title: The diagnostic criteria and structure of catatonia.
abstract: BACKGROUND
  The classification of catatonia has fluctuated and underwent recent changes in DSM-5. The current study examines the prevalence of catatonia signs, estimates the utility of diagnostic features, identifies core catatonia signs, and explores their underlying structure.
  
  
  METHODS
  We screened 339 acutely ill medical and psychiatric patients with the Bush Francis Catatonia Rating Scale (BFCRS). We examined prevalence and severity of catatonia signs and compared BFCRS, DSM-IV and DSM-5 diagnoses. We used principal component analysis (PCA) to examine the factorial validity of catatonia and item response theory (IRT) to estimate each sign's utility and reliability.
  
  
  RESULTS
  Out of the 339 patients, 300 were diagnosed with catatonia using the BFCRS and 232 catatonia diagnoses were validated by the treating provider based on selection for treatment with benzodiazepines or electroconvulsive therapy. Of the 232 validated catatonia cases, 211 (91%) met DSM-IV criteria but only 170 (73%) met DSM-5 criteria for catatonia. Staring was the most prevalent catatonia sign. PCA identified three components, interpretable as "Increased, Abnormal and Decreased Psychomotor Activity," although 63% of the variance was unexplained. IRT showed that Excitement, Waxy Flexibility and Immobility/Stupor were the best indicators of each factor. The BFCRS had many redundant items and as a whole had low reliability at low severity of catatonia, but good reliability at moderate-high severity of catatonia.
  
  
  CONCLUSIONS
  The structure of catatonia remains to be discovered.
authors.affiliation: Department of Psychiatry, Vanderbilt University, Nashville, TN, USA. Electronic address: jo.e.wilson@vanderbilt.edu.
authors.forename: Jo Ellen
authors.initials: JE
authors.lastname: Wilson
authors.affiliation: Department of Psychiatry, Vanderbilt University, Nashville, TN, USA. Electronic address: kathyniu@gmail.com.
authors.forename: Kathy
authors.initials: K
authors.lastname: Niu
authors.affiliation: Department of Psychiatry, Vanderbilt University, Nashville, TN, USA. Electronic address: steve.nicolson@vanderbilt.edu.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Nicolson
authors.affiliation: Department of Community Mental Health, University of Haifa, Israel. Electronic address: stezlev@gmail.com.
authors.forename: Stephen Z
authors.initials: SZ
authors.lastname: Levine
authors.affiliation: Department of Psychiatry, Vanderbilt University, Nashville, TN, USA. Electronic address: stephan.heckers@vanderbilt.edu.
authors.forename: Stephan
authors.initials: S
authors.lastname: Heckers
mesh_terms: D000328:Adult; D001569:Benzodiazepines / Q000627:therapeutic use; D002389:Catatonia / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy; D004565:Electroconvulsive Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D025341:Principal Component Analysis; D011569:Psychiatric Status Rating Scales / Q000592:standards*; D011594:Psychometrics; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D001569:Benzodiazepines
keywords: Catatonia; DSM-5; DSM-IV; Diagnosis; Item response theory; Principal component analysis