title: Symptomatic spinal metastasis: A systematic literature review of the preoperative prognostic factors for survival, neurological, functional and quality of life in surgically treated patients and methodological recommendations for prognostic studies.
abstract: OBJECTIVE
  While several clinical prediction rules (CPRs) of survival exist for patients with symptomatic spinal metastasis (SSM), these have variable prognostic ability and there is no recognized CPR for health related quality of life (HRQoL). We undertook a critical appraisal of the literature to identify key preoperative prognostic factors of clinical outcomes in patients with SSM who were treated surgically. The results of this study could be used to modify existing or develop new CPRs.
  
  
  METHODS
  Seven electronic databases were searched (1990-2015), without language restriction, to identify studies that performed multivariate analysis of preoperative predictors of survival, neurological, functional and HRQoL outcomes in surgical patients with SSM. Individual studies were assessed for class of evidence. The strength of the overall body of evidence was evaluated using GRADE for each predictor.
  
  
  RESULTS
  Among 4,818 unique citations, 17 were included; all were in English, rated Class III and focused on survival, revealing a total of 46 predictors. The strength of the overall body of evidence was very low for 39 and low for 7 predictors. Due to considerable heterogeneity in patient samples and prognostic factors investigated as well as several methodological issues, our results had a moderately high risk of bias and were difficult to interpret.
  
  
  CONCLUSIONS
  The quality of evidence for predictors of survival was, at best, low. We failed to identify studies that evaluated preoperative prognostic factors for neurological, functional, or HRQoL outcomes in surgical patients with SSM. We formulated methodological recommendations for prognostic studies to promote acquiring high-quality evidence to better estimate predictor effect sizes to improve patient education, surgical decision-making and development of CPRs.
authors.affiliation: Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Anick
authors.initials: A
authors.lastname: Nater
authors.affiliation: Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Allan R
authors.initials: AR
authors.lastname: Martin
authors.affiliation: Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Canada.
authors.forename: Arjun
authors.initials: A
authors.lastname: Sahgal
authors.affiliation: Department of Neurosurgery, The National Hospital for Neurology and Neurosurgery, and Institute of Neurology, University College London, London, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Choi
authors.affiliation: Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.|Department of Neurosurgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Michael G
authors.identifier: http://orcid.org/0000-0002-5722-6364
authors.initials: MG
authors.lastname: Fehlings
mesh_terms: D016208:Databases, Factual; D003657:Decision Making; D003661:Decision Support Techniques; D006801:Humans; D011379:Prognosis; D011788:Quality of Life; D013125:Spinal Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery