Rationale & objective: Ventricular assist devices (VADs) are used for end-stage heart failure not amenable to medical therapy. Acute kidney injury (AKI) in this setting is common due to heart failure decompensation, surgical stress, and other factors. Little is known about national trends in AKI diagnosis and AKI requiring dialysis (AKI-D) and associated outcomes with VAD implantation. We investigated national estimates and trends for diagnosed AKI, AKI-D, and associated patient and resource utilization outcomes in hospitalizations in which implantable VADs were placed.
Study design: Cohort study of 20% stratified sample of US hospitalizations.
Setting & participants: Patients who underwent implantable VAD placement in 2006 to 2015.
Exposure: No AKI diagnosis, AKI without dialysis, AKI-D.
Outcomes: In-hospital mortality, length of stay, estimated hospitalization costs.
Analytical approach: Multivariate logistic and linear regression using survey design methods to account for stratification, clustering, and weighting.
Results: An estimated 24,140 implantable VADs were placed, increasing from 853 in 2006 to 3,945 in 2015. AKI was diagnosed in 56.1% of hospitalizations and AKI-D occurred in 6.5%. AKI diagnosis increased from 44.0% in 2006 to 2007 to 61.7% in 2014 to 2015; AKI-D declined from 9.3% in 2006 to 2007 to 5.2% in 2014 to 2015. Mortality declined in all AKI categories but this varied by category: those with AKI-D had the smallest decline. Adjusted hospitalization costs were 19.1% higher in those with diagnosed AKI and 39.6% higher in those with AKI-D, compared to no AKI.
Limitations: Administrative data; timing of AKI with respect to VAD implantation cannot be determined; limited pre-existing chronic kidney disease ascertainment; discharge weights not derived for subpopulation of interest.
Conclusions: A decreasing proportion of patients undergoing VAD implantation experience AKI-D, but mortality among these patients remains high. AKI diagnosis with VAD implantation is increasing, possibly reflecting changes in AKI surveillance, awareness, and coding.
Keywords: AKI incidence; Acute kidney injury (AKI); dialysis; heart failure; hospital length-of-stay; hospitalization cost; in-hospital mortality; ventricular assist device (VAD).
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