Impact of Acute Kidney Injury in Patients Hospitalized With Pneumonia.

OBJECTIVES: Pneumonia is a common cause of hospitalization and can be complicated by the development of acute kidney injury. Acute kidney injury is associated with major adverse kidney events (death, dialysis, and durable loss of renal function [chronic kidney disease]). Because pneumonia and acute kidney injury are in part mediated by inflammation, we hypothesized that when acute kidney injury complicates pneumonia, major adverse kidney events outcomes would be exacerbated. We sought to assess the frequency of major adverse kidney events after a hospitalization for either pneumonia, acute kidney injury, or the combination of both.

DESIGN AND SETTING: We conducted a retrospective database analysis of the national Veterans Affairs database for patients with a admission diagnosis of International Classification of Diseases-9 code 584.xx (acute kidney injury) or 486.xx (pneumonia) between October 1, 1999, and December 31, 2005. Three groups of patients were created, based on the diagnosis of the index admission and serum creatinine values: 1) acute kidney injury, 2) pneumonia, and 3) pneumonia with acute kidney injury. Patients with mean baseline estimated glomerular filtration rate less than 45 mL/min/1.73 m were excluded.

MEASUREMENTS AND MAIN RESULTS: The primary endpoint was major adverse kidney events defined as the composite of death, chronic dialysis, or a permanent loss of renal function after the primary discharge. The observations of 54,894 subjects were analyzed. Mean age was 68.7 ± 12.3 years. The percentage of female was 2.4, 73.3% were Caucasian, and 19.7% were African-American. Differences across the three diagnostic groups were significant for death, 25% decrease in estimated glomerular filtration rate from baseline, major adverse kidney events following admission, and major adverse kidney events during admission (all p < 0.0001). Death alone and major adverse kidney events after discharge were most common in the pneumonia + acute kidney injury group (51% died and 62% reached major adverse kidney events). In both unadjusted and adjusted time to event analyses, patients with pneumonia + acute kidney injury were most likely to die or reach major adverse kidney events.

CONCLUSIONS: When acute kidney injury accompanies pneumonia, postdischarge outcomes are worse than either diagnosis alone. Patients who survive a pneumonia hospitalization and develop acute kidney injury are at high risk for major adverse kidney events including death and should receive careful follow-up.