title: Clusters of event reactions among recipients of Project Liberty mental health counseling.
abstract: OBJECTIVE
  This study aimed to determine a pattern in the frequency with which individuals who manifested distress reactions resembling diagnostic syndromes of posttraumatic stress disorder (PTSD) and major depressive disorder accessed services provided by Project Liberty.
  
  
  METHODS
  Hierarchical cluster analysis was applied to 31 reactions to stress (event reactions) shown by 465,428 recipients of Project Liberty counseling, to determine how well event reactions mapped onto traditional diagnostic criteria. Service recipients were tracked when they first sought Project Liberty counseling during the 27 months after the attacks. Those who reported three or more reactions associated with these clusters were characterized as having possible diagnosable conditions.
  
  
  RESULTS
  Strong consistent clusters corresponding to traumatic stress and depressive symptoms emerged, with 26 percent, 16 percent, and 8 percent of service recipients rated as having possible PTSD, major depressive disorder, or both, respectively. Taken together, this group constituted over 40 percent of service recipients served by Project Liberty almost every month throughout the 27 months of its existence.
  
  
  CONCLUSIONS
  Event reactions, as reported by Project Liberty crisis counselors, many of whom were nonclinicians, mapped coherently onto diagnostic syndromes, suggesting that a checklist of such reactions may be useful to disaster counselors as a cost-effective screening and planning instrument. The steady entry over time into Project Liberty counseling by a substantial number of individuals experiencing high levels of distress underscores the need for providing long-term access to mental health services postdisaster.
authors.affiliation: Department of Psychiatry, Division of Health Services Research, Mount Sinai School of Medicine, New York City, USA.
authors.forename: Carlos T
authors.initials: CT
authors.lastname: Jackson
authors.forename: George
authors.initials: G
authors.lastname: Allen
authors.forename: Susan M
authors.initials: SM
authors.lastname: Essock
authors.forename: M Jameson
authors.initials: MJ
authors.lastname: Foster
authors.forename: Carol B
authors.initials: CB
authors.lastname: Lanzara
authors.forename: Chip J
authors.initials: CJ
authors.lastname: Felton
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Donahue
mesh_terms: D016000:Cluster Analysis; D003156:Community Mental Health Services / Q000706:statistics & numerical data*; D015897:Comorbidity; D003419:Crisis Intervention / Q000706:statistics & numerical data*; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005500:Follow-Up Studies; D005610:Freedom; D006801:Humans; D008403:Mass Screening / Q000706:statistics & numerical data; D009519:New York City; D010552:Personality Assessment / Q000706:statistics & numerical data; D011594:Psychometrics; D047851:September 11 Terrorist Attacks / Q000523:psychology* / Q000706:statistics & numerical data; D013223:Statistics as Topic; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D014600:Utilization Review / Q000706:statistics & numerical data