title: Morbidity and mortality of complex spine surgery: a prospective cohort study in 679 patients validating the Spine AdVerse Event Severity (SAVES) system in a European population.
abstract: BACKGROUND
  Most literature on complications in spine surgery has been retrospective or based on national databases with few variables. The Spine AdVerse Events Severity (SAVES) system has been found reliable and valid in two Canadian centers, providing precise information regarding all adverse events (AEs).
  
  
  OBJECTIVE
  This study aimed to determine the mortality and examine the incidence of morbidity in patients undergoing complex spinal surgery, including pediatric patients, and to validate the SAVES system in a European population.
  
  
  METHODS
  A prospective, consecutive cohort study was conducted using the SAVES version 2010 in the period from January 1, 2013 until December 31, 2013. A retrospective analysis was performed on all patients operated from November 1, 2011 until October 31, 2012 for comparison.
  
  
  METHODS
  Patients undergoing spinal surgery at a tertiary referral center comprised the patient sample.
  
  
  METHODS
  Morbidity and mortality were determined according to the newest version of the SAVES system and compared with the Canadian cohort. Other outcomes were length of stay, readmission, unplanned second surgery during index admission, as well as wound infections requiring revision.
  
  
  METHODS
  All patients undergoing spinal surgery at an academic tertiary referral center in the study period were prospectively included. The newest version of SAVES system was used, and a research coordinator collected all intraoperative and perioperative data prospectively. Once a week all patients were reviewed for additional events, validation of the data, and clarification of any questions. Patients were grouped according to the type of admission (elective of emergency) and age, and subgrouped according to a major diagnostic group. The survival status was registered on January 31, 2014 to obtain 30-day survival.
  
  
  RESULTS
  A total of 679 consecutive cases were included with 100% data completion. The in-hospital mortality was 1.3% and the 30-day mortality was 2.7%; all occurring after emergency procedures. The number of intraoperative AEs was 162 (overall incidence 20%), and the number of postoperative AEs was 1,415 (overall incidence 77%). Of the patients, 2.2% had postoperative infections requiring surgical revision.
  
  
  CONCLUSIONS
  A prospective registration improves AE recognition, and our data confirm the generalizability of the SAVES system to pediatric and non-Canadian populations.
authors.affiliation: Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, 9 Blegdamsvej, 2100 Copenhagen, Denmark. Electronic address: svenhka@gmail.com.
authors.forename: Sven
authors.initials: S
authors.lastname: Karstensen
authors.affiliation: Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, 9 Blegdamsvej, 2100 Copenhagen, Denmark.
authors.forename: Tanvir
authors.initials: T
authors.lastname: Bari
authors.affiliation: Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, 9 Blegdamsvej, 2100 Copenhagen, Denmark.
authors.forename: Martin
authors.initials: M
authors.lastname: Gehrchen
authors.affiliation: Combined Neurosurgical and Orthopedic Spine Program, Vancouver General Hospital, University of British Columbia, Floor 6, Blusson Spinal Cord Center, 818 West 10th Ave., Vancouver, British Columbia V5Z 1M9, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Street
authors.affiliation: Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, 9 Blegdamsvej, 2100 Copenhagen, Denmark.
authors.forename: Benny
authors.initials: B
authors.lastname: Dahl
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005060:Europe; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects*; D011183:Postoperative Complications / Q000401:mortality / Q000473:pathology*; D011446:Prospective Studies; D012189:Retrospective Studies; D013131:Spine / Q000601:surgery*; D015599:Trauma Severity Indices
keywords: Adverse events; Cohort; Complex; Complications; Morbidity; Prospective