Association of insomnia severity and comorbid medical and psychiatric disorders in a health plan-based sample: Insomnia severity and comorbidities

Background: Insomnia is commonly associated with one or more comorbid illnesses. Data on the relationship between insomnia severity and comorbid disorders are still limited, especially with regard to the use of well-validated measures of insomnia severity. Methods: A total of 2086 health plan enrollees, over-sampling for those with insomnia based on health claims, completed a telephone survey between April and June of 2006. Participants were categorized using four insomnia severity categories and compared on their administrative health claims' psychiatric and medical comorbidities. Results: Controlling for age and gender, the odds ratio for having at least one psychiatric diagnosis was 5.04 (CI = 3.24-7.84) for severe insomnia, 2.63 (CI = 1.97-3.51) for moderate insomnia, and 1.7 (CI = 1.30-2.23) for subthreshold insomnia compared with those with no insomnia. Similarly. the odds ratio for having treatment for at least one chronic disease was 2.83 (CI = 1.84-4.35) for severe insomnia, 2.34 (CI = 1.83-2.99) for moderate insomnia, and 1.55 (CI = 1.25-1.92) for Subthreshold insomnia compared with the no insomnia group. Conclusions: Increasing insomnia severity is associated with increased chronic medical and psychiatric illnesses. Further research is needed to better understand associations between insomnia severity and individual psychiatric and chronic medical comorbidities. (C) 2009 Elsevier B.V. All rights reserved.