title: Progression from unipolar depression to schizophrenia.
abstract: OBJECTIVE
  To examine progression from unipolar depression (UD) to schizophrenia and to identify groups of UD patients at elevated risk for progression.
  
  
  METHODS
  Historical prospective cohort study using data from Danish national registers. The sample included 71 932 individuals who received a diagnosis of UD in Denmark between January 1, 1995, and May 31, 2013. Analyses were conducted using Kaplan-Meier estimates and Cox regressions.
  
  
  RESULTS
  The 18.5-year cumulative incidence of schizophrenia was 5.5% in women and 8.4% in men. The strongest predictors of progression included younger age (adjusted hazard ratio (AHR) for individuals 18-24 vs. 40+ = 7.42, 95% confidence interval = [6.29, 8.74]), psychotic symptoms at index UD diagnosis (AHR = 3.70 [3.18, 4.31]), previous disorder with psychotic features (AHR = 3.71 [3.31, 4.16]), and previous illicit substance use disorder (AHR = 1.66 [1.40, 1.97]). Groups of UD patients with different combinations of risk factors had elevated risk for progression, with 10-year cumulative incidences ranging from 9% to 62%. To conclude, at the time of UD diagnosis, the strongest risk factors for progression to schizophrenia include male sex, younger age, past/current psychotic symptoms, and illicit substance use disorders. These clinical predictors may aid in targeting monitoring for schizophrenia among patients with UD.
authors.affiliation: National Center for Register-Based Research, Department of Economics and Business Economics, Aarhus University, Aarhus, Denmark.|The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Musliner
authors.affiliation: National Center for Register-Based Research, Department of Economics and Business Economics, Aarhus University, Aarhus, Denmark.|The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.|CIRRAU - Center for Integrated Register-based Research at Aarhus University, Aarhus, Denmark.
authors.forename: Trine
authors.initials: T
authors.lastname: Munk-Olsen
authors.affiliation: The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.|Psychosis Research Unit, Department of Clinical Medicine, Aarhus University Hospital, Risskov, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Mors
authors.affiliation: The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.|Psychosis Research Unit, Department of Clinical Medicine, Aarhus University Hospital, Risskov, Denmark.
authors.forename: Søren D
authors.initials: SD
authors.lastname: Østergaard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003718:Denmark / Q000453:epidemiology; D003865:Major Depressive Disorder / Q000523:psychology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology*; D055815:Young Adult
keywords: depressive disorder; disease progression; historical cohort studies; schizophrenia