title: Reducing the Diagnostic Heterogeneity of Schizoaffective Disorder.
abstract: OBJECTIVE
  Clinical outcome studies of schizoaffective disorder patients have yielded conflicting results. One reason is the heterogeneity of samples drawn from the schizoaffective disorder population. Here, we studied schizoaffective disorder patients who showed marked functional impairment and continuous signs of illness for at least 6 months (i.e., DSM criteria B and C for schizophrenia).
  
  
  METHODS
  We assessed 176 chronic psychosis patients with a structured interview (SCID-IV-TR) and the Diagnostic Interview for Genetic Studies schizoaffective disorder module. We diagnosed 114 patients with schizophrenia and 62 with schizoaffective disorder. The two groups were similar with regard to age, gender, and race. We tested for group differences in antecedent risk factors, clinical features, and functional outcome.
  
  
  RESULTS
  The schizoaffective disorder group differed from the schizophrenia group on two measures only: they showed higher rates of suicidality (more suicide attempts,p< 0.01; more hospitalizations to prevent suicide,p< 0.01) and higher anxiety disorder comorbidity (p< 0.01).
  
  
  CONCLUSIONS
  When schizoaffective disorder patients meet DSM criteria B and C for schizophrenia, they resemble schizophrenia patients on several measures used to assess validity. The increased rate of anxiety disorders and suicidality warrants clinical attention. Our data suggest that a more explicit definition of schizoaffective disorder reduces heterogeneity and may increase validity.
authors.affiliation: Psychiatric Neuroimaging Program, Department of Psychiatry and Behavioral Sciences, Vanderbilt University , Nashville, TN , USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Seldin
authors.affiliation: Psychiatric Neuroimaging Program, Department of Psychiatry and Behavioral Sciences, Vanderbilt University , Nashville, TN , USA.
authors.forename: Kristan
authors.initials: K
authors.lastname: Armstrong
authors.affiliation: Psychiatric Neuroimaging Program, Department of Psychiatry and Behavioral Sciences, Vanderbilt University , Nashville, TN , USA.
authors.forename: Max L
authors.initials: ML
authors.lastname: Schiff
authors.affiliation: Psychiatric Neuroimaging Program, Department of Psychiatry and Behavioral Sciences, Vanderbilt University , Nashville, TN , USA.
authors.forename: Stephan
authors.initials: S
authors.lastname: Heckers
keywords: clinical characteristics; nosology; outcome; psychosis; schizoaffective disorder; schizophrenia