title: Contrast-induced acute kidney injury and risk of adverse clinical outcomes after coronary angiography: a systematic review and meta-analysis.
abstract: BACKGROUND
  Contrast-induced acute kidney injury (CI-AKI) has been associated with mortality, although it has been suggested this association may be attributable to confounding. We performed a systematic review and meta-analysis to characterize the associations between CI-AKI and subsequent clinical outcomes.
  
  
  RESULTS
  We identified studies using MEDLINE (1950 to June 2011) and Embase (1980 to June 2011), manual bibliographic searches, and contact with experts. We included observational studies that characterized outcomes among patients with and without AKI (based on changes in serum creatinine) after coronary angiography. Eligible studies reported at least 1 of mortality, cardiovascular events, end-stage renal disease, or length of hospital stay. Thirty-nine observational studies met inclusion criteria. Of 34 studies reporting mortality (including 139 603 participants), 33 reported an increased risk of death in those with CI-AKI, although the effect size varied between studies (I(2)=93.5%). Between-study heterogeneity was partially explained by whether adjustment for confounding features was performed (11 studies without adjustment; pooled crude risk ratio, 8.19; 95% confidence interval, 4.30-15.60; I(2)=77.3% versus 23 studies with adjustment; pooled adjusted risk ratio, 2.39; 95% confidence interval, 1.98-2.90; I(2)=88.3%). CI-AKI was consistently associated with an increased risk of cardiovascular events in 14 studies, end-stage renal disease in 3 studies, and prolonged hospitalization in 11 studies.
  
  
  CONCLUSIONS
  CI-AKI is associated with an increased risk of mortality, cardiovascular events, renal failure, and prolonged hospitalization. However, the association between CI-AKI and mortality is strongly confounded by baseline clinical characteristics that simultaneously predispose to both kidney injury and mortality, and the risk attributable to CI-AKI is much lower than that reported from unadjusted studies.
authors: Department of Medicine, University of Calgary, Calgary, Alberta, Canada. mjames@ucalgary.ca
authors: Matthew T
authors: MT
authors: James
authors: Susan M
authors: SM
authors: Samuel
authors: Megan A
authors: MA
authors: Manning
authors: Marcello
authors: M
authors: Tonelli
authors: William A
authors: WA
authors: Ghali
authors: Peter
authors: P
authors: Faris
authors: Merril L
authors: ML
authors: Knudtson
authors: Neesh
authors: N
authors: Pannu
authors: Brenda R
authors: BR
authors: Hemmelgarn
mesh_terms: D000208:Acute Disease; D015986:Confounding Factors, Epidemiologic; D003287:Contrast Media / Q000008:administration & dosage / Q000009:adverse effects*; D017023:Coronary Angiography / Q000009:adverse effects; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000473:pathology; D007674:Kidney Diseases / Q000139:chemically induced / Q000175:diagnosis* / Q000401:mortality; D011446:Prospective Studies; D012306:Risk; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media