title: Total disc arthroplasty versus anterior cervical interbody fusion: use of the Spine Tango registry to supplement the evidence from randomized control trials.
abstract: BACKGROUND
  Several randomized controlled trials (RCTs) have compared patient outcomes of anterior (cervical) interbody fusion (AIF) with those of total disc arthroplasty (TDA). Because RCTs have known limitations with regard to their external validity, the comparative effectiveness of the two therapies in daily practice remains unknown.
  
  
  OBJECTIVE
  This study aimed to compare patient-reported outcomes after TDA versus AIF based on data from an international spine registry.
  
  
  METHODS
  A retrospective analysis of registry data was carried out.
  
  
  METHODS
  Inclusion criteria were degenerative disc or disc herniation of the cervical spine treated by single-level TDA or AIF, no previous surgery, and a Core Outcome Measures Index (COMI) completed at baseline and at least 3 months' follow-up. Overall, 987 patients were identified.
  
  
  METHODS
  Neck and arm pain relief and COMI score improvement were the outcome measures.
  
  
  METHODS
  Three separate analyses were performed to compare TDA and AIF surgical outcomes: (1) mimicking an RCT setting, with admission criteria typical of those in published RCTs, a 1:1 matched analysis was carried out in 739 patients; (2) an analysis was performed on 248 patients outside the classic RCT spectrum, that is, with one or more typical RCT exclusion criteria; (3) a subgroup analysis of all patients with additional follow-up longer than 2 years (n=149).
  
  
  RESULTS
  Matching resulted in 190 pairs with an average follow-up of 17 months that had no residual significant differences for any patient characteristics. Small but statistically significant differences in outcome were observed in favor of TDA, which are potentially clinically relevant. Subgroup analyses of atypical patients and of patients with longer-term follow-up showed no significant differences in outcome between the treatments.
  
  
  CONCLUSIONS
  The results of this observational study were in accordance with those of the published RCTs, suggesting substantial pain reduction both after AIF and TDA, with slightly greater benefit after arthroplasty. The analysis of atypical patients suggested that, in patients outside the spectrum of clinical trials, both surgical interventions appeared to work to a similar extent to that shown for the cohort in the matched study. Also, in the longer-term perspective, both therapies resulted in similar benefits to the patients.
authors.affiliation: Institute for Evaluative Research in Medicine, Stauffacherstrasse 78, 3014 Bern, Switzerland.
authors.forename: Lukas P
authors.initials: LP
authors.lastname: Staub
authors.affiliation: Institute for Evaluative Research in Medicine, Stauffacherstrasse 78, 3014 Bern, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Ryser
authors.affiliation: Institute for Evaluative Research in Medicine, Stauffacherstrasse 78, 3014 Bern, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Röder
authors.affiliation: Spine Centre Division, Department of Teaching, Research and Development, Schulthess Klinik, Lengghalde 2, CH-8008 Zurich, Switzerland.
authors.forename: Anne F
authors.initials: AF
authors.lastname: Mannion
authors.affiliation: Comparative Effectiveness, Cost and Outcome Research Centre, University of Washington, 4333 Brooklyn Ave NE, Seattle, WA 98104, USA.
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Jarvik
authors.affiliation: Department of Orthopaedic Surgery, Salem Spital, Schänzlistrasse 39, Bern 3025, Switzerland.
authors.forename: Max
authors.initials: M
authors.lastname: Aebi
authors.affiliation: Institute for Evaluative Research in Medicine, Stauffacherstrasse 78, 3014 Bern, Switzerland. Electronic address: emin.aghayev@memcenter.unibe.ch.
authors.forename: Emin
authors.initials: E
authors.lastname: Aghayev
mesh_terms: D000328:Adult; D001178:Arthroplasty / Q000009:adverse effects*; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D012042:Registries; D013123:Spinal Fusion / Q000009:adverse effects*
keywords: Propensity score-based matching; Randomized controlled trial; Registry; Spine Tango