Clinical outcomes of persistent severe acute kidney injury among patients with KDIGO stage 2 or 3 AKI

Introduction: The burden of persistent (>= 3 days) severe AKI (PS-AKI) is poorly described among inpatients with stage 2-3 AKI in the ward or ICU. Quantification could motivate targeted interventions to decrease duration of AKI in these high-risk patients. Methods: This retrospective cohort study included adult patients discharged from January 1, 2017, to December 31, 2019, from US hospitals in the PINC AI Healthcare Database. Patients with KDIGO stage 2 or 3 AKI, length of stay (LOS) >= 3 days, >= 3 serum creatinine measures, and no history of renal transplant, dialysis, or stage 5 chronic kidney disease (CKD) were included. Patients were classified as PS-AKI (stage 3 AKI lasting >= 3 days or with death in <= 3 days, or stage 2 or 3 AKI with dialysis in <= 3 days) or not persistent severe AKI (NPS-AKI)(stage 3 AKI for <= 2 days, or stage 2 AKI without dialysis in <= 3 days). Outcomes during index (initial) hospitalization were PS-AKI incidence, ICU use and in-hospital mortality, and during 30-day (post-discharge) were readmissions, in-hospital mortality, dialysis, and "new" dialysis (dialysis among patients without dialysis during index hospitalization). For index outcomes, we used a sensitivity definition, PS-AKISens, that excluded patients who met PS-AKI criteria by dialysis/death in <= 3 days of AKI onset. Multivariable-adjusted logistic regression quantified differences between PS-AKI and NPS-AKI, overall, and separately for ICU and non-ICU patients. Results: Among 126,528 inpatients with stage 2 or 3 AKI, PS-AKI developed in 24.4% (30,916), with 39% of PS-AKI occurring in non-ICU patients. With NPS-AKI as the reference group, adjusted odds ratios (aORs) (95% CI) for PS-AKI and for PS-AKISens were 2.15 (2.09-2.21) and 1.28 (1.24-1.32) for ICU use and 4.58 (4.41-4.75) and 1.79 (1.70-1.89) for in-hospital mortality during index hospitalization. For outcomes during 30-days post-discharge, aORs for PS-AKI vs. NPS-AKI were 1.07 (1.02-1.11) for readmissions, 1.33 (1.18-1.49) for in-hospital mortality, 15.66 (13.87-17.67) for dialysis, and 6.80 (5.84-7.93) for new dialysis. Despite higher mortality among ICU patients, aORs for outcomes during index and 30-days post-discharge were similar for ICU and non-ICU patients. Discussion/Conclusion: In and out of the ICU, PS-AKI frequently affected inpatients with stage 2 or 3 AKI and was independently associated with worse clinical outcomes during index hospitalization and during 30-days post-discharge. These results suggest that interventions to prevent persistence of severe AKI may reduce adverse clinical outcomes among patients with stage 2 or 3 AKI in or out of the ICU.