title: Hydrogel-coated coils versus bare platinum coils for the endovascular treatment of intracranial aneurysms (HELPS): a randomised controlled trial.
abstract: BACKGROUND
  Coated coils for endovascular treatment of cerebral aneurysm were developed to reduce recurrence and retreatment rates, and have been in clinical use for 8-9 years without robust evidence to determine their efficacy. We assessed the efficacy and safety of hydrogel-coated coils.
  
  
  METHODS
  This randomised trial was undertaken in 24 centres in seven countries. Patients aged 18-75 years with a previously untreated ruptured or unruptured cerebral aneurysm of 2-25 mm in maximum diameter were randomly allocated (1:1) to aneurysm coiling with either hydrogel-coated coils or standard bare platinum coils (control). Randomisation was done with a computer-generated sequence, stratified by aneurysm size, shape, and dome-to-neck ratio; intention to use assist device; and by region. Participants and those assessing outcomes were masked to allocation. Analysis was by modified intention to treat (excluding missing data). Primary outcome was a composite of angiographic and clinical outcomes at 18-month follow-up. We also did prespecified subgroup analyses of characteristics likely to be relevant to angiographic outcome. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN30531382.
  
  
  RESULTS
  249 patients were allocated to the hydrogel coil group and 250 to the control group. In 44 of 467 patients for whom an 18-month composite primary outcome was unavailable, 6-month angiographic results were used. 70 (28%) patients in the hydrogel group and 90 (36%) control patients had an adverse composite primary outcome, giving an absolute reduction in the proportion of adverse composite primary outcomes with hydrogel of 7·0% (95% CI -1·6 to 15·5), odds ratio (OR) 0·73 (0·49-1·1, p=0·13). In a prespecified subgroup analysis in recently ruptured aneurysms, there were more adverse composite primary outcomes in the control group than in the hydrogel group-OR 2·08 (1·24-3·46, p=0·014). There were 8·6% fewer major angiographic recurrences in patients allocated to hydrogel coils-OR 0·7 (0·4-1·0, p=0·049). There were five cases of unexplained hydrocephalus in not-recently-ruptured aneurysms in the hydrogel coil group and one case in the control group.
  
  
  CONCLUSIONS
  Whether use of hydrogel coils reduces late aneurysm rupture or improves long-term clinical outcome is not clear, but our results indicate that their use lowers major recurrence.
  
  
  BACKGROUND
  MicroVention Inc.
authors.affiliation: Department of Neuroradiology and University Department of Clinical Neurosciences, Western General Hospital, University of Edinburgh SINAPSE Collaboration, Edinburgh, UK. pwhite1@staff mail.ed.ac.uk
authors.forename: Philip M
authors.initials: PM
authors.lastname: White
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Lewis
authors.forename: Anil
authors.initials: A
authors.lastname: Gholkar
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Sellar
authors.forename: Hans
authors.initials: H
authors.lastname: Nahser
authors.forename: Christophe
authors.initials: C
authors.lastname: Cognard
authors.forename: Lynn
authors.initials: L
authors.lastname: Forrester
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Wardlaw
mesh_terms: D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging / Q000628:therapy*; D002533:Cerebral Angiography; D020099:Coated Materials, Biocompatible; D004621:Embolization, Therapeutic / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000009:adverse effects; D007391:International Cooperation; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010984:Platinum; D019233:Retreatment; D055502:Secondary Prevention; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D020099:Coated Materials, Biocompatible; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D010984:Platinum