title: Days-out-of-role associated with insomnia and comorbid conditions in the America Insomnia Survey.
abstract: BACKGROUND
  Insomnia is highly prevalent and impairing but also highly comorbid with other chronic physical/mental disorders. Population-based research has yet to differentiate the role impairments uniquely associated with insomnia per se from those due to comorbidity.
  
  
  METHODS
  A representative sample of 6791 adult subscribers to a large national US commercial health plan was surveyed by telephone about sleep and health. Twenty-one conditions previously found to be comorbid with insomnia were assessed with medical/pharmacy claims data and validated self-report scales. The Brief Insomnia Questionnaire, a fully structured, clinically validated scale, generated insomnia diagnoses according to inclusion criteria of DSM-IV-TR, ICD-10, and Research Diagnostic Criteria/International Classification of Sleep Disorders: Diagnostic and Coding Manual, Second Edition. The World Health Organization Disability Assessment Schedule-II assessed number of days in the past 30 when health problems prevented respondents from conducting their usual daily activities. Regression analyses estimated associations of insomnia with days-out-of-role controlling comorbidity.
  
  
  RESULTS
  Insomnia was significantly associated with days-out-of-role (.90 days/month) in a gross model. The association was reduced when controls were introduced for comorbidity (.42 days/month). This net association did not vary with number or type of comorbid conditions but was confined to respondents 35+ years of age. Insomnia was one of the most important conditions studied not only at the individual level, where it was associated with among the largest mean days-out-of-role, but also at the aggregate level, where it was associated with 13.6% of all days-out-of-role.
  
  
  CONCLUSIONS
  Insomnia has a strong net association with days-out-of-role that does not vary as a function of comorbidity.
authors.affiliation: Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Social Foundation Bamberg, Teaching Hospital of the University of Erlangen, Bamberg, Germany.
authors.forename: Goeran
authors.initials: G
authors.lastname: Hajak
authors.forename: Maria
authors.initials: M
authors.lastname: Petukhova
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Lakoma
authors.forename: Catherine
authors.initials: C
authors.lastname: Coulouvrat
authors.forename: Thomas
authors.initials: T
authors.lastname: Roth
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Sampson
authors.forename: Victoria
authors.initials: V
authors.lastname: Shahly
authors.forename: Alicia C
authors.initials: AC
authors.lastname: Shillington
authors.forename: Judith J
authors.initials: JJ
authors.lastname: Stephenson
authors.forename: James K
authors.initials: JK
authors.lastname: Walsh
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Kessler
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001294:Attitude to Health; D015897:Comorbidity; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004185:Disability Evaluation; D004311:Double-Blind Method; D005260:Female; D006306:Health Surveys; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology* / Q000523:psychology*; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult