Acute kidney injury following unselected emergency admission: role of the inflammatory response, medication and co-morbidity

BACKGROUND/AIMS: Acute kidney injury (AKI) following admission to hospital is associated with increased mortality, morbidity and length of stay. Factors that predispose patients to AKI frequently co-exist. The precise description of their representation in unselected admissions could help define mechanistic inter-relationships and optimise risk stratification strategies. Our aim was therefore to define precisely, using electronically available data, the variables that are associated with AKI.

METHODS: A cohort study of 112,987 emergency admissions to an urban academic medical centre between 2006 and 2010 was performed. Post-admission AKI was defined using KDIGO aligned, proportionate changes in serum creatinine, denominated by the first measured. AKI correlated with co-morbidities, medications received and the C-reactive protein concentration (CRP).

RESULTS: The relationship between post-admission AKI and putative risk factors was defined in univariate and multivariate analyses. Inclusion of CRP in multivariate analyses significantly reduced the strength of association between some co-variables such as radiological contrast and gentamicin administration but not others.

CONCLUSION: The effect of CRP in these analyses supports the role of systemic inflammation in susceptibility to post-admission AKI. It accounts for the greater part of univariate associations between AKI and some nephrotoxic agents, placing the risk attributable to their use in context. Quantification of the systemic inflammatory response may have utility in AKI risk stratification, integrating various determinants of susceptibility.