcomes were 30-day mortality, requirement for mechanical ventilation and inotropic support (MV/IS), and requirement for renal replacement therapy (RRT).

Results: A total of 1,241 patients were included (no-AKI, 1,018; risk, 130; injury, 63; failure, 30). On multivariate analysis, factors predicting development of AKI include severity of pneumonia (adjusted odds ratio [AOR], 1.74; 95% CI, 1.46-2.08; P <.0001), elevated C-reactive protein (AOR, 1.04; 95% CI, 1.03-1.06; P <.0001), and prior use of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin-II-receptor blockers (AIIBs) (AOR, 1.77; 95% CI, 1.19-2.58; P = .005). Adjusting for severity of pneumonia, RIFLE criteria independently predicted 30-day mortality (AOR, 1.48; 95% CI, 1.15-1.91; P = .002), requirement for MV/IS (AOR, 2.22; 95% CI, 1.74-2.83; P <.0001), and RRT (AOR, 3.20; 95% CI, 2.01-5.11; P <.0001). Prior use of ACEIs or AIIBs was not associated with adverse outcome in either the entire cohort or patients without AKI.

Conclusion: The RIFLE classification is a simple tool to assess and classify AKI on admission and independently predicts 30-day mortality and the need for MV/IS and RRT in patients with CAP. CHEST 2010; 138(4):825-832