Supplementary Material for: Reduced Mortality Associated with Acute Kidney Injury Requiring Dialysis in the United States

Background: Dialysis-requiring acute kidney injury (AKI-D) is a documented complication of hospitalization and procedures. Temporal incidence of AKI-D and related hospital mortality in the US population has not been recently characterized. We describe the epidemiology of AKI-D as well as associated in-hospital mortality in the US. Methods: Retrospective cohort of a national discharge data (n = 86,949,550) from the Healthcare Cost and Utilization Project's National Inpatient Sample, 2001-2011 of patients' hospitalization with AKI-D. Primary outcomes were AKI-D and in-hospital mortality. We determined the annual incidence rate of AKI-D in the US from 2001 to 2011. We estimated ORs for AKI-D and in-hospital mortality for each successive year compared to 2001 using multiple logistic regression models, adjusted for patient and hospital characteristics, and stratified the analyses by sex and age. We also calculated population-attributable risk of in-hospital mortality associated with AKI-D. Results: The adjusted odds of AKI-D increased by a factor of 1.03 (95% CI 1.02-1.04) each year. The number of AKI-D-related (19,886-34,195) in-hospital deaths increased almost 2-fold, although in-hospital mortality associated with AKI-D (28.0-19.7%) declined significantly from 2001 to 2011. Over the same period, the adjusted odds of mortality for AKI-D patients were 0.60 (95% CI 0.56-0.67). Population-attributable risk of mortality associated with AKI-D increased (2.1-4.2%) over the study period. Conclusions: The incidence rate of AKI-D has increased considerably in the US since 2001. However, in-hospital mortality associated with AKI-D hospital admissions has decreased significantly.