Date Published: June 24, 2019
Publisher: Public Library of Science
Author(s): Benjamin R. Griffin, Zhiying You, John Holmen, Megan SooHoo, Katja M. Gist, James F. Colbert, Michel Chonchol, Sarah Faubel, Anna Jovanovich, Micah Chan.
Severe acute kidney injury (AKI) is associated with subsequent infection. Whether AKI followed by a return to baseline creatinine is associated with incident infection is unknown.
We hypothesized that risk of both short and long term infection would be higher among patients with AKI and return to baseline creatinine than in propensity score matched peers without AKI in the year following a non-infectious hospital admission.
Retrospective, propensity score matched cohort study.
We identified 494 patients who were hospitalized between January 1, 1999 and December 31, 2009 and had AKI followed by return to baseline creatinine. These were propensity score matched to controls without AKI.
The predictor variable was AKI defined by International Classification of Diseases, Ninth Revision (ICD-9) codes and by the Kidney Disease Improving Global Outcomes definition, with return to baseline creatinine defined as a decrease in serum creatinine level to within 10% of the baseline value within 7 days of hospital discharge. The outcome variable was incident infection defined by ICD-9 code within 1 year of hospital discharge.
AKI followed by return to baseline creatinine was associated with a 4.5-fold increased odds ratio for infection (odds ratio 4.53 [95% CI, 2.43–8.45]; p<0.0001) within 30 days following discharge. The association between AKI and subsequent infection remained significant at 31–60 days and 91 to 365 days but not during 61–90 days following discharge. Among patients from an integrated health care delivery system, non-infectious AKI followed by return to baseline creatinine was associated with an increased odds ratio for infection in the year following discharge.
Acute kidney injury (AKI) is a common and widely recognized cause of morbidity and mortality in hospitalized patients. The incidence of AKI has been increasing over the past decade and is now observed in up to 20% of all inpatient admissions [1–3], which amounts to approximately 17 million cases annually in the United States. Furthermore, AKI has been shown to independently increase in-hospital morbidity and mortality[3, 5–7], which adds an estimated $10 billion in additional health care expenditures annually.
This study demonstrates that among patients from an integrated health care delivery system, non-infectious AKI with return to baseline creatinine was associated with increased odds of infection in the year after discharge compared to propensity-score matched controls without AKI. While previous studies have established AKI as a risk factor for subsequent in-hospital infection, little is known about infection rates following discharge. Our results demonstrate that short-term 30 day infection rates are significantly higher among patients with AKI during hospitalization, even though serum creatinine values returned to baseline. Strikingly, while there was no difference in the odds of infection among cases compared to controls at 90 days post discharge, the odds of infection were significantly higher among cases in the period of 91–365 days following discharge, suggesting a long-term association well after serum creatinine had returned to baseline at discharge.