title: A systematic review of clinical and surgical predictors of complications following surgery for degenerative cervical myelopathy.
abstract: OBJECTIVE
  Although generally safe and effective, surgery for the treatment of cervical spondylotic myelopathy (CSM) is associated with complications in 11%-38% of patients. Several predictors of postoperative complications have been proposed but few are used to detect high-risk patients. A standard approach to identifying "at-risk" patients would improve surgeons' ability to prevent and manage these complications. The authors aimed to compare the complication rates between various surgical procedures used to treat CSM and to identify patient-specific, clinical, imaging, and surgical predictors of complications.
  
  
  METHODS
  The authors conducted a systematic review of the literature and searched MEDLINE, MEDLINE in Process, EMBASE, and Cochrane Central Register of Controlled Trials from 1948 to September 2013. Cohort studies designed to evaluate predictors of complications and intervention studies conducted to compare different surgical approaches were included. Each article was critically appraised independently by 2 reviewers, and the evidence was synthesized according to the principles outlined by the Grading of Recommendation Assessment, Development and Evaluation (GRADE) Working Group.
  
  
  RESULTS
  A total of 5472 citations were retrieved. Of those, 60 studies met the inclusion criteria and were included in the review. These studies included 36 prognostic cohort studies and 28 comparative intervention studies. High evidence suggests that older patients are at a greater risk of perioperative complications. Based on low evidence, other clinical factors such as body mass index, smoking status, duration of symptoms, and baseline severity score, are not predictive of complications. With respect to surgical factors, low to moderate evidence suggests that estimated blood loss, surgical approach, and number of levels do not affect rates of complications. A longer operative duration (moderate evidence), however, is predictive of perioperative complications and a 2-stage surgery is related to an increased risk of major complications (high evidence). In terms of surgical techniques, higher rates of neck pain were found in patients undergoing laminoplasty compared with anterior spinal fusion (moderate evidence). In addition, with respect to laminoplasty techniques, there was a lower incidence of C-5 palsy in laminoplasty with concurrent foraminotomy compared with nonforaminotomy (low evidence).
  
  
  CONCLUSIONS
  The current review suggests that older patients are at a higher risk of perioperative complications. A longer operative duration and a 2-stage surgery both reflect increased case complexity and can indirectly predict perioperative complications.
authors.affiliation: Toronto Western Hospital, University Health Network; and.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Tetreault
authors.affiliation: Toronto Western Hospital, University Health Network; and.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ibrahim
authors.affiliation: University of Ontario Institute of Technology (UOIT), UOIT-CMCC Centre for the Study of Disability Prevention and Rehabilitation, Toronto, Ontario, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Côté
authors.affiliation: Toronto Western Hospital, University Health Network; and.
authors.forename: Anoushka
authors.initials: A
authors.lastname: Singh
authors.affiliation: Toronto Western Hospital, University Health Network; and.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fehlings
mesh_terms: D002574:Cervical Vertebrae / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods; D006801:Humans; D065406:Laminoplasty / Q000379:methods; D011183:Postoperative Complications / Q000209:etiology / Q000601:surgery; D013118:Spinal Cord Diseases / Q000601:surgery*; D055009:Spondylosis / Q000601:surgery*
keywords: ACDF = anterior cervical discectomy and fusion; ADF = anterior decompression and fusion; BMI = body mass index; CDH = cervical disc herniation; CSM = cervical spondylotic myelopathy; EOLP = expansive open-door laminoplasty; GRADE = Grades of Recommendation Assessment, Development and Evaluation; ICD = International Classification of Disease; JOA = Japanese Orthopaedic Association; KQ = key question; OPLL = ossification of the posterior longitudinal ligament; PCB = plate cage Benezech; cervical spondylotic myelopathy; complications; degenerative; surgery; systematic review