title: Does ascorbic acid protect against contrast-induced acute kidney injury in patients undergoing coronary angiography: a systematic review with meta-analysis of randomized, controlled trials.
abstract: OBJECTIVE
  This study sought to perform a systematic review with meta-analysis of randomized controlled trials comparing the use of ascorbic acid with placebo or other treatment options for the treatment of contrast induced-acute kidney injury (CI-AKI) in patients undergoing coronary angiography.
  
  
  BACKGROUND
  CI-AKI remains the most widely discussed and debated topic in cardiovascular medicine, with its incidence increasing due to an increasing number of contrast media-enhanced radiological procedures being performed.
  
  
  METHODS
  MEDLINE, Embase, and Cochrane central databases were searched from inception to May 2013, without language restrictions. For a study to be selected, it had to report the incidence of CI-AKI as an outcome measure. Studies were excluded if at least 1 study arm did not have ascorbic acid administered alone or with saline solution hydration. Data were extracted by 1 author, and random checks were made by another author.
  
  
  RESULTS
  Nine randomized, controlled trials reported data on the incidence of CI-AKI in 1,536 patients who had completed the trial and were included in the final analysis. Patients receiving ascorbic acid had 33% less risk of CI-AKI compared with patients receiving placebo or an alternate pharmacological treatment (risk ratio by random-effects model: 0.672; 95% confidence interval, 0.466 to 0.969; p = 0.034).
  
  
  CONCLUSIONS
  Ascorbic acid provides effective nephroprotection against CI-AKI and may form a part of effective prophylactic pharmacological regimens.
authors.affiliation: Department of Surgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom. Electronic address: sadat.umar@gmail.com.
authors.forename: Umar
authors.initials: U
authors.lastname: Sadat
authors.forename: Ammara
authors.initials: A
authors.lastname: Usman
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Gillard
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Boyle
mesh_terms: D058186:Acute Kidney Injury / Q000139:chemically induced* / Q000453:epidemiology; D001205:Ascorbic Acid / Q000627:therapeutic use*; D015986:Confounding Factors, Epidemiologic; D003287:Contrast Media / Q000009:adverse effects*; D017023:Coronary Angiography / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D015994:Incidence; D016017:Odds Ratio; D020011:Protective Agents / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D016896:Treatment Outcome; D014815:Vitamins / Q000627:therapeutic use*
chemical_list: D003287:Contrast Media; D020011:Protective Agents; D014815:Vitamins; D001205:Ascorbic Acid
keywords: CI; CI-AKI; RCT; ROS; RR; acute kidney injury; angiography; ascorbic acid; confidence interval; contrast-induced acute kidney injury; contrast-induced nephropathy; randomized, controlled trial; reactive oxygen species; risk ratio