title: Strategies to improve the credibility of meta-analyses in spine surgery: a systematic survey.
abstract: BACKGROUND
  Meta-analyses are powerful tools that can synthesize existing research, inform clinical practice, and support evidence-based care. These studies have become increasingly popular in the spine surgery literature, but the rigor with which they are being conducted has not yet been evaluated.
  
  
  OBJECTIVE
  Our primary objectives were to evaluate the methodological quality (credibility) of spine surgery meta-analyses and to propose strategies to improve future research. Our secondary objectives were to evaluate completeness of reporting and identify factors associated with higher credibility and completeness of reporting.
  
  
  METHODS
  This study is based on a systematic survey of meta-analyses.
  
  
  METHODS
  We evaluated credibility according to the Users' Guide to the Medical Literature and completeness of reporting according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.
  
  
  METHODS
  We systematically searched MEDLINE, EMBASE, and The Cochrane Library, and two reviewers independently assessed eligibility, credibility, and completeness of reporting. We used multivariable linear regression to evaluate potential associations. Interrater agreement was quantified using kappa and intraclass correlation (ICC) coefficients.
  
  
  RESULTS
  We identified 132 eligible meta-analyses of spine surgery interventions. The mean credibility score was 3 of 7 (standard deviation [SD], 1.4; ICC, 0.86), with agreement for each item ranging from 0.54 (moderate) to 0.83 (almost perfect). Clinical questions were judged as sensible in 125 (95%), searches were exhaustive in 102 (77%), and risk of bias assessments were undertaken in 91 (69%). Seven (5%) meta-analyses addressed possible explanations for heterogeneity using a priori subgroup hypotheses and 24 (18%) presented results that were immediately clinically applicable. Investigators undertook duplicate assessments of eligibility, risk of bias, and data extraction in 46 (35%) and rated overall confidence in the evidence in 24 (18%). Later publication year, increasing Journal Impact Factor, increasing number of databases, inclusion of Randomized Controlled Trials, and inclusion of non-English studies were significantly associated with higher credibility scores (p<.05). The mean score for reporting was 18 of 27 (SD, 4.4; ICC, 0.94).
  
  
  CONCLUSIONS
  The credibility of many current spine surgery meta-analyses is limited. Researchers can improve future meta-analyses by performing exhaustive literature searches, addressing possible explanations of heterogeneity, presenting results in a clinically useful manner, reproducibly selecting and assessing primary studies, addressing confidence in the pooled effect estimates, and adhering to guidelines for complete reporting.
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7. Electronic address: nathan.evaniew@medportal.ca.
authors.forename: Nathan
authors.initials: N
authors.lastname: Evaniew
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7.
authors.forename: Leon
authors.initials: L
authors.lastname: van der Watt
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7.
authors.forename: Mohit
authors.initials: M
authors.lastname: Bhandari
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7.
authors.forename: Michelle
authors.initials: M
authors.lastname: Ghert
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7.
authors.forename: Ilyas
authors.initials: I
authors.lastname: Aleem
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7.
authors.forename: Brian
authors.initials: B
authors.lastname: Drew
authors.affiliation: McMaster University, Department of Surgery, Division of Orthopaedics, 293 Wellington St. N, Hamilton ON, Canada, L8L 8E7.
authors.forename: Gordon
authors.initials: G
authors.lastname: Guyatt
mesh_terms: D006801:Humans; D015201:Meta-Analysis as Topic; D013124:Spinal Injuries / Q000601:surgery*
keywords: Credibility; Meta-analysis; Reporting; Research methodology; Spine surgery; Systematic review