title: A novel postoperative seizure classification for long-term mortality of patients with intractable epilepsy: comparison with the Engel system.
abstract: BACKGROUND
  To explore the association of clinical seizure pattern with the long-term prognosis after epilepsy surgery is important for patient counseling and risk management.
  
  
  OBJECTIVE
  To study the long-term mortality after surgery of intractable epilepsy patients with a novel classification of clinical patterns by long-term frequency and duration of seizure compared with the Engel classification.
  
  
  METHODS
  We conducted a longitudinal cohort study by enrolling 280 patients with epilepsy who underwent anterior temporal lobectomy between 1987 and 2002. In addition to the Engel classification, we proposed a novel classification of clinical patterns pertaining to at least 1 year of follow-up of the frequency and duration of seizures after surgery (inactive, delayed, intermittent, and intensive groups). We followed the vital status of these members until 2007 to obtain a 15-year survival rate for each classification. The standardized mortality ratio and hazard ratios with proportional hazards regression model by the extent of severity were estimated.
  
  
  RESULTS
  The overall 15-year survival rate for patients who underwent anterior temporal lobectomy was 95.1%. The standardized mortality ratio estimates (95% confidence interval) for our classification showed a gradient relationship from 0.6 (0.1-2.3), 2.5 (0.7-6.3), 7.6 (0.8-27.3), and 8.9 (3.2-19.3) for inactive, delayed, intermittent, and intensive groups, respectively (Trend test, P = .04), whereas the corresponding estimates were 0.8 (0.2-2.2), 5.9 (1.2-17.2), 6.7 (2.5-14.7), and 7.2 (0.8-25.9) for Engel I to IV, respectively, which showed a less increasing trend (Trend test, P = .82). Similar findings were noted for hazard ratios for the 2 classifications.
  
  
  CONCLUSIONS
  The proposed novel classification with long-term observed frequency and duration of seizures after surgery is more informative for predicting long-term mortality than the Engel classification.
authors.affiliation: Neurosurgery, The Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Yang-Hsin
authors.initials: YH
authors.lastname: Shih
authors.forename: Amy Ming-Fang
authors.initials: AM
authors.lastname: Yen
authors.forename: Der-Jen
authors.initials: DJ
authors.lastname: Yen
authors.forename: Ling-Pin
authors.initials: LP
authors.lastname: Hung
authors.forename: Hsiu-Hsi
authors.initials: HH
authors.lastname: Chen
authors.forename: Horng-Huei
authors.initials: HH
authors.lastname: Liou
mesh_terms: D000328:Adult; D004827:Epilepsy / Q000145:classification* / Q000453:epidemiology / Q000401:mortality* / Q000601:surgery; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D017063:Outcome Assessment, Health Care / Q000379:methods; D011184:Postoperative Period; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012640:Seizures / Q000145:classification* / Q000601:surgery*; D016019:Survival Analysis; D013624:Taiwan / Q000453:epidemiology; D016896:Treatment Outcome