title: The incidence of adjacent segment disease requiring surgery after anterior cervical diskectomy and fusion: estimation using an 11-year comprehensive nationwide database in Taiwan.
abstract: BACKGROUND
  The incidence of symptomatic adjacent segment disease (ASD) after anterior cervical diskectomy and fusion (ACDF) was reported as 2.9%/y in a previous cohort of 374 patients. Few other data corroborate the incidence and natural history of ASD.
  
  
  OBJECTIVE
  To calculate the incidence of ASD after ACDF that required secondary fusion surgery.
  
  
  METHODS
  The retrospective study used an 11-year nationwide database to analyze the incidences. All patients who underwent ACDF for cervical disk diseases were identified through diagnostic and procedure codes. Kaplan-Meier and Cox regression analyses were performed.
  
  
  RESULTS
  From 1997 to 2007, covering 241 800 725.8 person-years, 19 385 patients received ACDF and 568 had ≥ 2 ACDF operations. The incidence of secondary ACDF operations was 7.6 per 1000 person-years. At the end of the 10-year cohort, 94.4% of patients who had received 1 ACDF remained free from secondary ACDF. The average time interval between the first and second ACDF was 23.3 months. After adjustment for comorbidities and socioeconomic status, secondary ACDF operations were more likely performed on male patients (hazard ratio = 1.27; P = .008) 15 to 39 years of age (hazard ratio = 1.45; P = .009) and 40 to 59 years of age (hazard ratio = 1.41, P = .002, respectively).
  
  
  CONCLUSIONS
  Repeat ACDF surgery for ASD cumulated steadily in an annual incidence of approximately 0.8%, much lower than the reported incidence of symptomatic ASD. However, at the end of this 10-year cohort, a considerable portion of patients (5.6%) received a second operation. Younger and male patients are more likely to receive such second operations.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Jau-Ching
authors.initials: JC
authors.lastname: Wu
authors.forename: Laura
authors.initials: L
authors.lastname: Liu
authors.forename: Huang
authors.initials: H
authors.lastname: Wen-Cheng
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Chin-Chu
authors.initials: CC
authors.lastname: Ko
authors.forename: Ching-Lan
authors.initials: CL
authors.lastname: Wu
authors.forename: Tzeng-Ji
authors.initials: TJ
authors.lastname: Chen
authors.forename: Henrich
authors.initials: H
authors.lastname: Cheng
authors.forename: Tung-Ping
authors.initials: TP
authors.lastname: Su
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002574:Cervical Vertebrae / Q000601:surgery*; D015331:Cohort Studies; D015897:Comorbidity; D016208:Databases, Factual / Q000706:statistics & numerical data; D017586:Diskectomy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007405:Intervertebral Disc Displacement / Q000453:epidemiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D013123:Spinal Fusion / Q000706:statistics & numerical data*; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult