title: Cognitive impairment before and six months after cardiac surgery increase mortality risk at median 11 year follow-up: a cohort study.
abstract: BACKGROUND
  The additive effects of cognitive impairment and depression on mortality risk after cardiac surgery are unknown.
  
  
  METHODS
  Patients were assessed on a battery of six neurocognitive measures before cardiac surgery (N = 521) and at six month follow up (N = 377/521, 72.4%). Cognitive impairment classification was based on cognitive test scores 1 SD below age and sex matched normative data, and classified according to amnestic, non-amnestic and mixed cognitive impairment subtypes. Survival analyses entered cognitive impairment subtypes and depression interactions terms adjusted for 12 common risk factors.
  
  
  RESULTS
  There were 5407 person years for analysis (median 11.1 year survival, interquartile range of 7.9 to 13.1) and 176 deaths (33.8%) by the census date. Before cardiac surgery, patients with a mixed-cognitive impairment (adjusted hazard ratio (HR) = 2.53; 95% confidence interval (CI), 1.57-4.06, p<.001) and non-amnestic cognitive impairment (adjusted HR = 1.51; 95%, 1.00-2.32, p = .05) were at greater mortality risk. Six month analyses corroborated that the mixed-cognitive impairment group were at higher mortality risk (adjusted HR = 2.35; 95% CI, 1.30-4.25, p = .005). When change in neurocognitive functioning over time was analyzed, a higher mortality risk was evident only amongst patients with cognitive impairment evident at baseline and six months (adjusted HR = 1.83; 95% CI, 1.08-3.10, p = .03). No cognition by depression interaction term was significant.
  
  
  CONCLUSIONS
  These data suggest that a mixed cognitive impairment subtype, and continuing cognitive impairment before and six months after cardiac surgery, is associated with long term mortality, independent of depression and common risk factors.
authors.affiliation: Cardiac Surgery Research, Dept. of Surgery, Flinders Medical Centre and Flinders University of South Australia, Australia; School of Psychology, The University of Adelaide, Australia.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Tully
authors.forename: Bernhard T
authors.initials: BT
authors.lastname: Baune
authors.forename: Robert A
authors.initials: RA
authors.lastname: Baker
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures; D003072:Cognition Disorders / Q000150:complications* / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology* / Q000401:mortality*; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors; D015996:Survival Rate; D013997:Time Factors
keywords: Cardiac surgery; Cognitive impairment; Depression; Heart disease; Survival analysis