title: Impact of collaterals on the efficacy and safety of endovascular treatment in acute ischaemic stroke: a systematic review and meta-analysis.
abstract: OBJECTIVE
  We aimed to investigate the role of pretreatment collateral status in predicting the efficacy and safety of endovascular treatment (EVT) in acute ischaemic stroke due to cervical and/or cerebral arterial occlusions.
  
  
  METHODS
  Relevant full-text articles published since 1 January 2000, investigating correlations between collateral status and any efficacy or safety outcome in patients undergoing EVT in cohort or case-control studies, or randomised clinical trials, were retrieved by PubMed and manual search. Two authors extracted data from eligible studies and assessed study quality. Risk ratios (RR) were pooled for good versus poor collaterals for outcomes based on a random-effects model. Sensitivity and subgroup analyses were conducted.
  
  
  RESULTS
  In total, 35 (3542 participants) and 23 (2652 participants) studies were included in qualitative review and quantitative meta-analysis, respectively. Overall, good pretreatment collaterals increased the rate of favourable functional outcome at 3 months (RR=1.98, 95% CI 1.64 to 2.38; p<0.001), and reduced the risks of periprocedural symptomatic intracranial haemorrhage (RR=0.59, 95% CI 0.43 to 0.81; p=0.001) and 3-month mortality (RR=0.49, 95% CI 0.38 to 0.63; p<0.001), as compared with poor collaterals, in patients with acute ischaemic stroke under EVT. No individual study could alter the estimate of overall effect of collateral status, but there were moderate to significant heterogeneities between subgroups of studies with different modes of EVT, different arterial occlusions and different collateral grading methods.
  
  
  CONCLUSIONS
  Good pretreatment collateral status is associated with higher rates of favourable functional outcome, and lower rates of symptomatic intracranial haemorrhage and mortality, in patients with acute ischaemic stroke receiving endovascular therapies.
authors.affiliation: Division of Neurology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Leng
authors.affiliation: Division of Neurology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Department of Neurology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Fang
authors.affiliation: Division of Neurology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong.
authors.forename: Thomas W H
authors.initials: TW
authors.lastname: Leung
authors.affiliation: Division of Epidemiology, the Hong Kong Branch of the Chinese Cochrane Center, School of Public Health and Primary Care, the Chinese University of Hong Kong, Hong Kong.
authors.forename: Chen
authors.initials: C
authors.lastname: Mao
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Zhongrong
authors.initials: Z
authors.lastname: Miao
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Liu
authors.affiliation: Division of Neurology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong.
authors.forename: Ka Sing
authors.initials: KS
authors.lastname: Wong
authors.affiliation: Department of Neurology, Neurovascular Imaging Research Core, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Liebeskind
mesh_terms: D002545:Brain Ischemia / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D003097:Collateral Circulation / Q000502:physiology*; D057510:Endovascular Procedures / Q000009:adverse effects*; D006801:Humans; D020521:Stroke / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome