Introduction: Insomnia is prevalent in adults with major depressive disorder (MDD) and is a key diagnostic criterion of MDD; however, little is understood about the burden of insomnia symptom severity in MDD. We evaluated the relationship between insomnia symptom severity and the clinical, economic, and patient-centric burden among community-dwelling individuals with MDD.
Methods: Respondents with diagnosed depression who reported insomnia symptoms in the past 12 months (N = 4402) were identified from the 2019 United States National Health and Wellness Survey. Multivariable analyses assessed the association of Insomnia Severity Index (ISI) with health-related outcomes while controlling for sociodemographic and health characteristics. Further analyses also controlled for depression severity (9-item Patient Health Questionnaire).
Results: Mean ISI score was 14.3 ± 5.6. Higher ISI was associated with greater depression severity (r = .51, p < .001). After adjustments, a one-standard deviation (5.6-point) increase in ISI score was significantly associated with higher depression (rate ratio [RR] = 1.36), anxiety (RR = 1.33) and daytime sleepiness (RR = 1.16) levels, more healthcare provider (RR = 1.13) and emergency room visits (RR = 1.31), hospitalizations (RR = 1.21), work productivity and activity impairment (RRs = 1.27 and 1.23, respectively), and poorer mental and physical health-related quality of life (β = -3.853 and -1.999, respectively) (p < .001). These findings remained statistically significant when controlling for concurrent depression severity.
Conclusion: In adults with MDD, greater insomnia symptom severity is associated with worse health-related outcomes, which suggests the importance of addressing insomnia symptoms as a clinical target for treating MDD.
Keywords: MDD; burden of illness; depression; insomnia.
© 2023 The Authors. Brain and Behavior published by Wiley Periodicals LLC.