title: Comparing four competing models of depressive symptomatology: a confirmatory factor analytic study of 986,647 U.S. veterans.
abstract: BACKGROUND
  Few rigorous studies have examined the factor structure of major depression symptoms as assessed by current diagnostic systems. This study evaluated four competing models of depressive symptomatology among a large, heterogeneous sample of U.S. veterans.
  
  
  METHODS
  To determine the best fitting model of major depressive symptoms among four competing models, this study conducted a series of confirmatory factor analyses on a national sample of 986,647 U.S. veterans.
  
  
  RESULTS
  A two-factor model first reported by Krause, Reed, and McArdle (2010) provided superior fit to symptom-level data compared to three other models. The optimal model consists of a somatic factor including anhedonia, sleep difficulties, fatigue, appetite changes, concentration difficulties, and psychomotor agitation; and a non-somatic factor including depressed mood, feelings of worthlessness, and thoughts of death. Factorial invariance testing found this model to be invariant by gender and major depression diagnosis.
  
  
  CONCLUSIONS
  A widely used self-report measure of depression was used and the sample consisted solely of veterans so further study is needed with clinician-administered measures and non-veteran samples.
  
  
  CONCLUSIONS
  Together, these findings support separating symptoms of major depression into somatic and non-somatic factors which may have clinical relevance, and help clarify debates about the factor structure of depressive symptoms.
authors.affiliation: United States Department of Veterans Affairs New England Mental Illness Research, Education, and Clinical Center, 950 Campbell Avenue, 151D, West Haven, CT 06516, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA. Electronic address: Jack.Tsai@yale.edu.
authors.forename: Jack
authors.initials: J
authors.lastname: Tsai
authors.affiliation: Departments of Psychology and Psychiatry, University of Toledo, Toledo, OH 63606, USA.
authors.forename: Jon D
authors.initials: JD
authors.lastname: Elhai
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA; United States Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, Clinical Neurosciences Division, VA Connecticut Healthcare System, West Haven, CT 06516, USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Pietrzak
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA; Veterans Affairs Northeast Program Evaluation Center, West Haven, CT 06516, USA.
authors.forename: Rani A
authors.initials: RA
authors.lastname: Hoff
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA; United States Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, Clinical Neurosciences Division, VA Connecticut Healthcare System, West Haven, CT 06516, USA.
authors.forename: Ilan
authors.initials: I
authors.lastname: Harpaz-Rotem
mesh_terms: D000328:Adult; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D014481:United States; D014728:Veterans / Q000523:psychology*
keywords: Confirmatory factor analyses; Depression; Veterans