title: Time-based partitioning model for predicting neurologically favorable outcome among adults with witnessed bystander out-of-hospital CPA.
abstract: BACKGROUND
  Optimal acceptable time intervals from collapse to bystander cardiopulmonary resuscitation (CPR) for neurologically favorable outcome among adults with witnessed out-of-hospital cardiopulmonary arrest (CPA) have been unclear. Our aim was to assess the optimal acceptable thresholds of the time intervals of CPR for neurologically favorable outcome and survival using a recursive partitioning model.
  
  
  RESULTS
  From January 1, 2005 through December 31, 2009, we conducted a prospective population-based observational study across Japan involving consecutive out-of-hospital CPA patients (N = 69,648) who received a witnessed bystander CPR. Of 69,648 patients, 34,605 were assigned to the derivation data set and 35,043 to the validation data set. Time factors associated with better outcomes: the better outcomes were survival and neurologically favorable outcome at one month, defined as category one (good cerebral performance) or two (moderate cerebral disability) of the cerebral performance categories. Based on the recursive partitioning model from the derivation dataset (n = 34,605) to predict the neurologically favorable outcome at one month, 5 min threshold was the acceptable time interval from collapse to CPR initiation; 11 min from collapse to ambulance arrival; 18 min from collapse to return of spontaneous circulation (ROSC); and 19 min from collapse to hospital arrival. Among the validation dataset (n = 35,043), 209/2,292 (9.1%) in all patients with the acceptable time intervals and 1,388/2,706 (52.1%) in the subgroup with the acceptable time intervals and pre-hospital ROSC showed neurologically favorable outcome.
  
  
  CONCLUSIONS
  Initiation of CPR should be within 5 min for obtaining neurologically favorable outcome among adults with witnessed out-of-hospital CPA. Patients with the acceptable time intervals of bystander CPR and pre-hospital ROSC within 18 min could have 50% chance of neurologically favorable outcome.
authors.affiliation: Department of Emergency Medicine, Mito Kyodo General Hospital, University of Tsukuba, Mito City, Ibaraki, Japan. mican-philia@sunny.ocn.ne.jp
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Abe
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Tokuda
authors.forename: E Francis
authors.initials: EF
authors.lastname: Cook
mesh_terms: D000328:Adult; D000368:Aged; D016887:Cardiopulmonary Resuscitation; D004632:Emergency Medical Services; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D006761:Hospitals; D006801:Humans; D008297:Male; D008954:Models, Biological; D011379:Prognosis; D015203:Reproducibility of Results; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome