title: Reliability of the Spinal Instability Neoplastic Score (SINS) among radiation oncologists: an assessment of instability secondary to spinal metastases.
abstract: BACKGROUND
  The Spinal Instability Neoplastic Score (SINS) categorizes tumor related spinal instability. It has the potential to streamline the referral of patients with established or potential spinal instability to a spine surgeon. This study aims to define the inter- and intra-observer reliability and validity of SINS among radiation oncologists.
  
  
  METHODS
  Thirty-three radiation oncologists, across ten international sites, rated 30 neoplastic spinal disease cases. For each case, the total SINS (0-18 points), three clinical categories (stable: 0-6 points, potentially unstable: 7-12 points, and unstable: 13-18 points), and a binary scale ('stable': 0-6 points and 'current or possible instability'; surgical consultation recommended: 7-18 points) were recorded. Evaluation was repeated 6-8 weeks later. Inter-observer agreement and intra-observer reproducibility were calculated by means of the kappa statistic and translated into levels of agreement (slight, fair, moderate, substantial, and excellent). Validity was determined by comparing the ratings against a spinal surgeon's consensus standard.
  
  
  RESULTS
  Radiation oncologists demonstrated substantial (κ=0.76) inter-observer and excellent (κ=0.80) intra-observer reliability when using the SINS binary scale ('stable' versus 'current or possible instability'). Validity of the binary scale was also excellent (κ=0.85) compared with the gold standard. None of the unstable cases was rated as stable by the radiation oncologists ensuring all were appropriately recommended for surgical consultation.
  
  
  CONCLUSIONS
  Among radiation oncologists SINS is a highly reliable, reproducible, and valid assessment tool to address a key question in tumor related spinal disease: Is the spine 'stable' or is there 'current or possible instability' that warrants surgical assessment?
authors.affiliation: Division of Spine, Department of Orthopaedics, University of British Columbia and Vancouver Coastal Health, Vancouver, BC, Canada. charles.fisher@vch.ca.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Fisher
authors.forename: Rowan
authors.initials: R
authors.lastname: Schouten
authors.forename: Anne L
authors.initials: AL
authors.lastname: Versteeg
authors.forename: Stefano
authors.initials: S
authors.lastname: Boriani
authors.forename: Peter Pal
authors.initials: PP
authors.lastname: Varga
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Rhines
authors.forename: Norio
authors.initials: N
authors.lastname: Kawahara
authors.forename: Daryl
authors.initials: D
authors.lastname: Fourney
authors.forename: Lorna
authors.initials: L
authors.lastname: Weir
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Reynolds
authors.forename: Arjun
authors.initials: A
authors.lastname: Sahgal
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fehlings
authors.forename: Ziya L
authors.initials: ZL
authors.lastname: Gokaslan
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D063305:Organ Dysfunction Scores; D018787:Radiation Oncology / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D012107:Research Design; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013125:Spinal Neoplasms / Q000150:complications* / Q000503:physiopathology / Q000556:secondary*; D013131:Spine / Q000503:physiopathology