title: Longitudinal follow up of primary insomnia patients in a psychiatric clinic.
abstract: OBJECTIVE
  Insomnia could be a symptom of underlying psychiatric or physical disorder, a risk factor for other psychiatric disorder, or a discrete psychiatric disorder per se. In order to determine the nosological status of primary insomnia, an outcome study was carried out to investigate its diagnostic stability and its relationship to subsequent psychiatric disorders.
  
  
  METHODS
  Fifty-three primary insomnia patients in a university hospital psychiatric outpatient clinic were assessed by retrospective case note review, followed by a 6 month prospective follow up with Structured Clinical Interview Schedule for DSM-IV In-patient (SCID-I/P, version 2.0, and a sleep questionnaire.
  
  
  RESULTS
  The majority of patients (n =44, 83%) did not develop other psychiatric disorders after 13.4+/-1.2 years from the onset of insomnia. Nine patients (17%) developed mood disorder (n =6), anxiety disorder (n =2) and somatoform disorder (n =1) at 6.3+/-2.3 years after the onset of insomnia. Subjective deterioration of insomnia and a shorter duration of sleep symptoms at the first consultation were associated with the development of secondary psychiatric disorders. Approximately one-third (n =17, 32%) reported symptoms improvement and six (13.2%) were free from medications. Better education was the only factor that predicted improvement in symptoms.
  
  
  CONCLUSIONS
  There existed a longitudinal diagnostic stability of primary insomnia in a majority of clinical patients. However, in a proportion of patients, it might either be a risk factor or a prodrome of mood or anxiety disorders.
authors.affiliation: Department of Psychiatry, Shatin Hospital, and Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: Samson Yat-yuk
authors.initials: SY
authors.lastname: Fong
authors.forename: Yun Kwok
authors.initials: YK
authors.lastname: Wing
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001008:Anxiety Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong; D006785:Hospitals, University; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D019964:Mood Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D010044:Outpatient Clinics, Hospital / Q000706:statistics & numerical data; D010353:Patient Education as Topic; D011567:Psychiatric Department, Hospital / Q000706:statistics & numerical data; D012189:Retrospective Studies; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D013001:Somatoform Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology