title: Comorbidity burden is not associated with higher mortality after out-of-hospital cardiac arrest.
abstract: OBJECTIVE
  We investigated whether comorbidity burden of comatose survivors of out-of-hospital cardiac arrest (OHCA) affects outcome and if comorbidity modifies the effect of target temperature management (TTM) on final outcome.
  
  
  METHODS
  The TTM trial randomized 939 patients to 24 h of TTM at either 33 or 36 °C with no difference regarding mortality and neurological outcome. This post-hoc study of the TTM-trial formed a modified comorbidity index (mCI), based on available comorbidities from the Charlson comorbidity index (CCI).
  
  
  RESULTS
  Bystander cardiopulmonary resuscitation (CPR) decreased with higher comorbidity group, p = 0.01. Comorbidity groups were univariately associated with higher mortality compared to mCI0 (HRmCI1: 1.55, CI: 1.25-1.93, p < 0.001, HRmCI2: 2.01, CI: 1.55-2.62, p < 0.001, HRmCI ≥ 3: 2.16, CI: 1.57-2.97, p < 0.001). When adjusting for confounders there was a consistent, nonsignificant association between level of comorbidity and mortality (HRmC11: 1.17, CI: 0.92-1.48, p = 0.21, HRmCI2: 1.28, CI: 0.96-1.71, p = 0.10, HRmCI ≥ 3: 1.37, CI: 0.97-1.95, p = 0.08). There was no interaction between comorbidity burden and level of TTM on outcome, p = 0.61.
  
  
  CONCLUSIONS
  Comorbidity burden was associated with higher mortality following OHCA, but when adjusting for confounders, the influence was no longer significant. The association between mCI and mortality was not modified by TTM. Comorbidity burden is associated with lower rates of bystander cardiopulmonary resuscitation after OHCA.
authors.affiliation: a The Heart Centre, Copenhagen University Hospital , Copenhagen , Denmark.
authors.forename: Matilde
authors.initials: M
authors.lastname: Winther-Jensen
authors.affiliation: a The Heart Centre, Copenhagen University Hospital , Copenhagen , Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Kjaergaard
authors.affiliation: b Department of Anesthesia and Intensive Care , Helsingborg Hospital , Helsingborg , Sweden.
authors.forename: Niklas
authors.initials: N
authors.lastname: Nielsen
authors.affiliation: c Department of Intensive Care , Leeuwarden Medical Centrum , Leeuwarden , The Netherlands.
authors.forename: Michael
authors.initials: M
authors.lastname: Kuiper
authors.affiliation: d Department of Anesthesia and Intensive Care , Skåne University Hospital , Lund , Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Friberg
authors.affiliation: a The Heart Centre, Copenhagen University Hospital , Copenhagen , Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Søholm
authors.affiliation: a The Heart Centre, Copenhagen University Hospital , Copenhagen , Denmark.
authors.forename: Jakob Hartvig
authors.initials: JH
authors.lastname: Thomsen
authors.affiliation: a The Heart Centre, Copenhagen University Hospital , Copenhagen , Denmark.
authors.forename: Martin
authors.initials: M
authors.lastname: Frydland
authors.affiliation: a The Heart Centre, Copenhagen University Hospital , Copenhagen , Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Hassager
mesh_terms: D000368:Aged; D001315:Australia / Q000453:epidemiology; D001833:Body Temperature Regulation; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects / Q000401:mortality; D003128:Coma / Q000175:diagnosis / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy*; D015897:Comorbidity; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000175:diagnosis / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy*; D016016:Proportional Hazards Models; D020127:Recovery of Function; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: Out-of-hospital cardiac arrest; comorbidity; neurological outcome; target temperature management