Insomnia, comorbidity, and risk of injury among insured Americans: results from the America Insomnia Survey.

Study Objectives: To estimate associations of broadly defined insomnia (i.e., meeting inclusion criteria for International Classification of Diseases, Tenth Revision (ICD-10), Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), or Research Diagnostic Criteria/International Classification of Sleep Disorders, Second Edition (RDC/ICSD-2) diagnosis) with workplace/nonworkplace injuries controlling for comorbid conditions among workers in the America Insomnia Survey (AIS). Design/Setting: Cross-sectional telephone survey. Participants: National sample of 4,991 employed health plan subscribers (age 18 yr and older). Interventions: None. Measurements and Results: Broadly defined insomnia with duration of at least 12 mo was assessed with the Brief Insomnia Questionnaire (BIQ). Injuries in the 12 mo before interview were assessed with a standard self-report measure of injuries causing role impairment or requiring medical attention. Eighteen comorbid condition clusters were assessed with medical/pharmacy claims records and self-reports. Insomnia had significant gross associations (odds ratios, ORs) with both workplace and nonworkplace injuries (OR 2.0 and 1.5, respectively) in logistic regression analyses before controlling for comorbid conditions. The significant population attributable risk proportions (PARPs) of total injuries with insomnia was 4.6% after controlling for comorbid conditions. Only 2 other conditions had PARPs exceeding those of insomnia. The associations of insomnia with injuries did not vary significantly with worker age, sex, or education, but did vary significantly with comorbid conditions. Specifically, insomnia was significantly associated with workplace and nonworkplace injuries (OR 1.8 and 1.5, respectively) among workers having no comorbid conditions, with workplace but not nonworkplace injuries (OR 1.8 and 1.2, respectively) among workers having 1 comorbid condition, and with neither workplace nor nonworkplace injuries (OR 0.9 and 1.0, respectively) among workers having 2 or more comorbid conditions. Conclusions: The associations of insomnia with injuries vary with comorbid conditions in ways that could have important implications for targeting workplace interventions.