title: Clinical correlates of insomnia in patients with chronic illness.
abstract: BACKGROUND
  Patients with chronic insomnia are more likely to develop affective disorders, cardiac morbidity, and other adverse health outcomes, yet many clinicians tend to trivialize the complaint of insomnia or to attribute it only to psychiatric causes.
  
  
  OBJECTIVE
  To estimate the prevalence and longitudinal course of insomnia in patients with documented chronic medical illness and/or depression and to quantify the associations between specific chronic conditions and insomnia.
  
  
  METHODS
  The presence of mild or severe insomnia was based on responses to a sleep questionnaire completed by 3445 patients with at least 1 of 5 physician-identified chronic conditions (hypertension, diabetes, congestive heart failure, myocardial infarction, or depression) at baseline; a subsample of 1814 patients completed follow-up questionnaires at 2 years. Using multivariate techniques, we evaluated the relationship between chronic conditions, patient-reported comorbidities, and insomnia (complaints of initiating and maintaining sleep), adjusting for sociodemographics and health habits.
  
  
  RESULTS
  Sixteen percent of study patients had severe and 34% had mild insomnia at baseline. At 2-year follow-up, 59% (95% confidence interval, 55%-63%) of patients with mild insomnia and 83% (95% confidence interval, 78%-88%) of patients with severe insomnia at baseline still had sleep problems. Odds ratios corresponding to mild and severe insomnia for key risk factors were as follows: current depressive disorder, 2.6 and 8.2; subthreshold depression, 2.2 and 3.4; congestive heart failure, 1.6 and 2.5; obstructive airway disease, 1.6 and 1.5; back problems, 1.4 and 1.5; hip impairment, 2.2 and 2.7; and prostate problems, 1.6 and 1.4. The majority of insomnia-comorbidity associations observed at baseline persisted at 2-year follow-up.
  
  
  CONCLUSIONS
  Patients with insomnia require follow-up, as the majority continue to be bothered by difficulty initiating and maintaining sleep. In addition to detecting affective disorders in patients with insomnia, clinicians should focus on medical conditions that disturb sleep, especially cardiopulmonary disease, painful musculoskeletal conditions, and prostate problems.
authors.affiliation: Department of Medicine, University of Wisconsin, Madison, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Katz
authors.forename: C A
authors.initials: CA
authors.lastname: McHorney
mesh_terms: D000402:Airway Obstruction / Q000150:complications; D002908:Chronic Disease; D003863:Depression / Q000150:complications; D005260:Female; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009140:Musculoskeletal Diseases / Q000150:complications; D011469:Prostatic Diseases / Q000150:complications; D015203:Reproducibility of Results; D012307:Risk Factors; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications* / Q000209:etiology