title: The Impact of Comorbid Depression on Educational Inequality in Survival after Acute Coronary Syndrome in a Cohort of 83 062 Patients and a Matched Reference Population.
abstract: BACKGROUND
  Patients with low socioeconomic position have higher rates of mortality after diagnosis of acute coronary syndrome (ACS), but little is known about the mechanisms behind this social inequality. The aim of the present study was to examine whether any educational inequality in survival after ACS was influenced by comorbid conditions including depression.
  
  
  METHODS
  From 2001 to 2009 all first-time ACS patients were identified in the Danish National Patient Registry. This cohort of 83 062 ACS patients and a matched reference population were followed for incident depression and mortality until December 2012 by linkage to person, patients and prescription registries. Educational status was defined at study entry and the impact of potential confounders and mediators (age, gender, cohabitation status, somatic comorbidity and depression) on the relation between education and mortality were identified by drawing a directed acyclic graph and analysed using multiple Cox regression analyses.
  
  
  RESULTS
  During follow-up, 29 583(35.6%) of ACS patients and 19 105(22.9%) of the reference population died. Cox regression analyses showed an increased mortality in the lowest educated compared to those with high education in both ACS patients and the reference population. Adjustment for previous and incident depression or other covariables only attenuated the relations slightly. This pattern of associations was seen for mortality after 30 days, 1 year and during total follow-up.
  
  
  CONCLUSIONS
  In this study the relative excess mortality rate in lower educated ACS patients was comparable with the excess risk associated with low education in the background population. This educational inequality in survival remained after adjustment for somatic comorbidity and depression.
authors.affiliation: Research Center for Prevention and Health, Rigshospitalet - Glostrup, Copenhagen University, Glostrup, Denmark.
authors.forename: Merete
authors.initials: M
authors.lastname: Osler
authors.affiliation: Department of Cardiology Y, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: Eva
authors.initials: E
authors.lastname: Prescott
authors.affiliation: Department of Psychiatry O, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Ida Kim
authors.initials: IK
authors.lastname: Wium-Andersen
authors.affiliation: Research Center for Prevention and Health, Rigshospitalet - Glostrup, Copenhagen University, Glostrup, Denmark.
authors.forename: Else Helene
authors.initials: EH
authors.lastname: Ibfelt
authors.affiliation: Department of Psychiatry O, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Martin Balslev
authors.initials: MB
authors.lastname: Jørgensen
authors.affiliation: Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Per Kragh
authors.initials: PK
authors.lastname: Andersen
authors.affiliation: Research Center for Prevention and Health, Rigshospitalet - Glostrup, Copenhagen University, Glostrup, Denmark.
authors.forename: Terese Sara Høj
authors.initials: TS
authors.lastname: Jørgensen
authors.affiliation: Department of Psychiatry, Frederiksberg Hospital, Frederiksberg, Denmark.
authors.forename: Marie Kim
authors.initials: MK
authors.lastname: Wium-Andersen
authors.affiliation: Research Center for Prevention and Health, Rigshospitalet - Glostrup, Copenhagen University, Glostrup, Denmark.
authors.forename: Solvej
authors.initials: S
authors.lastname: Mårtensson
mesh_terms: D054058:Acute Coronary Syndrome / Q000453:epidemiology*; D016022:Case-Control Studies; D015897:Comorbidity; D003718:Denmark; D003863:Depression / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D012042:Registries / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors