title: Factors associated with a change in functional outcome between one month and six months after cardiac arrest: a retrospective cohort study.
abstract: OBJECTIVE
  The appropriate time point of evaluation of functional outcome in cardiac arrest survivors remains a matter of debate. In this cohort study we posed the hypothesis that there are no significant changes in Cerebral Performance Categories (CPC) between one month and six months after out-of hospital cardiac arrest. If changes were present we aimed to identify reasons for these changes.
  
  
  METHODS
  Based on a cardiac arrest registry, a potential change in CPC and mortality between one month and six months after cardiac arrest was analysed. Variables that were associated with these changes were identified.
  
  
  RESULTS
  Thirty percent of 681 patients showed a significant change in functional outcome and mortality between one month and six months after out-of hospital cardiac arrest, 12% improved in CPC, 1% deteriorated, 17% died. The only factor that was associated with an improvement in CPC in the multivariate analysis was time to restoration of spontaneous circulation (ROSC) (RRR 1.04, 95% CI 1.01-1.06, per minute). We could not find any significant factors associated with a deterioration of CPC. Factors that were associated with mortality were age (RRR 1.03, 95% CI 1.01-1.06) and ventricular fibrillation as initial cardiac rhythm (RRR 0.34, 95% CI 0.16-0.71).
  
  
  CONCLUSIONS
  There is a relevant change of functional outcome even one month after out-of hospital cardiac arrest. Especially when studies compare patient groups with unequal arrest times, and an unequal distribution of initial cardiac rhythms a follow-up period longer than one month should be considered for the final outcome evaluation after cardiac arrest.
authors.affiliation: Universitätsklinik für Notfallmedizin, Medical University of Vienna, Währinger Gürtel 18-20/6D, 1190 Wien, Austria.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Arrich
authors.forename: Andrea
authors.initials: A
authors.lastname: Zeiner
authors.forename: Fritz
authors.initials: F
authors.lastname: Sterz
authors.forename: Andreas
authors.initials: A
authors.lastname: Janata
authors.forename: Thomas
authors.initials: T
authors.lastname: Uray
authors.forename: Nina
authors.initials: N
authors.lastname: Richling
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Behringer
authors.forename: Harald
authors.initials: H
authors.lastname: Herkner
mesh_terms: D000367:Age Factors; D001317:Austria / Q000453:epidemiology; D016887:Cardiopulmonary Resuscitation; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013997:Time Factors