title: The Selection of Open or Percutaneous Endoscopic Lumbar Discectomy According to an Age Cut-off Point: Nationwide Cohort Study.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To provide an age cut-off of percutaneous endoscopic lumbar discectomy (PELD) for optimal reoperation rate with nationwide population-based data.
  
  
  BACKGROUND
  Open discectomy is the standard operation for lumbar herniated intervertebral disk disease (HIVD). PELD has shown noninferior outcome to open discectomy and there is increasing interest with regard to PELD. However, PELD may not be a suitable option for all age groups.
  
  
  METHODS
  We selected 15,817 patients who underwent open discectomy (n = 12,816) or PELD (n = 3001) in 2003 from the Korean Health Insurance Review & Assessment Service (HIRA) database. All patients in the cohort were followed until December 31, 2008, and the minimum follow-up period was 5 years. A time-to-event survival analysis was conducted. The primary endpoint was any type of second lumbar spine surgery during the follow-up period. Minimum P-value approach and a 2-fold cross-validation approach were utilized to determine an age cut-off point.
  
  
  RESULTS
  The optimal age cut-off point was determined as 57 years. PELD for older patients (≥57 years) had a higher reoperation risk during the postoperative 3.4 years (hazard ratio [HR] at 1 yr, 1.75; 2 yr, 1.57; and 3 yr, 1.41). However, the reoperation risk was not higher after PELD for patients younger than 57 years, from 1.9 years, than open discectomy (HR at 2 yr, 0.86; 3 yr, 0.78; 4 yr, 0.70; and 5 yr, 0.63).
  
  
  CONCLUSIONS
  In the present study, we showed that an age cut-off point of PELD for optimal reoperation rate may be 57 years, based on nationwide population-based data. The reoperation rate does not seem to be higher for patients younger than 57 years after PELD than after open discectomy; however, PELD for older patients should be applied after careful consideration.
  
  
  METHODS
  3.
authors.affiliation: *Department of Neurosurgery, Seoul National University Hospital, Seoul, South Korea †Department of Neurosurgery, Seoul National University College of Medicine, Seoul, South Korea ‡Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, South Korea §Clinical Research Institute, Seoul National University Hospital, Seoul, South Korea ¶Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, South Korea ∥Division of Medical Statistics, Medical Research Collaborating Center, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea **Health Insurance Review and Assessment Service, Seoul, Korea; and ††Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Chi Heon
authors.initials: CH
authors.lastname: Kim
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
authors.forename: Yunhee
authors.initials: Y
authors.lastname: Choi
authors.forename: Sukyoun
authors.initials: S
authors.lastname: Shin
authors.forename: Myo Jeong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Juhee
authors.initials: J
authors.lastname: Lee
authors.forename: Byung Joo
authors.initials: BJ
authors.lastname: Park
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D017587:Diskectomy, Percutaneous / Q000379:methods; D004724:Endoscopy / Q000379:methods; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008161:Lumbosacral Region / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies; D016896:Treatment Outcome