title: Long-term outcomes and predictors of chronic insomnia: a prospective study in Hong Kong Chinese adults.
abstract: OBJECTIVE
  We aimed to determine the longitudinal course and outcome of chronic insomnia in a five-year prospective study in Hong Kong Chinese adults.
  
  
  METHODS
  Two thousand three hundred and sixteen middle-aged adults (53.3% females, 46.3 ± 5.1 years old at follow-up) were recruited at baseline and follow-up. Participants were divided into three groups: non-insomnia, insomnia symptoms, and insomnia syndrome (insomnia symptoms plus daytime symptoms). Upper airway inflammatory diseases, mental problems, and medical problems were additionally assessed at follow up.
  
  
  RESULTS
  The incidence of insomnia (symptoms and syndrome) was 5.9%. The persistence rate of insomnia syndrome was 42.7% for insomnia syndrome and 28.2% for insomnia symptoms. New incidence of insomnia was associated with younger age, unemployment, and daytime symptoms, while persistence of insomnia was associated with female sex, lower education level, and daytime symptoms at the baseline (p<0.05). Baseline insomnia syndrome was significantly associated with upper airway inflammatory diseases (including asthma and laryngopharyngitis; adjusted OR=1.97-17.9), mental problems, and medical conditions (including arthritis, psychiatric disorders, chronic pain, and gastroesophageal reflux disease; AOR=2.29-3.77), whereas baseline insomnia symptoms were associated with poor mental health (AOR=2.43), psychiatric disorders (AOR=2.39), and chronic pain (AOR=2.95).
  
  
  CONCLUSIONS
  Chronic insomnia is a common problem with considerable persistence and incidence rates among middle-aged Chinese adults. Insomnia syndrome has a higher persistence rate with more mental and medical comorbidities when compared with insomnia symptoms without daytime consequences.
authors.affiliation: Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region.
authors.forename: Jihui
authors.initials: J
authors.lastname: Zhang
authors.forename: S P
authors.initials: SP
authors.lastname: Lam
authors.forename: S X
authors.initials: SX
authors.lastname: Li
authors.forename: M W M
authors.initials: MW
authors.lastname: Yu
authors.forename: A M
authors.initials: AM
authors.lastname: Li
authors.forename: R C W
authors.initials: RC
authors.lastname: Ma
authors.forename: A P S
authors.initials: AP
authors.lastname: Kong
authors.forename: Y K
authors.initials: YK
authors.lastname: Wing
mesh_terms: D000328:Adult; D000367:Age Factors; D002908:Chronic Disease; D015897:Comorbidity; D004522:Educational Status; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology / Q000209:etiology*; D011795:Surveys and Questionnaires; D014478:Unemployment / Q000706:statistics & numerical data