Background: The reported incidence and mortality of acute kidney injury (AKI) in patients in intensive care units (ICUs) is remarkably different even with standardized AKI criteria. The aim of this study was to investigate the correlation between the incidence and mortality of patients with AKI in ICUs.
Methods: We systematically reviewed clinical studies regarding adult ICU patients with AKI using Kidney Disease: Improving Global Outcomes-equivalent criteria from 2004 to May 1, 2018. We searched MEDLINE, EMBASE, and Cochrane Library to investigate the correlation between the incidence and mortality of patients with AKI in each cohort. Studies with small number of participants (less than 500) were excluded. The correlation between the incidence of AKI and mortality of patients was evaluated using a regression model.
Results: Our review yielded 76 cohorts, comprising 564,455 patients in ICU (median age, 60.5 years; men, 59.5%). The mortality of all patients did not correlate with the incidence of AKI in each cohort; however, the mortality of patients with AKI significantly decreased [squared correlation coefficient (R) = 0.18, regression coefficient (β) = -0.25, P < 0.001] as the incidence of AKI increased. This correlation was also observed in a subgroup analysis limited to the clinical setting of general ICUs, and among patients with mild or severe AKI.
Conclusions: An inverse correlation between the incidence of AKI and the mortality of patients with AKI may indicate an advantage of frequent AKI occurrence, possibly because of increased awareness and larger exposure to AKIs; further study is needed, however, to confirm the causality.
Trial registration: The protocol was registered in PROSPERO database (CRD 42019129322).