title: Bidirectional relationships between acute kidney injury and chronic kidney disease.
abstract: OBJECTIVE
  Chronic kidney disease (CKD) remains one of the most potent predictors of acute kidney injury (AKI); however, recent epidemiologic studies have demonstrated a complex interplay between these two clinical entities. A growing body of evidence supports a bidirectional relationship: AKI leads to CKD, and the presence of CKD increases the risk of AKI. Additionally, several studies suggest that the presence of underlying CKD does modify the relation between AKI and adverse outcomes. In this article, we will review recent studies supporting the hypothesis that AKI leads to CKD and will explore the role of CKD as an effect modifier for AKI.
  
  
  RESULTS
  A recent meta-analysis confirms the association between AKI and the development of CKD and end-stage renal disease. Patient survival and renal outcomes after AKI are influenced by the presence of underlying CKD. AKI survivors with complete recovery of renal function remain at elevated risk of developing de-novo CKD, which may influence long-term survival; however, recovery of kidney function after AKI is associated with better long-term survival and renal function.
  
  
  CONCLUSIONS
  Recent findings support a strong association between AKI and CKD. There is uncertainty as to whether this relationship is causal. CKD is an effect modifier in AKI.
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Canada.
authors.forename: Neesh
authors.initials: N
authors.lastname: Pannu
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D020127:Recovery of Function; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D017741:Survivors; D013997:Time Factors; D016896:Treatment Outcome