Abstract Background and Aims Little is known about which patients to follow-up after an episode of acute kidney injury (AKI) for future risks. The aim of this review is to assess the association between AKI and the incidence or progression of chronic kidney disease (CKD) or end-stage kidney disease (ESKD), stratified by subcategories of AKI-stages, -durations, and clinical settings. Method A systematic search of the literature in PubMed and Embase was performed by two reviewers to identify studies that examined CKD incidence (development of CKD stage ≥3), CKD progression (worsening of kidney function in patients with CKD stage ≥3), or ESKD, in patients with AKI versus patients without AKI. The risk of bias was assessed using the Newcastle-Ottawa Scale. Relative effect estimates (odds and hazard ratios) were pooled using a random effects model. Results In total, 48 retrospective and 13 prospective studies, encompassing 140.985 patients with AKI, were included in this review. All the studies were of moderate or high quality. The pooled effect ratio was 3.36 (95% confidence interval (CI) 2.68-4.03) for CKD incidence (n = 31 studies). This remained 3.40 (95% CI 1.79-5.00) in a sub analysis including patients with a recovered kidney function post-AKI, and 1.49 (95% CI 1.44-1.55) in a sub analysis including patients with an AKI lasting less than 3 days (Fig. 1). Overall, the effect ratio for CKD progression (n = 11 studies) was 1.70 (95% CI 1.38-2.01) and 3.81 (95% CI 2.58-5.04) for ESKD (n = 24 studies). The increased risk of these two outcomes were not seen in the sub analyses only including patients with AKI lasting less than 3 days. Overall, there is an observable higher risk for CKD incidence, CKD progression, and ESKD with increased AKI staging, although not always statistically significant. Minimal variations were observed across clinical settings. Conclusion In our review, including over 60 studies, we found that AKI was associated with an increased risk of CKD incidence, CKD progression, and ESKD. Patients with higher AKI-stages had even larger risks. Notably, even brief episodes of AKI (lasting less than 3 days) were associated with a higher risk of CKD incidence compared to patients without AKI. In contrary, the risk for ESKD is not enlarged in a sub analysis including patients with recovered kidney function compared to patients without AKI. These result warrant close monitoring of the kidney function post-AKI, specifically in patients with AKI lasting 3 days or longer. Future research should focus more on the risk of CKD progression in order to tailor follow-up care in these more vulnerable patients.
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