To Örebro University

BACKGROUND: The association between specific psychiatric disorders and insomnia is well established, but the prevalence of insomnia in obsessive-compulsive disorder (OCD) is unknown. This population-based study examined the prevalence of insomnia in patients with OCD compared to unaffected individuals from the general population and to their unaffected full siblings, and evaluated the contribution of psychiatric comorbidities to this association.

METHODS: Individuals diagnosed with OCD (31,856) were identified from a cohort of 13,017,902 individuals living in Sweden anytime during 1973 and 2013. Logistic regression analyses were used to investigate the odds of insomnia in individuals with OCD, compared to the general population and their unaffected full siblings. Sensitivity analyses were performed in subgroups from which all individuals with comorbid psychiatric conditions were excluded, one at a time.

RESULTS: Individuals with OCD had almost 7-fold increased odds of receiving an insomnia diagnosis or being dispensed a drug with specific indication for insomnia, compared to unaffected individuals from the general population (42.2% vs. 11.0%, respectively; OR=6.92 [95% CI, 6.76-7.08]). Familiar factors shared with siblings and comorbid conditions did not fully explain this association, but when individuals with comorbid depression and anxiety disorders were excluded, the odds of insomnia were significantly reduced (OR=4.97 [95% CI, 4.81-5.14] and OR=4.51 [95% CI, 4.33-4.69], respectively).

LIMITATIONS: Due to the intrinsic coverage issues of the registers, results may not be generalizable to milder forms of the disorder and to individuals who do not seek help.

CONCLUSIONS: Insomnia should be systematically evaluated and managed in individuals with OCD, particularly in those with comorbid anxiety and depression.