title: Associations of fluid overload with mortality and kidney recovery in patients with acute kidney injury: A systematic review and meta-analysis.
abstract: OBJECTIVE
  Fluid resuscitation is commonly administered to maintain adequate renal perfusion in critically ill patients to prevent or even treat acute kidney injury (AKI). However, recent studies show that fluid overload is common and might be associated with poor outcomes in patients with AKI. Hence, the objective of this study was to assess the associations of fluid overload with mortality and kidney recovery in patients with AKI.
  
  
  METHODS
  We electronically searched original articles published in peer-reviewed journals from their inception to January 2015 in PubMed, EMBASE, the Cochrane Library databases, Google Scholar, and Chinese database (SinoMed). We additionally searched the reference lists of all retrieved articles. We performed a systematic review and meta-analysis of all eligible cohort or case-control studies of fluid overload in patients with AKI. The primary outcomes were mortality and kidney recovery. We pooled adjusted odds ratios (ORs) with 95% confidence intervals (95% CIs) by using Review Manager 5.2 (The Cochrane Collaboration, Oxford, UK).
  
  
  RESULTS
  A total of 5095 patients from 12 cohort studies published from 2008 to 2014 were included. A significant positive association was found between fluid overload and mortality in patients with AKI (OR, 2.23; 95% CI, 1.66-3.01), with similar findings in sepsis (OR, 2.27; 95% CI, 1.69-to 3.03) and nonsepsis subgroups (OR, 3.40; 95% CI, 2.50-4.63). There was also a significant association between mean fluid balance (continuous variables) and mortality (OR, 1.16; 95% CI, 1.07-1.27). Although there was a trend of lower rate of kidney recovery in the fluid overload group, there was no significant association between fluid overload and kidney recovery (OR, 0.66; 95% CI, 0.37-1.15), or dialysis dependence (OR, 0.72; 95% CI, 0.38-1.35).
  
  
  CONCLUSIONS
  Fluid overload is associated with an increased risk of mortality in patients with AKI. The evidence of the relationship between fluid overload and kidney recovery is insufficient.
authors.affiliation: Division of Nephrology, West China Hospital of Sichuan University, Sichuan, Chengdu, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Division of Nephrology, West China Hospital of Sichuan University, Sichuan, Chengdu, China.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Division of Nephrology, West China Hospital of Sichuan University, Sichuan, Chengdu, China. Electronic address: dszhbf@163.com.
authors.forename: Yongshu
authors.initials: Y
authors.lastname: Diao
authors.affiliation: Division of Nephrology, West China Hospital of Sichuan University, Sichuan, Chengdu, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Division of Nephrology, West China Hospital of Sichuan University, Sichuan, Chengdu, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Fu
mesh_terms: D058186:Acute Kidney Injury / Q000453:epidemiology / Q000401:mortality*; D016638:Critical Illness; D005440:Fluid Therapy / Q000009:adverse effects; D006801:Humans; D007668:Kidney; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000628:therapy; D020127:Recovery of Function; D006435:Renal Dialysis; D018805:Sepsis / Q000453:epidemiology / Q000401:mortality*; D014883:Water-Electrolyte Imbalance / Q000453:epidemiology* / Q000209:etiology
keywords: Acute kidney injury; Fluid overload; Kidney recovery; Meta-analysis; Mortality