Readmissions after Acute Kidney Injury during Left Ventricular Assist Device Implantation Hospitalization

Background: Acute kidney injury (AKI) frequently complicates hospitalizations for left ventricular assist device (LVAD) implantation. Little is known about the relationship of AKI with subsequent readmissions, and we investigated the relationship of AKI during LVAD implantation hospitalization with all-cause and cause-specific 30-day readmissions. Methods: We used a United States (US) nationwide all-payer administrative database, identifying patients who underwent implantable LVAD placement 2010-2015. Patients were classified into 3 mutually exclusive groups based on presence and severity of AKI during the LVAD placement hospitalization: no AKI, AKI, and AKI requiring dialysis (AKI-D). Outcomes were all-cause and cause-specific 30-day readmissions. Results: Within 30 days after discharge 25.4% of patients were readmitted. Of those without AKI, 23.9% were readmitted, compared to 25.5% of those with AKI and 42.2% of those with AKI-D. Compared to no AKI (adjusted for demographics, index hospitalization and chronic comorbidity factors, and year), odds of 30-day readmission were 2.18 (95% CI 1.37-3.49) times higher for those with AKI-D, whereas those with AKI not requiring dialysis had similar 30-day readmission risk (OR 1.03 [95% CI 0.89-1.20]). Those with AKI-D had higher risk of 30-day readmission for infection (OR 2.02 [95% CI 1.13-3.61]), gastrointestinal (GI) bleed (2.32 [95% CI 1.24-4.34]), and kidney disease (13.9 [95% CI 4.0-48]). There was no increased risk for stroke readmission with AKI or AKI-D. Conclusion: AKI-D was associated with highest -30-day readmission risk, possibly related to negatively synergistic effects of LVAD, kidney dysfunction, and dialysis related factors on infection and GI bleeding risks. AKI alone was not associated with increased readmission risk.